Bacterial cellulose/attapulgite magnetic composites as an efficient adsorbent for heavy metal ions and dye treatment

Nanocellulose-Based Materials for Water Pollutant Removal: A Review

Cellulose in the nano regime, defined as nanocellulose, has been intensively used for water treatment. Nanocellulose can be produced in various forms, including colloidal, water redispersible powders, films, membranes, papers, hydrogels/aerogels, and three-dimensional (3D) objects. They were reported for the removal of water contaminants, e.g., heavy metals, dyes, drugs, pesticides, pharmaceuticals, microbial cells, and other pollutants from water systems. This review summarized the recent technologies for water treatment using nanocellulose-based materials. A scientometric analysis of the topic was also included. Cellulose-based materials enable the removal of water contaminants, and salts offer advanced technologies for water desalination. They are widely used as substrates, adsorbents, and catalysts. They were applied for pollutant removal via several methods such as adsorption, filtration, disinfection, coagulation/flocculation, chemical precipitation, sedimentation, filtration (e.g., ultrafiltration (UF), nanofiltration (NF)), electrofiltration (electrodialysis), ion-exchange, chelation, catalysis, and photocatalysis. Processing cellulose into commercial products enables the wide use of nanocellulose-based materials as adsorbents and catalysts.

Acid modified attapulgite loaded with bacillomycin D for mold inhibition and mycotoxin removal

Molds and mycotoxins pose severe threats to health. Bacillomycin D (BD) can effectively inhibit mold growth. Attapulgite (ATP) can provide a good carrier for antimicrobial agents. Natural ATP was acid-modified to obtain H-ATP. It was used to load BD to obtain a novel composite material (H-ATP-BD). The results showed H-ATP had better adsorption performance than ATP. BD was adsorbed up to 93.13 % by adding 30 mg H-ATP and stirring at 40 ℃ for 120 min. Fourier transform infrared spectra (FTIR), size and zeta potential, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results confirmed successful loading of BD onto H-ATP. The composite showed good inhibition of Aspergillus and adding 0.6 % H-ATP-BD composite was effective in removing 89.06 % of aflatoxin B1 (AFB1) at 50 °C. Model fitting indicated that AFB1 removal was a spontaneous exothermic reaction. This research will lay the foundation for the development of efficient and green antimicrobial and toxin-reducing materials.

Recent developments in synthesis of attapulgite composite materials for refractory organic wastewater treatment: a review

Attapulgite clay, due to its unique crystalline hydrated magnesium-aluminium silicate composition and layer-chain structure, possesses exceptional adsorption and catalytic properties, which enable it or its composites to be utilized as adsorbents and catalysts for wastewater treatment. But the drawbacks of attapulgite are also very obvious, such as relatively low specific surface area (compared to traditional adsorbents such as activated carbon and activated alumina), easy aggregation, and difficulty in dispersion. In order to fully utilize and improve the performance of attapulgite, researchers have conducted extensive research on its modification, but few specialized works have comprehensively evaluated the synthesis, applications and challenges for attapulgite-based composite materials in refractory organic wastewater treatments. This paper provides a comprehensive review of controllable preparation strategies, characterization methods and mechanisms of attapulgite-based composite materials, as well as the research progress of these materials in refractory organic wastewater treatment. Based on this review, constructive recommendations, such as deep mechanism analysis from molecular level multi-functional attapulgite-based material developments, and using biodegradable materials in attapulgite-based composites, were proposed.

Functionalization of bacterial cellulose: Exploring diverse applications and biomedical innovations: A review

The demand for the functionalization of additive materials based on bacterial cellulose (BC) is currently high due to their potential applications across various sectors. The preparation of BC-based additive materials typically involves two approaches: in situ and ex situ. In situ modifications entail the incorporation of additive materials, such as soluble and dispersed substances, which are non-toxic and not essential for bacterial cell growth during the production process. However, these materials can impact the yield and self-assembly of BC. In contrast, ex situ modification occurs subsequent to the formation of BC, where the additive materials are not only adsorbed on the surface but also impregnated into the BC pellicle, while the BC slurry was homogenized with other additive materials and gelling agents to create composite films using the casting method. This review will primarily focus on the in situ and ex situ functionalization of BC then sheds light on the pivotal role of functionalized BC in advancing biomedical technologies, wound healing, tissue engineering, drug delivery, bone regeneration, and biosensors.

A sustainable bioprocess to produce bacterial cellulose (BC) using waste streams from wine distilleries and the biodiesel industry: evaluation of BC for adsorption of phenolic compounds, dyes and metals

BACKGROUND

The main challenge for large-scale production of bacterial cellulose (BC) includes high production costs interlinked with raw materials, and low production rates. The valorization of renewable nutrient sources could improve the economic effectiveness of BC fermentation while their direct bioconversion into sustainable biopolymers addresses environmental pollution and/or resource depletion challenges. Herein a green bioprocess was developed to produce BC in high amounts with the rather unexplored bacterial strain Komagataeibacter rhaeticus, using waste streams such as wine distillery effluents (WDE) and biodiesel-derived glycerol. Also, BC was evaluated as a bio-adsorbent for phenolics, dyes and metals removal to enlarge its market diversification.

RESULTS

BC production was significantly affected by the WDE mixing ratio (0-100%), glycerol concentration (20-45 g/L), type of glycerol and media-sterilization method. A maximum BC concentration of 9.0 g/L, with a productivity of 0.90 g/L/day and a water holding capacity of 60.1 g water/g dry BC, was achieved at 100% WDE and ≈30 g/L crude glycerol. BC samples showed typical cellulose vibration bands and average fiber diameters between 37.2 and 89.6 nm. The BC capacity to dephenolize WDE and adsorb phenolics during fermentation reached respectively, up to 50.7% and 26.96 mg gallic acid equivalents/g dry BC (in-situ process). The produced BC was also investigated for dye and metal removal. The highest removal of dye acid yellow 17 (54.3%) was recorded when 5% of BC was applied as the bio-adsorbent. Experiments performed in a multi-metal synthetic wastewater showed that BC could remove up to 96% of Zn and 97% of Cd.

CONCLUSIONS

This work demonstrated a low-carbon approach to produce low-cost, green and biodegradable BC-based bio-adsorbents, without any chemical modification. Their potential in wastewater-treatment-applications was highlighted, promoting closed-loop systems within the circular economy era. This study may serve as an orientation for future research towards competitive or targeted adsorption technologies for wastewater treatment or resources recovery.

