Starch, cellulose, pectin, gum, alginate, chitin and chitosan derived (nano)materials for sustainable water treatment: A review

Insight into the hydrophobic functionalization of cellulose microfibrils using the Passerini three-component reaction

The aqueous catalyst-free one-pot Passerini 3-component reaction (P-3CR) was employed for the functionalization of dialdehyde cellulose (DAC) derived from the periodate oxidation of microfibrillated cellulose (MFC) with insights provided by 13C and 15N CP-MAS NMR and FTIR analyses. The kinetics of the P-3CR revealed rapid progress within the initial 2 h, reaching a plateau between 6 and 18 h. The reaction achieved a maximum degree of substitution (DS) with only 1 equivalent of carboxylic acid and isocyanide with respect to the number of aldehydes, therefore demonstrating the atom economy character of the P-3CR performed on MFC. Variable DS values (0.08 to 0.37) were achieved by altering the degree of oxidation of DAC (ranging from 0.48 to 1.1) when reacted with heptanoic acid and tert-butyl isocyanide. Additionally, aliphatic chain lengths of carboxylic acids from C4 to C11 were successfully used for the functionalization of DAC with distinct hydrophobic chains. Furthermore, while cosolvents negatively affected the DS when using heptanoic acid, a significant increase was observed in the case of undecanoic acid due to an improved solubility of the reagent. The aqueous medium P-3CR can thus be considered a versatile tool to tailor the functionalization of MFC and provide it with hydrophobicity.

Mechanistic insights of PO43- functionalized carbon nitride homojunction hydrogels in photocatalytic-self-Fenton-peroxymonosulfate system for tetracycline degradation

In this study, metal-free PO43- enriched g-C3N4/g-C3N4 (PGCN) homojunction alginate 3D beads were developed for in-situ H2O2 production under visible light. Later, the photocatalytic-self-Fenton system was integrated with peroxymonosulfate for tetracycline degradation. Initially, the PO43- enriched g-C3N4 (PCN) and a homojunction composed of PCN and g-C3N4 (GCN) were prepared via the wet-impregnation method. Later, PGCN homojunction was formulated into 3D alginate beads through the blend-crosslinking method. The comprehensive characterization of the homojunction beads affirmed the closer contact between the semiconductors, alteration of the bandgap, faster channelization of electron-hole pairs, and improved separation of charge carriers that attributed to higher catalytic efficacy. The PGCN beads exhibited a maximum H2O2 production of 535 ± 12 µM under visible light irradiation for 60 min. The homojunction hydrogels displayed 99 ± 0.25 % tetracycline degradation in 20 min in the photocatalytic-self-Fenton-PMS system. The experimental studies also claimed a maximum chemical oxygen demand removal of 81 ± 3.6 % in 20 min with maximum reusability of beads up to 20 cycles. The Z-scheme electron migration mechanism is proposed based on the results aided by scavenger and electron spin resonance analysis. Overall, the as-synthesized alginate-supported homojunction-based photocatalytic-self-Fenton-peroxymonosulfate system is highly versatile and reusable for energy and environmental remediation.

Strong, tough, conductive and transparent nanocellulose hydrogel based on Ca2+-induced cross-linked double-networks and its adsorption of methylene blue dye

A novel multi-performance SHNC/SA/CaCl2 hydrogel with multi-performance was prepared via ultra-low-temperature freeze-thaw cycling and Ca2+ cross-linking for the removal of methylene blue (MB) from industrial wastewater. Various methods were used to characterize the structure and properties of hydrogel, and the internal structure of hydrogel showed a three-dimensional network with hydrogen and ester bonds. The SHNC/SA/CaCl2-15 hydrogel exhibited the highest tensile properties (elongation = 800 %), viscoelasticity (90 kPa), compressive strength (0.45 MPa), tensile strength (0.47 MPa) and ionic conductivity (4.34 S/cm). The maximum adsorption capacity of 2 g SHNC/SA/CaCl2-15 hydrogel was 608.49 mg/g at 40 °C, pH = 8 and adsorption 24 h. The adsorption process of hydrogel toward MB was more consistent with the second-order kinetic model and Langmuir isothermal adsorption model. According to the Langmuir isotherm model, the maximum monolayer adsorption capacity of SHNC/SA/CaCl2-15 hydrogel toward MB can reach 613.88 mg/g. Finally, it was found that the removal rate of SHNC/SA/CaCl2-15 hydrogel for MB was still as high as 90 % after five cycles of the adsorption-desorption test, and it could be reused. The hydrogel can be used as cheap and reusable adsorption material for cationic dyes. Our study provides a new perspective for the development of multifunctional cellulose hydrogel adsorbent materials.

Hierarchical mesoporous TiO2/starch-based microparticles used as an efficient and reusable adsorbent for removal of water-soluble dye

The widespread use of organic dyes in various industrial applications, driven by rapid industrialization, has become a significant environmental concern. Thus, highly efficient and reusable adsorbent for removal of pollutant dyes have gained increasing attention in water treatment. In this study, we present TiO2 nanoparticle-embedded mesoporous starch-based microparticle (TiO2@MSMP) with hierarchical rose-like structure were synthesis by using acetone precipitation of short-chain glucan (SCG) obtained from waxy maize starch. The resulting TiO2@MSMP exhibits an A-type crystalline polymorph and mean particle size of approximately 2 μm, displaying a type IV adsorption isotherm with a mean pore diameter of 19 nm and an average surface area of 12.34 m2/g. The adsorption ability of TiO2@MSMP towards methyl orange (MO) and crystal violet (CV) were 85.8 mg/g and 103.8 mg/g, respectively. The reusability of TiO2@MSMP was achieved by UV irradiation, which resulted in photodegradation of the adsorbed dye over 80 % while maintaining good absorption ability and structural stability during the recycling process. Given its cost-effectiveness, high adsorption capacity, and excellent reusability, TiO2@MSMP holds promise as an effective and environmentally friendly adsorbent with significant potential for removing dyes from aqueous solutions and purifying water.

Preparation and characterization of cellulose-chitosan/β-FeOOH composite hydrogels for adsorption and photocatalytic degradation of methyl orange

Biopolymer-based hydrogels have received great attention in wastewater treatment due to their excellent properties, e.g., high adsorption capacity, fast kinetics, reusability and ease of operation. In the present work, cellulose-chitosan/β-FeOOH composite hydrogels were prepared via co-dissolution and regeneration process as well as hydrothermal in situ synthesis of β-FeOOH. Effect of β-FeOOH loading on the properties of the composite hydrogels and the removal efficiency of methyl orange (MO) was investigated. Results showed that β-FeOOH was uniformly loaded onto the hydrogel framework, and the nanoporous structure of composite hydrogels could increase not only the effective contact area between β-FeOOH and the pollutants but also the active sites. Moreover, the increased β-FeOOH loading led to the enhanced MO removal rate under light conditions. When the loading time was extended from 6 h to 9 h, the MO removal rate increased by 21%, which can be mainly due to the photocatalytic degradation. In addition, MO removal rate reached 97.75% within 40 min under optimal conditions and attained 80.81% after five repetitions. The trapping experiment and EPR results indicated that the main active species were hydrogel radicals and holes. Consequently, this work provides an effective preparation approach for cellulose-chitosan/β-FeOOH composite hydrogel with high adsorption and photocatalytic degradation, which would hold great promise for wastewater treatment applications.

Biopolymer-based beads for the adsorptive removal of organic pollutants from wastewater: Current state and future perspectives

Among biopolymer-based adsorbents, composites in the form of beads have shown promising results in terms of high adsorption capacity and ease of separation from the effluents. This review addresses the potential of biopolymer-based beads to remediate wastewaters polluted with emerging organic contaminants, for instance dyes, active pharmaceutical ingredients, pesticides, phenols, oils, polyaromatic hydrocarbons, and polychlorinated biphenyls. High adsorption capacities up to 2541.76 mg g-1 for dyes, 392 mg g-1 for pesticides and phenols, 1890.3 mg g-1 for pharmaceuticals, and 537 g g-1 for oils and organic solvents have been reported. The review also attempted to convey to its readers the significance of wastewater treatment through adsorption by providing an overview on decontamination technologies of organic water contaminants. Various preparation methods of biopolymer-based gel beads and adsorption mechanisms involved in the process of decontamination have been summarized and analyzed. Therefore, we believe there is an urge to discuss the current state of the application of biopolymer-based gel beads for the adsorption of organic pollutants from wastewater and future perspectives in this regard since it is imperative to treat wastewater before releasing into freshwater bodies.

