Adsorption of Cr(VI) using thermally activated weed Salvinia cucullata

Adsorption behavior of Mo(VI) from aqueous solutions using tungstate-modified magnetic nanoparticle

A new magnetic nanoparticle modified with sodium tungstate (Mnp-Si-W) was synthesized and employed for the sorption of molybdenum from aqueous solutions. The prepared nanoparticles (Mnp-Si-W) were characterized by different advanced techniques. Different parameters that influenced the adsorption percent of Mo(VI) were investigated using a batch process. Based on a systematic investigation of the adsorption isotherms and kinetics models, Mo(VI) adsorption follows the Langmuir model and pseudo-second-order kinetics. According to the Langmuir isotherm model, the Mnp-Si-W nanoparticles exhibited a maximum adsorption capacity of 182.03 mg g-1 for Mo(VI) at pH 2.0. The effect of competing ions showed that the prepared nanoparticles have a high selectivity for the sorption of molybdenum. Moreover, the effect of some interfering anions on Mo(VI) ion sorption is found in the following order: phosphate < sulfate < chromate. Finally, the nanoparticle (Mnp-Si-W) can be successfully reused five times.

Preparation of a highly functionalized activated carbon from waste third-monomer pressure filter liquid for removal of methylene blue in aqueous solution

Third monomer dimethyl isophthalate-5-sodium sulfonate (SIPM) is an additive widely used to modify polyester chips. During the manufacture of SIPM, large amounts of waste third-monomer pressure filter liquid are produced. As the liquid contains lots of toxic organics and highly concentrated Na₂SO₄, it will cause serious environmental pollution if discharged directly. In this study, highly functionalized activated carbon (AC) was prepared by directly carbonizing the dried waste liquid under ambient pressure. Structural and adsorption properties of the prepared AC were analyzed and evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption analysis and methylene blue (MB) as the adsorbate, respectively. Results showed that the adsorption capacity of the prepared AC to MB reached the highest when carbonization was conducted at 400 °C. XRD analysis showed that the AC has a disordered graphite-like crystal structure. FT-IR and XPS analyses showed that there were plenty of carboxyl and sulfonic functional groups in the AC. The adsorption follows the pseudo-second-order kinetic model and the isotherm process is consistent with the Langmuir model. The adsorption capacity increased with increasing solution pH and dropped when the solution pH exceeded 12. Increasing solution temperature favors the adsorption, where the maximum value can reach as high as 2816.4 mg g^-1 at 45 °C, more than double the values reported to date. The adsorption of MB on the AC is mainly controlled by the electrostatic interaction between MB and the anionic form of carboxyl and sulfonic groups.

Adsorption of Hexavalent Chromium Using Activated Carbon Produced from Sargassum ssp.: Comparison between Lab Experiments and Molecular Dynamics Simulations

Adsorption is one of the most successful physicochemical approaches for removing heavy metal contaminants from polluted water. The use of residual biomass for the production of adsorbents has attracted a lot of attention due to its cheap price and environmentally friendly approach. The transformation of Sargassum-an invasive brown macroalga-into activated carbon (AC) via phosphoric acid thermochemical activation was explored in an effort to increase the value of Sargassum seaweed biomass. Several techniques (nitrogen adsorption, pHPZC, Boehm titration, FTIR and XPS) were used to characterize the physicochemical properties of the activated carbons. The SAC600 3/1 was predominantly microporous and mesoporous (39.6% and 60.4%, respectively) and revealed a high specific surface area (1695 m2·g-1). To serve as a comparison element, a commercial reference activated carbon with a large specific surface area (1900 m2·g-1) was also investigated. The influence of several parameters on the adsorption capacity of AC was studied: solution pH, solution temperature, contact time and Cr(VI) concentration. The best adsorption capacities were found at very acid (pH 2) solution pH and at lower temperatures. The adsorption kinetics of SAC600 3/1 fitted well a pseudo-second-order type 1 model and the adsorption isotherm was better described by a Jovanovic-Freundlich isotherm model. Molecular dynamics (MD) simulations confirmed the experimental results and determined that hydroxyl and carboxylate groups are the most influential functional groups in the adsorption process of chromium anions. MD simulations also showed that the addition of MgCl2 to the activated carbon surface before adsorption experiments, slightly increases the adsorption of HCrO4- and CrO42- anions. Finally, this theoretical study was experimentally validated obtaining an increase of 5.6% in chromium uptake.