An Updated Overview of Magnetic Composites for Water Decontamination

Water contamination by harmful organic and inorganic compounds seriously burdens human health and aquatic life. A series of conventional water purification methods can be employed, yet they come with certain disadvantages, including resulting sludge or solid waste, incomplete treatment process, and high costs. To overcome these limitations, attention has been drawn to nanotechnology for fabricating better-performing adsorbents for contaminant removal. In particular, magnetic nanostructures hold promise for water decontamination applications, benefiting from easy removal from aqueous solutions. In this respect, numerous researchers worldwide have reported incorporating magnetic particles into many composite materials. Therefore, this review aims to present the newest advancements in the field of magnetic composites for water decontamination, describing the appealing properties of a series of base materials and including the results of the most recent studies. In more detail, carbon-, polymer-, hydrogel-, aerogel-, silica-, clay-, biochar-, metal-organic framework-, and covalent organic framework-based magnetic composites are overviewed, which have displayed promising adsorption capacity for industrial pollutants.

A novel oyster shell biocomposite for the efficient adsorptive removal of cadmium and lead from aqueous solution: Synthesis, process optimization, modelling and mechanism studies

This study highlights the effectiveness of oyster shell biocomposite for the biosorption of Cd(II) and Pb(II) ions from an aqueous solution. The aim of this work was to modify a novel biocomposite derived from oyster shell for the adsorption of Cd(II) and Pb(II) ions from aqueous solution. The studied revealed the specific surface BET surface area was 9.1476 m2/g. The elemental dispersive x-ray analysis (EDS) indicated that C, O, Ag, Ca were the predominant elements on the surface of the biocomposite after which metals ions of Cd and Pb were noticed after adsorption. The Fourier transform Irradiation (FT-IR) revealed the presence of carboxyl and hydroxyl groups on the surface. The effect of process variables on the adsorption capacity of the modified biocomposite was examined using the central composite design (CCD) of the response surface methodology (RSM). The process variables which include pH, adsorbent dose, the initial concentration and temperature were the most effective parameters influencing the uptake capacity. The optimal process conditions of these parameters were found to be pH, 5.57, adsorbent dose, 2.53 g/L, initial concentration, 46.76 mg/L and temperature 28.48°C for the biosorption of Cd(II) and Pb(II) ions from aqueous solution at a desirability coefficient of 1. The analysis of variance (ANOVA) revealed a high coefficient of determination (R2 > 0.91) and low probability coefficients for the responses (P < 0.05) which indicated the validity and aptness of the model for the biosorption of the metal ions. Experimental isotherm data fitted better to the Langmuir model and the kinetic data fitted better to the pseudo-second-order model. Maximun Cd(II) and Pb(II) adsorption capacities of the oyster shell biocomposite were 97.54 and 78.99 mg/g respectively and was obtained at pH 5.56 and 28.48°C. This investigation has provided the possibility of the utilization of alternative biocomposite as a sustainable approach for the biosorption of heavy metal ions from the wastewater stream.

Fabrication of cationic cellulose nanofibrils/sodium alginate beads for Congo red removal

Congo red is hard to remove from dye wastewater due to its structure stability and high chemical oxygen demand. In this study, cationic cellulose nanofibrils (CCNF) prepared from herb residues was physically crosslinked with sodium alginate (SA) in the presence of calcium ions, and the obtained CCNF/SA beads were used to adsorb Congo red. Results showed that CCNF/SA beads with porous internal structure were beneficial to adsorption. The maximum adsorption capacity of Congo red could reach to 518.4 mg/g, which was superior to most cellulose-based adsorption materials. Furthermore, the equilibrium adsorption isotherms and XPS analysis indicated the adsorption for Congo red was a physical process, and hydrogen bond and electrostatic adsorption were proposed as dominant adsorption mechanism. In addition, the Congo red removal efficiency of the beads was still higher than 70% after three cycles. Therefore, this high efficiency and green beads have great potential as adsorbents for anionic dyes removal.

Bioremediation of n-alkanes, polycyclic aromatic hydrocarbons, and heavy metals from wastewater using seaweeds

The removal of n-alkanes, polycyclic aromatic hydrocarbons, and heavy metals from wastewater using three dried seaweeds Ulva intestinalis Linnaeus (green alga), Sargassum latifolium (Turner) C.Agardh (brown alga), and Corallina officinalis Kützing (red alga) has been shown to evaluate their potential usage as inexpensive adsorbents. Under natural environmental conditions, numerous analytical methods, including zeta potential, energy dispersive X-ray spectroscopy (EDX), SEM, and FT-IR, are used in this study. The results showed that n-alkanes and polycyclic aromatic hydrocarbons adsorption increased with increasing contact time for all three selected algae, with a large removal observed after 15 days, while the optimal contact time for heavy metal removal was 3 h. S. latifolium dry biomass had more potential as bioadsorbent, followed by C. officinalis and then U. intestinalis. S. latifolium attained removal percentages of 65.14%, 72.50%, and 78.92% for light n-alkanes, heavy n-alkanes, and polycyclic aromatic hydrocarbons (PAHs), respectively, after 15 days. Furthermore, it achieved removal percentages of 94.14, 92.62, 89.54, 87.54, 82.76, 80.95, 77.78, 73.02, and 71.62% for Mg, Zn, Cu, Fe, Cr, Pb, Cd, Mn, and Ni, respectively, after 3 h. Carboxyl and hydroxyl from FTIR analysis took part in wastewater treatment. The zeta potentials revealed that algal cells have a negatively charged surface, and the cell surface of S. latifolium has a more negative surface charge than U. intestinalis and C. officinalis. Our study suggests that seaweeds could play an important role in wastewater treatment and thus help as an economical, effective, and ecofriendly bioremediation system for ecological health and life protection.