Synergistic antimicrobial action of chitosan-neem extracts nanoformulation as a promising strategy for overcoming multi-drug resistant bacteria

The objective of the present study was to analyze and identify the phytochemical components found in neem leaf extracts using gas chromatography-mass spectrometry (GC-MS) and Fourier-transform infrared spectroscopy (FTIR) methods. The extract samples were acquired using ethyl acetate (EA) and petroleum ether (PE) solvents. Moreover, the extracts were assessed for their antibacterial and antioxidant features. In addition, chitosan nanoparticles (Cs NPs) containing neem extracts were synthesized and evaluated for their potential antibacterial properties, explicitly targeting multi-drug resistant (MDR) bacteria. The neem extracts were analyzed using GC-MS, which identified components such as hydrocarbons, phenolic compounds, terpenoids, alkaloids, and glycosides. Results revealed that the PE extract showed significant antibacterial activity against a range of bacteria. In addition, the PE extract exhibited significant antioxidant activity, exceeding both the EA extract and vitamin C. In addition, both extracts exhibited notable antibiofilm activity, significantly inhibiting the production of biofilm. The Cs NPs, loaded with neem extracts, exhibited significant antibacterial action against multidrug-resistant (MDR) microorganisms. The Cs NPs/EA materials had the greatest zone of inhibition values of 24 ± 2.95 mm against Pseudomonas aeruginosa. Similarly, the Cs NPs/PE materials exhibited a zone of inhibition measurement of 22 ± 3.14 mm against P. aeruginosa. This work highlights the various biochemical components of neem extracts, their strong abilities to combat bacteria and oxidative stress, and the possibility of Cs NPs containing neem extracts as effective treatments for antibiotic-resistant bacterial strains.

Starch-based hydrogels for environmental applications: A review

Water sources have become extremely scarce and contaminated by organic and inorganic industrial and agricultural pollutants as well as household wastes. Poisoning water resources by dyes and metals is a problem because contaminated water can leak into subsurface and surface sources, causing serious contamination and health problems. Therefore, developing wastewater treatment technologies is valuable. Today, hydrogels have attracted considerable attention owing to their broad applications. Hydrogels are polymeric network compositions with significant water-imbibing capacity. Hydrogels have potential applications in diverse fields such as biomedical, personal care products, pharmaceuticals, cosmetics, and biosensors. They can be prepared by using natural (biopolymers) and synthetic polymers. Synthetic polymer-based hydrogels obtained from petrochemicals are not environmentally benign; thus, abundant plant-based polysaccharides are found as more suitable compounds for making biodegradable hydrogels. Polysaccharides with many advantages such as non-toxicity, biodegradability, availability, inexpensiveness, etc. are widely employed for the preparation of environmentally friendly hydrogels. Polysaccharides-based hydrogels containing chitin, chitosan, gum, starch (St), etc. are employed to remove pollutants, metals, and dyes. Among these, St has attracted a lot of attention. St can be mixed with other compounds to make hydrogels, which remove dyes and metal ions to variable degrees of efficiency. Although St has numerous advantages, it suffers from drawbacks such as low stability, low water solubility, and fast degradability in water which limit its application as an environmental adsorbent. As an effective way to overcome these weaknesses, various modification approaches to form starch-based hydrogels (SBHs) employing different compounds have been reported. The preparation methods and applications of SBH adsorbents in organic dyes, hazardous materials, and toxic ions elimination from water resources have been comprehensively discussed in this review.

MXene/ZnS/chitosan-cellulose composite with Schottky heterostructure for efficient removal of anionic dyes by synergistic effect of adsorption and photocatalytic degradation

Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of •O2-, h+, and •OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.

A combination of chitosan nanoparticles loaded with celecoxib and kartogenin has anti-inflammatory and chondroprotective effects: Results from an in vitro model of osteoarthritis

Loading drugs in drug delivery systems can increase their retention time and control their release within the knee cavity. Hence, we aimed to improve the therapeutic efficacy of celecoxib and kartogenin (KGN) through their loading in chitosan nanoparticles (CS NPs). Celecoxib-loaded nanoparticles (CNPs) and KGN-loaded nanoparticles (K-CS NPs) were prepared using the absorption method and covalent attachment, respectively, through an ionic gelation process. The morphology, particle size, zeta potential, polydispersity index (PDI), conjugation efficiency (CE), encapsulation efficiency (EE), the in vitro release of the drug from NPs, as well as MTT and hemolysis assays, were evaluated. Then, the IL-1β-stimulated chondrocytes were treated with CNPs and K-CS NPs, individually or in combination, to explore their potential chondroprotective and anti-inflammatory effects. CNPs and K-CS NPs showed sizes of 352.6 ± 22.5 and 232.7 ± 4.5 nm, respectively, suitable for intra-articular (IA) injection. Based on the hemolysis results, both NPs exhibited good hemocompatibility within the studied range. Results showed that treating IL-1β-pretreated chondrocytes with CNPs or K-CS NPs remarkably limited the negative effects of IL-1β, especially when both types of NPs were used together. Therefore, injecting these two NPs into the knee cavity may improve drug bioavailability, rapidly suppress inflammation and pain, and promote cartilage regeneration. Meanwhile, for the first time, the study investigated the effect of the simultaneous use of celecoxib and KGN to treat osteoarthritis (OA).

Innovative Green Alginate-Cellulose Composite for Light Lanthanides: Experimental Design and Comprehensive Studies on Kinetics, Equilibrium, Thermodynamics, and Reusability

Nowadays, there is a great interest in efficient adsorbent development due to the recent demand for lanthanides, which are widely used in high-tech technology. Alginates, owing to their natural occurrence, gel formation capability, and safety, could be promising feasible adsorbents for lanthanide removal. This study proposes the alginate-cellulose composite as an ecological, sustainable adsorbent for light lanthanide sorption. The structure, morphology, qualitative and quantitative compositions, average diameter, and pHpzc of the composite were discussed in great detail. Using the batch approach, sorption trials were performed to evaluate the metal sorption performance. The maximum lanthanide accumulation was attained at pH 5.0 and a dosage of 0.05 g. The uptake kinetics are successfully explained by the Ho and McKay model, whereas the equilibrium data is best represented by the Langmuir equation. The presence of Cl-, NO3 -, SO4 2-, Ni(II), and Co(II) did not have any impact on the adsorption capacity. In turn, the presence of Fe(III) ions led to a 15 % reduction in the adsorption. The lanthanide ions were eluted from the adsorbent following the treatment with 0.1 M HNO3. The adsorbent retained over 95 % of its initial adsorption capacity after 6 series of sorption/desorption studies.

Robust CA-GO-TiO2/PTFE Photocatalytic Membranes for the Degradation of the Azithromycin Formulation from Wastewaters

We have developed an innovative thin-film nanocomposite membrane that contains cellulose acetate (CA) with small amounts of TiO2-decorated graphene oxide (GO) (ranging from 0.5 wt.% to 2 wt.%) sandwiched between two polytetrafluoroethylene (PTFE)-like thin films. The PTFE-like films succeeded in maintaining the bulk porosity of the support while increasing the thermal and chemical robustness of the membrane and boosting the catalytic activity of TiO2 nanoparticles. The membranes exhibited a specific chemical composition and bonding, with predominant carbon-oxygen bonds from CA and GO in the bulk, and carbon-fluorine bonds on their PTFE-like coated sides. We have also tested the membranes' photocatalytic activities on azithromycin-containing wastewaters, demonstrating excellent efficiency with more than 80% degradation for 2 wt.% TiO2-decorated GO in the CA-GO-TiO2/PTFE-like membranes. The degradation of the azithromycin formulation occurs in two steps, with reaction rates being correlated to the amount of GO-TiO2 in the membranes.