Removal of hexavalent chromium via biochar-based adsorbents: State-of-the-art, challenges, and future perspectives

Chromium originates from geogenic and extensive anthropogenic activities and significantly impacts natural ecosystems and human health. Various methods have been applied to remove hexavalent chromium (Cr(VI)) from aquatic environmental matrices, including adsorption via different adsorbents, which is considered to be the most common and low-cost approach. Biochar materials have been recognized as renewable carbon sorbents, pyrolyzed from various biomass at different temperatures under limited/no oxygen conditions for heavy metals remediation. This review summarizes the sources, chemical speciation & toxicity of Cr(VI) ions, and raw and modified biochar applications for Cr(VI) remediation from various contaminated matrices. Mechanistic understanding of Cr(VI) adsorption using different biochar-based materials through batch and saturated column adsorption experiments is documented. Electrostatic interaction and ion exchange dominate the Cr(VI) adsorption onto the biochar materials in acidic pH media. Cr(VI) ions tend to break down as HCrO₄^-, CrO₄^2-, and Cr₂O₇^2- ions in aqueous solutions. At low pH (∼1-4), the availability of HCrO₄^- ions attributes the electrostatic forces of attraction due to the available functional groups such as -NH₄⁺, -COOH, and -OH₂⁺, which encourages higher adsorption of Cr(VI). Equilibrium isotherm, kinetic, and thermodynamic models help to understand Cr(VI)-biochar interactions and their adsorption mechanism. The adsorption studies of Cr(VI) are summarized through the fixed-bed saturated column experiments and Cr-contaminated real groundwater analysis using biochar-based sorbents for practical applicability. This review highlights the significant challenges in biochar-based material applications as green, renewable, and cost-effective adsorbents for the remediation of Cr(VI). Further recommendations and future scope for the implications of advanced novel biochar materials for Cr(VI) removal and other heavy metals are elegantly discussed.

Bidirectional Interaction Between Cancer Cells and Platelets Provides Potential Strategies for Cancer Therapies

Platelets are essential components in the tumor microenvironment. For decades, clinical data have demonstrated that cancer patients have a high risk of thrombosis that is associated with adverse prognosis and decreased survival, indicating the involvement of platelets in cancer progression. Increasing evidence confirms that cancer cells are able to induce production and activation of platelets. Once activated, platelets serve as allies of cancer cells in tumor growth and metastasis. They can protect circulating tumor cells (CTCs) against the immune system and detachment-induced apoptosis while facilitating angiogenesis and tumor cell adhesion and invasion. Therefore, antiplatelet agents and platelet-based therapies should be developed for cancer treatment. Here, we discuss the mechanisms underlying the bidirectional cancer-platelet crosstalk and platelet-based therapeutic approaches.

Removal of Cr (VI) from aqueous solution by activated charcoal derived from Sapindus trifoliate L fruit biomass using continuous fixed bed column studies

In this study, the removal of hexavalent chromium from aqueous solution were examined using activated charcoal derived from Sapindus trifoliate L fruit biomass in continuous fixed-bed column studies. The activated S. trifoliate L fruit charcoal was prepared by treating the fruit powder using concentrated nitric acid solution. Experiments were performed to investigate the effect of bed height and initial concentration on the breakthrough and saturation times. The breakthrough and saturation time increases with increase in bed height and initial concentration of chromium solutions. The maximum adsorption capacity of S. trifoliate L charcoal for hexavalent chromium was found to be 1.719 mg/g in the bed height 15 cm and initial concentration 10 mg/L, respectively. Column data required at various conditions were explained using Bohart-Adams and Thomas model. Two models were found to be suitable to describe the definite part of the dynamic behaviour of the column with regard to bed-height and initial concentration of hexavalent chromium. On comparison of Adjusted R² and estimated standard error, the Thomas model was found to best-fitted model and can be used to predict the adsorption of the hexavalent chromium in fixed-bed column studies. Activated S. trifoliate L fruit charcoal was characterised by SEM-EDX and FTIR analysis.

