Chromium Sorption Research Articles

Factors affecting the sorption of trivalent chromium by zeolite synthesized from coal fly ash

This research was initiated to determine the effects of different constituents and properties of zeolite synthesized from fly ash (ZFA) on Cr(III) sorption. The uptake of Cr(III) by ZFA was influenced greatly by pH, increasing with the increase in pH. The pH was controlled mainly by calcium-related components (especially CaCO 3 and free CaO) and zeolite components in ZFAs. Sorption maximum of Cr(III) ( Q m ), determined by a repeated batch equilibration method, ranged from 22.29 to 99.91 mg/g for the 14 ZFAs. The Q m value correlated significantly with Ca-related components. The correlation coefficients were 0.9467, 0.5469, 0.7521, and 0.9195 for total Ca, CaCO 3, CaSO 4, and f.CaO, respectively. The Q m value was also closely related to cation-exchange capacity ( r = 0.6872 ) and specific surface area ( r = 0.7249 ). Correlation coefficients of Q m with dissociated Fe 2O 3 and Al 2O 3 were much higher than those of total Fe and total Al contents, respectively. It was suggested that, in ZFAs, zeolite and iron oxide acted as ion exchanger and adsorbent for Cr(III), respectively, while Ca components elevated the pH of the reaction system and consequently promoted ion exchange and adsorption and caused the surface precipitation of chromium hydroxide.

Chromium (III) removal by weak acid exchanger Amberlite IRC-50 (Na)

Chromium (III) sorption on a weakly macroporous cation exchanger Amberlite IRC-50 (Na) is studied as a function of time and temperature. The rate constant values for chromium (III) sorption are calculated both for film and particle diffusion processes. The temperature is found to have a positive effect on both the diffusional processes. The high values of energy of activation confirm the particle diffusional nature of the process. The pH changes in the system show a competition between the Cr(OH) 2+ and H + ions for the exchange sites of the adsorbent. Equilibrium data are explained with the help of Langmuir equation. Various thermodynamic parameters (Δ H°, Δ S° and Δ G°) from chromium (III) exchange on the resin are calculated.

TRACE ELEMENTS REMOVAL FROM WATER USING MODIFIED ACTIVATED CARBON

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion‐sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $ 23 and compatibility with the traditional household filtration system.

Retention profile and subsequent chemical speciation of chromium (III) and (VI)) in industrial wastewater samples employing some onium cations loaded polyurethane foams

The retention of chromium (VI) from aqueous media onto tetraphenylarsonium chloride (TPAs +Cl −) or tetraphenylphosphonium bromide (TPP +Br −) immobilized polyurethane foams (PUFs) was fast and followed first order reaction. The kinetic data of the retention step were subjected to Weber-Morris, Lagergren, Bhattacharya and Venkobachar and Bt kinetic models. The results revealed that, film and intraparticle transport might be the two steps controlling the rate of chromium (VI) sorption from the aqueous acid solutions of pH ∼ zero. The positive values of the Δ H of chromium (VI) retention by the reagents loaded PUFs were interpreted as an endothermic process. Under the optimum pH (pH ∼ zero ) of the aqueous solution, the proposed TPAs +Cl − or TPP +Br − immobilized PUFs was successfully used in a series of medical syringe (30, 50 mL capacity) as pulse columns for complete collection of chromium (VI) species present in fresh and industrial wastewater samples at ultra trace low level of chromium (VI) (≤ 0.05 μg mL − 1 ). The collected chromium (VI) species onto TPAs +Cl − or TPP +Br −–PUFs was then stripped quantitatively (98–102 ± 2.6%) from the pulse columns with NaOH (2.0 mol L − 1 ) and subsequently analyzed photometrically. The chromium (VI) ions could be pre concentrated up to 100-fold from large volume of water samples. The proposed pulse foam columns were applied successfully for complete collection, recovery (97.5 ± 2.6%, n = 5) and subsequent chemical speciation of chromium (III) and (VI) in wastewater samples. The results are in good agreement with the reported and standard methods at 95% confidence.

Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark

In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

Sorption and desorption studies of chromium(VI) from nonviable cyanobacterium Nostoc muscorum biomass

This communication presents results pertaining to the sorptive and desorptive studies carried out on chromium(VI) removal onto nonviable freshwater cyanobacterium ( Nostoc muscorum) biomass. Influence of varying the conditions for removal of chromium(VI), such as the pH of aqueous solution, the dosage of biosorbent, the contact time with the biosorbent, the temperature for the removal of chromium, the effect of light metal ions and the adsorption–desorption studies were investigated. Sorption interaction of chromium on to cyanobacterial species obeyed both the first and the second-order rate equation and the experimental data showed good fit with both the Langmuir and freundlich adsorption isotherm models. The maximum adsorption capacity was 22.92 mg/g at 25 °C and pH 3.0. The adsorption process was endothermic and the values of thermodynamic parameters of the process were calculated. Various properties of the cyanobacterium, as adsorbent, explored in the characterization part were chemical composition of the adsorbent, surface area calculation by BET method and surface functionality by FTIR. Sorption–desorption of chromium into inorganic solutions and distilled water were observed and this indicated the biosorbent could be regenerated using 0.1 M HNO 3 and EDTA with upto 80% recovery. The biosorbents were reused in five biosorption–desorption cycles without a significant loss in biosorption capacity. Thus, this study demonstrated that the cyanobacterial biomass N. muscorum could be used as an efficient biosorbent for the treatment of chromium(VI) bearing wastewater.

Removal of selected metals from drinking water using modified powdered block carbon

This paper presents the possible alternative removal options for the development of safe drinking water supply in the trace elements affected areas. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causes various adverse effects on living bodies. Performance of three filter bed method was evaluated in the laboratory. Experiments have been conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon (PBC), powder carbon steel and ball ceramic in the ion-sorption columns as a cleaning process. The PBC modified is a satisfactory and practical sorbent for trace elements (arsenite and chromate) dissolved in water.

Quaternized Poly(4-Vinylpyridine) Coated Activated Carbon: Diffusion Controlled Sorption of Chromium(VI)

Quaternized poly(4-vinylpyridine) coated activated carbon has been proven to be successful in removal and recovery of Cr(VI) from aqueous solution. However, the key component of the mass transfer operations and the diffusion coefficient has not been determined. In this study, adsorption of Cr(VI) was investigated at different initial concentrations. A finite bath diffusion control model with changing bulk concentrations was derived analytically, and a constant related to radius of the absorbent particle and the fractional attainment of adsorption was first introduced into this model. Results indicated that the adsorbent provided fast adsorption kinetics and the modified diffusion-control model fitted the experimental data well. The observed sorption kinetics was consistent with the finite bath diffusion, with an average value of 4.10× 10−6 cm2 ∕s for the product of the distribution coefficient and the effective diffusivity in the adsorption of Cr(VI) on the quaternized poly(4-vinylpyridine) coated activat...

Biosorption of chromium by Termitomyces clypeatus

The manuscript describes removal of chromium from aqueous solution by biomass of different moulds and yeasts. The biomass of Termitomyces clypeatus (TCB) is found to be the most effective of all the fungal species tested. The sorption of hexavalent chromium by live TCB depends on the pH of the solution, the optimum pH value being 3.0. The process follows Langmuir isotherm (regression coefficient 0.998, χ 2-square 5.03) model with uniform distribution over the surface which gets strong support from the X-ray elemental mapping of chromium adsorbed biomass. The amino, carboxyl, hydroxyl, and phosphate groups of the biomass are involved in chemical interaction with the chromate ion forming a cage like structure depicted by scanning electron microscopic (SEM) and Fourier transform infrared spectroscopic (FTIR) results. Desorption and FTIR studies also exhibited that Cr 6+ is reduced to trivalent chromium on binding to the cell surface. The level of chromium concentration present in the effluent of tannery industries’ is reduced to a permissible limit using TCB as adsorbent.

Column study on the adsorption of Cr(III) and Cr(VI) using Pumice, Yarıkkaya brown coal, Chelex-100 and Lewatit MP 62

In the present study, adsorption of Cr(III) and Cr(VI) on Pumice (Pmc), Yarıkkaya (YK) brown coal, Chelex-100, and Lewatit MP 62 is examined at room temperature and at initial chromium concentration of 1.0 × 10 −3 mol/L. Column method was carried out as a function of pH, concentration of Cr(III) and Cr(VI) ions, volume of samples and flow rate. The experimental data were evaluated by Freundlich and Langmuir isotherm models. The dynamic breakthrough capacities of the adsorbents for Cr(III) and Cr(VI) were calculated. The maximum chromium sorption occurred at 5 mL/min flow rate and 25 mL volume for all adsorbents. The results showed that the two readily available adsorbents namely Pmc and YK, were suitable for removing chromium from aqueous solution.