Synergistic antimicrobial action of nanocellulose, nanoselenium, and nanocomposite against pathogenic microorganisms

Recently, there has been a surge in curiosity regarding the application of biopolymer-derived nanomaterials, primarily attributable to their extensive array of potential applications. In this study, nanocellulose was extracted from algae, biomolecule substances synthesized selenium nanoparticles, and a simple nanocomposite of nanocellulose and nanoselenium was elaborated using nanocellulose as a reducing agent under hydrothermal conditions. These nanocomposite materials have markedly improved properties at low concentrations. Our obtained polymers were characterized using techniques including Fourier-transform infrared spectroscopy, X-ray powder diffraction, Thermo gravimetric analysis (TGA), Scanning electron microscopic (SEM), Energy Dispersive X-ray analysis (EDX), Transmission electron microscopic (TEM), Zeta Potential and Dynamic Light Scattering (DLS). The size of nanocellulose, nanoselenium, and nanocomposite ranged from 35 to 85 nm. Antimicrobial investigation of the prepared nanopolymers was tested against Gram-negative bacteria such as Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538, Gram-positive bacteria such as Escherichia coli ATCC8739 and Pseudomonas aeruginosa ATCC 90274 and fungi such as Candida albicans ATCC 10221 besides Aspergillus fumigatus. In antibacterial action tests, nanoselenium showed significant efficacy against Bacillus subtilis with a 12 mm zone of inhibition, while the nanocomposite eclipsed all microorganisms. Nanocellulose and the nanocomposite were potent against Staphylococcus aureus (14 mm and 16 mm zones of inhibition, respectively). The nanocomposite showed potential against Escherichia coli and Pseudomonas aeruginosa (17 mm and 15 mm zones of inhibition, respectively). All polymers effectively inhibited Candida albicans growth (18 mm for the nanocomposite). The minimum inhibitory concentrations (MIC) for three polymers have also been established. While nanocellulose displayed a MIC of 62.5 μg/ml in contradiction to Staphylococcus aureus, nanoselenium demonstrated a significant MIC of 3.95 μg/ml against Bacillus subtilis. These findings highlight the potential of the nanocomposite (nanocellulose-nanoselenium) as a broad-spectrum antimicrobial polymer.

Phosphorylated chitin from shrimp shell waste: A robust solution for cadmium remediation

In this work, chitin (CT) was isolated from shrimp shell waste (SSW) and was then phosphorylated using diammonium hydrogen phosphate (DAP) as a phosphorylating agent in the presence of urea. The prepared samples were characterized using Scanning Electron Microscopy (SEM) and EDX-element mapping, Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA/DTG), conductometric titration, Degree of Substitution (DS) and contact angle measurements. The results of characterization techniques reveal the successful extraction and phosphorylation of chitin. The charge content of the phosphorylated chitin (P-CT) was 1.510 mmol·kg-1, the degree of substitution of phosphorus groups grafted on the CT surface achieved the value of 0.33. The adsorption mechanisms appeared to involve electrostatic attachment, specific adsorption (CdO or hydroxyl binding), and ion exchange. Regarding the adsorption of Cd2+, the effect of the adsorbent mass, initial concentration of Cd2+, contact time, pH, and temperature were studied in batch experiments, and optimum values for each parameter were identified. The experimental results revealed that P-CT enhanced the Cd2+ removal capacity by 17.5 %. The kinetic analyses favored the pseudo-second-order model over the pseudo-first-order model for describing the adsorption process accurately. Langmuir model aptly represented the adsorption isotherms, suggesting unimolecular layer adsorption with a maximum capacity of 62.71 mg·g-1 under optimal conditions of 30 °C, 120 min, pH 8, and a P-CT dose of 3 g·L-1. Regeneration experiments evidenced that P-CT can be used for 6 cycles without significant removal capacity loss. Consequently, P-CT presents an efficient and cost-effective potential biosorbent for Cd2+ removal in wastewater treatment applications.

Sustainable adsorbent frameworks based on bio-resourced materials and biodegradable polymers in selective phosphate removal for waste-water remediation

Phosphorus to an optimum extent is an essential nutrient for all living organisms and its scarcity may cause food security, and environmental preservation issues vis-à-vis agroeconomic hurdles. Undesirably excess phosphorus intensifies the eutrophication problem in non-marine water bodies and disrupts the natural nutrient balance of the ecosystem. To overcome such dichotomy, biodegradable polymer-based adsorbents have emerged as a cost-effective and implementable approach in striking a "desired optimum-undesired excess" balance pertaining to phosphate in a sustainable manner. So far, the reports on adopting such adsorbent-approach for wastewater remediation remained largely scattered, unstructured, and poorly correlated. In this background, the contextual review comprehensively discusses the current state-of-the-art in utilizing biodegradable polymeric frameworks as an adsorbent system for phosphate removal and its efficient recovery from the aquatic ecosystem, while highlighting their characteristics-specific functional efficiency vis-à-vis easiness of synthetic and commercial viability. The overview further delves into the sources and environmental ramifications of excessive phosphorus in water bodies and associated mechanistic pathways of phosphorus removal via adsorption, precipitation, and membrane filtration enabled by biodegradable (natural and synthetic) polymeric substrates. Finally, functionality optimization, degradability tuning, and adsorption selectivity of biodegradable polymers are highlighted, while aiming to strike a balance in "removal-recovery-reuse" dynamics of phosphate. Thus, the current review not only paves the way for future exploration of biodegradable polymers in sustainable cost-effective adsorbents for phosphorus removal but also can serve as a guide for researchers dealing with this critical issue.

Occurrence and fate of pharmaceutical pollutants in wastewater: Insights on ecotoxicity, health risk, and state-of-the-art removal

Pharmaceutical active compound (PhAC) residues are considered an emerging micropollutant that enters the aquatic environment and causes harmful ecotoxicity. The significant sources of PhACs in the environment include the pharmaceutical industry, hospital streams, and agricultural wastes (animal husbandry). Recent investigations demonstrated that wastewater treatment plants (WWTPs) are an important source of PhACs discharging ecosystems. Several commonly reported that PhACs are detected in a range level from ng L-1 to μg L-1 concentration in WWTP effluents. These compounds can have acute and chronic adverse impacts on natural wildlife, including flora and fauna. The approaches for PhAC removals in WWTPs include bioremediation, adsorption (e.g., biochar, chitosan, and graphene), and advanced oxidation processes (AOPs). Overall, adsorption and AOPs can effectively remove PhACs from wastewater aided by oxidizing radicals. Heterogeneous photocatalysis has also proved to be a sustainable solution. Bioremediation approaches such as membrane bioreactors (MBRs), constructed wetlands (CWs), and microalgal-based systems were applied to minimize pharmaceutical pollution. Noteworthy, applying MBRs has illustrated high removal efficiencies of up to 99%, promising prospective future. However, WWTPs should be combined with advanced solutions, e.g., AOPs/photodegradation, microalgae-bacteria consortia, etc., to treat and minimize their accumulation. More effective and novel technologies (e.g., new generation bioremediation) for PhAC degradation must be investigated and specially designed for a low-cost and full-scale. Investigating green and eco-friendly PhACs with advantages, e.g., low persistence, no bioaccumulation, less or non-toxicity, and environmentally friendly, is also necessary.

Chitin/calcite composite extracted from shell waste as a low-cost adsorbent for removal of tetracycline and ciprofloxacin: Effects and mechanisms

Recently, water contamination caused by the misuse of antibiotics has become a growing concern. In this study, an economical chitin/calcite composite (CCA) was extracted from crab shell waste, and the effects and mechanisms of its removal of ciprofloxacin (CIP) and tetracycline (TC) from aqueous solution were investigated. The functional groups of chitin and the metal phase of calcite gave CCA the ability to remove antibiotics. Experiments on kinetics, isothermal adsorption, thermodynamics, co-removal, and reusability were conducted to systematically explore the adsorption performances of CCA toward antibiotics. The pseudo-second-order (FSO) and Langmuir models suited the data obtained from experiments best and displayed a good fit for the chemisorption and a certain homogeneity of adsorption sites. At 25 °C, the maximum adsorption capacities (Qmax) toward CIP and TC were 228.86 and 150.76 mg g-1, respectively. The adsorption mechanisms of CCA with TC and CIP are pH dependent since pH can affect the surface charge of CCA and the form in which CIP and TC are existing. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) demonstrated that the keto-O and carboxyl groups of CIP and the carbonyl, hydroxyl, and amido groups of TC could be responsible for the binding with the calcite and the functional groups of chitin through surface complexation, cation bridge and hydrogen bonding.

Curdlan/sodium carboxymethylcellulose composite adsorbents: A biodegradable solution for organic dye removal from water

Composite adsorbent comprised of curdlan (CURD) and sodium carboxymethylcellulose (CMC) were fabricated through a single-step heating process, targeting the removal of methylene blue (MB) from wastewater. The CURD/CMC composite adsorbents had a honeycomb porous structure. The integration of CMC not only increased the storage modulus of the CURD/CMC composite hydrogels but also affected the thermal stability and swelling behavior of the composite adsorbents in different pH solutions. Specifically, the addition of 1.2 % CMC increased the peak temperature (184.73 °C) of CURD/CMC composite adsorbent melting by 5.99 °C compared to CURD adsorbent. The addition of CMC improved the swelling ratio of the composite adsorbent at pH 3,7, and 12 with swelling ratio up to 918.07 %. The synergistic interaction between CURD and CMC led to an enhanced adsorption capacity of the aerogel for MB, achieving a maximum adsorption capability of 385.85 mg/g. Adsorption isotherm assessments further demonstrated that the Langmuir isotherm model well fitted the adsorption data of the composite adsorbent on MB. Collectively, these findings underscore the potential of the developed biodegradable adsorbents as promising adsorbents for efficiently eliminating organic dyes from water.

