Removal of dyes from wastewater using Eucalyptus wood fiber loaded nanoscale zero-valent iron: Characterization and removal mechanism.

Wood fiber as a natural and renewable material has low cost and plenty of functional groups, which owns the ability to adsorb dyes. In order to improve the application performance of wood fiber in dye-pollution wastewater, Eucalyptus wood fiber loaded nanoscale zero-valent iron (EWF-nZVI) was developed to give EWF magnetism and the ability to degrade dyes. EWF-nZVI was characterized via FTIR, XRD, zeta potential, VSM, SEM-EDS and XPS. Results showed that EWF-nZVI owned a strong magnetism of 96.51 emu/g. The dye removal process of EWF-nZVI was more in line with the pseudo-second-order kinetics model. In addition, the Langmuir isotherm model fitting results showed that the maximum removal capacities of Congo red and Rhodamine B by EWF-nZVI were 714.29 mg/g and 68.49 mg/g at 328 K, respectively. After five adsorption-desorption cycles, the regeneration efficiencies of Congo red and Rhodamine B were 74 % and 42 % in turn. The dye removal mechanisms of EWF-nZVI included redox degradation (Congo red and Rhodamine B) and electrostatic adsorption (Congo red). In summary, EWF-nZVI is a promising biomass-based material with high dye removal capacities. This work is beneficial to promote the large-scale application of wood fiber in water treatment.

Appraisal of Chitosan-Gum Arabic-Coated Bipolymeric Nanocarriers for Efficient Dye Removal and Eradication of the Plant Pathogen Botrytis cinerea.

The treatment of textile wastewater comprising many dyes as contaminants endures an essential task for environmental remediation. In addition, combating antifungal multidrug resistance (MDR) is an intimidating task, specifically owing to the limited options of alternative drugs with multitarget drug mechanisms. Incorporating natural polymeric biomaterials for drug delivery provides desirable properties for drug molecules, effectively eradicating MDR fungal growth. The current study fabricated the bipolymeric drug delivery system using chitosan-gum arabic-coated liposome 5ID nanoparticles (CS-GA-5ID-LP-NPs). This study focused on improving the solubility and sustained release profile of 5I-1H-indole (5ID). These NPs were characterized and tested mechanically as a dye adsorbent as well as their antifungal potencies against the plant pathogen, Botrytis cinerea. CS-GA-5ID-LP-NPs showed 71.23% congo red dye removal compared to crystal violet and phenol red from water and effectively had an antifungal effect on B. cinerea at 25 µg/mL MIC concentrations. The mechanism of the inhibition of B. cinerea via CS-GA-5ID-LP-NPs was attributed to stabilized microtubule polymerization in silico and in vitro. This study opens a new avenue for designing polymeric NPs as adsorbents and antifungal agents for environmental and agriculture remediation.

Synthesis, characterization, and selective dye adsorption by pH- and ion-sensitive polyelectrolyte galactomannan-based hydrogels.

Three novel polyelectrolyte galactomannan hydrogels (PGHs) were fabricated by chemically crosslinking quaternary ammonium galactomannan (QAG) and carboxymethyl galactomannan (CMG), and employed for the removal of Congo Red (CR) and Methylene Blue (MB). Physicochemical characterization revealed that the PGHs are chemically and physically crosslinked. The PGHs are pH- and ion-sensitive, and their physical crosslinking can be destroyed by artificial urine; water swelling capacity (100.6-321.9 g/g dry gel) and artificial urine swelling capacity (35.9-80.5 g/g dry gel). The adsorption of CR and MB was studied and found to be pH-dependent and selective. The maximum adsorption capacities of CR and MB on the QAG and CMG gels are 1441 and 94.52 mg/g, respectively, and their adsorption kinetics and isotherm behavior obey the pseudo-second-order kinetics model and Langmuir isotherm model, respectively. The adsorption mechanism is dominated by electrostatic interactions and hydrogen bonding. Further, the PGHs have excellent salt resistance and are reusable.

Novel CaCO3/chitin aerogel: Synthesis and adsorption performance toward Congo red in aqueous solutions.