Bacterial Cellulose Aerogels Derived from Pineapple Peel Waste for the Adsorption of Dyes

Valorization of pineapple peel waste is an attractive research topic because of the huge quantities of this byproduct generated from pineapple processing industries. In this study, the extract from pineapple waste was collected to produce a hydrogel-like form containing bacterial cellulose fibers with a three-dimensional structure and nanoscale diameter by the Acetobacter xylinum fermentation process. The bacterial cellulose suspension was subsequently activated by freeze-drying, affording lightweight aerogels as potential adsorbents in wastewater treatment, in particular the adsorptive removal of organic dyes. Intensive tests were carried out with the adsorption of methylene blue, a typical cationic dye, to investigate the influence of adsorption conditions (temperature, pH, initial dye concentration, time, and experiment scale) and aerogel-preparation parameters (grinding time and bacterial cellulose concentration). The bacterial cellulose-based aerogels exhibited high adsorption capacity not only for methylene blue but also for other cationic dyes, including malachite green, rhodamine B, and crystal violet (28-49 mg/g). However, its activity was limited for most of the anionic dyes, such as methyl orange, sunset yellow, and quinoline yellow, due to the repulsion of these anionic dyes with the aerogel surface, except for the case of congo red. It is also an anionic dye but has two amine groups providing a strong interaction with the hydroxyl group of the aerogel via hydrogen bonding. Indeed, the aerogel has a substantially large congo red-trapping capacity of 101 mg/g. Notably, the adsorption process exhibited similar performances, upscaling the solution volume to 50 times. The utilization of abundant agricultural waste in the simple aerogel preparation to produce a highly efficient and biodegradable adsorbent is the highlight of this work.

Carbonized bacterial cellulose/FeMn composite as efficient catalyst toward contaminant degradation: The crucial role of hydrogen reduction

The structure especially the active site manipulation of Fenton-like catalysts was essential for the efficient removal of organic contaminants in the aquatic environment. In this study, the carbonized bacterial cellulose/FeMn oxide composite (CBC@FeMnO_x) were synthetized and modified by hydrogen (H₂) reduction to obtain the carbonized bacterial cellulose/FeMn composite (CBC@FeMn), with emphasis on the processes and mechanisms for atrazine (ATZ) attenuation. The results showed that H₂ reduction did not change the microscopic morphology of the composites but destroy the Fe-O and Mn-O structures. Compared with the CBC@FeMnO_x composite, the H₂ reduction could promote the removal efficiency from 62% to 100% for CBC@FeMn, as well as the enhancement of degradation rate from 0.021 min^-1 to 0.085 min^-1. The quenching experiments and electron paramagnetic resonance (EPR) displayed that the hydroxyl radicals (•OH) was the major contributor for ATZ degradation. The investigation for Fe and Mn species indicated that H₂ reduction could increase the content of Fe(II) and Mn(III) in the catalyst, thus improving the generation of •OH and accelerating the cycle process between Fe(III)/Fe(II). Owing to the excellent reusability and stability, it was indicated that the H₂ reduction can be considered as an efficient way to regulate the chemical valence of the catalyst, thus enhancing the removal efficiency of aquatic contaminants.

An Eco-Friendly Adsorbent Based on Bacterial Cellulose and Vermiculite Composite for Efficient Removal of Methylene Blue and Sulfanilamide

In this work, a novel composite of bacterial cellulose (BC) and expanded vermiculite (EVMT) composite was used to adsorb dyes and antibiotics. The pure BC and BC/EVMT composite were characterized using SEM, FTIR, XRD, XPS and TGA. The BC/EVMT composite exhibited a microporous structure, providing abundant adsorption sites for target pollutants. The adsorption performance of the BC/EVMT composite was investigated for the removal of methylene blue (MB) and sulfanilamide (SA) from an aqueous solution. The adsorption capacity of BC/ENVMT for MB increased with increasing pH, while the adsorption capacity for SA decreased with increasing pH. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. As a result, the adsorption of MB and SA by the BC/EVMT composite was found to follow the Langmuir isotherm well, indicating a monolayer adsorption process on a homogeneous surface. The maximum adsorption capacity of the BC/EVMT composite was found to be 92.16 mg/g for MB and 71.53 mg/g for SA, respectively. The adsorption kinetics of both MB and SA on the BC/EVMT composite showed significant characteristics of a pseudo-second-order model. Considering the low cost and high efficiency of BC/EVMT, it is expected to be a promising adsorbent for the removal of dyes and antibiotics from wastewater. Thus, it can serve as a valuable tool in sewage treatment to improve water quality and reduce environmental pollution.

Fabrication of a corn stalk derived cellulose-based bio-adsorbent to remove Congo red from wastewater: Investigation on its ultra-high adsorption performance and mechanism

A cellulose-based bio-absorbent with various and plenty of amino groups was successfully prepared from corn stalk to achieve quantitative removal of Congo red from wastewater with wide pH values (5 ≤ pH ≤ 10). The maximum removal amount was 8.0 mmol·g^-1 (5572 mg·g^-1) under pH = 6.0 and 45 °C, which was obviously higher than reported absorbents. Investigation on dynamic adsorption and recyclability in authentic wastewater found that the removal efficiency of Congo red was >98 % within 180 min and decreased slightly in industrial water after five cycles, denoting this adsorbent with great potential for environmental application. The characterization results proved that 7.58 mmol·g^-1 of different amino groups (-NH₂, -NH- and -NR₂) were introduced on adsorbent surface by two steps of modification and were the major functional groups for adsorption of Congo red. The inferred adsorption mechanism revealed that Congo red could be adsorbed equivalently on the amino groups by strong electrostatic interactions or hydrogen bonds. Different amino groups played different roles in adsorption due to great differences in protonation ability in 5 ≤ pH ≤ 10. The study was expected to high-efficiently remove Congo red from acidic or alkaline wastewater, and offered an alternative strategy for biowaste treatment of corn stalks in a high value-added manner.

Preparation of a novel hydrogel of sodium alginate using rural waste bone meal for efficient adsorption of heavy metals cadmium ion

Adsorption has been an important method for removing heavy metals from industrial wastewater. However, there has been a lack of an environmentally friendly, low-cost, biodegradable and easily recyclable material. China produces bones are not fully utilized leads to a waste of resources Therefore, efficient application of bone meal (BM) for remediation of contaminants in water would provide a promising alternative for resource utilization of bones. In this paper, we use a combination of BM and sodium alginate (SA) to prepare a novel BM/SA/calcium ion (BM/SA/Ca²⁺) double cross-linked composite hydrogel (BMSAH). Enhance the mechanical structure of SA while making the BM easy to recycle and reuse. The morphology and structure of the BMSAH were characterized using FT-IR spectroscopy and SEM-EDS. suggesting that the BMSAH can provide a larger specific surface area and high number of adsorption sites. The effects of the solution pH, ionic strength and contact time on the adsorption capacity of the BMSAH were investigated in depth, Under different conditions, BMSAH has a strong adsorption capacity of >90 %. XPS and FT-IR analysis showed that Cd²⁺ was adsorbed mainly via coordination interactions and hydrogen bonds with the carboxyl groups and nitrogen atoms in the BMSAH. A pseudo-second-order kinetic model, particle diffusion model and Isothermal adsorption lines indicate that the surface of the BMSAH is non-uniform suggesting that the adsorption of heavy metal ions by the BMSAH involves a combination of surface adsorption and intraparticle diffusion mechanisms, which is an overall chemical-physical adsorption process. In addition, the adsorption capacity of BMSAH remained above 90 % after three desorption cycles. Our work provides a new method for the preparation of a low-cost, high mechanical performance, biodegradable and easily recyclable physical hydrogels used for the removal of heavy metal ions.