Powdered silk: A promising biopolymer for the treatment of dye contaminated water

Discharge of textile dye effluents into water bodies is creating stress to aquatic life and contaminating water resources. In this study, a new biopolymer adsorbent silk fibroin (SF) was prepared from Bombyx mori silk fibroin (SF) and used for removal of Solochrome Black-T (SB-T) from water. This innovative adsorbent exhibits an exceptional adsorption capacity of 20.08 mg/g, achieving a removal efficiency of approximately 98.6 % within 60 min. Notably, the powdered SF adsorbent demonstrates rapid kinetics, surpassing the performance of previously reported similar adsorbents in adsorption capacity and reaction speed. The molecular weight and particle diameter of the material were observed to be > 1.243 kDa and 3 μm, respectively. The experimental investigations were performed on different parameters, viz., adsorbent dosage, contact time, repeatability, and desorption-adsorption study. The experimental data well fit for the Langmuir model (R2 = 0.937, qmax = 20.08 mg/g) and the pseudo-second-order kinetics (R2 = 0.921 and qe = 1.496 mg/g). Compared to the adsorbents reported in the literature, the newly prepared SF showed high adsorption capacity and faster kinetics to address real-life situations. The novelty of this work extends beyond its remarkable adsorption capabilities. The SF adsorbent offers a cost-effective, sustainable solution and regenerable adsorption material with minimal negative environmental impacts. This regenerability, with its versatility and broad applicability, positions powdered SF fibroin as a transformative technology in water treatment and environmental protection.

Efficient photocatalytic remediation of lerui acid brilliant blue dye using radiation- prepared carboxymethyl cellulose/acrylic acid hydrogel supported by ZnO@Ag

Organic dye pollution from textiles and other industries presents a substantial risk to people and aquatic life. The use of photocatalysis to decolorize water using the strength of UV light is one of the most important remediation techniques. In the present study, a novel nanocomposites hydrogel including carboxymethyl cellulose (CMC), acrylic acid (AAc), Zinc oxide (ZnO), and silver (Ag) nanoparticles was produced using an eco-friendly γ-irradiation technique for photocatalytic decolorization applications. ZnO and Ag nanoparticles were distributed in the CMC/AAc hydrogel matrix without significant aggregation. SEM, XRD, EDX, TEM, and FTIR analyses were used to assess the physicochemical characteristics of the nanocomposite samples. Carboxymethyl cellulose/acrylic acid/Zinc oxide doped silver (CMC/PAAc/ZnO@Ag) nanocomposite hydrogels were developed and utilized in the photocatalytic decolorization of the lerui acid brilliant blue dye (LABB) when exposed to ultraviolet (UV) radiation. UV- Vis spectrophotometry was utilized to analyze the optical properties of the produced nanostructure. Regarding the decolorization of the LABB, the impacts of operational variables were investigated. The optimum conditions for decolorization (93 %) were an initial concentration of 50 mg/L, pH = 4, catalyst dosage of 50 g/L, and exposure time of 90 min. The results illustrated that the LABB acidic dye from wastewater was remarkably decolored.

Structurally Modified Polysaccharides: Physicochemical Properties, Biological Activities, Structure-Activity Relationship, and Applications

Polysaccharides are an important class of biomolecules derived from several sources. However, the inherent structure of polysaccharides prevents them from exhibiting favorable physicochemical properties, which restricts their development in agriculture, industry, food, and biomedicine. This paper systematically summarizes the changes in the primary and advanced structures of modified polysaccharides, and focuses on the effects of various modification methods on the hydrophobicity, rheological properties, emulsifying properties, antioxidant activity, hypoglycemic, and hypolipidemic activities of polysaccharides. Then there is a list the applications of modified polysaccharides in treating heavy metal pollutants, purifying water resources, improving beverage stability and bread quality, and precisely delivering the drug. When summarized and reviewed, the information above can shed further light on the relationship between polysaccharide structure and function. Determining the structure-activity relationship provides a scientific basis for the direction of molecular modifications of polysaccharides.

Starch biocomposites preparation by incorporating organosolv lignins from potato crop residues

Plastic wastes accumulated due to food packaging pose environmental threats. This study proposes biopolymeric films containing lignins extracted from potato crop residues (PCR) through organosolv treatment as a green alternative to non-degradable food packaging. The isolation process yielded 43.9 wt% lignins with a recovery rate of 73.5 wt% achieved under optimum conditions at 180 °C with 50 % v/v ethanol. The extracted lignins were then incorporated into a starch matrix to create biocomposite films. ATR-FTIR analysis confirmed interactions between the starch matrix and extracted lignins, and XRD analysis showed the amorphous structure of lignins, reducing film crystallinity. The addition of 1 wt% of extracted lignins resulted in a 87 % reduction in oxygen permeability, a 25 % increase in the thermal stability of the film, and a 78 % enhancement in antioxidant. Furthermore, introducing 3 wt% lignins led to the lowest water vapor transmission rate, measuring 9.3 × 10-7 kg/s·m2. Morphological studies of the films demonstrated a homogeneous and continuous structure on both the surface and cross-sectional areas when the lignins content was below 7 wt%. These findings highlight the potential of using organosolv lignins derived from potato crop residues as a promising additive for developing eco-friendly films designed for sustainable food packaging.

Lignin-functionalized cobalt for catalytic reductive degradation of organic dyes in simple and hybrid binary systems

To fulfill the unprecedented valorization approaches for lignocellulose, this work focuses on the potential of lignin-derived catalytic systems for bio-remediation, which are natural materials perceived to address the increased demand for eco-conscious catalyzed processes. A useful lignin-functionalized cobalt (Lig-Co) catalyst has been prepared, well-characterized and deployed for the catalyzed reducing decomposition of stable harmful organic pollutants such as methylene blue (MB) and methyl orange (MO), in simple and binary systems. The multifunctional character of lignin and the presence of various active sites can promote effectively loaded metal nanoparticles (NPs). Considerably, optimizing detoxification tests showed that the uncatalyzed use of NaBH4 as a reductive agent led to an incomplete reduction of organic contaminants over a long period of up to 65 min. Interestingly, Lig-Co catalyst exhibited a high reduction rate and turnover frequency of up to 99.23% and 24.12 min-1 for MB, respectively, while they reached 99.25% and 26.21 min-1 for MO at normal temperature. Kinetically quick catalytic reaction was also demonstrated for the hybrid system, in which the rate constant k was 0.175 s-1 and 0.165 s-1 for MB and MO, respectively, within a distinctly low reaction time of around 120 s. The reproducibility of the Lig-Co catalyst induces a desirable capacity to reduce stable dyes present simultaneously in the binary system, with 6 successive catalytic runs and over 80% of activity retained. Such robust findings underline the considerable interest in developing future lignin-mediated catalytic transformations and upscaling biomass-derived products, to meet the growing demand for sustainable and eco-friendly alternatives in various industries.

Quantitative Determination of Metal Ion Adsorption on Cellulose Nanocrystals Surfaces

Nanocellulose is a bio-based material that holds significant potential in the field of water purification. Of particular interest is their potential use as a key sorbent material for the removal of metal ions from solution. However, the structure of metal ions adsorbed onto cellulose surfaces is not well understood. The focus of this work is to determine quantitatively the three-dimensional distribution of metal ions of different valencies surrounding negatively charged carboxylate functionalized cellulose nanocrystals (CNCs) using anomalous small-angle X-ray scattering (ASAXS). These distributions can affect the water and ionic permeability in these materials. The data show that increasing the carboxylate density on the surface of the CNCs from 740 to 1100 mmol/kg changed the nature of the structure of the adsorbed ions from a monolayer into a multilayer structure. The monolayer was modeled as a Stern layer around the CNC nanoparticles, whereas the multilayer structure was modeled as a diffuse layer on top of the Stern layer around the nanoparticles. Within the Stern layer, the maximum ion density increases from 1680 to 4350 mmol of Rb+/(kg of CNC) with the increase in the carboxylate density on the surface of the nanoparticles. Additionally, the data show that CNCs can leverage multiple mechanisms, such as electrostatic attraction and the chaotropic effect, to adsorb ions of different valencies. By understanding the spatial organization of the adsorbed metal ions, the design of cellulose-based sorbents can be further optimized to improve the uptake capacity and selectivity in separation applications.