Fluoride removal efficiencies and mechanism of schwertmannite from KMnO4/MnO2-Fe(II) processes

Fluoride has an adverse effect on both the environment and industrial production. In particular, wastewater from smelting systems containing high concentrations of fluoride is a major cause of fluoride pollution. Based on the characteristics of such wastewater, a targeted and integrated method for removal fluoride using schwertmannite is proposed. The schwertmannite, prepared from the oxidation of Fe(II) by KMnO₄ (Ksw) and MnO₂(Msw), effectively removed fluoride within 30 min under certain conditions. Under most experimental conditions, the removal efficiency of F ion by Ksw was always 13 % higher than that by Msw, which is attributed to the different concentrations of OH^- and SO₄^2- for ion exchange. The calculations showed that the chemical formulas of Ksw and Msw are Fe₈O₈(OH)_5.42±0.04(SO₄)_1.29±0.02 and Fe₈O₈(OH)_5.28±0.04(SO₄)_1.36±0.02, respectively. In the Ksw system, 0.70 mol of OH^- and 0.30 mol of SO₄^2- were released per mole of F ions sorbed; those released for the Msw system were 0.69 mol and 0.31, respectively. The results showed that OH^- played a primary role in the ion exchange and the schwertmannite showed good practicability for actual industrial wastewater.

Removal performance and mechanism of poly(N1,N1,N3,N3-tetraallylpropane-1,3-diaminium chloride) toward Cr(VI)

The adsorption characteristic and mechanism of poly(N¹,N¹,N³,N³-tetraallylpropane-1,3-diaminium chloride) (PTAPDAC) toward Cr(VI) ions were systematically investigated. Results showed that the removal efficiency of PTAPDAC toward Cr(VI) could reach above 98% at pH = 3-6. The equilibrium data of Cr(VI) adsorbed by PTAPDAC fitted the Langmuir model well, and the maximum sorption capacity deduced from the Langmuir model at 293 K was 273.17 mg g^-1. The adsorption of PTAPDAC toward Cr(VI) was rapid and reached equilibrium within 60 min, and the adsorption kinetic process was relevant to the pseudo-second-order kinetic model. Moreover, the activation energy E _a was calculated as -22.505 kJ mol^-1. The adsorption processes were spontaneous and exothermic driven by an increase in entropy, which involved electrostatic attraction, ion exchange, and redox reactions. The X-ray photoelectron spectroscopy analysis revealed that approximately 64.5% of Cr(VI) reduced to be Cr(III), and 24.29% of -C-NH⁺ deprotonated. The combination of reduced Cr(III) with tertiary amine groups resulted in a positively charged tertiary amine group, which further promoted Cr(VI) adsorption, thereby increasing the adsorption capacity of PTAPDAC toward Cr(VI). Therefore, PTAPDAC has a broad application prospect in removing Cr(VI) ions in wastewater.

Selection of suitable adsorbent for the removal of Cr(VI) by using objective based multiple attribute decision making method

The objective of the current manuscript is to develop a systematic and simplified expert system for the selection of suitable adsorbent to treat Cr(VI). Selection of adsorbent among the large options available by considering all possible factors and their interaction is required in an easy, organized and rational way. In this study, fuzzy logic is used for the choosing an appropriate adsorbent for the Cr(VI) removal. Multiple attribute decision making (MADM) is utilized to work out the relative weighting values for the chosen sorbent. The preference index is calculated by using the subjective and objective weights. The normalized value associated with each parameter has given on the basis of effect of each parameter on the removal of Cr(VI) and uptake capacity of each material. The associated MADM method results and the barriers of the approach is mentioned to lay the basis for in addition enhancement.