Cellulose/inorganic nanoparticles-based nano-biocomposite for abatement of water and wastewater pollutants

Nanostructured materials offer a significant role in wastewater treatment with diminished capital and operational expense, low dose, and pollutant selectivity. Specifically, the nanocomposites of cellulose with inorganic nanoparticles (NPs) have drawn a prodigious interest because of the extraordinary cellulose properties, high specific surface area, and pollutant selectivity of NPs. Integrating inorganic NPs with cellulose biopolymers for wastewater treatment is a promising advantage for inorganic NPs, such as colloidal stability, agglomeration prevention, and easy isolation of magnetic material after use. This article presents a comprehensive overview of water treatment approaches following wastewater remediation by green and environmentally friendly cellulose/inorganic nanoparticles-based bio-nanocomposites. The functionalization of cellulose, functionalization mechanism, and engineered hybrid materials were thoroughly discussed. Moreover, we also highlighted the purification of wastewater through the composites of cellulose/inorganic nanoparticles via adsorption, photocatalytic and antibacterial approach.

Study on Preparation of Chitosan/Polyvinyl Alcohol Aerogel with Graphene-Intercalated Attapulgite(GO-ATP@CS-PVA) and Adsorption Properties of Crystal Violet Dye

Adsorption is one of the effective methods of treating dye wastewater. However, the selection of suitable adsorbent materials is the key to treating dye wastewater. In this paper, GO-ATP was prepared by an intercalation method by inserting graphene oxide (GO) into the interlayer of alabaster attapulgite (ATP), and GO-ATP@CS-PVA aerogel was prepared by co-blending-crosslinking with chitosan (CS) and polyvinyl alcohol (PVA) for the adsorption and removal of crystalline violet dye from the solution. The physicochemical properties of the materials are characterized by various methods. The results showed that the layer spacing of the GO-ATP increased from 1.063 nm to 1.185 nm for the ATP, and the specific surface area was 187.65 m²·g^-1, which was 45.7% greater than that of the ATP. The FTIR results further confirmed the success of the GO-ATP intercalation modification. The thermogravimetric analysis (TGA) results show that the aerogel has good thermal stability properties. The results of static adsorption experiments show that at 302 K and pH 9.0, the adsorption capacity of the GO-ATP@CS-PVA aerogel is 136.06 mg·g^-1. The mass of the aerogel after adsorption-solution equilibrium is 11.4 times that of the initial mass, with excellent adsorption capacity. The quasi-secondary kinetic, Freundlich, and Temkin isotherm models can better describe the adsorption process of the aerogel. The biobased composite aerogel GO-ATP@CS-PVA has good swelling properties, a large specific surface area, easy collection and a low preparation cost. The good network structure gives it unique resilience. The incorporation of clay as a nano-filler can also improve the mechanical properties of the composite aerogel.

Chitosan Modified by Kombucha-Derived Bacterial Cellulose: Rheological Behavior and Properties of Convened Biopolymer Films

This work investigates the rheological behavior and characteristics of solutions and convened biopolymer films from Chitosan (Chi) modified by kombucha-derived bacterial cellulose (KBC). The Arrhenius equation and the Ostwald de Waele model (power-law) revealed that the Chi/KBC solutions exhibited non-Newtonian behavior. Both temperature and KBC concentration strongly affected their solution viscosity. With the selection of a proper solvent for chitosan solubilization, it may be possible to improve the performances of chitosan films for specific applications. The elasticity of the prepared films containing KBC 10% w/w was preferable when compared to the controls. FTIR analysis has confirmed the presence of bacterial cellulose, chitosan acetate, and chitosan lactate as the corresponding components in the produced biopolymer films. The thermal behaviors of the Chi (lactic acid)/KBC samples showed slightly higher stability than Chi (acetic acid)/KBC. Generally, these results will be helpful in the preparation processes of the solutions and biopolymer films of Chi dissolved in acetic or lactic acid modified by KBC powder to fabricate food packaging, scaffolds, and bioprinting inks, or products related to injection or direct extrusion through a needle.

Chitosan-Coated Bacterial Cellulose (BC)/Hydrolyzed Collagen Films and Their Ascorbic Acid Loading/Releasing Performance: A Utilization of BC Waste from Kombucha Tea Fermentation

SCOBY bacterial cellulose (BC) is a biological macromolecule (considered as a by-product) that grows at the liquid-air interface during kombucha tea fermentation. In this study, BC:HC (hydrolyzed collagen) blend films coated with 1 wt% chitosan (CS) were loaded with ascorbic acid to study loading/releasing performance. At first, the mechanical properties of the blend films were found to be dependent on HC ratio. After chitosan coating, the coated films were stronger due to intermolecular hydrogen bonding interaction and the miscibility of two matrixes at the interface. The antibacterial activity test according to the AATCC Test Method revealed that chitosan-coated BC/HC films exhibited excellent antimicrobial activity against S.aureus growth from the underneath and the above film when compared to BC and BC:HC films. Moreover, chitosan was attractive to ascorbic acid during drug loading. Consequently, its releasing performance was very poor. For BC:HC blend films, ascorbic acid loading/releasing performance was balanced by water swellability, which was controlled using blending formulation and coating. Another advantage of BC films and BC:HC blend films was that they were able to maintain active ascorbic acid for a long period of time, probably due to the presence of plenty of BC hemiacetal reducing ends (protective group).