Thermally-activated gelatin-chitosan-MOF hybrid aerogels for efficient removal of ibuprofen and naproxen

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most frequently used drugs and have been frequently detected in aquatic environments. This paper demonstrates a thermally-activated gelatin-chitosan and amine-functionalized metal-organic framework (UiO-66-NH2) aerogel (CGC-MOF), which was successfully synthesized for the efficient removal of ibuprofen (IBP) and naproxen (NPX). Various characterization tools were used to systematically analyze the microstructure and physicochemical properties of the synthesized aerogel. In addition, the effect of key reaction parameters as well as batch and continuous-flow fixed-bed column experiments were carried out to elucidate the adsorption process. Several functional groups in the biopolymer network, combined with excellent MOF properties, synergistically couple to form an adsorbent with great performance. The mesoporous aerogel activated at 200 °C (CGC-MOF200) exhibited a high specific surface area (819.6 m2/g) that is valuable in providing abundant adsorption active sites that facilitate the efficient adsorption of IBP and NPX. CGC-MOF200 exhibited an excellent removal of IBP and NPX, accounting to 99.28 % and 96.39 %, respectively. The adsorption process followed the pseudo-second-order kinetics and the Freundlich isotherm models, suggesting heterogeneous and chemisorption adsorption processes. Overall, this work provides new and valuable insights into the development of a promising biopolymer-MOF composite aerogel for environmental remediation.

Chitosan nanoplatforms in agriculture for multi-potential applications - Adsorption/removal, sustained release, sensing of pollutants & delivering their alternatives - A comprehensive review

An increase in the global population has led to an increment in the food consumption, which has demanded high food production. To meet the production demands, different techniques and technologies are adopted in agriculture the past 70 years, where utilization of the industry-manufactured/synthetic pesticides (SPTCs - e.g., herbicides, insecticides, fungicides, bactericides, nematicides, acaricides, avicides, and so on) is one of them. However, it has been later revealed that the usage of SPTCs has negatively impacted the environment - especially water and soil, and also agricultural products - mainly foods. Though preventive measures are taken by government agencies, still the utilization rate of SPTCs is high, and consequently, their maximum residual limit (MRL) levels in food are above tolerance, which further results in serious health concerns in humans. So, there is an immediate need for decreasing the utilization of the SPTCs by delivering them effectively at reduced levels in agriculture but with the required efficacy. Apart from that, it is mandatory to detect/sense and also to remove them to lessen the environmental pollution, while developing effective alternative techniques/technologies. Among many suitable materials that are developed/idenified, chitosan, a bio-polymer has gained great attention and is comprehensively implemented in all the above-mentioned applications - sensing, delivery and removal, due to their excellent and required properties. Though many works are available, in this work, a special attention is given to chitosan and its derivatives (i.e., chitosan nanoparticles (CNPs))based removal, controlled release and sensing of the SPTCs - specifically herbicides and insecticides. Moreover, the chitosan/CNPs-based protective effects on the in vivo models during/after their exposure to the SPTCs, and the current technologies like clustered regularly interspaced short palindromic repeats (CRISPR) as alternatives for SPTCs are also reviewed.

Polydopamine-functionalized electrospun poly(vinyl alcohol)/chitosan nanofibers for the removal and determination of Cu(II)

Environmentally friendly and recycled polydopamine-functionalized electrospun poly(vinyl alcohol)/chitosan nanofibers (PVA/CS/PDA) were prepared through a low-energy-consumption procedure. The PDA coating endows PVA/CS/PDA nanofibers with good water stability. The PVA/CS/PDA nanofibers have a fibrillar and porous structure that is favorable for Cu(II) to access the active sites of the nanofibers. The adsorption isotherm and kinetics data preferably conform to the Liu isotherm and pseudo-second-order kinetic models, respectively. The maximum adsorption capacity of Cu(II) ions by PVA/CS/PDA nanofibers from the Liu isotherm model is 326.5 mg g-1. The PVA/CS/PDA nanofibers exhibit higher adsorption capacity than some other reported adsorbents. The adsorption mechanism study demonstrates that the Cu(II) adsorption is mainly ascribed to the complexation of Cu(II) with the imino, amino, and hydroxy moieties in PVA/CS/PDA nanofibers. The nanofibers can be employed for 5 cycles without significantly deteriorating performance. More interestingly, a fluorometry method based on the oxidation mimic enzyme activity of Cu(II) was developed to detect low concentrations of Cu(II) using the nanofibers as an adsorbent to preconcentrate Cu(II). The limit of detection is 0.42 mg L-1. The successful removal and detection of Cu(II) in Pearl River and mineral water samples demonstrates the great potential of PVA/CS/PDA nanofibers to remediate Cu(II)-polluted water.

Functionalizing natural polymers to develop green adsorbents for wastewater treatment applications

The present study provides an overview of scientific developments made in the last decade in the field of green adsorbents focusing on the modifications in natural polymers and their applications such as, wastewater treatment, and ion exchange. For this purpose, an introduction to the various methods of modifying natural polymers is first given, and then the properties, application, and future priorities of green adsorbents are also discussed. Methods of modification of natural polymers under homogeneous and heterogeneous conditions using modifiers with different properties are also described. Various methods for modifying natural polymers and the use of the obtained green adsorbents are reviewed. A comparison of the sorption properties of green adsorbents based on natural polymers and other adsorbents used in industry has also been carried out. With the participation of green adsorbents based on natural polymers, the properties of treated wastewaters having toxic metal ions, organic dyes, petroleum products, and other harmful compounds was analyzed. Future perspectives on green adsorbents based on natural polymers are as also highlighted.

An efficient multi-functional ternary reusable nanocomposite based on chitosan@TiO2@Ag NP immobilized on cellulosic fiber as a support substrate for wastewater treatment

To effectively remove heavy metals, organic contaminants, and pathogenic bacteria from wastewater, an efficient multi-functional ternary nanocomposite based on chitosan (CS), titanium dioxide (TiO2 NP), and silver nanoparticles (Ag NP) was prepared. Different tools were used to confirm the successful synthesis of the CS/TiO2 NP/Ag NP nanocomposite. Then, the CS/TiO2 NP/Ag NPnanocomposite was immobilized on the cellulosic fiber as a support substrate for its easy removal and reuse. On a lab scale, CS/TiO2 NP/Ag NP nanocomposite@cellulosic fiber was used to remove Cu (II) ions, methyl orange (MO), and methylene blue (MB), as well as inhibit microbes. The results demonstrate that the greatest removal of Cu (II) ions was 95 % at a concentration of 50 mg/L, pH 5, a temperature of 25 °C, an agitation speed of 200 rpm with 1 g adsorbent dose, and a contact time of 150 min. The pseudo-second-order model explained the batch adsorption kinetics well, while the Langmuir model explained the adsorption isotherm well with an adsorption capacity of 7.71 mg/g. Adsorption thermodynamic parameters revealed that adsorption is a spontaneous, exothermic, increased randomness, and non-specific chemisorption approach. The photodegradation of MO and MB by CS/TiO2 NP/Ag NP nanocomposite@cellulosic fiber was investigated. The results reveal that at pH 3, the MO dye showed the highest photodegradation percentage (90 %), while the MB dye displayed the highest photodegradation percentage (94 %) at pH 11, after an irradiation time of 120 min under visible light. The rate constants for MO and MB were 0.01218 and 0.01412 min-1, respectively. The results antimicrobial activities showed that the CS/TiO2 NP/Ag NP nanocomposite@cellulosic fiber showed excellent antibacterial activity against S. aureus (95 ± 2 %) and E. coli (93 ± 3 %) as well as good antifungal activity against C. albicans (77 ± 2 %).