Phosphorus removal from aqueous solution using modified walnut and almond wooden shell and recycling as soil amendment

Modified walnut wooden shell (MWWS) and almond wooden shell (MAWS) as novel anion exchangers were used to remove phosphorus (P) from aqueous solution. The raw and modified agricultural wastes were characterized using total N, total P, FT-IR spectra, SEM, BET, and EXD analysis. The effect of different parameters such as pH (4 to 8), contact time (5 to 600 min), and adsorbent dosage (1 to 8 g L^-1) on P adsorption was investigated. Adsorption of P onto MWWS and MAWS was studied using the batch technique with different concentration of P (5 to 200 mg L^-1) at 25 ± 2 °C. The P adsorption isotherms were fitted with the Freundlich and Langmuir equations. The k and n values were 1.57 mg g^-1 and 1.88 for MWWS and 1.91 mg g^-1 and 2.24 for MAWS, respectively. The maximum P adsorption capacities for MWWS and MAWS were 22.73 and 14.71 mg g^-1, respectively. The desorption-regeneration experimental results indicated about 4% and 3% reductions in MWWS and MAWS P adsorption efficiency after four consecutive regeneration cycles, respectively. The data well fitted with Pseudo-second-order kinetic model (R² ≥ 0.99), indicating that chemical interactions dominate the P adsorption process. Incubation studies showed the rate of P release in treated soil with P-loaded modified biosorbents was higher than control. Therefore, the MWWS and MAWS can potentially be used as an excellent adsorbent in remediation of contaminated waters by P and then recycled to soil.

In-situ microbially induced Ca2+ -alginate polymeric sealant for seepage control in porous materials

This paper presents a novel approach of using in-situ microbially induced Ca2+ -alginate polymeric sealant for seepage control in porous materials. This process comprises two steps: (i) generation of insoluble calcium carbonate inside the pores of porous materials (such as sand) through a microbially induced carbonate precipitation (MICP) process in-situ and (ii) injection of sodium alginate for in-situ gelation via reaction between alginate and Ca2+ ions. The experimental results showed that the hydraulic conductivity/permeability of sand decreased with the increase in alginate concentration. When 5% alginate was used with a CaCO3 concentration of 0.18 g g-1 sand, the permeability of the alginate-treated sand reduced from 5.0 × 10-4 to 2.2 × 10-9  m s-1 . The scanning electron microscopy images revealed that a film-type coating was formed around sand particles with spherical round crystals embedded. Furthermore, the in-situ formed Ca-alginate polymeric sealant can also be used for the removal of Cu2+ ion and suspended particles from contaminated water by more than 90%. Built on the current research, the envisioned practical application of the proposed method may include clogging fractured rock, reducing seepage and prevent piping through dams, excavation dewatering, and forming barriers for remediating specific contaminants.

Adsorption of Hexavalent Chromium by Eucalyptus camaldulensis bark/maghemite Nano Composite

In the present study, Eucalyptus camaldulensis bark/maghemite composite (ECMC) was used for potential application as a low-cost adsorbent for the removal of Cr(VI) from aqueous solution. The structural characterization, morphology and elemental analysis of ECMC were performed by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX) and X-ray Diffraction (XRD). The effects of various independent parameters, contact time, initial Cr(VI) concentration, temperature, pH, and adsorption were investigated. It was found that the adsorption capacity of ECMC increases with increasing Cr(VI) concentration and temperature. The optimum pH was found to be 2 for the removal of Cr(VI) by ECMC. The adsorption capacity was found to be 70.1 mg/g with 0.1 g ECMC at pH 2 and 30 °C. Additionally, 10 and 50 mg/L Cr(VI) were removed from 100 mL aqueous solution by 0.1 g ECMC with 99 % and 93.46 % removal efficiencies, respectively. Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Jovanovic, Smith, Koble Korringen, Vieth-Sladek and Sips Isotherm Models were applied to the experimental data to understand the adsorption mechanism better. The Freundlich Isotherm Model described the adsorption process better (R2 = 0.991) among the other isotherms studied.