Adsorption of Heavy Metal Ions Copper, Cadmium and Nickel by Microcystis aeruginosa

To investigate the treatment effect of algae biosorbent on heavy metal wastewater, in this paper, the adsorption effect of M. aeruginosa powder on heavy metal ions copper, cadmium and nickel was investigated using the uniform experimental method, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and TG-DSC comprehensive thermal analysis. The experimental results showed that the initial concentration of copper ion solution was 25 mg/L, the temperature was 30 °C, the pH value was 8 and the adsorption time was 5 h, which was the best condition for the removal of copper ions by algae powder adsorption, and the removal rate was 83.24%. The initial concentration of cadmium ion solution was 5 mg/L, the temperature was 35 °C, the pH value was 8 and the adsorption time was 4 h, which was the best condition for the adsorption of cadmium ion by algae powder, and the removal rate was 92.00%. The initial nickel ion solution concentration of 15 mg/L, temperature of 35 °C, pH value of 7 and adsorption time of 1 h were the best conditions for the adsorption of nickel ions by algae powder, and the removal rate was 88.67%. The spatial structure of algae powder changed obviously before and after adsorbing heavy metals. The functional groups such as amino and phosphate groups on the cell wall of M. aeruginosa enhanced the adsorption effect of heavy metal ions copper, cadmium and nickel. Additionally, M. aeruginosa adsorption of heavy metal ions copper, cadmium, nickel is an exothermic process. The above experiments show that M. aeruginosa can be used as a biological adsorbent to remove heavy metals, which lays a theoretical foundation for the subsequent treatment of heavy metal pollution by algae.

Gellan gum/bacterial cellulose hydrogel crosslinked with citric acid as an eco-friendly green adsorbent for safranin and crystal violet dye removal

In this study, ex-situ crosslinked gellan gum (GG)/bacterial cellulose (BC) hydrogels have been investigated as good absorbents for the removal of safranin and crystal violet dye pollutants. The preparation involves a cost-effective and easy-to-perform crosslinking procedure, using citric acid (CA) as a green crosslinker. The physicochemical and mechanical properties of the crosslinked hydrogels were examined by FTIR, TGA, SEM, XRD, and unconfined compression analyses. The swelling capacity of the hydrogels as a function of pH was investigated. CA depicted to improve structural stability as a crosslinker. The dye removal capacity of the hydrogels as good adsorbents was explored and showed higher efficiency in the removal of safranin dye as compared to crystal violet with optimum adsorption capacities obtained as 17.57 and 13.49 mg/g, respectively. Adsorption kinetics and isotherm models as well as thermodynamics examined. Results showed the adsorption process well fitted the pseudo 2nd-order kinetic and Langmuir-Freundlich models while temperature dependence study depicted to be exothermic. Furthermore, no significant loss of removal efficiency of the hydrogel adsorbent was observed even after five adsorption-desorption cycles. Based on the revealed results, the prepared hydrogel may serve as an effective adsorbent for the removal of dyes from the aqueous phase.

Production of coffee-dyed bacterial cellulose as a bio-leather and using it as a dye adsorbent

Owing to its sustainability and environmentally friendliness, bacterial cellulose (BC) has received attention as a zero-waste textile material. Since the color of original BC was mostly yellowish white, a dyeing process is necessary to suggest BC as a textile. Thus, this study aimed to suggest a natural dyeing method using coffee to produce an eco-friendly coffee-dyed bacterial cellulose (BC-COF) bio-leather and to propose a reusing method as a dye adsorbent. To determine the dyeing and mordanting conditions with the highest color strength value, parameters such as dyeing temperature, time, mordanting methods were evaluated. Fourier-transform infrared spectroscopy and X-ray diffraction analysis confirmed that BC-COF was successfully colorized with coffee without changing its chemical and crystalline structures. In addition, field-emission scanning electron microscopy and Brunauer-Emmett-Teller surface area analysis confirmed that coffee molecules were successfully incorporated into fiber structures of BC. The effects of pH, concentration, temperature, and time on the adsorption of methylene blue dye using BC-COF bio-leather were also evaluated using ultraviolet-visible spectroscopy and zeta potential measurement. The results showed that BC-COF was found to be most effective when pH 6 of methylene blue solution with a concentration of 50 mg/L was adsorbed for 30 minutes at 25°C. Moreover, BC-COF could be reused for multiple times and had better dye adsorption rate compared to the original BC. From the results, it was confirmed that BC-COF could be employed as a dye adsorbent.

Recent advances in magnetic composites as adsorbents for wastewater remediation

The scarcity of clean drinking water combined with other environmental and anthropogenic effects necessitates the demand for development of advanced technology for cleaning polluted water. Adsorption is one such technique that does not produce toxic byproducts and solves the problem of cleaning contaminated water at a lower cost. In recent years, magnetic composites, as adsorbent, have gained lot of attention due to their reusability which makes them sustainable and economical. This review article describes the challenges related to water quality, scarcity and then summarizes the current treatment technologies and advancement in the field of adsorption to resolve the prevailing concerns. The review includes an insight into the recent research being carried out in the field of magnetic composites and nanocomposites, as adsorbent, covering, probably, all aspects of what is going around the globe. Different materials, like polymers, biomaterials, clays and metal organic framework (MOF)-based magnetic composites and their applications in wastewater treatment processes have been included. The article is a comprehensive review on the application of different materials to detoxify various diverse pollutants with prime focus on magnetic composites. The thorough study of this review will surely bring upcoming researchers closer to the future possibilities of research in wastewater treatment.

Stimuli-responsive composite hydrogels with three-dimensional stability prepared using oxidized cellulose nanofibers and chitosan

Stimuli-responsive hydrogels have garnered the attention of the hydrogel industry, as they are able to change their physical and chemical properties based on changing external stimuli such as pH, temperature, ionic strength, electromagnetic fields, and light. However, stimuli-responsive hydrogel applications are hindered due to their inevitable swelling and shrinkage. Bacterial cellulose (BC), a natural hydrogel with tightly packed cellulose nanofibers (CNFs) was oxidized into dialdehyde BC (DABC) and was composited with chitosan (CS), a readily available natural polymer, to develop a mechanically adaptive hydrogel composite under different pH conditions. Composites exhibit pH sensitivity by presenting higher mechanical properties under acidic conditions and lower mechanical properties under basic conditions owing to the protonation of amino groups of the chitosan chains. Osmotic pressure is built up under acidic conditions, increasing the mechanical strength of the composites. The good three-dimensional stability of composites enables them to consistently maintain their volume when exposed to acidic or basic conditions.

