Adsorption of Methylene Blue, Bromophenol Blue, and Coomassie Brilliant Blue by α-chitin nanoparticles

Removal of bromophenol blue from polluted water using a novel azo-functionalized magnetic nano-adsorbent

Water pollution from organic dyes poses a serious danger to the environment. In the present work, we report a novel adsorbent (ADFS) based on azo-dye-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of the anionic dye bromophenol blue (BPB) from contaminated water. The fabricated SPIONs, azo dye, and ADFS adsorbent were characterized with FTIR and UV-vis absorption spectroscopy, 1HNMR spectroscopy, mass spectrometry, SEM imaging, dynamic light scattering (DLS), zeta potential measurements, vibrating sample magnetometry, thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. DLS measurements showed a particle size of 46.1 and 176.5 nm for the SPIONs and the ADFS, respectively. The adsorbent exhibited an adsorption capacity of 7.43 mg g-1 and followed the pseudo-second-order kinetics model (r2 = 0.9981). The ADFS could efficiently remove BPB from water after stirring for 120 minutes at room temperature and pH 2. The adsorption process was proved to occur via physisorption, as revealed by the Freundlich isotherm (n = 1.82 and KF = 11.5). Thermodynamic studies implied that the adsorption is spontaneous (-8.03 ≤ ΔG ≤ -0.58 kJ mol-1) and enthalpy-driven might take place via van der Waals interactions and/or hydrogen bonding (ΔH = -82.19 kJ mol-1 and ΔS = -0.24 kJ mol-1 K-1).

Fabrication of chitin-glucan nanofibers: Insights into mushroom pretreatment and subsequent acidic deep eutectic solvent-based esterification

Mushrooms contain chitin-glucan complex (CGC), a natural copolymer of chitin and glucan, and nanofibrillation enhances its applicability. Here, a novel method was used to fabricate chitin-glucan nanofibers (CGNFs) from white button mushrooms. The first stage was to pretreat the raw mushroom using hot water and alkali to remove water-soluble glucans and alkali-soluble proteins, respectively, producing a CGC amenable to nanofibrillation. The second stage was nanofibrillation via esterification using acidic deep eutectic solvents (DESs) and subsequent ultrasonication. Five choline chloride-based DESs containing mono- or dicarboxylic acid were tested for the CGC esterification. DESs with strong dicarboxylic acids expedited nanofibrillation by homogeneously dispersing the solid CGC, swelling CGC fibrils, and facilitating acidity-dependent esterification leading to steric and electrostatic repulsions. One CGNF, namely CGNF_CCMnA, was characterized: it contained chitin and glucan at an approximate ratio of 8:2 and exhibited desirable properties as nanomaterials, including small diameter (11 nm) and high colloidal (zeta potential < -30 mV above pH 5.8) and thermal stability (Tm, 315 °C). CGNF_CCMnA was tested for the adsorption to methylene blue, revealing a maximum adsorption capacity of 82.58 mg/g. The proposed approach is an efficient and readily applicable method to fabricate various mushroom-derived safe CGNFs and to produce related nanomaterials.

Magnetic nanocellulose-based adsorbent for highly selective removal of malachite green from mixed dye solution

Herein, a novel magnetic adsorbent (BC/AA/MN@Fe3O4) was successfully prepared from waste bamboo fiber tissue and montmorillonite, and subsequently applied for the highly selective removal of malachite green (MG, removal efficiency = 97.3 %) from the mixed dye solution of MG with methyl orange (MO, removal efficiency = 4.5 %). The magnetic adsorbent has a high porosity with abundant mesopores. In the single dye MG solution, the adsorbent could effectively remove MG over a wide pH range from 4 to 10, and the maximum adsorption capacity (qmax) was 2282.3 mg/g. Moreover, the magnetic adsorbent could remove MG from various solutions including mixed dye solution, high salinity solution, and real river water dye solution. The thermodynamic results proved that the adsorption process of MG was spontaneous and endothermic. The adsorption of MG was due to the comprehensive effects of electrostatic attraction, hydrogen bonding interactions and ions exchange, between the adsorbent and MG. Furthermore, the BC/AA/MN@Fe3O4 exhibited an excellent reusability with adsorption efficiency above 53.4 % after five consecutive cycles. Therefore, the prepared magnetic nanocellulose-based adsorbent was expected to be a promising material for highly selective adsorption and separation of MG from mixed dye solution.

Toward pulping process for enhancing the RS-black liquors as precursor of activated carbons for aqueous adsorbent purposes

This work deals with providing a green pulping process of rice straw with zero waste discharged, via valorization of its by-product as a promising precursor for production of carbon nanostructures. The carbon nanostructures (BL-CNSs) from rice straw pulping liquors (BLs) are prepared in one step with phosphoric acid activation. The carbon nanostructures (BL-CNSs) from rice straw pulping liquors (BLs) are prepared in one step with phosphoric acid activation. The optimal pulping approach for achieving effective adsorbent (BL-CNSs) of cationic and anionic dyes is recommended from using different BLs precursors resulting from different reagents (alkaline, neutral, and acidic reagents). The carbon precursors are characterized by elemental, thermal (TGA and DTG) and ATR FTIR analyses. While the impact of pulping route on performance of CNSs is evaluated by their adsorption of iodine, cationic dye and anionic dye, as well as ATR-FTIR, textural characterization, and SEM. The data of elemental analysis displayed a high Carbon content ranges from 57.85 to 66.69% suitable for CNSs preparation, while the TGA showed that Sulphur-containing BLs (Kraft, neutral sulfite and acidic sulfite) have higher degradation temperature and activation energies as compared with other BLs. The optimum BL-CNSs adsorbent is prepared from the disposed neutral sulfite black liquor, with the following characteristics: cationic dye adsorption capacity 163.9 mg/g, iodine value 336.9 mg/g and SBET 310.6 m2/g. While the Kraft-CNSs provided highest anionic adsorption (70.52 mg/g). The studies of equilibrium and kinetic adsorption of dyes showed that the adsorption equilibrium of all investigated BL-CNSs toward MB follow the Langmuir and mainly Freundlich models for BB adoption. Their adsorption kinetics are a good fit with the pseudo-second-order model. The textural characterization and SEM revealed the CNSs exhibit a mixture of mesoporous and microporous structure.

