Removal of chromium (VI) using poly(methylacrylate) functionalized guar gum

Retrieval of Cu2+ and Cd2+ ions from aqueous solutions using sustainable guar gum/PVA/montmorillonite nanocomposite films: effect of temperature and adsorption isotherms

Uncontrolled or improperly managed wastewater is considered toxic and dangerous to plants, animals, and people, as well as negatively impacting the ecosystem. In this research, the use of we aimed to prepare polymer nanocomposites (guar gum/polyvinyl alcohol, and nano-montmorillonite clay) for eliminating heavy metals from water-based systems, especially Cu2+ and Cd2+ ions. The synthesis of nanocomposites was done by the green method with different ratios of guar gum to PVA (50/50), (60/40), and (80/20) wt%, in addition to glycerol that acts as a cross-linker. Fourier-transform infrared spectroscopy (FT-IR) analysis of the prepared (guar gum/PVA/MMT) polymeric nano-composites' structure and morphology revealed the presence of both guar gum and PVA's functional groups in the polymeric network matrix. Transmission electron microscopy (TEM) analysis was also performed, which verified the creation of a nanocomposite. Furthermore, theromgravimetric analysis (TGA) demonstrated the biocomposites' excellent thermal properties. For those metal ions, the extreme uptake was found at pH 6.0 in each instance. The Equilibrium uptake capacities of the three prepared nanocomposites were achieved within 240 min. The maximal capacities were found to be 95, 89 and 84 mg/g for Cu2+, and for Cd2+ were found to be 100, 91, 87 mg/g for guar gum (80/20, 60/40 and 50/50), respectively. The pseudo-2nd-order model with R2 > 0.98 was demonstrated to be followed by the adsorption reaction, according to the presented results. In less than 4 hours, the adsorption equilibrium was reached. Furthermore, a 1% EDTA solution could be used to revitalize the metal-ion-loaded nanocomposites for several cycles. The most promising nanocomposite with efficiency above 90% for the removal of Cu2+ and Cd2+ ions from wastewater was found to have a guar (80/20) weight percentage, according to the results obtained.

Microwave promoted graft copolymerization of poly(ethylacrylate) onto k-carrageenan for removal of Cd and Ni from aqueous solution

Microwave promoted graft copolymerization of poly (ethyl acrylate) onto kappa-carrageenan in presence of a redox pair (ascorbic acid and potassium persulfate) led to the formation of a novel copolymer hydrogel, kappa-carrageenan-graft-poly (ethylacrylate). By varying the reaction conditions such as the microwave power, reaction time, concentration of kappa-carrageenan, ascorbic acid and persulfate, copolymers of highest percentage grafting was obtained and characterized by FT-IR, SEM, TGA and XRD. The copolymer was evaluated as an adsorbent for the adsorption of Ni(II) and Cd(II). Various adsorption parameters such as contact time, pH, initial metal ion concentration, temperature, electrolyte strength and adsorbent dosage were varied to obtain the optimum conditions for the adsorption. The adsorption data for Cd(II), fitted better for Langmuir and Ni(II), fitted much better for Freundlich adsorption isotherm model. Maximum adsorption obtained for cadmium ions and nickel ions was 308.6 mg/g-1 and 305.8 mg/g-1 respectively. The adsorption of both metal ions followed pseudo second order kinetic model. The positive ΔH values endorsed the adsorption process to be endothermic in nature. The negative values of ΔG indicate the spontaneity of the adsorption process while the positive ΔS values showed that the adsorption of metal ions proceeded with increased randomness at the surface of the copolymer. High recovery percentage of the metal ions from the adsorbent indicates that the copolymer can be used for more adsorption cycles.