In this study, chitin aerogel doped with nano-calcium carbonate (CaCO3/chitin aerogel) was prepared by dissolving chitin in Na2CO3/Ca (OH)2/urea system followed by epichlorohydrin (ECH) addition as a cross-linker and then freeze-drying of the hydrogel. The as-obtained CaCO3/chitin aerogel showed good adsorption properties toward the adsorption of Congo Red (CR) with maximum adsorption capacity reaching approximately 266.4 mg·g-1. Besides, the adsorption capacity was affected by the initial concentration and pH. The adsorption kinetics revealed a second-order kinetics model of CaCO3/chitin aerogel toward CR, and the adsorption process was controlled by both the liquid film diffusion and intra-particle diffusion. In sum, chitin aerogel looks promising as an effective adsorbent for anion dye adsorption. The cost-effective and eco-friendly developed approaches are also of great interest for future environmental remediation.

Colloidal CdS sensitized nano-ZnO/chitosan hydrogel with fast and efficient photocatalytic removal of congo red under solar light irradiation.

Colloidal CdS sensitized nano-ZnO/chitosan (CdS@n-ZnO/CS) hydrogel was prepared and characterized extensively by XRD, SEM-EDS, TEM, UV-Vis DRS, FT-IR and TGA. The photocatalytic activity of CdS@n-ZnO/CS was evaluated with the photodegradation of congo red (CR) as an organic pollutant under solar light irradiation. The influences of initial dye concentration, catalyst dosage, recycling runs, and radical scavenger on decolorization of CR by CdS@n-ZnO/CS were investigated. 95% of CR was removed in just 1 min for 5.0 mg L-1 and 94.34% of CR was removed in 30 min for 100 mg L-1. CdS@n-ZnO/CS exhibited an excellent and ultra-fast performance toward CR removal under solar light due to the synergistic effect of adsorption by chitosan and photocatalysis by ZnO and CdS in CdS@n-ZnO/CS hydrogel. Radical trapping control experiments indicated that h+ and O2- played the major role for CR decolorization. The high performance of CdS@n-ZnO/CS hydrogel was also demonstrated under natural solar light irradiation, suggesting that CdS@n-ZnO/CS hydrogel could be used in practical wastewater treatment.

Processing Guar Gum into polyester fabric based promising mixed matrix membrane for water treatment.

A reactive and mechano-chemically stable support was prepared from Ag-nanoparticles decorated polyester fabric which was subsequently coated by a casting solution containing polyvinylidene fluoride matrix, guar gum (GG) exo-polysaccharide hydrophilic agent, and UiO-66 filler. FE-SEM, XRD, FT-IR, water contact angle technique, and mechanical stability tests were applied to characterize the prepared membranes. The water contact angle measurements indicated the hydrophilicity of the prepared membrane which can be attributed to the nature of bio-GG and UiO-66. The prepared membrane was employed for purifying contaminated waters containing N-cetyl-N,N,N-trimethylammonium bromide (CTAB) and congo-red (CR) dye through a cross-module set-up. The central composite design was also exploited to study the effect of operational parameters such as CTAB and CR concentration, pH solution, and pressure on the removal efficiency. Particularly, the bio-based GG/UiO-66 dispersion showed excellent self-healing properties, which enabled an effective pollutant separation ability and facilitated the recyclability/sustainability of the as-prepared membrane.

Highly efficient and fast removal of colored pollutants from single and binary systems, using magnetic mesoporous silica.