Biosynthesis of green CuO@C nanocomposite using Combretum indicum flower extract for organic dye removal: adsorption performance, modeling, and recyclability studies

Water contamination becomes one of the most high-priority environmental concerns, calling for the efficient treatment techniques. Bionanocomposites can be robust adsorbents, but the synthesis requires toxic chemicals or energy consuming and cause the secondary pollution. Green nanocomposites can be biogenically synthesized using the plant extract to end up with a critically safe strategy. Herein, we used the flower extract of Combretum indicum plant as a bio-based reductant and carbonaceous source for the green CuO@C nanocomposite. This green nanoadsorbent obtained a specific surface area of 17.33 m2/g, good crystallinity, and functional group-containing surface, i.e., -OH and -CONH-. We also conducted the optimization of parameters, i.e., concentration, CuO@C dose, pH, time, and temperature, and reached removal efficiencies towards malachite green (MG, 83.23%), Congo red (CR, 84.60%), brilliant blue (BB, 71.39%), and methylene blue (MB, 23.67%). The maximum adsorption capacities were found as ordered, MG (46.387 mg/g) > MB (23.154 mg/g) > BB (22.8 mg/g) > CR dye (11.063 mg/g). Through the intra-particle diffusion kinetic model, MG and BB adsorption endured a three-step process, while CR and MB adsorption was a two-step process. The recyclability of the green CuO@C nanocomposite was three cycles with 67.54% for the final cycle of BB removal. Moreover, the nanoadsorbent displayed a high stability, checked by X-ray diffraction, FT-IR analysis, EDX spectra, and SEM images. It is recommended that the green CuO@C nanocomposite biosynthesized using the Combretum indicum flower extract can be a good alternative for the dye treatment from wastewater.

Live Biomass of Rigidoporus vinctus: A Sustainable Method for Decoloration and Detoxification of Dyes in Water

In this study, white-rot fungus, Rigidoporus vinctus, collected from an unidentified fallen twig from Pathankot, Punjab, India, was used for biosorption of anionic Congo red and cationic Methylene blue dyes from an aqueous medium. The biosorption efficiency of the live biomass of Rigidoporus vinctus was investigated to optimize biosorbent dosage, process time, concentrations of dyes, and pH of solutions. The results indicated that Rigidoporus vinctus is more efficient than other reported bio-adsorbents for Congo red and Methylene blue dyes. The maximum biosorption activity of Rigidoporus vinctus for Congo red was found at pH 2, and that for Methylene blue was at pH 10, after 24 h of the reaction period. The process followed pseudo-second-order kinetics, which indicated that the interaction of both dyes to the adsorption sites on the surface of Rigidoporus vinctus was responsive to biosorption. The biosorption process could be well explained by the Langmuir isotherm for both dyes. The maximum monolayer biosorption capacity of Rigidoporus vinctus for Congo red and Methylene blue was observed to be 54.0 mg/g and 80.6 mg/g, respectively. The seed germination test was carried out, and it was assessed that the toxicity of dyes was reduced up to significant levels. Based on the present experimental findings, it can be concluded that biosorption using the live biomass of Rigidoporus vinctus can effectively decolorize dye-containing wastewater, thus reducing the hazardous effects of dyes on human beings.

Green Synthesis and Photocatalytic Dye Degradation Activity of CuO Nanoparticles

The degradation of dyes is a difficult task due to their persistent and stable nature; therefore, developing materials with desirable properties to degrade dyes is an important area of research. In the present study, we propose a simple, one-pot mechanochemical approach to synthesize CuO nanoparticles (NPs) using the leaf extract of Seriphidium oliverianum, as a reducing and stabilizing agent. The CuO NPs were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic activity of CuO NPs was monitored using ultraviolet-visible (UV-Vis) spectroscopy. The CuO NPs exhibited high potential for the degradation of water-soluble industrial dyes. The degradation rates for methyl green (MG) and methyl orange (MO) were 65.231% ± 0.242 and 65.078% ± 0.392, respectively. Bio-mechanochemically synthesized CuO NPs proved to be good candidates for efficiently removing dyes from water.

Novel sustainable composites made of car's waste and sodium titanate for the efficient photocatalytic removal of the bromophenol blue dye: study under solar and UV-Vis light

