Adsorption Of Hexavalent Chromium Research Articles

Efficient adsorption of chlorpheniramine and hexavalent chromium (Cr(VI)) from water system using agronomic waste material

In present study, we report Cornulaca-monacantha stem (CS) and its activated carbon (CS-AC) for the removal of Cr(VI) and chlorpheniramine (CP) from aqueous system. The chemical composition and surface characteristics of samples were investigated using instrumental techniques such as Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX). The surface area was determined by Brunauer-Emmett-Teller(BET) method. The BET surface area of CS-AC (288.67 m2/g) was found higher as compared to CS adsorbent (47.58 m2/g). The adsorption behavior of adsorbates was extremely dependent on the solutions pH. The maximum uptake for Cr(VI) and CP were observed at pH of 2.0 and 8.0, respectively. The equilibrium data adequately follow the Langmuir isotherm (R2 = 0.98–0.99), suggesting the monolayer sorption of adsorbate molecules. Kinetic investigations indicated that sorption behavior of Cr(VI) follow the pseudo-second-order model. While in case of CP, both pseudo-second-order and Elovich model provides the higher value of regression coefficient (R2). This revealed the chemical adsorption of adsorbate molecules. Thermodynamic study indicated the feasible, spontaneous and endothermic sorption of adsorbate molecules. The regeneration study implies that adsorbent was efficiently recovered from Cr(VI) and CP under different desorbing agents.The CS-AC adsorbent was possess 89.19% and 88.45% uptake for Cr(VI) and CP after 5th cycles of desorption-adsorption, respectively. Finally, we summarize that prepared adsorbent (CS-AC) is highly proficient, versatile and cost-effectively explored for Cr(VI) and CP decontamination from water system.

Novel crosslinked chitosan for enhanced adsorption of hexavalent chromium in acidic solution

To increase acid resistance, a water soluble diepoxy compound [1,2:7,8-diepoxyoctane (DEO)] as a new crosslinker was successfully used to crosslink chitosan beads (CS). The effects of crosslinking conditions (temperature, time, pH, and DEO concentrations) on weight loss and hexavalent chromium [Cr(VI)] adsorption performance of cross-linked chitosan beads (CS-DEO) in acidic solution were investigated. The prepared crosslinked chitosan beads were characterized by BET, SEM, TGA, XRD, and FT-IR analysis. Based on SEM images, morphological surface changes were observed after DEO treatment. TGA analysis results showed that thermal decomposition temperature of chitosan improved upon the crosslinking treatment. The XRD patters demonstrated that crosslinking reaction resulted in a slight reduction in the absorbent crystallinity. Furthermore, the prepared CS-DEO beads were stable in acidic solution and could efficiently adsorb Cr(VI). The CS-DEO beads cross-linked in 6 g/L of DEO solution at pH 10 and 50 °C for 5 h showed no weight loss but had high Cr(VI) adsorption capacity of 325.2 mg/g at pH 2.0, much higher than other reported chitosan-based adsorbents. The kinetic study of CS-DEO followed the pseudo-second-order kinetics. The adsorption isotherm of Cr(VI) on the CS-DEO beads could be fitted well by the Freundlich equation. Moreover, the prepared CS-DEO beads could be easily regenerated at least five times using 1 mol/L NaOH solutions without significant reduction in the Cr(VI) removal performance. DEO is a proper and favorable crosslinker for chitosan-based adsorbents. The prepared CS-DEO beads can be considered as a suitable and efficient adsorbent for Cr(VI) ions in aqueous solutions.

Effect of Process Variables, Adsorption Kinetics and Equilibrium Studies of Hexavalent Chromium Removal from Aqueous Solution by Date Seeds and its Activated Carbon by ZnCl2

The adsorption of hexavalent chromium by preparing activated carbon from date seeds with zinc chloride as chemical activator and granular date seeds was studied in a batch system. The characteristics of date seeds and prepared activated carbon (ZAC) were determined and found to have a surface area 500.01 m2/g and 1050.01 m2/g , respectively and iodine number of 485.78 mg/g and 1012.91 mg/g, respectively. The effects of PH value (2-12), initial sorbate concentration(50-450mg/L), adsorbent weight (0.004-0.036g) and contact time (30-150 min) on the adsorption process were studied . For Cr(VI) adsorption on ZAC, at 120 min time contact, pH solution 2 and 0.02 adsorbent weight will achieve an amount of 35.6 mg/g adsorbed . While when use date seeds as adsorbent , conditions of 3 solution pH, 0.02 absorbent weight , and 120 contact time gave 26.49 mg/g adsorbed amount. Using both Langmuir, Freundlich and Sips models were explain the dsorption isotherms. It declare that the Sips model fits well with the experimental data with a maximum Cr( VI) adsorption capacity for (ZAC) and granular date stone 233.493 and 208.055 mg/g, respectively . The kinetics data which obtained at different initial Cr(VI) concentrations were examined by using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models . The result gained showed that the second-order model was only describing well the empirical kinetics data of both (ZAC) and granular date seeds. It was noticed that the granular date seeds has adsorption performance lower than the (ZAC).

