Removal Of Hexavalent Chromium Ions Research Articles

Tuning electrochemical behavior and band gap energy of ammonium phosphomolybdate/polymer composite and facilitate reduction of Cr(VI) in contaminated water

Binary composites of ammonium phosphomolybdate (APM) with polyaniline and poly(N-methylaniline) namely APM/PAni and APM/PNMAni were synthesized respectively in situ by exploiting the oxidizing ability of APM. The composites were characterized using fourier transform infrared spectroscopy, powder X-ray diffraction, and scanning electron microscopy. Further, the electrochemical behavior of these composites was investigated using cyclic voltammetry. The redox peaks obtained for APM, APM/PAni and APM/PNMAni at 0.302, 0.228 and 0.298 V respectively could be attributed to MoV/MoVI electron process. The appreciable shift in the peak could be attributed to the electron donating behavior of methyl groups in APM/PNMAni. Additionally, the band gap energy was calculated using diffuse reflectance spectroscopy data. The optical band gap of the composites increased considerably as compared to APM. A higher band gap was observed for APM/PNMAni as compared to APM/PAni, indicating the influence of methyl substitution in tuning the band gap energy. In addition, the role of these composites and its constituents in the removal of hexavalent chromium ions from aqueous solution was also explored. The removal of Cr(VI) from aqueous solution was monitored using UV–Visible spectroscopy. While removal of Cr(VI) as high as 96.3 % could be achieved using polymers, composites exhibited the ability to reduce toxic Cr(VI) moieties to environmentally benign Cr(III) ions.

From waste cooking oil to oxygen-rich onion-like nanocarbons for the removal of hexavalent chromium from aqueous solutions

Vegetable cooking oil is used in domestic and commercial kitchens owing to its ability to modify and enhance the taste of the food through the frying process. However, as the oil is used through several frying cycles, it changes colour to dark brown and acquires an unpleasant smell. At this point, the waste oil is usually discarded, thereby finding its way into freshwater streams due to poor disposal and thus becoming an environmental pollutant. To provide an alternative, ‘green’ route to waste oil disposal, herein we report on the metal-free synthesis of onion-like nanocarbons (OLNCs) made from waste cooking oil via flame pyrolysis. The OLNCs were then applied in the removal of hexavalent chromium ions from aqueous solutions. The as-synthesised OLNCs were found to have similar properties (size, quasi-spherical shape etc.) to those synthesised from pure cooking oils. The Fourier-transform infrared spectroscopy data showed that the OLNCs contained C-O-type moieties which were attributed to the oxygenation process that took place during the cooking process. The OLNCs from waste oil were applied as an adsorbent for Cr(VI) and showed optimal removal conditions at pH = 2, t = 360 min, Co = 10 mg/L and Q0max = 47.62 mg/g, superior to data obtained from OLNCs prepared from pristine cooking oil. The results showed that the OLNCs derived from the waste cooking oil were effective in the removal of hexavalent chromium. Overall, this study shows how to repurpose an environmental pollutant (waste cooking oil) as an effective adsorbent for pollutant (Cr(VI)) removal. Significance: Waste cooking oil outperformed olive oil as a starting material for the production of OLNCs for the removal of toxic Cr(VI) from water. The superior performance of the OLNCs from waste cooking oil was attributed to the higher oxygen content found on their surface and acquired through the cooking process. Not only are the OLNCs produced from waste cooking oil effective in the removal of Cr(VI), but they can be used multiple times before replacement, which makes them sustainable.

Removal of Hexavalent Chromium Ion (Cr6+) From Industrial Effluents Using Low Cost Bio-Adsorbents: A Review

Removal of Hexavalent Chromium Ion (Cr6+) From Industrial Effluents Using Low Cost Bio-Adsorbents: A Review

Efficient removal of hexavalent chromium ions from simulated wastewater by functionalized anion exchange resin: Process optimization, isotherm and kinetic studies