In this research, W-doped sodium nanotube titanate (NaTNT) nanoparticles were used for the photocatalytic degradation of the bromophenol blue (BPB) dye. The NaTNT powder was mixed with car's tire powder (TP) to enhance its light absorption or was supported on recycled car's air filters (AFs) to facilitate its removal from the cleaned water after the degradation of the BPB. The SEM analysis indicated that the NaTNT nanoparticles and the TP had sizes in the range of 150-325 nm and 8-37 µm, respectively. Both powders were also studied by X-ray diffraction and found that the sodium titanate corresponds to the Na₂Ti₆O₁₃ with monoclinic phase, while the TP is formed by rubber, silicon, ZnS, and ZnO. The photocatalytic activity of the NaTNT powder was evaluated for the degradation of BPB dye (20 ppm) and obtained a maximum degradation of 95 and 80% under UV-Vis and natural solar light, respectively, after 4 h of irradiation. For the NaTNT + TP composite mixture, the maximum degradation was 87 and 68% under UV-Vis and solar light, respectively. The NaTNT and NaTNT + TP powders were supported on the AFs to form the AF + NaTNT and AF + NaTNT + TP composites. Those ones produced maximum degradation of 86% and 74% (under UV-Vis light), respectively. Besides, several initial pHs were tested for the contaminated water and determined that the maximum degradation of BPB (93-95%) is reached for the pHs of 3 and 7. Reuse experiments (3 cycles) revealed that the diminution of the BPB degradation percentage was 23% and 20% for the NaTNT and NaTNT + TP powders, respectively. Overall, it was demonstrated that the wasted car's air filters can be used as a support for photocatalytic powders, and this combination of AF + powder degrades the BPB with high efficiency.

Exploring the Biosorption of Methylene Blue Dye onto Agricultural Products: A Critical Review

Due to their higher specific area and, in most cases, higher adsorption capacity, nanomaterials are noteworthy and attractive adsorbents. Agricultural products that are locally available are the best option for removing methylene blue (MB) dye from aqueous solutions. Because it is self-anionic, FT-IR and SEM investigations of biosorption have confirmed the role of the functional group and its contribution to the formation of pores that bind cationic dye. It is endothermic if the adsorption of MB by an adsorbent is high as the temperature increases; on the other hand, exothermic if it is high as the temperature decreases. A basic medium facilitates adsorption with respect to pH; adsorption is proportional to the initial concentration at a certain level before equilibrium; after equilibrium, adsorption decreases. A pseudo-second-order model applies for certain agricultural products. As per plotted graph for the solid-phase concentration against the liquid-phase concentration, the Langmuir adsorption isotherm model is favored; this model describes a situation in which a number of molecules are adsorbed by an equal number of available surface sites, and there is no interaction between adsorbate molecules once all sites are occupied. In contrast, the Freundlich model depicts non-ideal multi-layer sorption onto heterogeneous surfaces via numerical analysis; with a value of n = 1, the result is a linear isotherm. If the value of n < 1 or n > 1, then it is chemical or physical adsorption, respectively. Based on an EDX analysis, relevant elements are confirmed. BET analysis confirms the surface area. Nanoproducts categorized as agricultural products exhibit the aforementioned tendency. Even though nanoparticles show positive outcomes in terms of higher adsorption, a high specific area for the targeted pollutant is needed in real-world applications. In the relevant sections herein, the behavior of thermodynamic parameters, such as enthalpy, entropy, and Gibbs free energy, are examined. There is some question as to which form of agricultural waste is the most effective adsorption medium. There is no direct answer because every form of agricultural waste has its own distinct chemical and physical characteristics, such as porosity, surface area, and strength.

Adsorption of Safranin-O dye by copper oxide nanoparticles synthesized from Punica granatum leaf extract

The development of new technologies for water and wastewater treatment is a growing need due to the occurrence of micropollutants, such as dyes, in water resources. In this sense, green-synthesized nanoparticles are being extensively studied, due to their low cost, non-toxicity, and high efficiency in adsorption processes. Thus, the present study reports the green synthesis of copper oxide nanoparticles (CuO-NP), obtained from pomegranate (Punica granatum) leaf extract, employed for the removal of Safranin-O (SO) dye. CuO-NP was characterized by physicochemical analysis. These analyzes suggested that the redox process occurred efficiently. Also, the material presented interesting elements for the removal of cationic dyes such as negative surface charge, high specific surface area, and predominance of mesopores. The kinetic data fitted the pseudo-second-order model, reaching equilibrium in 480 min. The equilibrium study resulted in a maximum adsorption capacity of 189.54 mg g^-1 at 298 K and the experimental data best fitted the Langmuir model. The effect of pH and ionic strength did not present significant changes, which demonstrates an advantage of this adsorbent over other materials. The regeneration study allowed to verify the possibility of reuse CuO-NP, since after 4 cycles the adsorption capacity was 44% of the initial value. Considering the results found, CuO-NP has a high potential for applicability in the treatment of water contaminated by dyes.

Adsorption of Methylene Blue on Azo Dye Wastewater by Molybdenum Disulfide Nanomaterials

In this study, flower-like MoS2 nanomaterials were synthesized by hydrothermal method with excess thiourea. The adsorption performance of MoS2 adsorbent for methylene blue (MB) in azo dye wastewater was studied. The morphology, crystal phase, and microstructure of nano MoS2 samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The effects of adsorption isotherm, kinetics, different hydrothermal time, and pH on the adsorption experiment were studied. The results showed that the MoS2 adsorbent with a hydrothermal time of 1 h had good adsorption properties for MB. The adsorption data accord with the Langmuir isotherm model, and the maximum adsorption capacity of MoS2 adsorbent is 200 mg/g, and the adsorption kinetics agrees well with the pseudo two-level model. The removal rate of MB is not significantly affected by the pH values. The large pH range can still maintain the removal rate above 93.47%, and the regeneration and recovery properties of MoS2 were also explored. Finally, the adsorption mechanism of MoS2 on MB is discussed.