Chitosan-coated-magnetite with Covalently Grafted Polystyrene Based Carbon Nanocomposites for Hexavalent Chromium Adsorption

Chitosan-coated-magnetite with Covalently Grafted Polystyrene Based Carbon Nanocomposites for Hexavalent Chromium Adsorption

Leveraging the Potential of Endomycorrhizal Spores and Montmorillonite for Hexavalent Chromium Adsorption from Aqueous Phase

AbstractMultidisciplinary approach involving biotechnology and chemistry opens up avenues to develop adsorbent materials that can be very useful to alleviate heavy metal toxicity. Towards this direction, we have explored the potential of endomycorrizhal fungal spores in conjunction with a clay mineral as a novel approach for chromium (VI) adsorption. The immobilization of AMF (Arbuscular Mycorrhizal fungus) spores in montmorillonite (in its Na+ form) provides a good platform to adsorb hexavalent chromium. The adsorption was observed at pH 2.0‐3.0 involving the electrostatic interaction between the functional groups present in the fungi‐clay biosorbent surface and tetraoxohydrochromate (VI) anion. Diverse characterization techniques such as Fourier Transform‐Infrared spectroscopy (FTIR), X‐ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), confocal microscopy and X‐ray fluorescence (XRF) were used to observe the interaction of chromium with the biosorbent. Batch adsorption studies involving the experimental variables such as pH variation, kinetics, isotherms and thermodynamics were performed. Pseudo second order kinetics coupled with a Langmuir adsorption capacity of 11.185 mg g−1was realized for this biosorption process. The biosorbent was stable and regenerated for three adsorption‐desorption cycles using sodium hydroxide.

Correction to: Preparation of Chitosan/Bone Char/ $${\hbox {Fe}}_{3} {\hbox {O}}_{4}$$ Fe 3 O 4 Nanocomposite for Adsorption of Hexavalent Chromium in Aquatic Environments

The original version of this article unfortunately contained a mistake.

Biosorption of Hexavalent Chromium by Pseudomonas aeruginosa Strain ANSC: Equilibria Isothermic, Kinetic and Thermodynamic Studies

Pseudomonas aeruginosa strain ANSC, a non-genetically modified bacterial strain isolated from soil was used to study and evaluate biosorption potentials for hexavalent chromium (Cr[VI]) from aqueous solution. Living, heat-killed, and permeabilised cells were all used and found to be capable of reducing and sorbing Cr(VI). The influences of initial Cr(VI) ion concentration (50-150 mg/L), contact time (2 h, 10 min intervals), pH (2-8), temperature (30-60℃) and biosorbent mass (1.0-5.0 g/l) were reported. Adsorption of Cr(VI) is highly pH- and temperature-dependent, and the results indicate that the optimum pH and temperature for removal were found to be 2 and 60℃ respectively. The hexavalent chromium biosorption equilibrium could be better described by Langmuir isotherm than it could by Freundlich isotherm. A comparison of kinetic models applied to the adsorption of Cr(VI) ions onto the biosorbents was evaluated for the pseudo first-order, pseudo second-order, and intra-particle diffusion kinetic models. Results show that the pseudo second-order kinetic model was evidenced to correlate better the experimental data. The rate of hexavalent chromium adsorption increased following permeabilisation of the outer and/or cytoplasmic membrane by surfactants such as Triton X100, Tween 80, toluene, sodium deoxycholate and sodium dodecyl sulphate. The adsorption process has been found endothermic, and thermodynamic parameters of Gibb's free energy (ΔG°), change in enthalpy (ΔH°) and change in entropy (ΔS°) were calculated. Pseudomonas aeruginosa strain ANSC evidenced an effective biosorbent for the removal of hexavalent chromium in aqueous form.