Recent advances in cellulose- and alginate-based hydrogels for water and wastewater treatment: A review

From the environmental perspective, it is essential to develop cheap, eco-friendly, and highly efficient materials for water and wastewater treatment. In this regard, hydrogels and hydrogel-based composites have been widely employed to mitigate global water pollution as this methodology is simple and free from harmful by-products. Notably, alginate and cellulose, which are natural carbohydrate polymers, have gained great attention for their availability, price competitiveness, excellent biodegradability, biocompatibility, hydrophilicity, and superior physicochemical performance in water treatment. This review outlined the recent progress in developing and applying alginate- and cellulose-based hydrogels to remove various pollutants such as dyes, heavy metals, oils, pharmaceutical contaminants, and pesticides from wastewater streams. This review also highlighted the effects of various physical or chemical methods, such as crosslinking, grafting, the addition of fillers, nanoparticle incorporation, and polymer blending, on the physiochemical and adsorption properties of hydrogels. In addition, this review covered the alginate- and cellulose-based hydrogels' current limitations such as low mechanical performance and poor stability, while presenting strategies to improve the drawbacks of the hydrogels. Lastly, we discussed the prospects and future directions of alginate- and cellulose-based hydrogels. We hope this review provides valuable insights into the efficient preparations and applications of hydrogels.

3D kaolinite/g-C3N4-alginate beads as an affordable and sustainable photocatalyst for wastewater remediation

Graphitic carbon nitride (GCN) is an efficient visible-light-driven metal-free semiconductor with superior photocatalytic activity. However, the main drawbacks of GCN include lower adsorption capacity, poor reusability and recoverability. To address these drawbacks, kaolinite/g-C3N4-alginate beads were fabricated using a cross-linking method to remove brilliant green dye from wastewater via photocatalysis. The characterization studies proved the alginate's potential capability in altering photocatalyst bandgap (2.78 to 2.55 eV) and minimizing recombination of electron-hole pairs. Kaolinite/g-C3N4-alginate photocatalyst removed 97 % of brilliant green (10 mg/L) in 90 min under visible light irradiation. The superior performance of the kaolinite/g-C3N4-alginate beads was ascribed to its improved adsorption and effective utilization of visible light. The key advantages of kaolinite/g-C3N4-alginate beads were their quick recovery and extended reusability upto ten cycles. The sustainability metrics analysis of kaolinite/g-C3N4-alginate beads confirmed the environmental suitability and practicability in wastewater remediation. This study provides new insights into the low-cost and sustainable preparation of highly reusable g-C3N4-based photocatalysts for environmental remediation.

Removal of radionuclide 99Tc from aqueous solution by various adsorbents: A review

Technetium isotope 99Tc is a main radioactive waste produced in the process of nuclear reaction, which has the characteristics of long half-life and strong environmental mobility, and can be bio-accumulated in organisms, resulting in serious threat to human health and ecosystem. Adsorption method is widely used in the field of removing radionuclides from water due to the advantages of high treatment rate, simple and mature industrial application. In this review paper, the recent advances in research and application of various adsorption materials for 99Tc pollution treatment were summarized and analyzed for the first time, including inorganic adsorbents, such as activated carbon, zero-valent iron, metallic minerals, clay minerals, layered double hydroxides (LDHs), tin-based materials, and sulfur-based materials; organic adsorbents, such as porous organic polymers (POPs), covalent-organic frameworks (COFs), metal-organic frameworks (MOFs), and ion exchange resin; and biological adsorbents, such as biopolymers (chitosan, cellulose, alginate), and microbial cells. The performance characteristics and the adsorption kinetics and isotherms of various adsorption materials were discussed. This review could deepen the understanding of the adsorptive removal of 99Tc from aqueous solution, and provide a reference for the future research in this field.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Recent advances in biopolymers-based carbon materials for supercapacitors

Supercapacitors as potential candidates for novel green energy storage devices demonstrate a promising future in promoting sustainable energy supply, but their development is impeded by limited energy density, which can be addressed by developing high-capacitance electrode materials with efforts. Carbon materials derived from biopolymers have received much attention for their abundant reserves and environmentally sustainable nature, rendering them ideal for supercapacitor electrodes. However, the limited capacitance has hindered their widespread application, resulting in the proposal of various strategies to enhance the capacity properties of carbon electrodes. This paper critically reviewed the recent research progress of biopolymers-based carbon electrodes. The advances in biopolymers-based carbon electrodes for supercapacitors are presented, followed by the strategies to improve the capacitance of carbon electrodes which include pore engineering, doping engineering and composite engineering. Furthermore, this review is summarized and the challenges of biopolymer-derived carbon electrodes are discussed. The purpose of this review is to promote the widespread application of biopolymers in the domain of supercapacitors.

Green synthesis of biocompatible Fe3O4 magnetic nanoparticles using Citrus Sinensis peels extract for their biological activities and magnetic-hyperthermia applications

Green synthesis of nanoparticles (NPs) is eco-friendly, biocompatible, cost-effective, and highly stable. In the present study, Citrus sinensis peel extract was utilized to the fabrication of superparamagnetic iron oxide nanoparticles (SPIONs). The fabricated SPIONs were first characterized using UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The UV-Vis spectra analysis displayed a peak at 259 nm due to the surface plasmon resonance. The FTIR spectrum showed bands at 3306 cm-1, and 1616 cm-1 revealed the protein's involvement in the development and capping of NPs. TEM analysis indicated that green synthesized SPIONs were spherical in shape with particle size of 20-24 nm. Magnetization measurements indicate that the synthesized SPIONs exhibited superparamagnetic behavior at room temperature. The antimicrobial activity, minimum inhibitory concentration (MIC), antioxidant potential, anti-inflammatory effect, and catalytic degradation of methylene blue by SPIONs were investigated in this study. Results demonstrated that SPIONs had variable antimicrobial effect against different pathogenic multi-drug resistant bacteria. At the highest concentration (400 μg/mL), SPIONs showed inhibition zones (14.7-37.3 mm) against all the target isolates. Furthermore, the MIC of synthesized SPIONs against Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, and Candida albicans were 3, 6.5, 6.5, 12.5, 50, 25 μg/mL, respectively. SPIONs exhibited strong antioxidant, anti-inflammatory, and catalytic dye degradation activities. Interestingly, Fe3O4 SPIONs shows optimum magnetic hyperthermia (MHT) techniques under an alternating magnetic field (AMF) measured in specific absorption rate (SAR) of 164, 230, and 286 W/g at concentrations 1, 5, and 10 mg/mL, respectively. Additionally, these newly fabricated SPIONs virtually achieve significant execution under the AMF in fluid MHT and are suitable for biomedical applications.

Magnetic biopolymers' nanocomposites from chitosan, lignin and phycosynthesized iron nanoparticles to remediate water from polluting oil

Targeting the remediation of oil pollution in water, the construction of super magnetic adsorbent nanocomposites (NCs) was achieved using the nanoparticles of chitosan (Cht), lignin (Lg) and phycosynthesized iron nanoparticles (Fe MNPs) using Gelidium amansii extract. The syntheses and conjugations of nanomaterials were authenticated via infrared spectral analysis and the structural physiognomies of them were appraised via electron microscopy and zeta analysis. The Lg NPs, Cht NPs, Fe MNPs and their composites (Lg/Cht MNCs) had mean particles' sizes of 42.3, 76.4, 14.2 and 108.3 nm, and were charged with - 32.7, + 41.2, + 28.4 and +37.5 mV, respectively. The magnetometer revealed the high magnetic properties of both Fe MNPs and Lg/Cht MNCs; the maximum swelling of Lg/Cht NPs (46.3 %), and Lg/Cht MNPs (33.8 %) was detected after 175 min. The diesel oil adsorption experiments with Lg/Cht MNPs, using batch adsorption practices, revealed the powerful potentiality of magnetic NCs to remove oil pollution in water; the maximum adsorption capacity (qt) was achieved with the conditions of pH = 7.5, adsorption period = 90 min and adsorbent dose = 200 mg/L. The magnetic Lg/Cht MNCs exhibited excellent recovery/reusability attributes for five adsorption cycles; the qt differences were negligible after the entire oil-adsorption cycles, with oil removal of >90 %. The innovative fabricated Lg/Cht MNCs could provide an effectual, sustainable and eco-friendly approach for the removal of pollutant oil in water resources.

Sustainable removal of phenol from wastewater using a biopolymer hydrogel adsorbent comprising crosslinked chitosan and κ-carrageenan

A biopolymer-based adsorbent comprising chitosan (CS) and κ-carrageenan (κ-Carr) was synthesised and evaluated to treat phenolic-contaminated water. The developed CS/κ-Carr hydrogel demonstrated excellent performance with a phenol adsorption uptake of 80 %. The morphologies of CS/κ-Carr hydrogels with different ratios of CS to κ-Carr ranging from 1:2 to 7:3 were characterised using scanning electron microscopy and atomic force microscopy; their chemical structures were investigated by spectral analyses using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry; their adsorption characteristics were determined using tests for swelling, chemical stability, hygroscopic moisture content, and hydrophilicity. Finally, a batch-type evaluation method demonstrated adsorption performance at 25 °C and pH 6.9. Adsorption isotherms and kinetic data were successfully obtained using the Freundlich and pseudo-second-order models, respectively. The results indicate that one-pot synthesis of an insoluble CS/κ-Carr hydrogel adsorbent exhibits considerable potential for the removal of phenol from aqueous solutions, providing an environmentally friendly technology enhancing the phenol adsorption performance of CS.