Environmental-Friendly Adsorbent Composite Based on Hydroxyapatite/Hydroxypropyl Methyl-Cellulose for Removal of Cationic Dyes from an Aqueous Solution

The aim of this study is to develop a new, efficient, and inexpensive natural-based adsorbent with high efficacy for the cationic dye methylene blue (MB). A natural-based nanocomposite based on hydroxyapatite (HAp) and hydroxypropyl methylcellulose (HPMC) was selected for this purpose. It was synthesized by the dissolution/reprecipitation method. A film with a homogeneous and smooth surface composed of nanoparticles was prepared from the nanocomposite. HPMC and HAp biopolymers were selected due to their compatibility, biodegradability, and non-toxicity. Total reflectance infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and calorimetric/thermal gravimetric (DSC/TGA) analysis results revealed the existence of strong physical interaction between the composite components. Scanning electron microscopy (SEM) observations show a composite sheet with a homogenous and smooth surface, indicating excellent compatibility between HPMC and HAp in the composite. The nanocomposite was evaluated as an adsorbent for organic dyes in an aqueous solution. The effects of solution pH, initial MB concentration, composite concentration, and adsorption time on the adsorption efficiency were evaluated. The highest adsorption rate was seen as 52.0 mg of MB/g composite. The adsorption rate reached equilibrium in about 20 min. Fitting of the adsorption data to the Langmuir and Freundlich adsorption models was investigated. Results showed that the adsorption process follows the Langmuir isotherm model. The kinetic study results revealed that the adsorption process was pseudo-second-order. The herein composite is an excellent alternative for use as contemporary industrial-scale adsorbents.

pH indicator films fabricated from soy protein isolate modified with chitin nanowhisker and Clitoria ternatea flower extract

Sensor films are finding wide range of applications. Different type of sensing films is fabricated for the identification of chemicals, ions, heavy metals, changes in the pH, etc. The present report is on the fabrication of pH sensitive films from completely natural sources-soy protein isolate, chitin nano whiskers and flower extract. The highly crystalline chitin nano whiskers (CNW) were extracted from prawn shell under neutral condition via steam explosion technique. Multifunctional Soy protein isolate (SPI) films were prepared by adding chitin nanowhisker and Clitoria ternatea flower extract and its effect on thermal, mechanical and moisture properties of SPI film was investigated. The isolated CNW presented a needle like morphology with a diameter of 10–50 nm and a crystallinity index of 99.67%. The extracted chitin nanowhisker was used to prepare biodegradable films with soy protein isolate immobilized with anthocyanin from Clitoria ternatea flower extract. The prepared Soy protein -chitin nanowhisker films was found to have a tensile strength of about 15.45 ± 0.97 MPa with 8% chitin nanowhisker addition. The addition of CTE was found to decrease the tensile strength of SPI-CNW film but was found to make the film pH sensitive. The developed indicator film showed visible color changes in acidic and basic medium and hence can be used to monitor the freshness of food materials.

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Thin films were fabricated from soy protein isolate, chitin and anthocyanin.

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Packaging films from fully greener and bio origin.

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pH sensing smart films.

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Easy to fabricate and handle.

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Superior mechanical properties and stability.

Optimization of protease production by Bacillus cereus HMRSC30 for simultaneous extraction of chitin from shrimp shell with value-added recovered products

Chitin extraction from shrimp shell powder (SSP) using protease-producing microbes is an attractive approach for valorizing shrimp shell waste because it is simple and environmentally friendly. In this study, the protease production and chitin extraction from SSP by Bacillus cereus HMRSC30 were simultaneously optimized using statistical approaches. As a result, fermentation in medium composed of 30 g/L SSP, 0.2 g/L MgSO₄ · 7H₂O, 3 g/L (NH₄)₂SO₄, 0.5 g/L K₂HPO₄, and 1.5 g/L KH₂PO₄ (pH 6.5) for 7 days maximized protease production (197.75 ± 0.33 U/mL) to approximately 1.64-fold compared to unoptimized condition (126.8 ± 0.047 U/mL). This level of enzyme production was enough to achieve 97.42 ± 0.28% deproteinization (DP) but low demineralization (DM) of 53.76 ± 0.21%. The high DM of 90% could be easily accomplished with the post-treatment using 0.4 M HCl and acetic acid. In addition, the study evaluated the possible roadmap to maximize the value of generated products and obtain additional profits from this microbial process. The observation showed the possibility of serving crude chitin as a bio-adsorbent with the highest removal capacity against Coomassie brilliant blue (97.99%), followed by methylene blue (74.42%). The recovered protease exhibited the function to remove egg yolk stain, indicating its potential for use as a detergent in de-staining. The results corroborated the benefits of microbial fermentation by B. cereus HMRSC30 as green process for comprehensive utilization of shrimp shell waste as well as minimizing waste generation along the established process.

Applications of chitin and chitosan based biomaterials for the adsorptive removal of textile dyes from water - A comprehensive review

The presence of pollutants in the water bodies deteriorate the water quality and make it unfit for use. From an environmental perspective, it is essential to develop new technologies for the wastewater treatment and recycling of dye contaminated water. The surface modified chitin and chitosan biopolymeric composites based adsorbents, have an important role in the toxic organic dyes from removal wastewater. The surface modification of biopolymers with various organics and inorganics produces more active sites at the surface of the adsorbent, which enhances dye and adsorbent interaction more reliable. Herein, the work brought in the thought of the application of various chitin and chitosan composites in wastewater remediation and suggested the versatility in composites for the development of rapid, selective and effective removal processes for the detoxification of a variety of organic dyes. It further emphasizes the existing obstruction and impending prediction for the deprivation of dyes via adsorption techniques.