In the present study, hazardous heavy metal ion hexavalent chromium (Cr(VI)) was removed from aqueous solution by using Indion GS-300 (IGS-300), strong base anion exchange resin. The process parameters for the removal of Cr(VI) were optimized using response surface methodology (RSM) approach. Procured resin was analyzed by various techniques like FTIR, and FESEM associated with elemental analysis which provided functional groups and surface structure of the adsorbents. Various batch adsorption experiments were conducted by varying parameters such as Cr(VI) concentrations from 5 mg/L to 45 mg/L, 2 to 10 pH, IGS-300 resin dosage between 0.38 and 1.88 g/L, and temperature of 20–40 °C with 90 min fixed contact time. Fixed time was determined from preliminary study of the present work. The maximum adsorption capacity of IGS-300 resin was found 294.11 mg/g and 98.20% of removal achieved with optimum conditions of 4 pH, 1.50 g/L adsorbent dosage, 15 mg/L Cr(VI) concentration and 35 °C temperature. The experimental data was found with best fitted Freundlich Isotherm and pseudo second order kinetic model. Regeneration study was also done on the adsorbed resins using different solution includes water, 0.1 M HCl, and 0.1 M NaOH. Up to 3 cycles of 0.1 M NaOH treatment, resin showed >50% Cr(VI) removal in aqueous solution whereas water and HCl were found less effective on third cycle. Therefore, this study found that IGS-300 resin is more efficient adsorbent for the removal of Cr(VI) from aqueous solutions and possessing highly significant regeneration capacity.

Effective removal of hexavalent chromium from water by sustainable nano-scaled waste avocado seeds: adsorption isotherm, thermodynamics, kinetics, and error function

Abstract In the current investigation, an efficient low-cost nano-scaled material was prepared from waste avocado seeds (NASs) and employed as a sustainable nanosorbent for removal of hexavalent chromium ions. The adsorption and surface characteristics with respect to the availability of functional groups, basic component elements, and structural properties of NASs were achieved by different techniques. Analysis of NASs referred to the presence of carbon and oxygen contents providing 97.21%. The NASs particles were homogenously identified and ranged between 18.68 and 19.05 nm. The impact of various affecting adsorption parameters on hexavalent chromium ions removal was elaborated and optimized at pH 2.0, NASs dose 10 mg, contact time 30 min, and temperature 25 °C by the batch adsorption assay. Fifteen linear and nonlinear modeling tests were applied to evaluate the adsorption isotherms and arranged in the following fitting order: Tempkin < BET < Dubinin-Radushkevich < Generalized < Halsey ˂ Flory–Huggins < Freundlich < Harkins–Jura ˂ Langmuir for linear formulas and Weber-van Vliet < Langmuir < Generalized < Radke–Prausnitz (II) < Radke–Prausnitz (III) < Fritz-Schlunder IV < Baudu < Multilayer < Fritz-Schlunder V < Toth for nonlinear formulas with 2 to 5 parameters. Linear and nonlinear pseudo-second-order models, intraparticle diffusion, and Elovich models were also scrutinized, and both pore diffusion and film were similarly involved in the rate-limiting step. The values of ΔS° (0.21 kJ/mol), ΔH° (− 41.02 kJ/mol) and ΔG° (− 28.30 to − 19.97 kJ/mol) at high concentration of hexavalent chromium (50 mg L−1) and a temperature range of 20–60 °C reflected the disordering, spontaneously exothermic adsorption process. The activation energy (Ea) was also confirmed to include the diffusion process at the activation energy in the rate-limiting step. The potential application of NASs in hexavalent chromium removal from wastewater, seawater, and tap water as real aqueous matrices referred to excellent percentage removal values in the range from 98.44 to 98.86%. Based on the outlined results, one can deduce that excellent performance and efficiency for removal of high hexavalent chromium concentration at high temperature, low nanosorbent mass, and low pH from different aqueous matrices were accomplished by the evaluated NAS nanosorbent. Accordingly, the investigated NAS nanosorbent is recommended to apply in high stress industrial and wastewater treatment plants.

Removal of hexavalent chromium ions and mixture dyes by electrospun PAN/graphene oxide nanofiber decorated with bimetallic nickel–iron LDH

The network of electrospun nanofibers modified by layered double hydroxides (LDHs) still needs to be thoroughly investigated in the field of adsorption of toxic metal ions and dyes from its aqueous solution. In the present study, an innovative electrospun nanofiber membrane was fabricated, which was used to eliminate pollutants from water. Polyacrylonitrile/graphene oxide (PAN/GO) composite nanofibrous membranes were fabricated by the electrospinning technique first, and next bimetallic nickel iron layered double hydroxide/PAN/GO (NiFe LDH/PAN/GO) composite nanofibrous membranes were synthesized by via hydrothermal method. The characterizations of the prepared nanofibers membranes were analyzed using FE-SEM, EDS element mapping, XRD, FTIR, AFM, and WCA. The adsorption behavior of binary mixture of Rose Bengal (RB) and Brilliant Blue (BB) dyes and metal ions of hexavalent chromium (Cr(VI)) by NiFe LDH/PAN/GO nanofibers were investigated via batch experiments based on central composite design (CCD) method. According to the Langmuir model, the maximum adsorption capacity of the NiFe LDH/PAN/GO toward mixture of RB and BB dyes and Cr(VI) ions are 6.19, 7.74 and 13.1 mg g−1, respectively. In addition, the fabricated LDH composite membranes after five times sequential adsorption/desorption experiments. The adsorption kinetics of pollutants follows the pseudo-first-order model. The adsorption process is spontaneous, endothermic, and enhancement of randomness. In addition, NaCl salt decreased the mixture of RB and BB dyes and metal Cr(VI) ions removal by the composite membranes.