Hyperbranched Polyethylenimine Modified Waste Fiberboard Activated Carbon for Enhanced Adsorption of Hexavalent Chromium

The objective of this work is to prepare a hyperbranched polyethylenimine (HBPEI) grafted activated carbon obtained from waste fiberboard for effectively removing Cr(VI) from aqueous solution. The waste fiberboard activated carbon (WFAC) was modified by HBPEI and cross-linked with glutaraldehyde (GA). The optimal modified conditions were as follows: HBPEI molecular weight 10,000 g/mol, HBPEI/WFAC (w/w) 0.5, GA concentration 0.25%, reaction time 60 min. Both pristine WFAC and HBPEI–WFAC were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), Scanning electronic microscopy (SEM), and Roman spectra. XPS data showed the obvious increase in nitrogen (from 0.72% to 6.65%) after modification. The results of FTIR and XPS suggested that HBPEI was chemically bonded onto the WFAC by the glutaraldehyde (GA) between the amine groups of WFAC and that of HBPEI. HBPEI was also probably grafted onto WFAC through the intermolecular interaction between the carboxylate groups of WFAC and the amine groups of HBPEI. However, the BET surface area of modified WFAC declined slightly (about 200 m2/g). The ID/IG of modified WFAC decreased from 0.92 to 0.82, which indicated that the modification process had no significant effect on the graphitization of activated carbon. The adsorption property onto HBPEI–WFAC and the factors containing contact time, pH value, and Cr(VI) concentration were also investigated. Analysis of the Cr(VI) adsorption data was well simulated by the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, and maximum Cr(VI) uptake of HBPEI–WFAC was 500 mg/g.

Adsorption of hexavalent chromium by activated carbon obtained from a waste lignocellulosic material (Ziziphus jujuba cores): Kinetic, equilibrium, and thermodynamic study

In aqueous solutions, hexavalent chromium Cr(VI) was successfully removed by activated carbon “ Z. jujuba rubidium carbonate-activated carbon” obtained from waste lignocellulosic material ( Ziziphus jujuba cores). Rubidium carbonate was used to prepare Z. jujuba rubidium carbonate-activated carbon by chemical activation using a 1:1 w/w ratio. Our results indicate that the obtained surface area of the activated carbon was equal to 608.31 m2/g. The adsorption study of Cr(VI) was investigated under batch conditions at constant stirring speed (220 r/min). Factors such as pH (1–6), temperature (20–40°C), adsorbent concentration (0.5–3 g/l), and initial Cr(VI) concentration (50–500 mg/l) were all studied to attain the maximum removal efficiency. Prior to the adsorption process, the morphology, elementary composition, and loss mass of activated carbon were characterized using scanning electron microscopy, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Fourier transform infrared analysis of the adsorbent demonstrated the presence of key functional groups associated with the adsorption phenomenon such as those of hydroxyl and aromatic groups. The obtained results showed that the optimal conditions for a maximum adsorption efficiency are 2 for pH, 1 g/l for activated carbon dosage and 100 mg/l for Cr(VI) concentration. The removal percentage increased from 27.2 to 62.08%. The kinetic sorption was described by a pseudo-second-order kinetic equation ( R2 ≈ 0.995). The Tóth ( R2 = 0.997) and Elovich models were best to explain the sorption phenomenon. Thermodynamic studies showed that the adsorption of Cr(VI) onto activated carbon was feasible, spontaneous, and endothermic at 20–40°C. This novel Z. jujuba rubidium carbonate-activated carbon derived from Z. jujuba core has been found to be effective for the removal of Cr(VI) and not harmful to the ecosystem.

Adsorption of hexavalent chromium by polyacrylonitrile-based porous carbon from aqueous solution.

Owing to the unique microporous structure and high specific surface area, porous carbon could act as a good carrier for functional materials. In this paper, polyacrylonitrile (PAN)-based porous carbon materials (PPC-0.6-600, PPC-0.8-600, PPC-0.6-800 and PPC-0.8-800) were prepared by heating KOH at 600°C and 800oC for the removal of Cr(VI) from aqueous solution. The adsorbent was characterized by the techniques of Fourier transform infrared spectroscopy (FT-IR), elementary analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption techniques. The results showed that the adsorption capacity increased with decreasing pH value of the initial solution. The adsorption capacity of Cr(VI) on PPC-0.8-800 was much greater than that on other materials, and maximum adsorption capacity were calculated to be 374.90 mg g−1. Moreover, PPC-0.8-800 had superior recyclability for the removal of Cr(VI) from wastewater, about 82% of its initial adsorption capacity was retained even after five cycles. The result of kinetic simulation showed that the adsorption of Cr(VI) on the PAN-based porous carbon could be described by pseudo-second-order kinetics. The adsorption process was the ionic interaction between protonated amine groups of PPC and HCrO4- ions.