High selectivity and adsorption proficiency of surfactant-coated selenium nanoparticles for dye removal application

The rate of environmental pollution augmenting at an alarming rate due to the continuous disposal of toxic dyes directly into the environment and water streams. The direct contact of dyes with water resources directly affects the living beings. The identification of superior methods for the treatment of water pollution caused due to effluent dyes needs higher consideration among researchers for the well-being of living flora and fauna. The available methods for controlling the decontamination of water through toxic dyes have various drawbacks. So, it is highly significant to develop such materials which can easily adsorb the dyes without causing any toxic effect on the environment and living beings. While keeping all the facts in mind, the current work highlights the comparative enhancement in adsorption capacity and selectivity of Brij-58-coated selenium nanoparticles (Brij-58@Se NPs) towards the removal of bromophenol blue (BB) dye from series of chosen dyes in aqueous media. The fabricated Se NPs were methodically characterized and the adsorption behaviour displayed fast adsorption efficiency (98% within 6 min) for BB dye out of series of chosen dyes. The optimization studies were carried out to verify the influence of working variables such as pH (2.0-12.0), response time (1-10 min), dosage amount (0.1-80 mg/l) and concentration of BB dye (1-70 ppm). The adsorption process found to be best fitted for Freundlich adsorption isotherm and pseudo first-order kinetic model. The interference studies of different cationic, anionic species including dyes or metal ions suggested the higher efficiency of Brij-58@Se NPs for adsorptive removal of BB dye from aqueous media. The efficacy of the adsorbent was further tested in six different water resources and displayed 95% adsorption efficiency for BB dye in different wastewater samples. Therefore, Brij-58@Se NP is expected as a potential adsorbent for the adsorption of organic dyes from wastewater samples.

Multifunctional ZnO nanoparticles bio-fabricated from Canna indica L. flowers for seed germination, adsorption, and photocatalytic degradation of organic dyes

The potential of green nanomaterials for environmental and agricultural fields is emerging due to their biocompatible, eco-friendly, and cost-effective performance. We report the use of Canna indica flowers extract as new capping and stabilizing source to bio-fabricate ZnO nanoparticles (ZnO NPs for dyes removal, seed germination. ZnO NPs was biosynthesized by ultrasound-assisted alkaline-free route to reach the critical green strategy. The physicochemical findings of ZnO revealed small crystallite size (27.82 nm), sufficient band-gap energy (3.08 eV), and diverse functional groups. Minimum‑run resolution IV approach found the most pivotal factors influencing on removal of Coomassie Brilliant Blue G-250. Uptake studies pointed out that pseudo second-order, and Langmuir were the best fitted models. Dye molecules behaved monolayer adsorption on ZnO surface layers, and controlled by chemisorption. Natural solar light was used as effective source for photocatalytic degradation of methylene blue (94.23% of removal and 31.09 mg/g of uptake capacity). Compared with H₂O and ZnSO₄, ZnO NPs positively affected the growth of shoot and root lengths (10.2-27.8%) of bean seedlings in most cases. ZnO acts an agrochemical for boosting weight gain, and germination ratio. This study may be promising for developing the recyclable, multifunctional ZnO nanoparticles for environmental and agricultural applications.

Reversible embroidered ball-like antireflective structure arrays inspired by leafhopper wings

Highly transparent leafhopper (Thaia rubiginosa) wings are self-decorated with embroidered ball-shaped proteinaceous brochosmoes as distinct anti-predator defenses. The non-sticky brochosomal coating serves as antireflective structures for camouflage in vegetated environments. Inspired by the leafhopper wings, this study reports a new type of reversible antireflection coating enabled by integrating self-assembly methodologies using a shape memory polymer. The resulting embroidered ball-like structure array establishes a refractive index transition on surface, and thereby behaves omnidirectional antireflective characteristics in a broadband visible light region. Interestingly, the highly transparent appearance can be instantly erased and recovered by submerging in common liquids, such as water and ethanol, or by applying contact pressures at ambient conditions. Furthermore, the reversibility and structure-shape effect on the antireflective characteristics are systematically evaluated in this study.

Fabrication of Photoactive Electrospun Cellulose Acetate Nanofibers for Antibacterial Applications

The aim of the study was to investigate the process of electrostatic fabrication of cellulose acetate (CA) nanofibers containing methylene blue (MB) as a photosensitizer. The electrical, physicochemical, and biocidal properties of the prepared material were given. CA nanofibers were prepared by electrospinning method using a solvent mixture of acetone and distilled water (9:1 vv−1) and different concentrations of CA (i.e., 10–21%). Additionally, methylene blue was implemented into the polymer solution with a CA concentration of 17% to obtain fibers with photo-bactericidal properties. Pure electrospun CA fibers were more uniform than fibers with MB (i.e., ribbon shape). Fiber diameters did not exceed 900 nm for the tested polymer solutions and flow rate below 1.0 mL h−1. The polymer properties (i.e., concentration, resistivity) and other parameters of the process (i.e., flow rate, an applied voltage) strongly influenced the size of the fibers. Plasma treatment of nanofibers resulted in reduced biofilm formation on their surface. The results of photo-bactericidal activity (i.e., up to 180 min) confirmed the high efficiency of inactivation of Staphylococcus aureus cells using fibers containing methylene blue (i.e., with and without plasma treatment). The most effective reduction in the number of biofilm cells was equal to 99.99 ± 0.3%.