Magnetic mesoporous silica material was tested as adsorbent for removal of two usual colored compounds present in industrial wastewater. The magnetic mesoporous silica was synthesized by modified sol-gel method and characterized from the morpho-textural, structural and magnetic point of view. The specific surface area and the total pore volume indicate a good adsorption capacity of the material, and the obtained saturation magnetization strength value denotes a good magnetic separation from solution. The adsorption capacity of magnetic mesoporous silica increases with the increase of the initial dye concentration, and the removal efficiency of the dyes was dependent on the pH of the solution and decreased with increasing temperature. The pseudo-second-order kinetic model described best the adsorption mechanism, and the maximum adsorption capacities were determined from the Sips isotherm model, being 88.29 mg/g for Congo Red and 208.31 mg/g for Methylene Blue. A complete thermodynamic evaluation was performed, by determining the free energy, enthalpy and entropy, and the result showed a spontaneous and exothermic adsorption process. The recovery and reutilization of the adsorbent were estimated in five cycles of adsorption-desorption, and the results indicated a good stability and reusability of magnetic mesoporous silica. The new magnetic mesoporous silica can be easily separated from solution, via an external magnetic field, and may be effectively applied as adsorbent for elimination of dyes from colored polluted waters.

Luffa cylindrica Immobilized with Aspergillus terreus QMS-1: an Efficient and Cost-Effective Strategy for the Removal of Congo Red using Stirred Tank Reactor.

Microbial populations within the rhizosphere have been considered as prosperous repositories with respect to bioremediation aptitude. Among various environmental contaminants, effluent from textile industries holds a huge amount of noxious colored materials having high chemical oxygen demand concentrations causing ecological disturbances. The study was aimed to explore the promising mycobiome of rhizospheric soil for the degradation of azo dyes to develop an efficient system for the exclusion of toxic recalcitrants. An effluent sample from the textile industry and soil samples from the rhizospheric region of Musa acuminata and Azadirachta indica were screened for indigenous fungi to decolorize Congo red, a carcinogenic diazo dye, particularly known for its health hazards to the community. To develop a bio-treatment process, Aspergillus terreus QMS-1 was immobilized on pieces of Luffa cylindrica and exploited in stirred tank bioreactor under aerobic and optimized environment. Quantitative estimation of Congo red decolorization was carried out using UV-Visible spectrophotometer. The effects of fungal immobilization and biosorption on the native structure of Luffa cylindrica were evaluated using a scanning electron microscope. A. terreus QMS-1 can remove (92%) of the dye at 100 ppm within 24 h in the presence of 1% glucose and 1% ammonium sulphate at pH 5.0. The operation of the bioreactor in a continuous flow for 12 h with 100 ppm of Congo red dye in simulated textile effluent resulted in 97% decolorization. The stirred tank bioreactor was found to be a dynamic, well maintained, no sludge producing approach for the treatment of textile effluents by A. terreus QMS-1 of the significant potential for decolorization of Congo red.Microbial populations within the rhizosphere have been considered as prosperous repositories with respect to bioremediation aptitude. Among various environmental contaminants, effluent from textile industries holds a huge amount of noxious colored materials having high chemical oxygen demand concentrations causing ecological disturbances. The study was aimed to explore the promising mycobiome of rhizospheric soil for the degradation of azo dyes to develop an efficient system for the exclusion of toxic recalcitrants. An effluent sample from the textile industry and soil samples from the rhizospheric region of Musa acuminata and Azadirachta indica were screened for indigenous fungi to decolorize Congo red, a carcinogenic diazo dye, particularly known for its health hazards to the community. To develop a bio-treatment process, Aspergillus terreus QMS-1 was immobilized on pieces of Luffa cylindrica and exploited in stirred tank bioreactor under aerobic and optimized environment. Quantitative estimation of Congo red decolorization was carried out using UV-Visible spectrophotometer. The effects of fungal immobilization and biosorption on the native structure of Luffa cylindrica were evaluated using a scanning electron microscope. A. terreus QMS-1 can remove (92%) of the dye at 100 ppm within 24 h in the presence of 1% glucose and 1% ammonium sulphate at pH 5.0. The operation of the bioreactor in a continuous flow for 12 h with 100 ppm of Congo red dye in simulated textile effluent resulted in 97% decolorization. The stirred tank bioreactor was found to be a dynamic, well maintained, no sludge producing approach for the treatment of textile effluents by A. terreus QMS-1 of the significant potential for decolorization of Congo red.

Covalent laccase immobilization on the surface of poly(vinylidene fluoride) polymer membrane for enhanced biocatalytic removal of dyes pollutants from aqueous environment.