Adsorption of hexavalent chromium by crushed brick: effect of operating parameters and modeling study

Adsorption of hexavalent chromium by crushed brick: effect of operating parameters and modeling study

Adsorption of hexavalent chromium by novel chitosan/poly(ethylene oxide)/permutit electrospun nanofibers

The Cr(vi) adsorption mechanism by CS/PEO/PT composite nanofibers includes electrostatic interaction, chelation, reduction and ion exchange.

Experimental Study on Adsorption of Hexavalent Chromium with Microwave-Assisted Alkali Modified Fly Ash

Coal fly ash, a kind of solid waste generated from coal-fired power stations, can be used as an absorbent for Cr(VI) from aqueous solution. The adsorption characteristics of microwave-assisted alkali modified fly ash to hexavalent chromium had been investigated. Many experimental conditions including pH, contact time, temperature, and fly ash dosage have significant impacts on adsorption performance of modified fly ash. The optimum conditions for the preparation of modified fly ash were as follows: microwave power 600 W, microwave temperature 60 °C, and microwave time 10 min. Batch experiments on adsorption isothermal characteristics of the fly ash modified under the optimal conditions were carried out. The results show that the adsorption of hexavalent chromium ions by modified fly ash is in accordance with the Freundlich and Langmuir isotherm adsorption models, which indicates that the adsorption process is monomolecular adsorption. Environmental-benign utilization of fly ash as low-cost adsorbents in wastewater treatment would bring long-term economic and environmental benefits.

Efficient removal of hexavalent chromium from water by an adsorption-reduction mechanism with sandwiched nanocomposites.

Hexavalent chromium Cr(vi), one of the most toxic contaminants, is released in the environment due to various anthropogenic activities. This study presents a novel sandwiched nanocomposite synthesized using graphene oxide (GO), manganese dioxide (MnO2) nanowires, iron oxide (Fe3O4) nanoparticles and polypyrrole (PPy) to remove hexavalent chromium ion Cr(vi) from water by an adsorption–reduction mechanism. In the sandwiched nanocomposites, GO provided enough surface area, functional groups, and hydrophilic surface for efficient absorption. Fe3O4 nanoparticles with excellent magnetic properties make it easy to separate and recover from water. Under acidic conditions, MnO2 nanowires act as both template and oxidant to initiate the polymerization of pyrrole monomers on its freshly activated surface to obtain GO/MnO2/Fe3O4/PPy (designated as GMFP) nanocomposite. GMFP could effectively adsorb Cr(vi) through electrostatic attraction, and the adsorbed Cr(vi) ions were partly reduced to trivalent chromium Cr(iii) (62%), resulting in the efficient adsorption and high removal of Cr(vi) from water. Hexavalent chromium adsorption by GMFP is strongly pH dependent and the adsorption kinetics followed the pseudo-second-order model. The Langmuir isothermal model described the adsorption isotherm data well and the maximum adsorption capacity was up to 374.53 mg g−1 at pH 2.0. These experimental results suggested that GMFP had great potential as an economic and efficient adsorbent of hexavalent chromium from wastewater, which has huge application potential.

Adsorption and kinetic studies of hexavalent chromium by dehydrated Scrophularia striata stems from aqueous solutions

Adsorption and kinetic studies of hexavalent chromium by dehydrated Scrophularia striata stems from aqueous solutions

Equilibrium, Kinetic and Adsorption Mechanisms of Chromium (VI) on Characterized Activated Carbon Synthesized from Phosphoric Acid Activation of Coconut Shells