One-pot synthesis of zinc oxide nanoparticles via chemical precipitation for bromophenol blue adsorption and the antifungal activity against filamentous fungi

In this research, zinc oxide nanoparticles (ZnONPs) were prepared via a facile one-pot chemical precipitation approach and applied in the adsorption of bromophenol blue (BRB) and as antifungal agents against the filamentous fungi and plant pathogens; Alternaria alternata CGJM3078, Alternaria alternata CGJM3006 and Fusarium verticilliodes CGJM3823. The ZnONPs were characterized by the UV-Vis, FTIR, XRD, TGA, BET, SEM, TEM, and EDX techniques, which showed efficient synthesis. The characteristics ZnO UV-Vis absorption band was observed at 375 nm, while the XRD showed an average ZnONPs crystalline size of 47.2 nm. The SEM and TEM images showed an irregular shaped and aggregated porous structure of 65.3 nm average-sized ZnONPs. The TGA showed 22.9% weight loss at 800 °C indicating the high thermal stability of ZnONPs, while BET analysis revealed a surface area, pore volume and pore diameter of 9.259 m2/g, 0.03745 cm3/g and 9.87 nm respectively. The Freundlich, pseudo-second-order, and intra-particle diffusion models showed R2 > 0.9494 and SSE < 0.7412, thus, exhibited the best fit to the isotherm and kinetics models. Thermodynamics revealed feasible, endothermic, random, and spontaneous adsorption of BRB onto the synthesized ZnONPs. The antifungal assay conducted depicts strong antifungal activities against all three tested fungi. Noticeably, ZnONPs (0.002-5 mg/mL) showed maximum activities with the largest zone of inhibition against A. alternata CGJM 3006 from 25.09 to 36.28 mm. This was followed by the strain F. verticilliodes CGJM 3823 (range from 23.77 to 34.77 mm) > A. alternata CGJM3078 (range from 22.73 to 30.63 mm) in comparison to Bleach 5% (positive control). Additionally a model was proposed based on the possible underlying mechanisms for the antifungal effect. This research demonstrated the potent use of ZnONPs for the adsorption of BRB and as effective antifungal agents.

The cross-talk between lateral sheet dimensions of pristine graphene oxide nanoparticles and Ni2+ adsorption

This study investigated the removal of nickel(ii) ions by using two sizes of graphene oxide nanoparticles (GO - 450 nm and GO - 200 nm). The thickness and lateral sheet dimensions of GO are considered to be an important adsorbent and promising method for sufficient removal of metals like nickel, lead, copper, etc. The graphite oxide was prepared by oxidation-reduction reaction (Hummers method), and the final product was labelled as GO - 450 nm. A tip sonicator was used to reduce the size of particles to 200 nm under controlled conditions (time and power of sonication). FTIR spectroscopy shows that both sizes of GO particles contain several types of oxygen groups distributed onto the surface of GO particles. Scanning electron microscopy (SEM) and the statistical analysis confirmed the formation of these two sizes of GO particles. The GO - 200 nm performed better removal of Ni(ii) compared with GO - 450 nm, due to more surfaces being available. The adsorption capacity of GO particles increased drastically from 45 mg g-1 to 75 mg g-1 for GO - 450 nm and GO - 200 nm respectively, these values were carried out after 2 h of incubation. The kinetics of adsorption and several parameters like initial concentration at equilibrium, pH, temperature, and adsorbent dose are controlled and studied by using UV-visible spectroscopy. The results indicated a significant potential of GO - 200 nm as an adsorbent for Ni(ii) ion removal. An additional experiment was performed to estimate the surface area of GO - 450 nm and GO - 200 nm, the results show that the surface areas of GO - 450 nm and GO - 200 nm are 747.8 m2 g-1 and 1052.2 m2 g-1 respectively.

Ultrasound-irradiated synthesis of 3-mercaptopropyl trimethoxysilane-modified hydroxyapatite derived from fish-scale residues followed by ultrasound-assisted organic dyes removal

We report a novel method for the synthesis of 3-mercaptopropyl trimethoxysilane-modified hydroxyapatite (FHAP-SH) derived from fish-scale residues by using ultrasound irradiation. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the FHAP-SH characterization. Then, the organic dye adsorption on the FHAP-SH was monitored through an ultrasound process. After the dye removal optimization, significant improvements were observed in the maximum adsorption capacities for Congo Red (CR, 500 mg g^-1), Coomassie Brilliant Blue G 250 (CB, 235 mg g^-1), and Malachite Green (MG, 625 mg g^-1). The adsorption behaviors of these dyes were fitted by using the Langmuir isotherm model with a high coefficient of determination values ranging from 0.9985 to 0.9969. The adsorption of the three dyes onto FHAP-SH was an endothermic process based on the adsorption thermodynamics model, while the adsorption kinetics analysis of the dyes presented a good alignment with the pseudo-second-order kinetics. The FHAP-SH exhibits a remarkably high adsorption capacity, is inexpensive, and fulfills the ecofriendly requirements of dye wastewater treatment, especially in the textile industry.

Adsorption of Methylene blue and Congo red from aqueous solution using synthesized alumina-zirconia composite

Alumina-zirconia (Al₂O₃-ZrO₂) composite was prepared by combustion method and used to remove Congo red and Methylene blue from aqueous solutions. It was characterized using SEM-EDS, XRD and gas adsorption techniques. The results obtained from gas adsorption and SEM agree with each other, showing meso- and macro-porosity of inter-agglomerate pores. The removal of the two dyes was pH dependent, acidic pH favoured Congo red removal, while basic pH favoured Methylene blue. The, mechanism of adsorption was not limited to electrostatic attraction between the adsorbent and the dye molecules. Adsorption kinetic of both dyes was consistent with Pseudo-second-order model. The data obtained fitted to Langmuir and Liu isotherm models, with the maximum adsorption capacity of 57. 50 and 53.44 mg g^-1 for Congo red and Methylene blue, respectively. The thermodynamic parameters indicated that the adsorption is spontaneous and exothermic. The mechanism of adsorption was elucidated using XRD and FTIR techniques.