Biosorption of hexavalent chromium by chemically modified seaweed, Cystoseira indica

Abstract The sorption of hexavalent chromium by marine brown algae Cystoseira indica , which was chemically-modified by cross-linking with epichlorohydrin (CB1, CB2), or oxidized by potassium permanganate (CB3), or only washed by distilled water (RB) was studied with variation in the parameters of contact time, pH, initial metal ion concentration and solid/liquid ratio. They were used for equilibrium sorption uptake studies with Cr(VI). The results indicate that biosorption equilibriums were rapidly established in about 2 h. The Cr(VI) adsorption was strictly pH dependent, and maximum removal of Cr(VI) on biosorbents were observed at pH 3.0. The maximum Chromium uptakes were 22.7, 24.2, 20.1 and 17.8 mg g −1 , respectively, for CB1, CB2, CB3 and RB. The order of maximum Cr(VI) uptakes for various biomasses was CB2 > CB1 > CB3 > RB. A comparison of different isotherm models revealed that the Dubinin–Radushkevich (D–R) isotherm model fitted the experimental data best based on R 2 , q max and standard error (S.E.) values and the mean energy of the sorption values indicated that biosorption of Cr(VI) by C. indica may be an ion exchange reaction.

Specific features of sorption of chromium(VI) anions by VION fibrous chemisorbents

Certain fundamental aspects of the process of sorption of chromium(VI) ions from aqueous solutions at pH 6 and 2 by VION fibrous anion-exchangers with varied basicity were revealed.

Batch and continuous biosorption of chromium(VI) by Rhizopus arrhizus

Biosorption of chromium using suspended and immobilized cells of Rhizopus arrhizus was studied by evaluating the physicochemical parameters of the solution such as initial chromium ion concentration in both batch and packed bed reactor. The Langmuir, Freundlich and Redlich–Peterson adsorption isotherm models were used in the equilibrium modeling. The Freundlich and Redlich–Peterson adsorption isotherm models were found to fit accurately with the experimental data. Batch experiments demonstrate that the sorption process corresponds to the second-order kinetic model and the kinetics of sorption indicates the process to be diffusion controlled. The diffusivity of chromium in Rhizopus-alginate gel beads was calculated using the shrinking core model, and the diffusivity values were in the ranges of 0.049 × 10 −5 to 0.521 × 10 −5 cm 2 s −1. A good fit was found in the case of controlling intraparticle diffusion for the sorption of chromium. Thomas model, Adams–Bohart and Wolborska models were used to represent the dynamic sorption of chromium using immobilized beads and the model parameters were evaluated using experimental data. The Thomas model represents well the sorption of chromium at different residence times whilst Adams–Bohart model was fitted better at the initial part of the breakthrough. Wolborska model also represents the sorption of chromium accurately.

Sorption of chromium(VI) on ion-exchange resins and sorbents

Sorption of Cr(VI) on AV-17 and EDE-10P anion exchangers, KU-2 and KB-4 cation exchangers, activated charcoal, and foamed graphite (STRG) is studied.

Chromium Removal and Sorption Mechanism from Aqueous Solutions by Wine Processing Waste Sludge

Wine processing waste sludge (WPWS) has been shown to be an effective sorbent for the sorption of heavy metals (i.e., chromium and nickel), but the mechanism of removal of hexavalent chromium [Cr(VI)] by WPWS remains obscure. The aims of this study were to determine the effects of temperature, initial concentration of Cr(VI), and particle size on the removal Cr(VI) using WPWS. The characteristics of WPWS were determined, and sorption mechanism studies were also performed. The WPWS used was a deposit mixture containing considerable quantities of chemical coagulation as well as activated sludge precipitation from the settling basins of a wastewater treatment plant. Differential scanning calorimetry (DSC) analysis revealed that the WPWS comprised abundant labile carbohydrates and few aromatic structures. According to the IR spectrum, carboxylic groups were the most important functional group in WPWS, interacting with chromium species by protonation and redox reaction. All kinetic experiments were conducted a...