Nanocellulose as green material for remediation of hazardous heavy metal contaminants

Heavy metal pollution generated by urban and industrial activities has become a major global concern due to its high toxicity, minimal biodegradability, and persistence in the food chain. These are the severe pollutants that have the potential to harm humans and the environment as a whole. Mercury, chromium, copper, zinc, cadmium, lead, and nickel are the most often discharged hazardous heavy metals. Nanocellulose, reminiscent of many other sustainable nanostructured materials, is gaining popularity for application in bioremediation technologies owing to its many unique features and potentials. The adsorption of heavy metals from wastewaters is greatly improved when cellulose dimension is reduced to nanometric levels. For instance, the adsorption efficiency of Cr³⁺ and Cr⁶⁺ is found to be 42.02% and 5.79% respectively using microcellulose, while nanocellulose adsorbed 62.40% of Cr³⁺ ions and 5.98% of Cr⁶⁺ ions from contaminated water. These nanomaterials are promising in terms of their ease and low cost of regeneration. This review addresses the relevance of nanocellulose as biosorbent, scaffold, and membrane in various heavy metal bioremediation, as well as provides insights into the challenges, future prospects, and updates. The methods of designing better nanocellulose biosorbents to improve adsorption efficiency according to contaminant types are focused.

Macroporous chitin microspheres prepared by surfactant micelle swelling strategy for rapid capture of lead (II) from wastewater

Heavy metal pollution of water source continues to be one of the most serious environmental problems which have attracted major global concern. Here, a macroporous chitin microsphere is prepared by surfactant micelle swelling strategy followed by modification with tetraethylenepentamine for Pb²⁺ removal from wastewater. The resultant adsorbent not only exhibits fast adsorption kinetic (>80% of its equilibrium uptake within 20 min) but also has high adsorption capacity of 218.4 ± 6.59 mg/g and excellent reusability (>75% of its initial adsorption capacity after five adsorption/desorption cycles). More importantly, under the continuous operating mode, the adsorbent can treat about 39,000 kg water/kg adsorbent, and the Pb²⁺ concentration decreases from 2000 μg/L to smaller than 10 μg/L, meeting the drinking water standard recommended by the World Health Organization (10 μg/L). All results indicate that the tetraethylenepentamine-modified macroporous chitin microspheres have great potential in the treatment of heavy metal contamination.

Bioremediation of micropollutants using living and non-living algae - Current perspectives and challenges

The emergence and continual accumulation of industrial micropollutants such as dyes, heavy metals, organic matters, and pharmaceutical active compounds (PhACs) in the ecosystem pose an alarming hazard to human health and the general wellbeing of global flora and fauna. To offer eco-friendly solutions, living and non-living algae have lately been identified and broadly practiced as promising agents in the bioremediation of micropollutants. The approach is promoted by recent findings seeing better removal performance, higher efficiency, surface area, and binding affinity of algae in various remediation events compared to bacteria and fungi. To give a proper and significant insight into this technology, this paper comprehensively reviews its current applications, removal mechanisms, comparative efficacies, as well as future outlooks and recommendations. In conducting the review, the secondary data of micropollutants removal have been gathered from numerous sources, from which their removal performances are analyzed and presented in terms of strengths, weaknesses, opportunities, and threats (SWOT), to specifically examine their suitability for selected micropollutants remediation. Based on kinetic, isotherm, thermodynamic, and SWOT analysis, non-living algae are generally more suitable for dyes and heavy metals removal, meanwhile living algae are appropriate for removal of organic matters and PhACs. Moreover, parametric effects on micropollutants removal are evaluated, highlighting that pH is critical for biodegradation activity. For selective pollutants, living and non-living algae show recommendable prospects as agents for the efficient cleaning of industrial wastewaters while awaiting further supporting discoveries in encouraging technology assurance and extensive applications.

Cellulose-Based Materials for Water Remediation: Adsorption, Catalysis, and Antifouling

Cellulose-based materials have been advanced technologies that used in water remediation. They exhibit several advantages being the most abundant biopolymer in nature, high biocompatibility, and contain several functional groups. Cellulose can be prepared in several derivatives including nanomaterials such as cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibrils (TOCNF). The presence of functional groups such as carboxylic and hydroxyls groups can be modified or grafted with organic moieties offering extra functional groups customizing for specific applications. These functional groups ensure the capability of cellulose biopolymers to be modified with nanoparticles such as metal-organic frameworks (MOFs), graphene oxide (GO), silver (Ag) nanoparticles, and zinc oxide (ZnO) nanoparticles. Thus, they can be applied for water remediation via removing water pollutants including heavy metal ions, organic dyes, drugs, and microbial species. Cellulose-based materials can be also used for removing microorganisms being active as membranes or antibacterial agents. They can proceed into various forms such as membranes, sheets, papers, foams, aerogels, and filters. This review summarized the applications of cellulose-based materials for water remediation via methods such as adsorption, catalysis, and antifouling. The high performance of cellulose-based materials as well as their simple processing methods ensure the high potential for water remediation.

Bacterial Cellulose: Production, Characterization, and Application as Antimicrobial Agent

Bacterial cellulose (BC) is recognized as a multifaceted, versatile biomaterial with abundant applications. Groups of microorganisms such as bacteria are accountable for BC synthesis through static or agitated fermentation processes in the presence of competent media. In comparison to static cultivation, agitated cultivation provides the maximum yield of the BC. A pure cellulose BC can positively interact with hydrophilic or hydrophobic biopolymers while being used in the biomedical domain. From the last two decades, the reinforcement of biopolymer-based biocomposites and its applicability with BC have increased in the research field. The harmony of hydrophobic biopolymers can be reduced due to the high moisture content of BC in comparison to hydrophilic biopolymers. Mechanical properties are the important parameters not only in producing green composite but also in dealing with tissue engineering, medical implants, and biofilm. The wide requisition of BC in medical as well as industrial fields has warranted the scaling up of the production of BC with added economy. This review provides a detailed overview of the production and properties of BC and several parameters affecting the production of BC and its biocomposites, elucidating their antimicrobial and antibiofilm efficacy with an insight to highlight their therapeutic potential.

Nanocellulose/palygorskite biocomposite membranes for controlled release of metronidazole

The incorporation of drugs in nanocomposites can be considered a potential strategy for controlled drug release. In this study, a nanocomposite based on bacterial cellulose and the palygorskite clay (BC/PLG) was produced and loaded with metronidazole (MTZ). The samples were characterized using X-ray diffraction (XRD) Spectroscopy, thermal analysis (TG/DTG) and Scanning Electron Microscopy (SEM). The barrier properties were determined to water vapor permeability (WVP). Adsorption tests with PLG were performed using MTZ and drug release profile of the membranes was investigated. The results indicated that PLG increased the crystallinity of the nanocomposites, and greater thermal stability when PLG concentration was 15.0% (BC/PLG15) was observed. WVP of the samples also varied, according to the clay content. Adsorption equilibrium was achieved from 400 mg/L of the PLG and a plateau in the MTZ release rates from BC/PLG was observed after 30 min. Therefore, the results of this study show the potential of these nanocomposite membranes as a platform for controlled drug release.

