Adsorption Capacity Of Chromium Research Articles

Chromium removal from wastewater using HSF and VF pilot-scale constructed wetlands: Overall performance, and fate and distribution of this element within the wetland environment

The current experimental work aimed at the investigation of the overall chromium removal capacity of constructed wetlands (CWs) and the chromium fate-distribution within a wetland environment. For this purpose, the experimental setup included the parallel operation and monitoring of two horizontal subsurface flow (HSF) pilot-scale CWs and two vertical flow (VF) pilot-scale CWs treating Cr-bearing wastewater. Samples were collected from the influent, the effluent, the substrate and the plants. Apart from the continuous experiment, batch experiments (kinetics and isotherm) were conducted in order to investigate the chromium adsorption capacity of the substrate material. According to the findings, HSF-CWs demonstrated higher removal capacities in comparison to VF-CWs, while in both types the planted units indicated better performance compared to the unplanted ones. Analysis in various wetland compartments and annual mass balance calculation highlighted the exceptional contribution of substrate to chromium retention, while Cr accumulation in plant was not so high. Finally, experimental data fitted better to the pseudo-second-order and Langmuir models regarding kinetics and isotherm simulation.

Encapsulation and immobilization of the S-layer protein of Lysinibacillus sphaericus in an alginate matrix for chromium adsorption

The S-layer proteins from several species of the Bacillaceae family, as well as the living biomass itself, have the capacity to accumulate toxic metal ions. More specifically, the adsorption of chromium is caused by protein biological activity, periplasmic biosorption and intracellular bioaccumulation mechanisms. This study was conducted to determine the chromium adsorption capacity of the S-layer protein of Lysinibacillus sphaericus and L. sphaericus strains. To enhance stability and efficiency, the S-layer protein was immobilized by entrapment in an alginate matrix, with the purpose of comparing the adsorption efficiency of the immobilized protein and the biomass. The immobilized S-layer protein adsorbed 44.33% of the total chromium (VI) (200 mg l−1) in the sample, while the non-immobilized treatments retained less than 30% of the dissolved metal. Our results show that, the S-layer protein may be considered important in the accumulation of toxic metals as well as promising and interesting for their metal adsorption intrinsic mechanism. Furthermore, its biological activity can potentially be enhanced through immobilization in an alginate matrix.

Removal of copper, nickel and chromium mixtures from metal plating wastewater by adsorption with modified carbon foam

In this study, the characterizations and adsorption efficiencies for chromium, copper and nickel were evaluated using manufacture-grade Fe2O3-carbon foam. SEM, XRD, XRF and BET analyses were performed to determine the characteristics of the material. Various pore sizes (12–420 μm) and iron contents (3.62%) were found on the surface of the Fe2O3-carbon foam. Fe2O3-carbon foam was found to have excellent adsorption efficiency compared to carbon foam for mixed solutions of cationic and anionic heavy metals. The adsorption capacities for chromium, copper and nickel were 6.7, 3.8 and 6.4 mg/g, respectively, which were obtained using a dual exponential adsorption model. In experiments with varying dosages of the Fe2O3 powder, no notable differences were observed in the removal efficiency. In a fixed-bed column test, Fe2O3-carbon foam achieved adsorption capacities for chromium, copper and nickel of 33.0, 12.0 and 9.5 mg/g, respectively, after 104 h. Based on these results, Fe2O3-carbon foam was observed to be a promising material for treatment of plating wastewater.

Removal of Cr(VI) from aqueous solution by rice husk derived magnetic sorbents

A novel magnetic porous sorbent obtained from agricultural waste rice husk was successfully synthesized through a simple carbon-thermal method. The sorbent was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, N2 sorption analysis, and X-ray photoelectron spectroscopy. The removal efficiency of the sorbent for Cr(VI) was also investigated. Chromium adsorption was fitted by the pseudo-second-order and Langmuir models. The maximum chromium adsorption capacity, Brunauer-Emmett-Teller surface area, and average Barrett-Joyner-Halenda pore size of the magnetic sorbent were 157. 7mg·g−1, 134. 1m2·g−1, and 4. 99 nm, respectively. The saturated magnetization of the novel adsorbent was 77. 8 emu·g−1, indicating that the material can facilitate separation and recovery from aqueous systems. The removal mechanisms of Cr(VI) were also discussed. The result illustrates that rice husk-derived magnetic carbonaceous materials are a potential adsorbent for Cr(VI) pollution treatment and provide a suitable method for the effective conversion of biomass waste, which may solve the problem of waste disposal and widen the applications of the materials.