The synthesis of nanocellulose-based nanocomposites for the effective removal of hexavalent chromium ions from aqueous solution

Abstract The present study reports the synthesis of a polydopamine (PDA)/nanocellulose (NC) nanocomposite for the effective removal of chromium ions from water. PDA was used to modify NC surface producing a nanocomposite namely PDA/NC, by in situ polymerization of dopamine on the surface of NC. Thereafter, the as-synthesized nanocomposite was characterized using familiar techniques such as Fourier transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy. All results indicated the successful combination of PDA and NC in one nanocomposite. The PDA/NC nanocomposite was evaluated for the removal of hexavalent Cr(vi) ions from an aqueous solution. The adsorption conditions, such as pH, contact time, and initial Cr(vi) concentration, were optimized. Adsorption kinetic studies revealed that Cr(vi) removal on the surface of PDA/NC nanocomposite followed the pseudo-second-order kinetic model. Furthermore, isotherm studies revealed that Cr(vi) removal followed the Langmuir isotherm model with a maximum adsorption capacity (q m) of 210 mg/g. The adsorption mechanism study indicated that the Cr(vi) removal was reached via complexation, adsorption, and chemical reduction. The reusability of a PDA/NC nanocomposite for the removal of Cr(vi) ions was studied up to five cycles with acceptable results. The high adsorption capacity and multiple removal mechanisms validated the effective applicability of PDA/NC nanocomposite as a useful adsorbent for the removal of Cr(vi) ions from aqueous solution.

Novel reusable amine-functionalized cellulose acetate beads impregnated aminated graphene oxide for adsorptive removal of hexavalent chromium ions

In this study, a multi-featured adsorbent was developed for the adsorptive removal of hexavalent chromium (Cr6+) ions. Herein, aminated graphene oxide (GO-NH2) was firstly synthetized and incorporated into cellulose acetate beads (CA) which were followed by surface amine-functionalization process. Varies characterization tools such as FT-IR spectroscopy, SEM, TGA, XRD, BET, XPS and zeta potential were employed to ensure the successful fabrication of GO-NH2@CA-NH2 composite beads. An enhancement in the adsorption performance was attained, while the adsorption equilibrium was closely gotten within only 60 min. Therefore, the adsorption capacity was boosted with increasing GO-NH2 ratio in the beads matrix from 10 to 25%. Furthermore, the adsorption process agreed with Freundlich isotherm model with a supreme adsorption capacity of 410.21 mg/g at pH 2, while data followed the pseudo-second-order kinetic model. Besides, thermodynamic studies denoted that the adsorption process was endothermic, randomness and spontaneous. The composite beads retained better adsorption characteristics for seven sequential cycles with ease of separation. The proposed adsorption of Cr6+ onto GO-NH2@CA-NH2 surface occurred via the electrostatic interactions, reduction process and coordinate–covalent bonds. These findings hypothesize that the fabricated GO-NH2@CA-NH2 beads could be act as easy-separable and reusable adsorbent for efficient adsorption of Cr6+ ions.

Removal of Chromium Ions from Aqueous Solution using Activated Pergularia daemia Carbon by Batch Adsorption Method

In this research, the stems of Pergularia daemia which is a kind of pick over were converted to activated carbon and were used for the removal of hexavalent chromium ion from aqueous solution. The effect of some parameters such as contact time, adsorbent dose, pH of solution, and other ionic strength of Cr (VI) onto the adsorbent. The equilibrium data were analyzed by Langmuir, and Freundlich isotherm models. Kinetic parameters were studied using following manner such as pseudo second order model, Elovich model and intraparticle diffusion model for adsorption process in addition the thermodynamic parameters such as change in free energy (G°), enthalpy (H°) and entropy (S°) were determined. The results revealed that in this process, the adsorption isotherm and kinetics have more conformity with Langmuir isotherm and pseudo-second-order kinetics, respectively and the thermodynamics study provide evidence about nature of adsorption process.