Over the years, water pollution due primarily to the discharge of toxic heavy metals from industrial activities has served as a major challenge in our quest to provide clean drinking water to millions of people across the world. Numerous cheap and environmentally friendly methods and technologies have been developed for the treatment of wastewater contaminated with heavy metals. Key among these technologies is the use of adsorbent as it is the most economical and efficient. In this present study, coconut shells were used to develop microporous adsorbent (activated carbon) through chemical activation by phosphoric acid (H3PO4). An analysis of the effect of various process parameters such as pH, temperature, initial metal ion concentration, adsorbent dose and contact time was conducted through batch adsorption of hexavalent chromium [Cr (VI)] on prepared AC sample. Initial Cr (VI) concentration was investigated through a range of 10 – 50 mg/L with the study showing an optimum concentration for AC of 20 mg/L for percentage removal (93.3%) but adsorption capacity (Qe) was highest for 50 mg/L (4.512 mg/g). The optimum conditions for adsorbent dose, contact time and temperature were determined as 6 g/L, 100 minutes and 30°C respectively for the prepared AC. Maximum adsorption was recorded for pH (2) at 88.2 5% (removal) and 4.41 mg/g (adsorption capacity) for AC. The experimental data obtained were modelled using various isotherms, including adsorption equilibrium isotherms, adsorption kinetic study and adsorption mechanisms with positive correlations (better fit) obtained for Freundlich isotherm, D-R isotherm (slightly), pseudo-second-order kinetic and Boyd models.

Chitosan-coated-magnetite with Covalently Grafted Polystyrene Based Carbon Nanocomposites for Hexavalent Chromium Adsorption

A chitosan-coated-magnetite with covalently grafted polystyrene (g-PS) based magnetic carbon nanocomposites composed of carbon coated magnetite nanoparticles with carbonized g-PS microsphere are prepared for effective hexavalent chromium (Cr(VI)) adsorption.

Preparation of Chitosan/Bone Char/$$\hbox {Fe}_{3}\hbox {O}_{4}$$Fe3O4 Nanocomposite for Adsorption of Hexavalent Chromium in Aquatic Environments

In this study, magnetic chitosan/bone char/\(\hbox {Fe}_{3}\hbox {O}_{4}\) nanocomposite (MCB–\(\hbox {Fe}_{3}\hbox {O}_{4}\) nanocomposite) was prepared and utilized as an adsorbent for the removal of Cr(VI) from aqueous environments. The effects of influencing parameters such as initial concentration of Cr(VI), adsorbent dose, initial pH, mixing rate, salinity and the existing of competing organic compounds on the adsorption of Cr(VI) were investigated. According to the obtained results, the adsorption process followed the pseudo-first-order kinetic model and Langmuir adsorption isotherm model. Decreasing initial pH from 11 to 2 resulted in increasing the removal efficiency (%) from 24.94 to 88.60%, respectively. Also, the efficiency (%) of Cr(VI) removal increased from 33.73 to 98.81% when the dose of adsorbent rose from 0.25 to 4.0 g/L, respectively. The presence of ethanol and humic acid in solution resulted in decreasing the removal efficiency (%) of Cr(VI) ions.

Enhancement adsorption of hexavalent chromium from aqueous solution on polypyrrole using ethylamine group

ABSTRACTA novel nanospheres adsorbent was successfully prepared using functionalized 1H-Pyrrole-1-ethanamine by homopolymerization. It could be easily protonated to form double-charged repeating structural units on the surface of nanospheres. The physic-chemical properties were characterized by SEM, TGA, XPS and Zeta potential. The effects of initial pH, adsorbent dosage, contact time, initial concentration, and ionic strength were studied in detail. The maximum adsorption capacity of Chromium(VI) was about 729.09 mg g−1 at room temperature. Electrostatic attraction played an important role in the adsorption process and the size of the ion group had a greater effect on the adsorption performance than the charge.

Adsorption of hexavalent chromium in aqueous solution on activated carbon prepared from apple peels

In the present study, activated carbon prepared from apple peels (ACAP) was used to remove chromium (VI) from aqueous solution. The characterization of this ACAP has been performed using different analytical techniques such as FTIR and SEM. The adsorption parameters studied were: pH [2- 7], adsorbent dose [0.025–0.15g/50mL], initial Cr(VI) concentration [10–50mg/L] and temperature [10–40°C]. Maximum Cr(VI) adsorption of 36.01mg/g was achieved using Cr(VI) concentration of 50mg/L, pH of 2, adsorbent dose of 0.05g/50mL, contact time of 4h and temperature of 28°C. This ACAP gave a Cr(VI) adsorption capacity better than a commercial activated carbon. The experimental data fitted well to Freundlich isotherm (R2 = 0.99) and kinetics followed the pseudo-second order model. Thermodynamic parameters, ΔG < 0, ΔH° = 1.99 (Kcal/mol) and ΔS° = 0.0079 (Kcal/Kmol) indicate that the adsorption process is spontaneous and endothermic.