Preparation of cross‐linked porous starch and its adsorption for chromium (VI) in tannery wastewater

Various cross‐linked amino starches were used for chromium (VI) adsorption in the environmental protection area. In order to improve chromium (VI) adsorption, the new cross‐linked amino starch with porous structure (CPS) was synthesized by reverse emulsion polymerization, using waxy corn starch after enzyme hydrolysis (ES) as raw material, N,N′‐methylene‐bis‐acrylamide (MBAA) as cross‐linking agent, and ceric ammonium nitrate as initiator. The effects of the volume ratio of oil phase/aqueous phase, the content of emulsifiers, ES, and MBAA on the swelling, solubility property, chromium (VI) adsorption capacity, grafting ratio, and conversion ratio of CPS were investigated. The properties and morphology of CPS have been characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. The maximum adsorption capacity for chromium (VI) ions of CPS reached 28.83 mg/g when the synthesis condition of CPS was controlled as Voil: VH2O 8:1, emulsifier 9%, starch 2%, and MBAA 10%. The new adsorption peaks of CPS at 1641 cm−1 and 1541 cm−1 proved the cross‐linking reaction between ES and MBAA. The thermal decomposition temperature of CPS was improved to 250°C, and the gelatinization temperature and enthalpy value of CPS were decreased compared with ES because of the occurrence of the cross‐linking reaction. The CPS was like a sponge with a large amount of pores, and the size of these pores was 5 µm. CPS also exhibited superior adsorption property to other heavy metal ions such as cadmium (II) and lead (II) (17.37 and 35.56 mg/g). Copyright © 2015 John Wiley & Sons, Ltd.

Treatment of metal-contaminated wastewater: A comparison of low-cost biosorbents

This study aimed to identify some optimum adsorption conditions for the use of low-cost adsorbent, seaweed (Ascophyllum nodosum), sawdust and reed plant (Phragmites australis) root, in the treatment of metal contaminated wastewater for the removal of cadmium, chromium and lead. The effect of pH on the absorption capacity of each of these biosorbents was found to be significant and dependent on the metal being removed. Post-adsorption FTIR analysis showed significant binding activities at the nitro NO groups site in all biosorbents, especially for lead. Competitive metal binding was found to have possibly affected the adsorption capacity for chromium by A. nodosum more than it affected sawdust and P. australis root. Adsorption is believed to take place mainly by ion exchange particularly at low pH values. P. australis root exhibited the highest adsorption for chromium at pH 2, cadmium at pH 10 and lead at pH 7. A. nodosum seaweed species demonstrated the highest adsorption capacity of the three biosorbents used in the study, for cadmium at pH 7 and for lead at pH 2. Sawdust proved to be an efficient biosorbent for lead removal only at pH 7 and 10. No significant effect of temperature on adsorption capacity was observed, particularly for cadmium and lead removal.

English

Adsorption of Chromium on dye contaminated soil has been studied using batch adsorption technique. This study is carried out to examine adsorption capacity of Chromium on contaminated soil. The influence of contact time, pH, variation of amount of soil, initial Cr Concentration, and particle size also studied. Results revealed that adsorption rate initially increases and equilibrium reached about one hour. Further increase in contact time did not show significant change in equilibrium concentration. The Langmuir and Freundlich isotherm were used to describe the adsorption equilibrium studies. Langmuir isotherm is best fits.

Removal of Hexavalent Chromium from Aqueous Solutions using Sawdust as a low Cost Adsorbent

In the present study, adsorbent is prepared from Delbergia sissoo, and used for Cr (VI) removal from aqueous solutions. Adsorbent is activated with the use of concentrated sulphuric acid. The adsorption of chromium (VI) from aqueous solutions by activated sawdust was studied under a batch and column mode and was demonstrated that the adsorbent prepared from sawdust has a significant capacity for adsorption of Cr (VI) from aqueous solution. The influence of pH, contact time, adsorbent dose and initial concentration of Cr (VI) on the chromium removal was investigated under the batch studies. Adsorption of Cr (VI) is highly pH-dependent and the results indicate that the optimum pH for the removal is 2. In column studies maximum removal was found at bed height 10 cm and flow rate of 1 ml/min. The capacity of chromium adsorption at equilibrium by these natural wastes increased with absorbent concentration. The suitability of adsorbents was tested with Langmuir and Freundlich isotherms and their constants were evaluated.