Fabrication of Cross-Linked PMMA/SnO2 Nanocomposites for Highly Efficient Removal of Chromium (III) from Wastewater

In recent times, developments in polymer application properties have required the design of different polymer structures more than ever. Cross-linked polymers (CPs) could be considered a good candidate material for potential applications when used in conjunction with nanoparticles. Cross-linked polymethyl methacrylate nanocomposites are considered to be one of the most commonly polymeric adsorbents due to their varied and simple modification methods. A new class of C-PMMA/SnO_2(a–d) nanocomposites have been fabricated as surface-selective adsorbents of Cr (III) with a good yield and different loading of SnO₂ nanoparticles. The morphology, molecular structures, and thermal stability of the new cross-linked polymers were examined using a Scanning electron microscope (SEM), the Fourier Transform Infrared method (FTIR), X-ray diffraction (XRD), and Thermogravimetric Analysis (TGA). The adsorption study of C-PMMA/SnO₂ was investigated, and an efficient level of adsorption for Cr (III) cations was detected. To evaluate the potential for the new polymers to be used as adsorbents against Cr (III) ions, the contact time, the initial concentration of Cr (III), and the effects of pH were studied. The introduction of SnO₂ into the polymer network enhanced the efficiency of the adsorption of heavy metals. The C-PMMA/SnO₂ is highly efficient at removing Cr (III) ions in wastewater samples at pH 6 for one hour. The adsorption study demonstrated that the adsorption capacity of C-PMMA/SnO₂c for Cr (III) was 1.76 mg /g, and its adsorption isotherm agreed with the Langmuir adsorption model.

Preparation of new bio-based chitosan/Fe2O3/NiFe2O4 as an efficient removal of methyl green from aqueous solution

Modified chitosan with various functional groups has high potential as an efficient adsorbent in removing water pollution. In this study, new magnetic adsorbent, bio-based chitosan/Fe2O3/NiFe2O4, was successfully prepared by green chemistry route involving mixing of chitosan as core moiety and Fe2O3/NiFe2O4 nanocomposite, and slow evaporation of solvent. Synthesized chitosan/Fe2O3/NiFe2O4 was characterized by FT-IR, TGA, XRD, VSM and FE-SEM. The FT-IR and XRD results confirmed that the successful preparation of chitosan/Fe2O3/NiFe2O4. Uniform dispersion of Fe2O3/NiFe2O4 nanoparticles with low aggregation was confirmed by FE-SEM. The as-prepared magnetic chitosan/Fe2O3/NiFe2O4 was developed as solid phase adsorbent to remove methyl green (MG) dye from aqueous solutions. Several important parameters such as contact time, pH, temperature and adsorbent dosage were investigated systematically. The high and fast MG dye removal (≈ 80%) occurs after 30 min. The optimal conditions for MG removal was recorded at pH = 8, contact time of 60 min, adsorbent dosage of 0.2 g and 25 °C and displayed a high MG dye removal percentage of 96.51% and adsorption capacity of 77.22 mg/g.

Symmetry breakdown in the sol-gel transition of a Guar gum transient physical network

The gelation of the mixture of guar gum and borax in an aqueous solution was studied by diffusing-wave spectroscopy microrheology. The Winter and Chambon power-law domain was evidenced at high-frequency range. The time-cure superposition was applied to the mean square displacement of the probe particles and the critical power-law behavior of the shifting factors was revealed close to the percolation threshold. Morphological characterization revealed the emergence of ribbon-like structures at high borax concentrations. The Rubinstein and Semenov plateau was demonstrated. The correlations between the critical exponents that govern the gelation of the transient networks were reviewed with regard to the scaling laws of both permanent and transient networks. Unlike permanent networks, the relation n₊= n_- was assumed as the unique condition to establish the hyperscaling laws in transient networks. Whereas, the symmetry breakdown of the longest relaxation time was found to be a common feature of the flowable gels.

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

Natural biopolymers, polymeric organic molecules produced by living organisms and/or renewable resources, are considered greener, sustainable, and eco-friendly materials. Natural polysaccharides comprising cellulose, chitin/chitosan, starch, gum, alginate, and pectin are sustainable materials owing to their outstanding structural features, abundant availability, and nontoxicity, ease of modification, biocompatibility, and promissing potentials. Plentiful polysaccharides have been utilized for making assorted (nano)catalysts in recent years; fabrication of polysaccharides-supported metal/metal oxide (nano)materials is one of the effective strategies in nanotechnology. Water is one of the world's foremost environmental stress concerns. Nanomaterial-adorned polysaccharides-based entities have functioned as novel and more efficient (nano)catalysts or sorbents in eliminating an array of aqueous pollutants and contaminants, including ionic metals and organic/inorganic pollutants from wastewater. This review encompasses recent advancements, trends and challenges for natural biopolymers assembled from renewable resources for exploitation in the production of starch, cellulose, pectin, gum, alginate, chitin and chitosan-derived (nano)materials.