Removal of hexavalent chromium ions using micellar modified adsorbent: isothermal and kinetic investigations.

Hexavalent chromium is a very poisonous oxyanion and has had a negative impact on human health. This study assessed the viability of removing chromium(vi) using micellar modified adsorbents. In this study, chromium(vi) was removed from locally accessible wheat bran using separate applications of anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants. The initial chromium content (5–12 ppm), pH (2–12), adsorbent dose (1–6 g/100 mL), agitation time (15–240 min), agitation speed (50–300 rpm), and temperature (15–50 °C) were all varied in the adsorption investigation. Pseudo first-order and second-order kinetic models were utilized to analyze the kinetic investigation. To determine thermodynamic parameters, the van't Hoff relationship was used. The maximum result for chromium(vi) uptake was obtained as 87.7%, 83.5% and 98.9% for WB, SDS-mWB, and CTAB-mWB, respectively, at an agitation time of 240 min (i.e., 4 h), temperature (i.e., 25–30 °C), agitation speed (150 rpm). However, both WB and CTAB-mWB derives metal ion removal at lower pH levels (2–4), whereas SDS-mWB requires a pH between 4 and 6 for maximum percentage removal of Cr(vi). The equilibrium data of WB and SDS-mWB were modeled by the Langmuir adsorption isotherm, while the data of CTAB-mWB fitted well in the Freundlich isotherm model. The kinetic analysis of WB, SDS-mWB, and CTAB-mWB revealed that the pseudo-second-order kinetic model provides a thorough explanation for each of these adsorbents. It was found that CTAB-mWB can preferably be used for the removal of chromium(vi) due to its high affinity with adsorbate molecules and adsorption capacity.

Bio-inspired one-step structure adjustment and chemical modification of melamine foam toward highly efficient removal of hexavalent chromium ions

• Polydopamine (PDA)-decorated melamine foam (MF) was successfully achieved. • Morphology of PDA on the MF skeleton was tailored. • The MF-PDA sample showed high adsorption capacity toward Cr(VI). • 53.7% of Cr(VI) was reduced to Cr(III) during the adsorption. • Mechanisms based on protonation effect and charge attraction were proposed. Providing highly efficient and economical adsorbents is the prerequisite for the heavy metal ions removal from wastewater through the adsorption method. Herein, the polydopamine (PDA)-coated melamine foam (MF) skeleton (MF-PDA) was achieved through the bio-inspired functionalization method. The results showed that the smooth surface of MF skeleton was successfully coated by PDA nanoparticles, leading to the changes of surface roughness and chemical features of MF skeleton. Studies on the adsorption behaviors toward highly toxic Cr(Ⅵ) by the MF-PDA samples showed that the MF-PDA samples had the good removal ability and the maximum adsorption capacity was about 240 mg/g at pH value of 2. In addition, the MF-PDA sample also showed high adsorption selectivity, high desorption ability and good reusability. Further analysis found that the coated PDA had a strong reduction effect on Cr(Ⅵ), and about 53.7% toxic Cr(Ⅵ) was reduced to low-toxic Cr(III) during the adsorption. Although PDA decoration method has already been used to assist the secondary modification or to enhance the modification efficiency of the other functionalization method, this work clearly declares that PDA exhibits great role in removing Cr(Ⅵ) and the MF-PDA sample is a promising adsorbent for removing highly toxic Cr(Ⅵ) from sewage.

Micro-mesoporous modified activated carbon from corn husks for removal of hexavalent chromium ions

Modified activated carbon sorbents (ACP-Zn and ACP-Zn-Fe) had been prepared from the activation of corn husks precursor to increase the chemical activity of the resulting adsorbents by increasing the number of active functional groups and generation of micro-mesoporous structures. Fourier transform infrared (FTIR) assessed the acidic surface properties of the prepared activated carbons that is due to the presence acidic functional groups such as –OH and –COOH which improves the removal efficiency of the produced sorbents. Textural characteristics revealed the generation of micro-mesoporous structures in ACP–Zn and ACP-Zn-Fe. Thus the combination of H3PO4 with Zn or Zn–Fe could enhance the mesoporosity with a considerable decrease in the adsorption of nitrogen. However, the formation of mesopores might be attributed to the template-like effects of the obtained Zn- of Zn-Fe compounds inside the carbon structure. These structures were employed as sorbents for removal of hexavalent chromium Cr(VI) ions from its aqueous solutions, and the removal efficiency reached ~ 86% for ACP-Zn-Fe and ~ 82% for ACP-Zn. The kinetic modeling studies revealed that the sorption process follows the pseudo-second-order model which indicates that the mechanism of process is chemisorptions. Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models were used to express the experimental data. The isotherm modeling studies revealed that the sorption process was fit with both Freundlich and Langmuir models with maximum capacity 24.8 and 30.3 mg/g for ACP-Zn and ACP-Zn-Fe, respectively.