Surface stress and shape relaxation of gelling droplets

Solidification is a heterogeneous transformation from liquid to solid, which usually combines transport, phase transition and mechanical strain. Predicting the shapes resulting from such a complex process is fascinating and has a wide range of implications from morphogenesis in biological tissues to industrial processes. For soft solids initially at equilibrium, elastic stresses, whether tensile or compressive, can be induced by heterogeneous volumetric deformations of the material. These stresses trigger surface instabilities leading to variations of curvature and shape of the solids. In this article, we study the shape evolution of elongated droplets of polymer and particle suspensions undergoing a solidification process caused by the inward diffusion of a gelling agent from the surface. We show experimentally and numerically that there appears a layer of gelled material growing at the surface. Due to volume contraction, this layer induces tensile stresses and drives a flow in the ungelled liquid core, resulting in the relaxation of the droplets toward spherical shapes. Over time, the thickness of this elastic membrane grows, hence the bending stiffness required to change its shape eventually balances the surface stresses, which arrests the relaxation process. These results provide general rules to understand the shape of solidifying materials combining both tension and bending driven deformations.

Bio-based functionalized adsorptive polymers for sustainable water decontamination: A systematic review of challenges and real-world implementation

The overwhelming concerns of water pollution, industrial discharges and environmental deterioration by various organic and inorganic substances, including dyes, heavy metals, pesticides, pharmaceuticals, and detergents, intrinsically drive the search for urgent and efficacious decontamination techniques. This review illustrates the various approaches to remediation, their fundamentals, characteristics and demerits. In this manner, the advantageous implementation of nature-based adsorbents has been outlined and discussed. Different types of lignocellulosic compounds (cellulose, lignin, chitin, chitosan, starch) have been introduced, and the most used biopolymeric materials in bioremediation have been highlighted; their merits, synthesis methods, properties and performances in aqueous medium decontamination have been described. The literature assessment reveals the genuine interest and dependence of academic and industrial fields to valorize biopolymers in the adsorption of various hazardous substances. Yet, the full potential of this approach is still confined by certain constraints, such as the lack of reliable, substantial, and efficient extraction of biopolymers, as well as their modest and inconsistent physicochemical properties. The futuristic reliance on such biomaterials in all fields, rather than adsorption, is inherently reliable on in-depth investigations and understanding of their features and mechanisms, which can guarantee a real-world application and green technologies.

Enhanced treatment of synthetic wastewater by bioaugmentation with a constructed consortium

Bioaugmentation by adding well-functioning mixed microorganism consortia represents a potentially useful approach to improve contaminant removal in wastewater treatment plants (WWTPs). However, unfavorable environmental conditions (i.e., low temperatures) can severely inhibit microbial activity, drawing our attention to constructing cold-tolerant microorganism preparations and investigating their availability in practical applications. Here we screened four in situ functional isolates from the activated sludge of secondary sedimentation tanks in WWTPs to construct a psychrophilic microbial consortium, which was used to perform bioaugmentation for enhanced removal of nitrogen and phosphorus under low temperatures. The consortium was established by cocultivation of four isolates, characterized by 16 S rRNA as the COD-degrading bacterium Aeromonas sp. Z3, aerobic denitrifying bacterium Acinetobacter sp. HF9, nitrifying bacterium Klebsiella sp. X8, and polyphosphate-accumulating bacterium Pseudomonas sp. PC5 respectively. The microorganism preparation was composed of Z3, HF9, X8, and PC5 under the ratio of 1: 1: 3: 1, which can exert optimal pollutant removal under the conditions of 12 °C, 6.0-9.0 pH, 120-200 r‧min-1, and a dosage of 5% (V/V). A 30-day continuous operation of the bioaugmented and control sequencing batch reactors (SBRs) was investigated, and the bioaugmented SBR showed a shorter start-up stage and a more stable operating situation. Compared to the control SBR, the COD, NH4+-N, TN, and TP removal efficiency of the bioaugmented SBR increased by an average of 7.95%, 9.05%, 9.54%, and 7.45% respectively. The analysis of the microbial community revealed that the introduced isolates were dominant in the activated sludge and that functional taxa such as Proteobacteria, Bacteroidota, and Actinobacteria were further enriched after a period of bioaugmentation. The study provides some basis and guidance for the practical application of how to strengthen the stable operation of WWTPs under low temperatures.

Biogenic adsorbents for removal of drugs and dyes: A comprehensive review on properties, modification and applications

This comprehensive review explores the potential and versatility of biogenic materials as sustainable and environmentally benign alternatives to conventional adsorbents for the removal of drugs and dyes. Biogenic adsorbents derived from plants, animals, microorganisms, algae and biopolymers have bioactive compounds that interact with functional groups of pollutants, resulting in their binding with the sorbent. These materials can be modified mechanically, thermally and chemically to enhance their adsorption properties. Biogenic hybrid composites, which integrate the characteristics of more than one material, have also been fabricated. Additionally, microorganisms and algae are analyzed for their ability to uptake pollutants. Various influential factors that contribute to the adsorption process are also discussed. The challenge, limitations and future prospects for research are reviewed and bridging gap between large scale application and laboratory scale. This comprehensive review, involves a combination of various biogenic adsorbents, going beyond the existing literature where typically only specific adsorbents are reported. The review also covers the isotherms, kinetics, and desorption studies of biogenic adsorbents, providing an improved framework for their effective use in removing pharmaceuticals and dyes from wastewater.

Gum-based nanocomposites for the removal of metals and dyes from waste water

The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved.

Tailoring the Swelling-Shrinkable Behavior of Hydrogels for Biomedical Applications

Hydrogels with tailor-made swelling-shrinkable properties have aroused considerable interest in numerous biomedical domains. For example, as swelling is a key issue for blood and wound extrudates absorption, the transference of nutrients and metabolites, as well as drug diffusion and release, hydrogels with high swelling capacity have been widely applicated in full-thickness skin wound healing and tissue regeneration, and drug delivery. Nevertheless, in the fields of tissue adhesives and internal soft-tissue wound healing, and bioelectronics, non-swelling hydrogels play very important functions owing to their stable macroscopic dimension and physical performance in physiological environment. Moreover, the negative swelling behavior (i.e., shrinkage) of hydrogels can be exploited to drive noninvasive wound closure, and achieve resolution enhancement of hydrogel scaffolds. In addition, it can help push out the entrapped drugs, thus promote drug release. However, there still has not been a general review of the constructions and biomedical applications of hydrogels from the viewpoint of swelling-shrinkable properties. Therefore, this review summarizes the tactics employed so far in tailoring the swelling-shrinkable properties of hydrogels and their biomedical applications. And a relatively comprehensive understanding of the current progress and future challenge of the hydrogels with different swelling-shrinkable features is provided for potential clinical translations.

Chitosan neem nanocapsule enhances immunity and disease resistance in nile tilapia (Oreochromis niloticus)

Finding eco-friendly alternatives for antibiotics in treating bacterial diseases affecting the aquaculture sector is essential. Herbal plants are promising alternatives, especially when combined with nanomaterials. Neem (Azadirachta indica) leaves extract was synthesized using a chitosan nanocapsule. Chitosan neem nanocapsule (CNNC) was tested in-vitro and in-vivo against the Aeromonas sobria (A. sobria) challenge in Nile tilapia. A preliminary experiment with 120 Nile tilapia was conducted to determine the therapeutic dose of CNNC, which was established to be 1 mg/L. A treatment study was applied for seven days using 200 fish categorized into four groups (10 fish/replicate: 50 fish/group). The first (control) and second (CNNC) groups were treated with 0 and 1 mg/L CNNC in water without being challenged. The third (A. sobria) and fourth (CNNC + A. sobria) groups were treated with 0 and 1 mg/L CNNC, respectively, and challenged with A. sobria (1 × 107 CFU/mL). Interestingly, CNNC had an in-vitro antibacterial activity against A. sobria; the minimum inhibitory concentration and minimum bactericidal concentration of CNNC against A. sobria were 6.25 and 12.5 mg/mL, respectively. A. sobria challenge caused behavioral alterations, skin hemorrhage, fin rot, and reduced survivability (60%). The infected fish suffered a noticeable elevation in the malondialdehyde level and hepato-renal function markers (aspartate aminotransferase, alanine aminotransferase, and creatinine). Moreover, a clear depletion in the level of the antioxidant and immune indicators (catalase, reduced glutathione, lysozymes, nitric oxide, and complement 3) was obvious in the A. sobria group. Treatment of the A. sobria-challenged fish with 1 mg/L CNNC recovered these parameters and enhanced fish survivability. Overall, CNNC can be used as a new versatile tool at 1 mg/L as a water treatment for combating the A. sobria challenge for sustainable aquaculture production.