A batch study of hexavalent chromium removal from synthetic wastewater using modified Russian knapweed flower powder

Aims: In this research, modified Acroptilon repens (Russian knapweed) flower powder was used as a novel adsorbent for removal of Cr (VI) from synthetic wastewater. Materials and Methods: The batch adsorption studies were performed under various laboratory conditions with initial chromium concentrations of 2, 10 and 15 mg/l, adsorbent dose of 0.05-0.2 g/100 ml, contact time of 30-240, min and pH of 2-9. The solution was mixed with a mechanical shaker with 120 r.p.m. at 20°C. The suitability of the adsorbent was evaluated using Langmuir, Freundlich and Temkin isotherm models. For kinetic study, pseudo-first-order and pseudo-second-order kinetics were used. Results: The results indicated that maximum adsorption was achieved in acidic conditions. The optimum pH for the removal was 2. The capacity of chromium adsorption at equilibrium conditions increased by increasing the concentration of the adsorbate. The results also showed that the removal efficiency of Cr (VI) increased with increasing contact time. On increasing the initial concentration of the Cr (VI) solution, chromium removal reduced. The Freundlich and Langmuir isotherm models gave better accordance to the adsorption data in comparison with the Temkin equation. Adsorption of Cr (VI) followed pseudo-second-order kinetics rather than the pseudo-first-order kinetics. Conclusion: This study showed that modified Russian knapweed flower powder can be used as an effective lignocellulosic biomaterial and biosorbent for removal of Cr (VI) from wastewater.

Removal of Hexavalent Chromium from Aqueous Solutions using N-octyl Quaternized Poly(4-vinylpyridine): Kinetic and Equilibrium Studies

The removal of chromium(VI) from aqueous solutions by poly(N-octyl-4-vinylpyridinium bromide) copolymer was investigated. Batch adsorption experiments were used to study the effect of experimental parameters on the equilibrium adsorption of chromium(VI). The adsorption characteristics of copolymer toward Cr(VI) in dilute aqueous solution were followed using UV-Vis spectrophotometry. The effect of concentration of chromium(VI) in solution on the metal uptake behavior of copolymer and the contact time were studied. It has been observed that the capacity of chromium adsorption on copolymer increases with initial metal concentration. Adsorption equilibrium was reached within 10 min. Equilibrium modeling of the process of Cr(VI) removal was carried out by using the Freundlich and Langmuir isotherms. The maxima adsorption capacity of chromium(VI) was found to be 26.31 mgg−1. Results also showed that the kinetic of adsorption is best described by a pseudo-second-order expression than a first-order model.

Equilibrium and kinetic studies of Cr (VI) removal from synthetic wastewater by Acroptilon repense flower powder

In this study the removal of Cr (VI) from synthetic wastewater was investigated using Acroptilon repens (Russian Knapweed) flower powder under various conditions (pH, contact time and initial concentration of Cr). The capacity of chromium adsorption at equilibrium conditions by this biosorbent was increased by adsorbate concentration. The results also showed that the removal efficiency of Cr (VI) was increased by increasing the contact time. By increasing the initial concentration of Cr (VI) solution, chromium removal was reduced. The suitability of adsorbents and their constants was tested or evaluated with the Langmuir, Freundlich and Temkin isotherms models. The results indicated that the Freundlich and Langmuir models (R2 > 0.99) gave a better concordance to the adsorption data in comparison with the Temkin equation (R2 = 0.97). The adsorption of Cr (VI) followed the pseudo-second-order kinetics (R2 = 0.991). The study showed that Acroptilon repens flower powder can be used as an effective lignocellulosic biomaterial and biosorbent for the removal of Cr (VI) from wastewater.

Biosorption and removal of chromium from water by using moringa seed cake (Moringa oleifera Lam.)

This study evaluated the adsorption capacity of chromium from contaminated aqueous solutions by using Moringa oleifera Lam. seeds. Parameters such as solution pH, adsorbent mass, contact time between solution and adsorbent, isotherms, thermodynamic, kinetics, and desorption were evaluated. The maximum adsorption capacity (Qm) calculated to be 3.191 mg g-1 for the biosorbent. Activated carbon was used for comparison purposes in addition to the biosorbent. The best fit was obtained by the Langmuir model for both adsorbents. The average desorption value indicated that both the biosorbent and activated carbon have a strong interaction with the metal. The results showed that the biosorbent has advantages owing to its low cost and efficiency in Cr3+ removal from contaminated waters.