Biocatalytic removal with laccase immobilized on diverse membranes offers an attractive option to search alternative to traditional wastewater treatment processes for the removal of high toxic azo dye. In this work, the modified poly(vinylidene fluoride) membrane (PVDF) with chemical stability and high mechanical strength was developed for laccase immobilization via covalent bonding. The key design for the synthesis of biocatalytic membrane is the construction of hybrid bio-inorganic structure on the surface of polydopamine (PDA)-coated PVDF (PDA@PVDF). In this respect, the PDA layer was used as a secondary platform for the grafting of 3-triethoxysilylpropylamine (APTES) modified Fe2O3@SiO2 cubes (FS@cubes) via a solvothermal process, resulting in the formation of FS@cubes-PDA@PVDF membrane. Subsequently, laccase was immobilized on the surface of FS@ cubes-PDA@PVDF via gluteraldehyde (GA) crosslinking (Lac-FS@ cubes-PDA@PVDF). The removal efficiency of congo red by Lac-FS@cubes-PDA @PVDF reached 97.1 % under optimal reaction conditions (pH 7.0 and temperature 35 ℃), which was more efficient than free laccase. Moreover, the as-prepared Lac-FS@cubes-PDA@PVDF not only exhibited an excellent stability after low temperature storage, but also showed an outstanding reusability. Therefore, we believe that this work opens up a potential strategy for removal of other water pollutants, and provide a simple and convenient way for large-scale applications of enzyme-catalysis.

Hemicelluloses-based magnetic aerogel as an efficient adsorbent for Congo red.

A renewable, efficient, and low-cost material is essential for adsorbing water pollution, such as dyes and heavy metal ions pollution. Here in, we demonstrate an aerogel to remove the dyes from water based on hemicellulose. The dialdehyde hemicelluloses (DAH) were synthesized by oxidation of hemicellulose extracted from straw with NaIO4. The hydrogels were prepared based on the dialdehyde hemicellulose and chitosan-Fe3O4 composite by the Schiff's base reaction, which were processed with vacuum freeze-drying technique to obtain aerogels. It was found that hydroxyl groups at C2 and C3 of hemicellulose were oxidized to aldehyde groups after modification, and the content of aldehyde group was 5.57 mmol/g. The maximum compress strength of aerogel was 0.37 MPa, and the maximum absorption capacity of Congo red dye was 137.74 mg/g. Aerogels with Fe3O4 exhibited magnetism which enables the aerogels to easily recycle. Meanwhile, the thermal stability, mechanical properties of the aerogels and its adsorption property to Congo red dye could be improved directly by the addition of Fe3O4.

Cereus sp. as potential biosorbent for removal of Congo red from aqueous solution: isotherm and kinetic investigations.

Elimination of toxic dyes from industrial effluents before discharge into the environment is very essential to reduce the impact created on the environment. The process of adsorption is widely used for the removal of toxic dyes through suitable adsorbents. In the present study, a novel adsorbent prepared from Cereus sp. for the removal of Congo red from the aqueous solution phase. Adsorption experiment was conducted in batch mode and the effect of adsorbent dose (1-12 g/l), dye concentration (100-250 mg/l), and contact time (5-120 min) was determined. Twelve isotherm models namely Langmuir, Freundlich, Jovanovic, Temkin, Elovich, Dubinin-Radushkevich, Halsey, Hill-Deboer, Flory-Huggins, Flower-Guggenheim, Kiselev, and Harkins-Jura were fitted with the experimental data. Cuticle-removed cladodes (CRC) from biomass gave maximum adsorption capacity of 27.02 mg/g, whereas cuticle (C) resulted in maximum adsorption capacity of 52.63 mg/g according to Langmuir isotherm. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetic models were examined. Pseudo-second-order kinetics better fitted for both adsorbents. This is the first exhaustive study to systematically find cuticle portion has better adsorption of Congo red than the cladodes of Cereus sp. The study also highlights that cutin polyesters present in the cuticle might be responsible for higher adsorption of dyes compared with its counterpart CRC. The present study provides the first evidence that cutin polymer can be used for adsorption of Congo red. It significantly contributes to advancement for new biobased materials for monitoring and remediation of water resources contaminated with toxic dyes.