RETRACTED: A review on biomacromolecular hydrogel classification and its applications

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and Author. The work included substantial parts copied without attribution from a prior work by Varaprasad et al (2017): https://doi.org/10.1016/j.msec.2017.05.096

Polymer Ligands Derived from Jute Fiber for Heavy Metal Removal from Electroplating Wastewater

Industrial operations, domestic and agricultural activities worldwide have had major problems with various contaminants caused by environmental pollution. Heavy metal pollution in wastewater also a prominent issue; therefore, a well built and economical treatment technology is demanded for pollution-free wastewater. The present work emphasized pure cellulose extracted from jute fiber and further modification was performed by a free radical grafting reaction, which resulted in poly(methyl acrylate) (PMA)-grafted cellulose and poly(acrylonitrile)-grafted cellulose. Subsequently, poly(hydroxamic acid) and poly(amidoxime) ligands were prepared from the PMA-grafted cellulose and PAN-grafted cellulose, respectively. An adsorption study was performed using the desired ligands with heavy metals such as copper, cobalt, chromium and nickel ions. The binding capacity (qe) with copper ions for poly(hydroxamic acid) is 352 mg g-1 whereas qe for poly(amidoxime) ligand it was exhibited as 310 mg g-1. Other metal ions (chromium, cobalt and nickel) show significance binding properties at pH 6. The Langmuir and Freundlich isotherm study was also performed. The Freundlich isotherm model showed good correlation coefficients for all metal ions, indicating that multiple-layers adsorption was occurred by the polymer ligands. The reusability was evaluated and the adsorbents can be reused for 7 cycles without significant loss of removal performance. Both ligands showed outstanding metals removal capacity from the industrial wastewater as such 98% of copper can be removed from electroplating wastewater and other metals (cobalt, chromium, nickel and lead) can also be removed up to 90%.

Microbial electrochemical systems for hydrogen peroxide synthesis: Critical review of process optimization, prospective environmental applications, and challenges

Hydrogen peroxide (H₂O₂) is an industrial chemical that has been widely adopted for various industrial applications, including water and wastewater treatment. Currently, the majority of H₂O₂ is being produced through the anthraquinone oxidation process, which is disadvantageous due to the requirement of toxic raw materials and high energy input. Recently, microbial electrochemical cells (MXCs), such as microbial fuel cells and microbial electrolysis cells, have demonstrated great potential for effective H₂O₂ production via cathodic oxygen-reduction reaction (ORR). Previous studies have specified key operational parameters for scaling-up of H₂O₂-producing MXCs, where improvements in production rate, conversion efficiency, product concentration and stability are attainable. Moreover, various systems have demonstrated their value proposition in the contaminant removal aspects through direct removal of various environmental pollutants, water disinfection, and many more. This review is intended to highlight promising ways of H₂O₂ production with MXCs and on-site environmental applications of bioelectrochemically-produced H₂O₂.

Preparation of C-MOx nanocomposite for efficient adsorption of heavy metal ions via mechanochemical reaction of CaC2 and transitional metal oxides

Three nanocomposites of carbon and MnOx (C-Mns) were prepared via mechanochemical reaction of CaC₂ with excessive MnO₂ in a planetary ball mill. Their structure and composition were analyzed by XPS, Raman, FT-IR, XRD, N₂ adsorption-desorption, SEM and TEM, respectively, and their adsorption performance for heavy metal ions was studied. In addition, a series of nanocomposites of carbon and transition metal oxides (C-MOx) were prepared by ball milling CaC₂ with excessive TiO₂, V₂O₅, Fe₂O₃, CuO, MoO₃, Co₂O₃, and CrO₃, respectively, and their adsorptivity was evaluated. C-Mn₁ is a micro-mesoporous sorbent with rich MnOx, alkynyl and oxygenated groups, and moderate specific area (∼180 m² g^-1), showing excellent Pb²⁺ adsorption with its saturated adsorptivity being 404.4 mg-Pb g^-1. Further, it is also effective for other heavy metals (Hg²⁺, Cd²⁺, Cr³⁺, Zn²⁺ and Cu²⁺). Some C-MOx show even better adsorptivity for Pb²⁺ and Hg²⁺, being superior to most of the advanced carbon-based sorbents. We reported herein a facile method for preparing a new kind of C-MOx nanocomposites for the efficient adsorption of heavy metal ions from wastewater.