Synthesis and Study of Magnesium Ferrite/Reduced Graphene Oxide (MgFe2O4/rGO) Nanocomposite Electrodes to Electrochemical Removal of Hexavalent Chromium Ion from Wastewater

Synthesis and Study of Magnesium Ferrite/Reduced Graphene Oxide (MgFe2O4/rGO) Nanocomposite Electrodes to Electrochemical Removal of Hexavalent Chromium Ion from Wastewater

Rational suitability of low cost activated carbon in removing hexavalent chromium ions from wastewater by uninterrupted mode of adsorption

Heavy metals such as chromium, lead, arsenic and others are dense metals whose contamination of water may exterminate life on earth at the niche in industrial activities, foodstuffs or medicines and so on. Activated carbons are very helpful in removing heavy metal ions from aqueous solutions by adsorption, and have been investigated by many researchers so far. The practical relevance of activated carbon made from de oiled soya in the removal of hexavalent chromium ions through continuous adsorption mode is reported in this paper. A breakthrough plot was plotted in finding the effect of initial concentration and adsorbent bed height in the adsorption of hexavalent chromium through activated carbon of de oiled soya. The breakthrough time and saturation time increased as the concentration of the initial solution shot up from 40 mg/L to 60 mg/L. The saturation time was in an incremental mode when the thickness of the adsorbent bed height in a fixed bed was increased from 5cm to 7cm for 40 mg/L initial concentration of hexavalent chromium. The Adams-Bohart’s model was found to fit perfectly the fixed bed column in the removal of hexavalent chromium from aqueous solutions. The fabricated adsorbent worked well in detoxifying hexavalent chromium metal ion contaminated wastewater.

A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent

AbstractThis study is focused on the adsorption of hexavalent chromium ions Cr(vi) using graphene oxide (GO). The GO was prepared by chemical oxidation (Hummers method) of graphite particles. The synthesized GO adsorbent was characterized by Fourier transform infrared spectroscopy and UV-Vis spectroscopy. It was used for the adsorption of Cr(vi) ions. The theoretical calculations based on density functional theory and Monte Carlo calculations were used to explore the preferable adsorption site, interaction type, and adsorption energy of GO toward the Cr(vi) ions. Moreover, the most stable adsorption sites were used to calculate and plot noncovalent interactions. The obtained results are important as they give molecular insights regarding the nature of the interaction between GO surface and the adsorbent Cr(vi) ions. The found adsorption energy of −143.80 kcal/mol is indicative of the high adsorptive tendency of this material. The adsorption capacity value of GO toward these ions is q = 240.361 mg/g.

Removal of Hexavalent Chromium Ions from Aqeous Medium using Chitosan Magnetic Nanocomposite Modified with Hexamine

This work integrates nanotechnology, adsorption, and magnetic separation to remove chromium (Cr) pollutant from industrial wastewater using magnetic nanoparticles. The magnetic nanocomposite consists of chitosan biopolymer and iron (Fe3O4) magnetic nanoparticles. The Fe3O4 magnetic nanoparticles were prepared by chemical co-precipitation technique and the chitosan magnetic nanocomposite (CMNC) was prepared by Ex situ process. Moreover, anoval amination of CMNC with hexamine  to get functionalized CMNC was performed to remove Cr (VI) in wider range of pH. The prepared Fe3O4 magnetic nanoparticles, CMNC and functionalized CMNC were characterized using different analytical techniques, XRD, FTIR, AFM, SEM, EDX and TGA. Batch adsorption was employed to determine the effects of pH. The adsorption results show that the functionalized CMNC possessed high activity for Cr (VI) removal in any condition of acidic, neutral and basic solutions with the percentage sorption of chromium reached to 91.7%. Sorption isotherms were fitted with the Langmuir, Freundlich and Temkin models, it was found that the Freundlich isotherm model have the best fit with R2=0.998 with functionalized CMNC. The kinetic data of Cr (VI) sorption with functionalized CMNC were fitted well with the pseudo-second order kinetic model. The reuse of the functionalized CMNC indicates that the adsorbent material is more than 80% adsorption capacity after five regeneration cycles. The results of this work shown that functionalized CMNC is a potential adsorbent to removal of Cr (VI) contaminated in a wider range of pH.