Development of carboxymethyl cellulose-graphene oxide biobased composite for the removal of methylene blue cationic dye model contaminate from wastewater

Utilizing Glutaraldehyde crosslinked sodium carboxymethyl cellulose (CMC-GA) hydrogel and its nanographene oxide composite (CMC-GA-GOx), an effective carboxymethyl cellulose-graphene oxide biobased composites adsorbent was developed for the adsorption removal of methylene blue (MB) cationic dye contaminate from industrial wastewater. The CMC-GA-GOx composites developed were characterized using FTIR, RAMAN, TGA, SEM, and EDX analysis instruments. Through batch experiments, several variables affecting the removal of MB dye, including the biocomposites GO:CMC composition, adsorption time, pH and temperature, initial MB concentration, adsorbent dosage, and NaCl concentration, were investigated under different conditions. The maximum dye removal percentages ranged between 93 and 98%. They were obtained using biocomposites CMC-GA-GO102 with 20% GO weight percent, adsorption time 25 min, adsorption temperature 25 °C, MB concentrations 10-30 ppm, adsorption pH 7.0, and 0.2 g adsorbent dose. The experimental data of the adsorption process suit the Langmuir isotherm more closely with a maximal monolayer adsorption capacity of 76.92 mg/g. The adsorption process followed the kinetic model of pseudo-second order. The removal of MB was exothermic and spontaneous from a thermodynamic standpoint. In addition, thermodynamic results demonstrated that adsorption operates most effectively at low temperatures. Finally, the reusability of the developed CMC-GA-GO102 has been proved through 10 successive cycles where only 14% of the MB dye removal percentage was lost. These results suggest that the developed CMC-GA-GO102 composite may be an inexpensive and reusable adsorbent for removing organic cationic dyes from industrial wastewater.

Cellulose nanofibers decorated with SiO2 nanoparticles: Green adsorbents for removal of cationic and anionic dyes; kinetics, isotherms, and thermodynamic studies

Cellulose nanofibers decorated with SiO2 nanoparticles (SiO2-CNF) were prepared by the extraction of cellulose nanofibers from Yucca leaves, followed by modification with SiO2 nanoparticles, and used as efficient materials for the removal of both anionic and cationic dyes from the aqueous solution. Prepared nanostructures were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction powder (XRD), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM) analysis. The adsorption capacity of the nanostructures was investigated for the removal of both cationic (Methylene Blue, MB, and Crystal Violet, CV) and anionic (Eriochrome Black-T, EB) dyes. The kinetics of adsorption were investigated using some well-known models, including intraparticular diffusion (IPD), pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich. The adsorption isotherms were also explored using the Langmuir, Freundlich, Temkin, and Redlich-Peterson models. The obtained results revealed that the adsorption processes follow PSO kinetic and Langmuir isotherm models. Thermodynamic parameters of the adsorption were measured at different temperatures, indicating the feasibility and spontaneity of the adsorption. The pH and salt effects on adsorption were also explored. Finally, according to the reusability tests, the prepared adsorbents showed high recoverability without considerable loss in adsorption efficiency after five repeated runs.

Metal/metal oxide-carbohydrate polymers framework for industrial and biological applications: Current advancements and future directions

Recently, the development and consumption of metal/metal oxide carbohydrate polymer nanocomposites (M/MOCPNs) are withdrawing significant attention because of their numerous salient features. Metal/metal oxide carbohydrate polymer nanocomposites are being used as environmentally friendly alternatives for traditional metal/metal oxide carbohydrate polymer nanocomposites exhibit variable properties that make them excellent prospects for a variety of biological and industrial uses. In metal/metal oxide carbohydrate polymer nanocomposites, carbohydrate polymers bind with metallic atoms and ions using coordination bonding in which heteroatoms of polar functional groups behave as adsorption centers. Metal/metal oxide carbohydrate polymer nanocomposites are widely used in woundhealing, additional biological uses and drug delivery, heavy ions removal or metal decontamination, and dye removal. The present review article features the collection of some major biological and industrial applications of metal/metal oxide carbohydrate polymer nanocomposites. The binding affinity of carbohydrate polymers with metal atoms and ions in metal/metal oxide carbohydrate polymer nanocomposites has also been described.

Nano/micro-cellulose-based materials as remarkable sorbents for the remediation of agricultural resources from chemical pollutants

Overusing pesticides, fertilizers, and synthetic dyes has significantly increased their presence in various parts of the environment. The transportation of these pollutants into agricultural soil and water through rivers, soils, and groundwater has seriously threatened human and ecosystem health. Applying techniques and materials to clean up agricultural sources from pesticides, heavy metals (HMs), and synthetic dyes (SDs) is one of the major challenges in this century. The sorption technique offers a viable solution to remediate these chemical pollutants (CHPs). Cellulose-based materials have become popular in nano and micro scales because they are widely available, safe to use, biodegradable, and have a significant ability to absorb substances. Nanoscale cellulose-based materials exhibit greater capacity in absorbing pollutants compared to their microscale counterparts because they possess a larger surface area. Many available hydroxyl groups (-OH) and chemical and physical modifications enable the incorporation of CHPs on to cellulose-based materials. Following this potential, this review aims to comprehensively summarize recent advancements in the field of nano- and micro-cellulose-based materials as effective adsorbents for CHPs, given the abundance of cellulosic waste materials from agricultural residues. The recent developments pertaining to the enhancement of the sorption capacity of cellulose-based materials against pesticides, HMs, and SDs, are deliberated.

Plant-derived polyphenolic compounds: nanodelivery through polysaccharide-based systems to improve the biological properties

Plant-derived polyphenols are naturally occurring compounds widely distributed in plants. They have received greater attention in the food and pharmaceutical industries due to their potential health benefits, reducing the risk of some chronic diseases due to their antioxidant, anti-inflammatory, anticancer, cardioprotective, and neuro-action properties. Polyphenolic compounds orally administered can be used as adjuvants in several treatments but with restricted uses due to chemical instability. The review discusses the different structural compositions of polyphenols and their influence on chemical stability. Despite the potential and wide applications, there is a need to improve the delivery of polyphenolics to target the human intestine without massive chemical modifications. Oral administration of polyphenols is unfeasible due to instability, low bioaccessibility, and limited bioavailability. Nano-delivery systems based on polysaccharides (starch, pectin, chitosan, and cellulose) have been identified as a viable option for oral ingestion, potentiate biological effects, and direct-controlled delivery in specific tissues. The time and dose can be individualized for specific diseases, such as intestinal cancer. This review will address the mechanisms by which polysaccharides-based nanostructured systems can protect against degradation and enhance intestinal permeation, oral bioavailability, and the potential application of polysaccharides as nanocarriers for the controlled and targeted delivery of polyphenolic compounds.

Cellulose-Based Ionic Conductor: An Emerging Material toward Sustainable Devices

Ionic conductors (ICs) find widespread applications across different fields, such as smart electronic, ionotronic, sensor, biomedical, and energy harvesting/storage devices, and largely determine the function and performance of these devices. In the pursuit of developing ICs required for better performing and sustainable devices, cellulose appears as an attractive and promising building block due to its high abundance, renewability, striking mechanical strength, and other functional features. In this review, we provide a comprehensive summary regarding ICs fabricated from cellulose and cellulose-derived materials in terms of fundamental structural features of cellulose, the materials design and fabrication techniques for engineering, main properties and characterization, and diverse applications. Next, the potential of cellulose-based ICs to relieve the increasing concern about electronic waste within the frame of circularity and environmental sustainability and the future directions to be explored for advancing this field are discussed. Overall, we hope this review can provide a comprehensive summary and unique perspectives on the design and application of advanced cellulose-based ICs and thereby encourage the utilization of cellulosic materials toward sustainable devices.