Super Effective Removal of Toxic Metals Water Pollutants Using Multi Functionalized Polyacrylonitrile and Arabic Gum Grafts

Super adsorbent polymers can be considered to be a very efficient solution for wastewater treatment. In general, their adsorption capacities depend on the type and amount of the functional groups present on the surface of the polymers, while their economic value is affected by their cost. Therefore, this study aims to understand the effect of multi-functionalization of cheap Arabic gum on the adsorption capability toward heavy metals. Graft copolymers of polyacrylonitrile (PAN) onto Arabic gum (AG) were prepared in aqueous solution using (KMnO₄/HNO₃) as a redox initiator. Chemical modification of the graft copolymer was carried out by reaction with hydrazine hydrochloride followed by hydrolysis in the basic medium. The modified graft product was characterized by various techniques, such as Fourier transform infrared spectroscopy (FTIR), elemental analysis, scanning electron microscope (SEM), and X-ray powder diffraction (XRD). The modified graft copolymer was used to adsorb Pb²⁺, Cd²⁺ and Cu²⁺ from their aqueous solutions using batch extraction. Different parameters influence the uptake behavior, including contact time, pH, and the initial concentration of the metal ions; all of these were investigated. The kinetics were investigated using the pseudo first order and pseudo second order, and the equilibrium data were analyzed using the Langmuir and Freundlich model. The modified graft product showed the superadsorbent capacity to obtain maximum values (Qmax) 1017, 413 and 396 mg/g for Pb²⁺, Cd²⁺ and Cu²⁺, respectively. Acid treatment with 0.2 M HNO₃ resulted in 96%, 99% and 99% metal recovery for the Pb²⁺, Cd²⁺ and Cu²⁺, respectively. This indicates the recyclability of product for further usage upon drying between treatments.

Interactive Studies on Synthetic Nanopolymer decorated with Edible Biopolymer and its Selective Electrochemical determination of L-Tyrosine

Herein, an edible biopolymer amine Modified Gum Acacia (MGA), successfully encumbered with Electron Beam irradiated Polypyrrole Nanospheres (EB-PPy NSs), was investigated for the effective role in L-Tyrosine (Tyr) biosensing application. The morphology of EB-PPy NSs decorated MGA (EB-PPy/MGA) hybrid nanobiocomposite has been studied by Scanning electron microscopy and its affirmed interactions were characterized by X-ray diffraction, Raman, FT-IR spectroscopy, UV-Visible spectroscopy, Thermo Gravimetric Analysis and Vibrating Sample Magnetometer. The hybrid nanobiocomposite manifested diamagnetic behavior with reduced saturation magnetization (Ms = 1.412 × 10-4 emu/g) to produce more adhesive surface. Amine chains in EB-PPy NSs and hydroxyl groups of MGA contributed to effective immobilization, thus enabling suitable orientation for Tyr determination. The electrochemical analysis illustrated that the proposed nanobiocomposite based sensor exhibited an excellent electrocatalytic activity toward selective determination of Tyr in the linear range of 0.4 to 600 µM with a lower detection limit of 85 nM, low oxidation potential of 0.72 V and good selectivity. Finally, the reliability of the constructed EB-PPy/MGA for Tyr detection was demonstrated in real samples.

Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields

The prospective uses of tree gum polysaccharides and their nanostructures in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. In addition to extensive applications of tree gums in food, there are substantial non-food applications of these commercial gums, which have gained widespread attention due to their availability, structural diversity and remarkable properties as 'green' bio-based renewable materials. Tree gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. This review focuses on non-food applications of several important commercially available gums (arabic, karaya, tragacanth, ghatti and kondagogu) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, environmental bioremediation, bio-catalysis, biosensors, coordination complexes of metal-hydrogels, and for antimicrobial and biomedical applications. Furthermore, polysaccharides acquired from botanical, seaweed, animal, and microbial origins are briefly compared with the characteristics of tree gum exudates.