Electrospun metal-organic frameworks with polyacrylonitrile as precursors to hierarchical porous carbon and composite nanofibers for adsorption and catalysis.

A facile and effective method has been developed to prepare hierarchical porous carbon nanofibers (PCNFs), carbon nanofibers supported nickel nanoparticles (PCNFs-Ni) and carbon nanofibers encapsulating gold nanoparticles (PCNFs-Au). PCNFs or PCNFs-Au were obtained by embedding metal-organic frameworks (e.g. ZIF-8 or ZIF-8-Au) into polyacrylonitrile via electrospinning and subsequent carbonization. In addition, PCNFs-Ni were obtained by impregnating PAN/ZIF-8 nanofibers in Ni(NO3)2·6H2O followed by carbonization. Both PCNF and PCNF-Ni exhibited excellent adsorption activities for methylene blue (MB) and congo red (CR). Especially, PCNF-Ni could be removed and separated via a magnet. PCNFs-Au showed excellent catalytic properties in the reduction reaction of 4-nitrophenol (4-NP).

Roles of functional microbial flocculant in dyeing wastewater treatment: Bridging and adsorption.

Congo red (CR) is a typical and widely used azo dye in industries. It possesses the serious threat to ecosystem and public for its indiscriminate discharge. Microbial flocculant (MBF) with various functional groups is a potential flocculant applied in dyeing wastewater treatment, and it has the advantages of high treatment efficiency, biodegradability and non-toxicity. In this study, the functional groups, amino group, ammonium group and acyloxy group, were grafted onto MBF to further improve its thermal stability, solubility and performance. Grafting copolymerization occurred at the amino group of MBF was confirmed by XPS. Polyaluminum silicate (PSA) and self-prepared functional microbial flocculant, MBF-g-P(AM-DAC), played different roles in CR wastewater treatment. PSA contributed to charge neutralization, but its yielded flocs were small. On the contrary, MBF-g-P(AM-DAC) possessed weak charge neutralization but big flocs. Its settlement efficiency has significantly improved. The unsaturated active sites on MBF-g-P(AM-DAC) and its flocs contributed to the adsorption of CR in terms of high surface area and adsorption capacity of the flocs. Physical adsorption and chemical adsorption were both discovered in the treatment.

Synthesis of cellulose acetate/chitosan/SWCNT/Fe3O4/TiO2 composite nanofibers for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions.

The potential of electrospun cellulose acetate/chitosan/single walled carbon nanotubes/ferrite/titanium dioxide (CA/chitosan/SWCNT/Fe3O4/TiO2) nanofibers was investigated for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions via the adsorption and photocatalytic reduction processes. The properties of synthesized SWCNT/Fe3O4/TiO2 and fibers were characterized using TEM, SEM, FTIR, XRD, TGA and BET analysis. In adsorption process, the influence of adsorbent type including SWCNT to Fe3O4 ratio, TiO2 to SWCNT/Fe3O4 ratio and SWCNT/Fe3O4/TiO2 concentration as well as the adsorption parameters including pH, contact time, and initial concentration of adsorbates on the Cr(VI), As(V), Methylene blue and Congo red adsorption in a batch mode was investigated. The reusability of nanofibers was also investigated for five adsorption-desorption cycles. The photocatalytic reduction of Cr(VI), As(V), Methylene blue and Congo red was also investigated using various nanofibrous catalysts. The obtained results indicated that the removal of Cr(VI) and As(V) using CA/chitosan/SWCNT/Fe3O4/TiO2 nanofibrous adsorbent via adsorption process could be preferred for the lower concentrations of metal ions. The photocatalytic reduction was an effective method for the Cr(VI), As(V) removal at higher concentrations and degradation of Methylene blue and Congo red under both lower and higher concentrations of azo dyes.