Biosorption of cationic and anionic dyes using the biomass of Aspergillus parasiticus CBS 100926T

Aspergillus parasiticus (A. parasiticus) CBS 100926^T was used as a biosorbent for the removal of Methylene Blue (MB), Congo Red (CR), Sudan Black (SB), Malachite Green Oxalate (MGO), Basic Fuchsin (BF) and Phenol Red (PR) from aqueous solutions. The batch biosorption studies were carried out as a function of dye concentration and contact time. The biosorption process followed the pseudo-first-order and the pseudo-second-order kinetic models and the Freundlich and Langmuir isotherm models. The resulting biosorbent was characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometer and Fourier Transformer Infrared Spectroscopy (FTIR) techniques. The results of the present investigation suggest that A. parasiticus can be used as an environmentally benign and low cost biomaterial for the removal of basic and acid dyes from aqueous solution.

NZF Nanoscale Particles: Synthesis, Characterization and its Effective Adsorption of Bromophenol Blue

The ferrospinels NixZn1_xFe2O4 (x = 0.0 and 0.6) nanoparticles (NPs) were successfully prepared by a sol-gel method and analyzed by TGA/DTA, XRD, SEM-EDS, UV-Vis-DRS, and pHIEP. The adsorption potential of NZF NPs towards the Bromophenol blue (BPB) dye was investigated. The batch adsorption efficiency parameters were studied including contact time, pH, initial dye concentrations and catalyst dosage. Results indicated that NZF crystallized in single-phase and exhibited smaller crystallite size (49 nm vs. 59.24 nm) than that of the pristine (ZF). The SEM analysis showed that the materials are elongated-like shape. NZF catalyst showed a red-shift of absorption bands and a more narrowed band gap (2.30 eV vs. 1.65 eV) as compared to ZF. The adsorption process was found to be highly dependent to the pH of the solution, dye concentration and adsorbent dose. Under optimum conditions of 5 mg.L–1 BPB, 0.5 g.L–1 NZF catalyst, pH = 6, and 25 °C, up to ≈ 86.30%  removal efficiency could be achieved after 60 min. Pseudo-second-order kinetic model gave the best fit with highest correlation coefficients (R2 ≥ 0.99). A high specific surface area, a stabilized dispersion state of NZF NPs and the electrostatic interaction between the BPB-2 anions and the NZF-H3O+active sites on NZF surface were believed to be the main factors that can be responsible for the high adsorption efficiency. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).  

Synthesis of hierarchically structured ɤ-Fe2O3-PPy nanocomposite as effective adsorbent for cationic dye removal from wastewater

Industrial dye effluents, which are a major wastage component that enter the natural environment, pose a significant health risk to human and aquatic life. Therefore, the effective removal of dye effluents is a major concern. Against this backdrop, in this study, a low-cost, earth-abundant, and ecofriendly ɤ-Fe₂O₃-PPy nanocomposite was prepared employing the conventional hydrothermal method. The morphology, functional groups, and elemental composition of ɤ-Fe₂O₃-PPy were characterized by XRD, SEM, XPS, and FTIR studies. Under optimized conditions, the prepared novel ɤ-Fe₂O₃-PPy nanocomposite showed a high methylene blue (MB) adsorption capacity of 464 mg/g, which is significantly higher than that of existing adsorbents such as CNTs and polymer-modified CNTs. The adsorption parameters such as pH, adsorbent dosage, and ionic strength were optimized to enhance the MB adsorption capacity. The adsorption results revealed that MB is adsorbed onto the adsorbent surface via electrostatic interactions, hydrogen bonding, and chemical binding interactions. In terms of practical application, the adsorbent's adsorption-desorption ability in conjunction with magnetic separation was investigated; the prepared ɤ-Fe₂O₃-PPy nanocomposite exhibited excellent adsorption and desorption efficiencies over more than seven adsorption-desorption cycles.

Biogenic and chemically synthesized Solanum tuberosum peel-silver nanoparticle hybrid for the ultrasonic aided adsorption of bromophenol blue dye

This work was aimed at the synthesis of a hybrid (STpe-AgNP), obtained by impregnation of silver nanoparticles (AgNP) onto Solanum tuberosum peel (STpe), for the ultrasonic assisted adsorption of bromophenol blue (BB) dye. SEM, FTIR, XRD, EDX, TGA and BET techniques were used to characterize the adsorbents. The XRD, SEM and EDX confirmed successful impregnation of AgNPs onto STpe to form the hybrid. The AgNPs impregnated onto the hybrid were found to be water stable at various pH values of 2.0-9.0. Chi-square (χ2 < 0.024) and linear regression (R2 > 0.996) showed that the Freundlich model was best fitted among the isotherm models, corroborated by the oriented site model. Kinetic analysis conformed to the intraparticle diffusion and pseudo-first-order rate equations, while thermodynamics displayed a physical, spontaneous and endothermic adsorption process. The presence of competing Pb(II), Ni(II), Cd(II) and Zn(II) metal ions in solution interfered with the adsorption of BB onto the biosorbents. In terms of reusability, STpe and STpe-AgNP showed BB desorption of 91.3% and 88.5% respectively, using NaOH as eluent. Ultra-sonication significantly enhanced the adsorption of BB by both adsorbents, but the impregnation of AgNPs only slightly improved adsorption of the dye from the simulated wastewater. This study also illustrated that pristine STpe biomass waste is a cheap viable option for the decontamination of BB from water.