Elaboration of novel polyaniline@Almond shell biocomposite for effective removal of hexavalent chromium ions and Orange G dye from aqueous solutions.

A novel polyaniline@Almond shell (PANI@AS) biocomposite was synthesized via facile in situ chemical polymerization method. The as-synthesized adsorbent was characterized using various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and potentiometric titration. A batch adsorption system was applied with the aim of investigating as-synthesized adsorbent ability to remove Cr(VI) ions and Orange G (OG) textile dye from aqueous solutions. Obtained results revealed that adsorption process was strongly depended upon the physicochemical parameters. The adsorption of Cr(VI) and OG dye onto PANI@AS was better described by the pseudo second-order-kinetic model and followed the Freundlich isotherm model. The maximum uptakes were 335.25 for Cr(VI) and 190.98mgg-1 for OG dye. We further evaluated that PANI@AS biocomposite could be regenerated easily with NaOH solution and efficiently reused for Cr(VI) and OG dye removal from aqueous media. Thus, these results indicated the potential practical application of PANI@AS biocomposite for wastewater treatment.

A novel superparamagnetic micro-nano-bio-adsorbent PDA/Fe3O4/BC for removal of hexavalent chromium ions from simulated and electroplating wastewater.

In order to improve the adsorption efficiency of the adsorbent and solve the problem of separation difficulty, a novel superparamagnetic micro-nano-bio-adsorbent (PDA/Fe3O4/BC) was prepared by in situ self-assembly of polydopamine (PDA). The results of scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), X-ray photoelectron spectrometer (XPS), and vibrating sample magnetometer (VSM) characterization showed that the size of bio-adsorbent was about 200nm. PDA and Fe3O4 modifications increased the specific surface area of adsorbent, changed the surface functional group of biochar (BC), and made the adsorbent have super-high magnetization (294.76emug-1). PDA/Fe3O4/BC was applied to treat Cr wastewater. The results show that the adsorption of Cr by PDA/Fe3O4/BC includes single-layer and multilayer adsorption. The adsorption follows the pseudo-second-order kinetic model. The adsorption is spontaneous and endothermic, and its maximum adsorption capacity and activation energy are 25.25mgg-1 at 318K and 23.108kJmol-1, respectively. After adsorption treatment, PDA/Fe3O4/BC still possesses high magnetization (233.04emug-1). PDA/Fe3O4/BC can treat actual electroplating wastewater with Cr(VI) concentration from 20mgL-1 to less than 0.2mgL-1, which met the PRC discharge standard (GB/21900-2008) of electroplating pollutants. Graphical abstract.

Removal of hexavalent chromium from water using polyaniline/ wood sawdust/ poly ethylene glycol composite: an experimental study.

Polyaniline/ Sawdust /Poly Ethylene Glycol/ (PANi/SD/PEG) composite synthesized chemically is used as an adsorbent to remove hexavalent chromium from water. Adsorption experiments have been done in batch and continuous (column) mode. Some parameter such as pH, contact time, PANi/SD/PEG dose, isotherms in batch mode and pH, column bed depth and fluid flow rate in column mode were investigated. Result shows that PANi/SD/PEG has a good performance to remove hexavalent chromium ion from aqueous media. By presence of PEG, prepared composite has been homogenized and further absorption has been occurred. The best adsorption occurs under pH2 and optimum contact time for removal of hexavalent chromium ion in batch experiment was about 30min. Adsorption of Cr (VI) by PANi/SD/PEG fitted well in Langmuir isotherms. Maximum adsorption of hexavalent chromium was calculated 3.2 (mg/g). In column experiments, pH and column bed depth were found to be more prominent than fluid flow rate. Though, about 22% of Cr (VI) can be recovered using 0.1M NaOH in the batch system, the recovered Cr (VI) in column system was less than 7.9%.

Fixed-bed column study for the removal of hexavalent chromium ions from aqueous solutions via pyrolysis of the rice husk

Fixed-bed column study for the removal of hexavalent chromium ions from aqueous solutions via pyrolysis of the rice husk