Guar gum and its composites as potential materials for diverse applications: A review

Naturally occurring polymers are currently of prime importance among which polysaccharides occupies superior position due to their easy availability, eco- friendly and non-toxic nature. Guar gum, one of the naturally occurring polymer, is a galactomannan acquired by ground endosperm of Cyamopsis tetragonolobus or Cyamopsis psoraloides. It belongs to the family leguminosae. Presence of large number of hydroxyl groups increases its H- bonding ability when dissolved in water that enhance the viscosity and gelling properties of the guar gum solution. Based upon these properties, guar gum is used in several industries such as textile, food, petrochemical, mining and paper for varied applications. It is used as suspending, emulsifying, gelling and stabilising agent in the conventional dosage forms. Last few decades have marked the increase in development of various composites of guar gum that have intrinsic utilization in various fields. Immobilization of guar gum with the others not only enhances its properties but also enriches its utilization in numerous fields for diverse applications such as water purification, drug delivery, pharmaceutical, cosmetic and food industries, etc. Guar gum derivatives are found to have therapeutic importance in certain physiological disorders also. In this review article, we have summarized various possible composites of guar gum and their most probable applications in different fields.

Enhanced Cr(VI) removal from acidic solutions using biochar modified by Fe3O4@SiO2-NH2 particles

Fe₃O₄@SiO₂-NH₂ magnetic particles with core-shell structure were attached on carboxylated biochar derived from phoenix tree leaves to synthesize a novel magnetic biochar for removing Cr(VI) ions from acidic solutions. FSEM, FTEM, XRD characterizations of the synthesized magnetic biochar revealed that the Fe₃O₄@SiO₂-NH₂ magnetic particles distributed uniformly on the surface or macrospores of carboxylated biochar by strong chemical bonding. The Cr(VI) ions adsorption capacity of magnetic biochar was 27.2mg·g^-1, surpassing original carboxylated biochar (18.2mg·g^-1). VSM and XPS characterizations demonstrated that the attached Fe₃O₄@SiO₂-NH₂ magnetic particles not only endowed biochar with perfect magnetic property (23emu·g^-1) but also provided complexing sites for binding Cr(III) cations reduced from Cr(VI) anions. The Cr(VI) ions removal by magnetic biochar contained three steps: (1) adsorption of Cr(VI) anions by protonated functional groups; (2) reduction of Cr(VI) anions to Cr(III) cations by electron-donor groups; and (3) chelation of Cr(III) cations by amine groups. The adsorption recycling test showed that magnetic biochar kept 85% of its initial Cr(VI) adsorption capacity at the sixth cycle, and the Fe leakage under pH1.0 was smaller than 0.25mg·L^-1. The results indicated that this novel magnetic biochar was applicable for the practical treatment of Cr(VI)-containing wastewater.

Guar gum as a promising starting material for diverse applications: A review

Guar gum is the powdered endosperm of the seeds of the Cyamopsis tetragonolobus which is a leguminous crop. The endosperm contains a complex polysaccharide called galactomannan, which is a polymer of d-galactose and d-mannose. This hydroxyl group rich polymer when added to water forms hydrogen bonding imparting significant viscosity and thickening to the solution. Due to its thickening, emulsifying, binding and gelling properties, quick solubility in cold water, wide pH stability, film forming ability and biodegradability, it finds applications in large number of industries. In last few decades a lot of research has been done on guar gum to fit it into particular application, as such or by its structural modifications. This review gives an overview of the nature, chemistry and properties of guar gum and discusses recent developments in its modifications and applications in major industries like hydraulic fracturing, explosives, food, agriculture, textile, paper, cosmetics, bioremediation, drug delivery, medical and pharmaceuticals. This article would help researchers engaged in biopolymer area and other end-users who want to begin research in natural polysaccharides.

Novel tunable composites based on bentonite and modified tragacanth gum for removal of acid dyes from aqueous solutions

A series of new adsorbents derived from tragacanth gum-graft-poly(methyl methacrylate) and bentonite (TG-g-PMMA/B) were synthesized.