Chromium(VI) biosorption by dried Rhizopus arrhizus: Effect of salt (NaCl) concentration on equilibrium and kinetic parameters

Some industrial wastewaters contain high quantities of salts besides heavy metal ions. The presence of salt ions leads to high ionic strength, which may significantly affect the performance of the biosorption process so the effect of salts on the biosorption of heavy metal ions should be investigated. In this study the biosorption of chromium(VI) from saline solutions on dried Rhizopus arrhizus was studied as a function of pH, initial chromium(VI) and salt (NaCl) concentrations in a batch system. The biosorption capacity of R. arrhizus strongly depended on solution pH and maximum chromium(VI) sorption capacity of sorbent was obtained at pH 2.0 both in the absence and in the presence of increasing concentrations of salt. Chromium(VI)–salt biosorption studies were performed at this pH value. Equilibrium uptakes of chromium(VI) increased with increasing chromium(VI) concentration up to 250 mg l −1 and decreased considerably by the presence of increasing concentrations of salt. At 100 mg l −1, initial chromium(VI) concentration, dried R. arrhizus biosorbed 78.0 mg g −1 of chromium(VI) in 72 h without salt medium. When salt concentration was raised to 50 g l −1, this value dropped to 64.0 mg g −1 of chromium(VI) at the same conditions resulting in 17.9% decrease of biosorption capacity. The equilibrium sorption data were analysed by using Freundlich, Langmuir, Redlich–Peterson and Langmuir–Freundlich (Sips), the two and three parameters adsorption models, using non-linear regression technique and isotherm constants were evaluated depending on salt concentration. The Langmuir–Freundlich (Sips) was the best suitable adsorption model for describing the biosorption of chromium(VI) individually and in salt-containing medium. Pseudo-first-order, pseudo-second-order and saturation type kinetic models described the biosorption kinetics accurately at all chromium(VI) concentrations in the absence and in the presence of changing concentrations of salt. Isotherm and saturation type kinetic constants varied due to the level of salt were expressed as a function of initial salt concentration.

Sorption and Preconcentration of Vanadium, Chromium, Manganese, and Lead on Silica Gel Modified with (3‐Mercaptopropyl) Trimethoxysilane

3‐mercaptopropyltrimethoxysilane, (CH3O)3SiCH2CH2CH2SH, loaded on silica gel was used as a preconcentration sorbent for V, Cr, Mn and Pb prior to their determination by graphite furnace atomic absorption spetrometry (GFAAS). Surface characteristics and surface area of the silica gel before and after chemical modification were determined by elemental analysis. The retention and recovery of the analyte elements were studied by applying batch and column techniques. The experimental parameters, such as the effect of pH of the sample, shaking time in batch technique, flow rate of the eluent, the concentration of acid solution in the column section, and the amount of silica on retention and elution have been investigated. All elements were quantitatively (≥90%) recovered in the batch technique with R.S.D. values of 3.0 for vanadium, 1.8 for chromium, 1.7 for manganese, and 0.4 for lead. The same recoveries were obtained in the column techniques for all elements, while manganese in sea water could not be succesfully recovered. Detection limits of the method for vanadium, chromium, manganese, and lead are 1.1, 1.4, 1.3, and 0.8 ng, respectively.

Chromium sorption on grape stalks encapsulated in calcium alginate beads

A novel sorbent based on 2% grape stalk wastes encapsulated in calcium alginate beads was investigated for the removal of Cr(VI) and Cr(III) from aqueous solutions. The sorbent proved to be efficient for chromium removal in both hexavalent and trivalent forms from aqueous solution at pH 3.0. In binary mixtures, the presence in solution of one of the forms enhances the sorption of the other which results in an increase of the amount of total chromium removed. This study suggests that the proposed sorbent can be used for the removal of chromium from wastewaters through a cost-effective and environmentally friendly process.

Removal of airborne hexavalent chromium mist using chitosan gel beads as a new control approach

Airborne hexavalent chromium is a known human respiratory carcinogen and allergen. Many workers are exposed to hexavalent chromium in various processes which chromium electroplating plants are the most common. In this study, the feasibility of a new control approach to remove this pollutant using chitosan beads as a biosorbent was investigated. Hexavalent chromium sorption was studied relative to pH, pollution concentration, sorbent concentration, temperature, and air velocity using one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations (10-5000 µg/m 3 ) was contacted to chitosan beads (3.3-20 g/L), floating in distilled water with adjusted pH (3-7), using an impinger at different temperatures (20 and 35 °C), and various velocities (1.12 and 2.24 m/s). The ANOVA test result showed that, there were statistical significant differences between factor levels except optimized pH levels. The higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, and higher levels of solution pH values, temperatures, and sorbent concentrations.

Thermodynamic of Chromium Sorption on Biomass Fungi from Aqueous Solution

Thermodynamic of Chromium Sorption on Biomass Fungi from Aqueous Solution