Effective Magnetic MOFs Adsorbent for the Removal of Bisphenol A, Tetracycline, Congo Red and Methylene Blue Pollutions

A magnetic metal−organic frameworks adsorbent (Fe₃O₄@MIL-53(Al)) was prepared by a typical solvothermal method for the removal of bisphenol A (BPA), tetracycline (TC), congo red (CR), and methylene blue (MB). The prepared Fe₃O₄@MIL-53(Al) composite adsorbent was well characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and fourier transform infrared spectrometer (FTIR). The influence of adsorbent quantity, adsorption time, pH and ionic strength on the adsorption of the mentioned pollutants were also studied by a UV/Vis spectrophotometer. The adsorption capacities were found to be 160.9 mg/g for BPA, 47.8 mg/g for TC, 234.4 mg/g for CR, 70.8 mg/g for MB, respectively, which is superior to the other reported adsorbents. The adsorption of BPA, TC, and CR were well-fitted by the Langmuir adsorption isotherm model, while MB followed the Freundlich model, while the adsorption kinetics data of all pollutants followed the pseudo-second-order kinetic models. The thermodynamic values, including the enthalpy change (ΔH°), the Gibbs free energy change (ΔG°), and entropy change (ΔS°), showed that the adsorption processes were spontaneous and exothermic entropy-reduction process for BPA, but spontaneous and endothermic entropy-increasing processes for the others. The Fe₃O₄@MIL-53(Al) was also found to be easily separated after external magnetic field, can be a potential candidate for future water treatment.

Hierarchically porous poly(amidoxime)/bacterial cellulose composite aerogel for highly efficient scavenging of heavy metals

Developing cheap, green, efficient and renewable adsorbents to address the issue of heavy metal pollution is highly desired for satisfying the requirements of economy sustainability and water security. Herein, a composite aerogel composed of bacterial cellulose (BC) and poly(amidoxime) (PAO) has been fabricated via a facile and scalable self-assembly and in situ oximation transformation for heavy metals removal. Benefiting from the unique three-dimensional (3D) interconnected porous architecture and high density of amidoxime functional moieties, the developed PAO/BC composite aerogel is capable of efficiently sequestrating heavy metals with exceptional sorption capacities, e.g. 571.5 mg g^-1 for Pb²⁺, 509.2 mg g^-1 for Cu²⁺, 494 mg g^-1 for Zn²⁺, 457.2 mg g^-1 for Mn²⁺, and 382.3 mg g^-1 for Cd²⁺, outperforming most reported nano-adsorbents. Meanwhile, the sorption equilibrium for the investigated five heavy metals is achieved within 25 min with high removal efficiencies. Significantly, the developed PAO/BC composite aerogels possess superior reusability performance. Furthermore, the PAO/BC aerogels-packed column can continuously and effectively treat the simulated wastewater with multiple heavy metals coexisting to below the threshold value in the drinking water recommended by World Health Organization (WHO), highlighting its feasibility in the complex environmental water.

Surface Modification of Attapulgite by Grafting Cationic Polymers for Treating Dye Wastewaters

In this study, the cationic polymer poly-epichlorohydrin-dimethylamine was immobilized on natural attapulgite to improve the dye adsorption capacities. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, nitrogen adsorption-desorption isotherms, scanning electron microscope (SEM) analysis, zeta potential analysis, and particle size analysis were used to determine the characteristics of modified attapulgite. Results showed that the poly-epichlorohydrin-dimethylamine had been successfully grafted onto the surface of attapulgite without altering its crystal structure. After cationic modification, the specific surface area of attapulgite obviously decreased, and its surface zeta potentials possessed positive values in the pH range from 3 to 11. The cation-modified attapulgite displayed high adsorption capacities for anionic dyes, and its maximum adsorption capacities were 237.4 mg/g for Reactive Black 5 and 228.3 mg/g for Reactive Red 239; this is corroborated by Langmuir’s isotherm studies. It was demonstrated that the two reactive dyes could be 100% removed from effluents when cation-modified attapulgite was used in column operation modes. Its treatment capacities were more than three times larger than that of activated carbon. The regeneration study verified better utilization and stability of the fabricated adsorbent in column operation. This work has conclusively confirmed the potential of the new modified attapulgite for effectively treating dye wastewaters.

Ex situ Synthesis and Characterization of High Strength Multipurpose Bacterial Cellulose-Aloe vera Hydrogels

The innate structural and functional properties of bacterial cellulose (BC) have been greatly improved by developing its composites with other materials for its applications in different fields. In the present study, BC-Aloe vera (BCA) gel composite with high tensile strength was ex situ developed and characterized for its potential applications in environmental and medical fields. FE-SEM micrographs showed the impregnation of Aloe vera gel into the fibril network of BC. The dry weight analysis showed the addition of 40 wt.% Aloe vera contents into the BC matrix. The addition of Aloe vera resulted in a 3-fold increase in the mechanical strength of BCA composite. The critical strain or stress concentration points were accurately identified in the composite using a three-dimensional digital image correlation (3D-DIC) system. The BCA composite retained water for an extended period of up to 70 h. The BCA composite effectively adsorbed Cu, Co, Fe, and Zn metals. Moreover, the BCA composite supported the adhesion and proliferation of MC3T3-E1 cells. The findings of this study suggest that the developed BCA composite could find multipurpose applications in different fields.

Hydroxypropyl-β-cyclodextrin-polyurethane/graphene oxide magnetic nanoconjugates as effective adsorbent for chromium and lead ions

In this work, hydroxypropyl-β-cyclodextrin-polyurethane magnetic nanoconjugates/reduced graphene oxide (HPMNPU/GO) supramolecules were prepared. The adsorbent was characterized using FTIR and SEM. The adsorbent was evaluated for its efficiency to remove Cr⁶⁺ and Pb²⁺ from aqueous solutions through batch adsorption studies following a Definitive Screening Design (DSD). Effects of solution pH, contact time, adsorbent dosage, initial metal concentration, ionic strength, GO/NC ratio and temperature on Cr ⁶⁺ and Pb ²⁺ adsorption were investigated. Optimization of the adsorption process was done using a desirability function of the Design Expert V11 software. A good agreement between experimental and predicted data proved the efficiency of this model for prediction of real optimum point. The batch experiments implied that the pseudo-second-order model (lowest sum of square error (SSE) values and correlation coefficients (R²) > 0.999) was better to describe the adsorption kinetics of Cr⁶⁺ and Pb²⁺ onto the HPMNPU/GO.