Biosorption of Cr(VI) and Zn(II) ions from aqueous solution onto the solid biodiesel waste residue: mechanistic, kinetic and thermodynamic studies

In this present study, the biosorption of Cr(VI) and Zn(II) ions from synthetic aqueous solution on defatted J atropha oil cake (DJOC) was investigated. The effect of various process parameters such as the initial pH, adsorbent dosage, initial metal ion concentration and contact time has been studied in batch-stirred experiments. Maximum removal of Cr(VI) and Zn(II) ions in aqueous solution was observed at pH 2.0 and pH. 5.0, respectively. The removal efficiency of Cr(VI) and Zn(II) ions from the aqueous solution was found to be 72.56 and 79.81%, respectively, for initial metal ion concentration of 500 mg/L at 6 g/L dosage concentration. The biosorbent was characterized by Fourier transform infrared, scanning electron microscopy and zero point charge. Equilibrium data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models and the best fit is found to be with the Freundlich isotherm for both Cr(VI) and Zn(II) metal ions. The kinetic data obtained at different metal ion concentration have been analysed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion models and were found to follow the pseudo-second-order kinetic model. The values of mass transfer diffusion coefficients (De) were determined by Boyd model and compared with literature values. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were analysed using the equilibrium constant values (Ke) obtained from experimental data at different temperatures. The results showed that biosorption of Cr(VI) and Zn(II) ions onto the DJOC system is more spontaneous and exothermic in nature. The results indicate that DJOC was shown to be a promising adsorbent for the removal of Cr(VI) and Zn(II) ions from aqueous solution.

Polymeric sorbents for removal of Cr(VI) from environmental samples

Chromium (Cr) is an important raw material in some chemical industries including paint, pigments, textiles, leather tanning, steel fabrication, electroplating, cement preservation, and canning industries. Once in the environment, Cr exists in various oxidation states depending on pH and concentration. Trivalent [Cr(III)] and hexavalent [Cr(VI)] forms are the most common with Cr(VI) being the most toxic to biota. The review discusses various types of polymeric sorbents that have been prepared for the extraction of Cr(VI) from environmental samples, mostly aqueous samples. Sorbents are categorized into biosorbents, hybrid sorbents, synthetic polymeric, and modified natural polymeric sorbents. Most of the emphasis will be on the advantages and disadvantages of different synthetic polymeric sorbents. Important parameters that define the performance of the sorbents, that is, binding capacity, equilibration time, optimum sample pH, and selectivity, are compared.

N-doped porous carbon with magnetic particles formed in situ for enhanced Cr(VI) removal

A newly designed N-doped porous carbon with magnetic nanoparticles formed in situ (RHC-mag-CN) was fabricated through simple impregnation then polymerization and calcination. The doped nitrogen in RHC-mag-CN was in the form of graphite-type layers with the composition of CN. The resultant nanocomposite maintained a high surface area of 1136 m(2) g(-1) with 18.5 wt% magnetic nanoparticles (Fe3O4 and Fe) inside, which showed a saturation magnetization (Ms) of 22 emu/g. When used as an adsorbent, the RHC-mag-CN demonstrated a very quick adsorption property for the removal of Cr(VI), during which 92% of Cr(VI) could be removed within 10 min for dilute solutions at 2 g L(-1) adsorbent dose. The high adsorption capacity (16 mg g(-1)) is related to the synergetic effects of physical adsorption from the surface area and chemical adsorption from complexation reactions between Cr(VI) and Fe3O4. Importantly, the basic CNs in RHC-mag-CN increase its negative charge density and simultaneously increase the adsorption of metallic cations, such as Cr(3+) formed in the acid solution from the reduction of Cr(VI). The formation of magnetic nanoparticles inside not only supplies complexing sites for the adsorption of Cr(VI), but also shows perfect magnetic separation performance from aqueous solution.

Accelerated Hexavalent Chromium [Cr (VI)] Reduction with Electrogenerated Hydrogen Peroxide in Microbial Fuel Cells

Cr(VI) was reduced at a carbon felt cathode in an air-cathode dual-chamber microbial fuel cell (MFC). The reduction of Cr(VI) was proven to be strongly associated with the electrogenerated H2O2 at the cathode. At pH 3.0, only 27.3% of Cr(VI) was reduced after 12h in the nitrogen-bubbling-cathode MFC, while complete reduction of Cr(VI) was achieved after 6h in the air-bubbling-cathode MFC in which the reduction of oxygen to H2O2was confirmed. The results showed that the efficient reduction of Cr(VI) could be achieved with an air-bubbling-cathode MFC.