Adsorption behavior of Cu(II) and Co(II) using chemically modified marine algae

In this study, brown algae-modified biomass Padina sanctae crucis was used for copper (Cu(II)) and cobalt (Co(II)) heavy metal ions adsorption in synthetic wastewater. The effects of solution pH and adsorption efficiency for Cu(II) and Co(II) removal from aqueous solutions were studied. In order to study the kinetic behavior of adsorption, pseudo-first-order, pseudo-second-order kinetic models, liquid film penetration, and Ritchie second-order models were used. The results showed that the pseudo-second-order kinetic model was able to describe adsorbent behavior in comparison to the other models. Moreover, in order to study adsorbent equilibrium behavior, Langmuir and Freundlich isothermal models were used. Based on the Langmuir model, the adsorption capacity of Co(II) and Cu(II) was determined and their values were 13.73 and 13.996 mg/g, respectively. It was shown that both metal ions adsorption process is favorable and adsorption is physical. In this research, thermodynamic parameters were also studied in order to determine Gibbs free energy for both metal ions which were negative, indicating that metal ions adsorption process is spontaneous and the degree of self-adsorption increases as temperature increases.

Removal of cadmium(II) from aqueous solutions by chemically modified maize straw

A new regenerable adsorbent was successfully prepared by modifying maize straw (MS) with succinic anhydride in xylene. The succinylated-maize straw (S-MS) was characterized by FTIR, solid-state MAS (13)C NMR spectroscopy, SEM-EDX and point of zero charge analysis. NaS-MS was successfully obtained after deprotonating the carboxylic acid groups of S-MS by Na2CO3 solution. Batch experiments were carried out with NaS-MS for the removal of Cd(II). The effects of pH, adsorbent dosage, contact time, initial concentration and temperature were investigated. The experimental data were best described by a pseudo-second-order kinetics and Langmuir adsorption models. Thermodynamic parameters (ΔG, ΔH, and ΔS) were also calculated from data obtained from experiments performed to study the effect of temperatures. NaS-MS could be regenerated at least five times in saturated NaCl solution without any loss. Furthermore, ∼97% of adsorbed Cd(II) ions could be recovered as the metal oxide. Finally, the adsorption mechanism of NaS-MS was discussed.

A new absorbent by modifying walnut shell for the removal of anionic dye: kinetic and thermodynamic studies

A novel, low cost and easy regeneration biosorbent, chem-modified walnut shell (MWNS), was studied to investigate its potential for removal of an anionic dye, reactive brilliant red K-2BP. The MWNS was synthesized with epichlorohydrin and diethylenetriamine as etherifying agent and crosslinking agent, respectively, and its characteristics were performed with Fourier transform infrared spectroscopy, scanning electron microscope, electron dispersive spectroscopy and thermogravimetric analysis. The influences of pH (0.5-11) and adsorbent dosage (0.1-6g/L) on adsorption capacity of MWNS were evaluated. The maximum K-2BP adsorption capacities (Qm) calculated by best fitting model (Langmuir) were 568.18 mg/g at 313 K, which was almost 10 times than that of raw material. The adsorption kinetic was well confirmed with pseudo-second-order equation. Thermodynamic studies demonstrated adsorption process by MWNS was spontaneous and endothermic. Furthermore, the regeneration capability of MWNS implied MWNS was a cheap, excellent and promising biosorbent for K-2BP removal in azo dye wastewater treatment.

Biosorption of heavy metal ions (Cu(2+), Mn (2+), Zn (2+), and Fe (3+)) from aqueous solutions using activated sludge: comparison of aerobic activated sludge with anaerobic activated sludge

The potential of using two different kinds of air drying of activated sludge (aerobic activated sludge and anaerobic activated sludge) for the removal of Cu(2+), Mn(2+), Zn(2+), and Fe(3+) from aqueous solutions was assessed. Results indicated that the maximum biosorption occurred at pH = 5.0 for Cu(2+), Zn(2+), and Mn(2+) and pH = 3.0 for Fe(3+). The kinetic parameters of biosorption data were found to be best fitted to the second-order equation. Also, it was found that the best dosage for biosorption was 0.2 g for both aerobic activated sludge and anaerobic activated sludge. The experimental results were fitted well to the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The maximum biosorption capacities of Cu(2+), Mn(2+), Zn(2+), and Fe(3+) for aerobic activated sludge were 65.789, 44.843, 64.935, and 75.756 mg/g, respectively, while they were 59.880, 49.020, 62.500, and 69.444 mg/g for anaerobic activated sludge, respectively. The mean free energy values evaluated from the D-R model indicated that the biosorptions of studied heavy metal ions onto activated sludge were taken place by chemical interaction. The results of this study provided valuable information on the biosorption of heavy metals by activated sludge that may contribute in wastewater treatment.