In situ growth of ZIF-8 nanoparticles on chitosan to form the hybrid nanocomposites for high-efficiency removal of Congo Red.

The zeolitic imidazole framework (ZIF-8) dotted chitosan (CS) nanocomposites (ZIF-8@CS) were fabricated via in-situ growth method. The morphology, structure and chemical state of ZIF-8@CS were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform IR spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption behavior of ZIF-8@CS composites on Congo Red (CR) in aqueous solution was systematically investigated. The adsorption isotherm data showed that the adsorption of CR by ZIF-8@CS was single-layer adsorption, which was consistent with the Langmuir isotherm model. The maximum adsorption capacity of ZIF-8@CS was 922 mg/g. The kinetics parameters were in accord with pseudo-second-order equation, which implied that the adsorption rate was mainly controlled by the chemisorption mechanism. The removal of CR was attributed to the participation of hydrogen bonds, electrostatic interactions, π-π conjugation and zinc coordination effects.

Adsorptive removal of acidic dye onto grafted chitosan: A plausible grafting and adsorption mechanism.

In the present research, a biopolymer Chitosan (C) grafted with ethylenediamine (EDA) and methyl acrylate (MA) were compared for the adsorption of Congo red dye from aqueous phase. The grafted chitosan product was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and point of zero charge to study the change in mechanical and thermal properties. The effects of process variables like adsorbent loading, initial dye concentration, initial solution pH, contact time and temperature on adsorption phenomena were investigated. The equilibrium isotherm data was analyzed using Langmuir and Freundlich isotherm models, and the adsorption followed the Langmuir isotherm model (R2 = 0.992 and 0.991 for EDAC and MAC, respectively). The maximum adsorption capacity of EDAC and MAC for Congo red uptake calculated from Langmuir isotherm model was 1607 mg/g and 1143 mg/g, respectively. The adsorption kinetics was studied using pseudo 1st and 2nd order models. Pseudo second order rate model provided the best fit for both grafted adsorbents with R2 ≥0.99. The values of Gibbs free energy (-9.628 and -8.878 kJ/mol), enthalpy (44.9 and 42.2 kJ/mol) and entropy (0.18 and 0.17 J/mol·K) revealed spontaneous and endothermic adsorption of Congo red onto EDAC and MAC surface. The pollutant adsorption test indicated that chitosan grafting with ethylenediamine is superior to Methyl acrylate grafting agent.

Cationic and anionic dyes removal by low-cost hybrid alginate/natural bentonite composite beads: Adsorption and reusability studies.

Using the extrusion method, novel hybrid beads were prepared from natural bentonite and alginate. Alginate to clay ratios was varied (1/1; 1/2 and 1/3) and used to eliminate two dyes (methylene blue and Congo red).Adsorbents were characterized by Fourier transformed infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller method (BET) from N2 adsorption-desorption isotherm at 77 K, and the point of zero charge (pHPZC). The adsorption of methylene blue and Congo red was studied according to different parameters. The results showed that isotherms were well described by the Langmuir model justifying monolayer and homogeneous adsorption. Kinetics were well followed the pseudo-second-order model. Adsorption capacities of MB onto A-B 1/1 and CR onto A-B 1/3 were 1171 and 95.55 mg/g respectively. MB adsorption on A-B 1/1 and CR adsorption on A-B 1/3 were endothermic and exothermic respectively. Regeneration study showed that dyes were successfully desorbed from A-B 1/1 and A-B 1/3 with removal percentages of 99.65% and 86.2% respectively in the first cycle. Hybrid alginate-bentonite composites are low-cost, effective and regenerable for a wide variety of dyes.

A facile approach for the reduction of 4­nitrophenol and degradation of congo red using gold nanoparticles or laccase decorated hybrid inorganic nanoparticles/polymer-biomacromolecules vesicles.