Adsorption of hexavalent chromium on Arundo donax Linn activated carbon amine-crosslinked copolymer

A composite sorbent (ACEDT) was prepared by grafting amine-group onto activated carbon (AC). Both raw AC and ACEDT were characterized by scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Batch experiments with variable pH, time, and concentrations of Cr(VI) were conducted to evaluate the sorption performance of Cr(VI) by both adsorbents from aqueous solutions. The total chromium in the aqueous solution was also recorded to study the mechanism of adsorption/transformation of Cr(VI). The ratio of the amount of Cr(VI) to Cr(III) on the sorbent was confirmed by the XPS analysis results. Langmuir, Freundlich and Temkin adsorption isotherms were used to fit the experimental equilibrium data and values of the parameters of the isotherms were reported. When compared with the untreated activated carbon, the modified activated carbon provided more faster kinetics and the sorbent exhibits greater adsorption capacity for chromium(VI) by comparing the maximum adsorption capacity calculated by Langmuir model. Overall, ACEDT can effectively remove Cr(VI) from aqueous solutions under a wide range of experimental conditions.

Efficacy of Fine-Grained Soil as Landfill Liner Material for Containment of Chrome Tannery Sludge

This paper evaluates the potential use of a fine-grained soil obtained from a site in West Bengal, India, as a suitable landfill liner material for the containment of hexavalent chromium from tanning waste sludge. The physico-chemical properties of the soil were determined. The soil adsorption affinity for hexavalent chromium was also assessed through adsorption batch and breakthrough column tests. The zero point charge (pHzpc) of the soil was found to be 7.3. The batch kinetics and column tests results indicated that the soil liner possesses a relatively good hexavalent chromium adsorption capacity at natural or slightly alkaline condition. The adsorption results showed that the hexavalent chromium uptake by the soil follows both Langmuir and Freundlich adsorption isotherms. This study also illustrated that the hexavalent chromium breakthrough curve in the column experiment reached equilibrium concentration after 3.5 pore volumes (900 h). Overall, this study showed that the fine-grained soil has the potential for usage as a landfill liner or as a component of a landfill barrier system to prevent chromium contamination from the tannery waste disposal.

Hexavalent chromium removal from aqueous solutions by using low-cost biological wastes: equilibrium and kinetic studies

The batch removal of hexavalent chromium from aqueous solutions using almond shell, activated sawdust, and activated carbon, which are low-cost biological wastes under different experimental conditions, was investigated in this study. The influences of initial concentration, adsorbent dose, adsorbent particle size, agitation speed, temperature, contact time, and pH of solution were investigated. The adsorption was solution pH dependent and the maximum adsorption was observed at a solution pH of 2.0. The capacity of chromium adsorption under equilibrium conditions increased with the decrease in particle sizes. The equilibrium was achieved for chromium ion after 30 min. Experimental results showed that low-cost biosorbents are effective for the removal of pollutants from aqueous solution. The pseudo-second-order kinetic model gave a better fit of the experimental data as compared to the pseudo-first-order kinetic model. Experimental data showed a good fit with the Freundlich isotherm model. Changes in the thermodynamic parameters, including Gibbs free energy (ΔGo), enthalpy (ΔHo), and entropy (ΔSo), indicated that the biosorption of hexavalent chromium onto almond shell, activated sawdust, and activated carbon was feasible, spontaneous, and endothermic in the temperature range 28–50 °C.

Experimental Study on Chromium Containment by Admixed Soil Liner

Chrome tanneries generate large quantities of chromium-laden sludge that require proper disposal in engineered landfills to prevent contamination of subsurface soils and groundwater and reduce the risk to public health and the environment. This study investigates the feasibility of using a fine-grained soil as a suitable landfill liner material for the effective containment of chromium in the sludge leachate. Several series of laboratory permeability, adsorption, and column tests were conducted using soil without and with selected additives (rice husk, bentonite, and fly ash) to determine permeability and adsorption and transport of chromium in the soil. Permeability tests showed that the field soil amended with 17% rice husk and 2% bentonite provides the desired hydraulic conductivity of 10−7 cm/s (or less) to minimize the leachate migration into the surrounding subsurface environment. The rice husk and bentonite admixtures significantly reduced the hydraulic conductivity of the soil from 3×10−7 to 2.8×10−9 cm/s, and this admixture was further tested for its effect on the adsorption and transport of chromium in the soil. The batch kinetics and column tests results showed that the soil possesses relatively high chromium adsorption capacity under natural or slightly alkaline condition. The batch tests showed that the amendment marginally improved the chromium adsorptive capacity of the soil. The column tests showed a slight increase in breakthrough time due to the presence of the amendment. The inclined base column tests showed that a mildly inclined liner configuration has a marginal effect on the chromium attenuation in the soil. Overall, this study showed that soil amended with 17% rice husk and 2% bentonite significantly decreased the hydraulic conductivity of the soil and slightly increased the adsorption of chromium, and therefore, has the potential for usage as a landfill liner in a landfill system to contain chromium contamination.