Free-standing SnS/carbonized cellulose film as durable anode for lithium-ion batteries

Metal sulfides have recently attracted broad attention for lithium-ion batteries (LIB) owing to their high theoretical capacity and long lifetime. However, the inferior structural integrity and low electron conductivity of metal sulfides limit their practical applications. A feasible strategy is to distribute these materials in conductive carbonaceous substrates with shapeable morphology. Here we report the design of free-standing films of tin sulfide (SnS) nanosheets distributed uniformly on carbonized bacterial cellulose (CBC) nanofibers. The SnS/CBC composites possess three dimensional interconnected nanostructures, which is crucial for the high conductivity and high lithium storage capacity. LIB using SnS/CBC as anode exhibits a reversible capacity of 872 mA h g^-1 at 100 mA g^-1 after 100 cycles, and the capacity remains as high as 527 mA h g^-1 at 2000 mA g^-1 after 1000 cycles. The free-standing sulfide-based nanocomposites with unique nanostructure composition and flexibility could be utilized as promising electrode materials for future LIB systems.

Bacterial cellulose-based magnetic nanocomposites: A review

Bacterial cellulose (BC) is a natural polymer that has unique and interesting structural, physical and chemical properties. These characteristics make it very attractive as a starting point for several novel developments in innovative research. However, the pristine BC lacks certain properties, in particular, magnetic property, which can be imparted to BC by incorporation of several types of magnetic nanoparticles. Magnetic nanocomposites based on BC exhibit additional magnetic functionality on top of the excellent properties of pristine BC, which make them promising materials with potential uses in various medical and environmental applications, as well as in advanced electronic devices. This review has compiled information about all classes of BC magnetic nanocomposites fabricated by various synthesis approaches and an overview of applications as well as improved features of these materials. A summary of the key developments of BC magnetic nanocomposites and emphasis on novel advances in this field is presented.

Aminophosphonic Acid Functionalized Cellulose Nanofibers for Efficient Extraction of Trace Metal Ions

Cellulose nanofibers were covalently functionalized using diethylenetriamine penta (methylene phosphonic acid) and studied for the extraction of heavy metal ions. The surface-functionalized nanofibers showed a high adsorption capacity towards heavy metal ions as compared to bare nanofibers. The elemental composition and surface morphology of the prepared bio-adsorbent was characterized by X-ray photoelectron spectroscopy, attenuated total reflectance infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive spectroscopy. The prepared material was studied to develop a column-based solid phase extraction method for the preconcentration of trace metal ions and their determination by inductively coupled plasma optical emission spectroscopy. The batch experimental data was well fitted to Langmuir adsorption isotherms (R2 > 0.99) and follows pseudo-second-order kinetics. The experimental variables such as sample pH, equilibrium time, column breakthrough, sorption flow rate, the effect of coexisting ions, and eluent type were systematically studied and optimized accordingly. The detection limit of the proposed method was found to be 0.03, 0.05, and 0.04 µg L-1 for Cu(II), Pb(II), and Cd(II), respectively. Certified Reference Materials were analyzed to validate the proposed method against systematic and constant errors. At a 95% confidence level, the Student's t-test values were less than the critical Student's t value (4.302). The developed method was successfully employed for the preconcentration and determination of trace metal ions from real water samples such as river water and industrial effluent.

Cr(VI) Sorption from Aqueous Solution: A Review

Hexavalent chromium (Cr(VI)) in water systems is a major hazard for living organisms, including humans. The most popular technology currently used to remove Cr(VI) from polluted water is sorption for its effectiveness, ease of use, low cost and environmental friendliness. The electrostatic interactions between chromium species and the sorbent matrix are the main determinants of Cr(VI) sorption. The pH plays a central role in the process by affecting chromium speciation and the net charge on sorbent surface. In most cases, Cr(VI) sorption is an endothermic process whose kinetics is satisfactorily described by the pseudo second-order model. A critical survey of the recent literature, however, reveals that the thermodynamic and kinetic parameters reported for Cr(VI) sorption are often incorrect and/or erroneously interpreted.

Bacterial Cellulose-Graphene Based Nanocomposites

Bacterial cellulose (BC) and graphene are materials that have attracted the attention of researchers due to their outstanding properties. BC is a nanostructured 3D network of pure and highly crystalline cellulose nanofibres that can act as a host matrix for the incorporation of other nano-sized materials. Graphene features high mechanical properties, thermal and electric conductivity and specific surface area. In this paper we review the most recent studies regarding the development of novel BC-graphene nanocomposites that take advantage of the exceptional properties of BC and graphene. The most important applications of these novel BC-graphene nanocomposites include the development of novel electric conductive materials and energy storage devices, the preparation of aerogels and membranes with very high specific area as sorbent materials for the removal of oil and metal ions from water and a variety of biomedical applications, such as tissue engineering and drug delivery. The main properties of these BC-graphene nanocomposites associated with these applications, such as electric conductivity, biocompatibility and specific surface area, are systematically presented together with the processing routes used to fabricate such nanocomposites.

A stiff ZnO/carbon foam composite with second-level macroporous structure filled ZnO particles for heavy metal ions removal

A stiff zinc oxide/carbon foam (ZnO/CF) composite as a desirable adsorbent for heavy metal ions was innovatively designed and fabricated by loading ZnO particles into a carbon foam with capsule-like second-level macropores. The features of the resulting composite were characterized by FESEM, XRD, BET, FTIR, and XPS. The effects of adsorption parameters on the Pb(II), Cr(III), and Cu(II) ions removal were studied through batch experiments. Results show that the ZnO/CF composite possesses a second-level macroporous structure filled ZnO particles, which has both mesoporous structure and Zn-O-C bond with the strongly synergistic effect. And meanwhile, it has a relatively high compression strength of 2.18 MPa at a density of 0.18 g cm^-3. The experimental maximum adsorption capacities for Pb(II), Cr(III), and Cu(II) ions reach 170.85 mg g^-1, 168.74 mg g^-1, and 104.61 mg g^-1 with relatively high partition coefficients of 5.803 mg g^-1 μM^-1, 1.169 mg g^-1 μM^-1, and 0.648 mg g^-1 μM^-1, respectively. The experimental data are in accordance with Langmuir isotherm and pseudo-second-order kinetic model. Moreover, the composite still exhibits a good adsorption performance even after five cycles.