Biosorption and regeneration potentials of magnetite nanoparticle loaded Solanum tuberosum peel for celestine blue dye

This research evaluated the adsorption of celestine blue (CB) onto a novel Solanum tuberosum waste-magnetite nanocomposite (Mt@STB), prepared by an ecofriendly impregnation of magnetite (Mt) nanoparticles onto Solanum tuberosum waste (STB). The adsorbents characterization revealed that Mt@STB had a surface area (18.92 m²/g), pHpzc (7.55), porous morphology as well as suitable functional groups for efficient sequestration of CB onto the composite. The SEM, XRD, and EDX showed successful incorporation of 31.21 nm average size Mt nanoparticles on Mt@STB. Faster kinetics of CB sequestration from the wastewater was obtained for Mt@STB (100 min) compared to STB (140 min). Among four isotherm models, the Langmuir exhibited the best fit with R² > 0.9971 and sum square errors (SSE) < 0.0151. The pristine STB and Mt@STB composite showed maximum monolayer CEB uptake of 7.61 and 9.02 mg/g, as well as optimum removal of 73.8 and 84.7%, respectively. The pseudo-second-order model was more suitable in the kinetic description, while thermodynamics revealed a physical, spontaneous, and endothermic CB uptake. Besides, the efficacy of the composite for CB was confirmed from efficient regeneration over three adsorption/desorption cycles, which specified the viability of Mt@STB as a sustainable material for the decontamination of CB polluted water. NOVELTY STATEMENT The adsorption of dyes from wastewaters has been widely studied due to the harmful effects on the ecosystem. However, research on the removal of celestine blue (CB) dye is rare despite its wide use in the nuclear and textile industries. Until date, there is no report on the adsorption of CB on biomaterial via biosorption. Therefore, the biosorption behavior of CB is presently unknown. Hence, this study reports the biosorption of CB onto a biosorbent (Solanum tuberosum peel [STB]) in an attempt to understand its biosorption behavior. Besides, the impregnation of magnetite (Mt) nanoparticles has been reported to enhance the uptake of most adsorbents for dye. To the best of our knowledge, such magnetic nanoparticle impregnation of STB has not been reported. We, therefore, synthesized a novel biowaste-magnetite composite (Mt@STB) and evaluated its potentials for the uptake as well as its reuse for CB biosorption.

Chitin and Chitinases: Biomedical And Environmental Applications of Chitin and its Derivatives

Disposal of chitin wastes from crustacean shell can cause environmental and health hazards. Chitin is a well known abundant natural polymer extracted after deproteinization and demineralization of the shell wastes of shrimp, crab, lobster, and krill. Extraction of chitin and its derivatives from waste material is one of the alternative ways to turn the waste into useful products. Chitinases are enzymes that degrade chitin. Chitinases contribute to the generation of carbon and nitrogen in the ecosystem. Chitin and chitinolytic enzymes are gaining importance for their biotechnological applications. The presence of surface charge and multiple functional groups make chitin as a beneficial natural polymer. Due to the reactive functional groups chitin can be used for the preparation of a spectrum of chitin derivatives such as chitosan, alkyl chitin, sulfated chitin, dibutyryl chitin and carboxymethyl chitin for specific applications in different areas. The present review is aimed to summarize the efficacy of the chitinases on the chitin and its derivatives and their diverse applications in biomedical and environmental field. Further this review also discusses the synthesis of various chitin derivatives in detail and brings out the importance of chitin and its derivatives in biomedical and environmental applications.

An Overview of the Water Remediation Potential of Nanomaterials and Their Ecotoxicological Impacts

Nanomaterials, i.e., those materials which have at least one dimension in the 1–100 nm size range, have produced a new generation of technologies for water purification. This includes nanosized adsorbents, nanomembranes, photocatalysts, etc. On the other hand, their uncontrolled release can potentially endanger biota in various environmental domains such as soil and water systems. In this review, we point out the opportunities created by the use of nanomaterials for water remediation and also the adverse effects of such small potential pollutants on the environment. While there is still a large need to further identify the potential hazards of nanomaterials through extensive lab or even field studies, an overview on the current knowledge about the pros and cons of such systems should be helpful for their better implementation.

The Nanosized Dye Adsorbents for Water Treatment

Clean water is a vital element for survival of any living creature and, thus, crucially important to achieve largely and economically for any nation worldwide. However, the astonishingly fast trend of industrialization and population growth and the arisen extensive water pollutions have challenged access to clean water across the world. In this regard, 1.6 million tons of dyes are annually consumed. Thereof, 10%–15% are wasted during use. To decolorize water streams, there is an urgent need for the advanced remediation approaches involving utilization of novel materials and technologies, which are cost and energy efficient. Nanomaterials, with their outstanding physicochemical properties, can potentially resolve the challenge of need to water treatment in a less energy demanding manner. In this review, a variety of the most recent (from 2015 onwards) opportunities arisen from nanomaterials in different dimensionalities, performances, and compositions for water decolorization is introduced and discussed. The state-of-the-art research studies are presented in a classified manner, particularly based on structural dimensionality, to better illustrate the current status of adsorption-based water decolorization using nanomaterials. Considering the introduction of many newly developed nano-adsorbents and their classification based on the dimensionality factor, which has never been employed for this sake in the related literature, a comprehensive review will be presented.

Shape-tunable CuO-Nd(OH)3 nanocomposites with excellent adsorption capacity in organic dye removal and regeneration of spent adsorbent to reduce secondary waste

Herein, we report for the first time, the synthesis of CuO-Nd(OH)₃ nanocomposites via a co-precipitation method coupled with the hydrothermal aging process. Varying the pH of the reaction medium, the shape of the nanocomposites could be controlled which determines their surface areas. These CuO-Nd(OH)₃ nanocomposites exhibit very high adsorption capacity with successful removal of ∼ 97% of brilliant blue G (BBG) from water in 180 min under ambient condition. The adsorption process primarily follows Lagergren pseudo-first-order kinetics. The Langmuir isotherm model fits well with a very high monolayer adsorption capacity of 394.1 mg g^-1 at 30 °C. The mechanistic study supports chemisorption-type adsorption between the dye molecule and the adsorbent. Regeneration of the spent adsorbent makes the whole process cyclic and eco-friendly.