Catalytic reduction of toxic 4­nitrophenol to 4­aminophenol and dye wastewater treatment over rapid, convenient gold nanoparticles or laccase decorated hybrid vesicles catalysts has attracted much attention. In current work, a stable building block was designed with inorganic gold nanoparticles and nano-conjugates; and a hybrid giant vesicles (AuNPs@vesicles) was self-assembled by using Pickering emulsion method. The vesicles were characterized by SEM, TEM, UV-vis and DLS measurements. The results showed that a temperature-responsive multifunctional building block based on BSA-PNIPAAm and gold nanoparticles was obtained. DLS results also indicated that the length of chains on the surface of AuNPs could change shorter with increasing of temperature (>32 °C) and also obtain an average diameter to ~190 nm. A substrate-rich (high concentration of 4­nitrophenol) microenvironment can be created around AuNPs, which can dramatically accelerate the interfacial AuNPs-catalyzed reactions. The AuNPs@vesicles as catalyst in the presence of freshly prepared NaBH4 has excellent catalytic performance for reduction of 4­nitrophenol (almost 100%). After laccase was capsulated into AuNPs@vesicles, the obtained active hybrid laccase⊂AuNPs@vesicles demonstrated high catalytic decolouration efficiency (>98.5%, nearly 2.3 times higher than that of free laccase) and excellent reusability. The possible mechanisms of reduction of 4­nitrophenol and dye decolouration was proposed. These novel giant vesicles could provide some new opportunities in wastewater treatment, bottom-up synthetic biology, bioinspired microstorage/microreactor and drug/gene delivery.

Green fabrication of bentonite/chitosan@cobalt oxide composite (BE/CH@Co) of enhanced adsorption and advanced oxidation removal of Congo red dye and Cr (VI) from water.

Bentonite/chitosan composite supported by green fabricated Co3O4 was successfully synthesized and its physicochemical properties were investigated utilizing several analytic techniques. The formation of the composite was confirmed by the XRD patterns, SEM, HRTEM images, and FT-IR analysis. The adsorption properties of bentonite/chitosan@Co3O4 for acidic dye (Congo red) and Cr(VI) ions were investigated. The kinetic studies reflected the saturation of the composite surface after 480 min for both Congo red molecules and Cr(VI) ions. Additionally, the systems are of chemisorption nature and showed excellent fitting with Pseudo-second order model. The mathematical parameters of the isotherm models revealed a monolayer uptake of Congo red molecules and Cr(VI) ions and represented mainly by the Langmuir model. The theoretical calculated maximum adsorption capacity (qmax) is 303 mg/g and 250 mg/g for Congo red molecules and Cr(VI) metal ions, respectively. The composite is of high reusability and can be used effectively for six runs of decontamination of Congo red molecules and Cr(VI) ions. Moreover, it is of high oxidation properties and can be used in the photocatalytic reduction of Congo red molecules and Cr(VI) ions from water. Besides that, bentonite/chitosan@Co3O4 green composite was used in purification of realistic water samples which make it one of the promising adsorbents.

Modified nickel ferrite nanocomposite/functionalized chitosan as a novel adsorbent for the removal of acidic dyes.

As a new type of magnetic adsorbent, a nickel ferrite nanocomposite modified by functionalized chitosan was developed to remove methyl orange and Congo red from aqueous solutions. This new adsorbent was characterized and utilizing batch adsorption approach, the mechanism of methyl orange and Congo red removal were probed. Following that the study on pertinent parameters which could influence the efficiency of the dyes removal, i.e. pH of the solution, initial dye concentration, dose of the adsorbent, and contact time were accomplished in order to arrive their optimized values by using response surface methodology. In addition, kinetics and isotherm studies were conducted on the developed system. Langmuir model was used to probe adsorption isotherm, acquiring adsorption capacity of 551.2 and 274.7 mg g-1 for methyl orange and Congo red, respectively. Both of methyl orange and Congo red adsorption kinetics obeyed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step and only 5 min was required to remove 50% of dyes. The fitting of experimental data was fulfilled with intra-particle diffusion reaching to conclusion that the adsorption kinetic could be controlled simultaneously by film diffusion and intra-particle diffusion. Furthermore, the desorption studies of dyes showed that the adsorbent is reusable.