Kinetics and thermodynamics of hexavalent chromium adsorption onto activated carbon derived from acrylonitrile-divinylbenzene copolymer

Adsorption of hexavalent chromium onto activated carbon derived from acrylonitrile-divinylbenzene has been studied in aspect to thermodynamic and kinetics. Chromium adsorption has been investigated using different process parameters like pH, carbon dosage, contact time and temperature. Maximum chromium adsorption capacity was obtained at low pHs and high temperature. Freundlich isotherm model represented the experimental data very well. Chromium adsorption followed the pseudo-second-order kinetic model, which indicated chemical adsorption. The activation energy of adsorption was calculated as 26.07kJ/mol. The mean free sorption energy was >22kJ/mol and adsorption enthalpy was +73.77kJ/mol. All thermodynamic and kinetic calculations indicated the chemical interaction between the carbon surface and chromium ions. The isosteric heat of adsorption increased with surface loading, indicating energetically homogeneous surface of produced activated carbon. Adsorption mechanism has been investigated using X-ray photoelectron spectroscopy.

Synthesis and characterization of polyaniline/zeolite nanocomposite for the removal of chromium(VI) from aqueous solution

The synthesis, characterization and capacity studies of ion exchange resin capable of coordinating with metal ion are reported. Zeolite was modified with conducting polyaniline by the polymerization of anilinium cation in and out side of zeolite channels and a nanocomposite of polyaniline/zeolite (PANI/zeolite) was obtained by the oxidative polymerization of anilinium cation with the zeolite structure. The product was characterized by UV–visible, FTIR, 1H NMR, XRD, SEM and TGA techniques. From FTIR studies it was obtained that the composite has a high content of PANI. SEM pictures in the present study show that the diameter of the PANI/zeolite nanocomposite is between 300 and 600 nm.Batch adsorption experiments were used to investigate the effect of various experimental parameters on the equilibrium adsorption of chromium(VI) on PANI/zeolite nanocomposite. The adsorption characteristics of the composite toward Cr(VI) in dilute aqueous solution were followed spectrophotometrically. The effect of contact time, size of the sorbent and the concentration of Cr(VI) in solution on the metal uptake behavior of the composite were studied. It has been observed that the capacity of chromium adsorption on PANI/zeolite increases with initial metal concentration, the metal ion adsorption on surfactant is well represented by the Freundlich isotherm.

Removal of Chromium (VI) from Aqueous Solution by Cellulose Modified with D-Glucose

Cellulose powder was grafted with the vinyl monomer glycidyl methacrylate using ceric ammonium nitrate as initiator and was further derived with D-Glucose (D-Glu) to build a adsorbent (Cell-g-GMA-D-Glu). Epoxy cellulose, which was made up of Cell-g-GMA and Cell-hydro-g-GMA, was found to contain 5.48 mmol g−1 epoxy groups. The adsorption process of the adsorbent was described by the Langmuir model of adsorption well and the maximum adsorption capacity of chromium (VI) reached to 54.59 mg g−1. The adsorption-desorption tests of the Cell-g-GMA-D-Glu exhibited that the reproducibility of the absorbent was well and the adsorbent could be reused six times at least.

Preparation and characterization of La(III) encapsulated silica gel/chitosan composite and its metal uptake studies

Lanthanum loaded silica gel/chitosan composite (LaSiCS) was prepared by mixing silica gel, LaCl 3·7H 2O and chitosan which was then cross-linked with glutaraldhyde. The LaSiCS composite was characterized using FT-IR, SEM-EDAX, XRD and BET. The adsorption of chromium(VI) ions onto LaSiCS composite has been investigated. The LaSiCS composite was found to have excellent chromium adsorption capacity than the silica gel/chitosan composite (SiCS), silica gel (Si) and chitosan (CS). The sorption experiments were carried out in batch mode to optimize various parameters viz., contact time, pH, initial chromium ion concentration, co-ions and temperature that influence the sorption. Langmuir and Freundlich adsorption models were applied to describe isotherm constants. Equilibrium data agreed very well with the Langmuir model. Thermodynamic studies revealed that the nature of chromium sorption was spontaneous and endothermic. The LaSiCS composite removes chromium by electrostatic adsorption coupled reduction/ion-exchange.