Characteristics of cellulosic amine-crosslinked copolymer and its sorption properties for Cr(VI) from aqueous solutions

A new cellulosic amine-crosslinked copolymer was prepared after the amination reaction with cotton stalk peel (CSP). The physicochemical characteristics of amine-crosslinked cotton stalk peel (AC-CSP) and raw CSP were determined after the surface analysis (including specific surface area, micropore volume and SEM), zeta potential analysis and spectrum analysis (FTIR and Raman spectrum). The sorption properties of AC-CSP for Cr(VI) were evaluated in the static, column sorption and desorption tests. The surface characteristics indicated the absence of porous adsorption in the potential Cr(VI) sorption mechanism. Zeta potential and spectrum analysis of AC-CSP illustrated the involvement of amine groups in the Cr(VI) sorption process. The sorption capacity of AC-CSP for Cr(VI) was 129.0mg/g as comparison with 14.8 mg/g of raw CSP. Flow rate and influent Cr(VI) concentration were demonstrated as two influencial factors in the column sorption tests. NaCl was used as the eluent, and the desorption efficiencies during three successive cycles were 75.9%, 69.8% and 64.3%, respectively. In addition, the results of the static, column sorption and desorption tests illustrated the complicated interactions between Cr(VI) and AC-CSP including complexation and ion exchange mechanisms.

Adsorption of Cr(VI) using Fe-crosslinked chitosan complex (Ch-Fe)

In the present investigation, Fe-chitosan crosslinked is used as adsorbent for the removal of chromium from aqueous solutions. The influence of pH, temperature and other ions was evaluated. pH 2.0 was found to be the optimum pH for adsorption of Cr(VI) onto Ch-Fe. Coordination of unsaturated sites for the iron(III) complex of polymer were considered to be the adsorption sites for Cr(VI) species, the predominant species being HCrO(4)(-). The Langmuir and Langmuir-Freundlich adsorption isotherm models were applied to describe the isotherm parameter for Cr(VI) adsorption. The results indicate that the Langmuir-Freundlich adsorption model and maximum adsorption capacity was calculated as 295 mg/g at 25 degrees C, with pH 4.7. Cr(VI) uptake on the adsorbent decreased from 295 mg/g at 25 degrees C to 209 mg/g at 65 degrees C. Rate constants as a function of temperature were evaluated with the help of a proposed second order kinetic model. The other coexisting ions, nitrate, chlorides and sulphate influenced Cr(VI) adsorption.

Theoretical models of sorption kinetics including a surface reaction mechanism: a review

A review of a certain class of theoretical models describing the kinetics of pollutants sorption onto various sorbents is presented. These assuming the rate of surface reaction as the rate-limiting step are considered. A special attention is paid to possible theoretical grounds of the most commonly applied mathematical expressions, such as the pseudo-second and the pseudo-first order equations. Simple theoretical considerations based on some fundamental theories suggest that these two formulae do not correspond to any specific physical model. They simply approximate well the behaviours predicted by many different theoretical approaches.

Adsorption of Cr(VI) using silica-based adsorbent prepared by radiation-induced grafting

Silica-based adsorbent was prepared by radiation-induced grafting of dimethylaminoethyl methacrylate (DMAEMA) onto the silanized silica followed by a protonation process. The FTIR spectra and XPS analysis proved that DMAEMA was grafted successfully onto the silica surface. The resultant adsorbent manifested a high ion exchange capacity (IEC) of ca. 1.30 mmol/g and the Cr(VI) adsorption behavior of the adsorbent was further investigated, revealing the recovery of Cr(VI) increased with the adsorbent feed and the equilibrium adsorption could be achieved within 40 min. The adsorption capacity, strongly depended on the pH of the solution, reached a maximum Cr(VI) uptake (ca. 68 mg/g) as the pH was in the range of 2.5-5.0. Furthermore, even in strong acidic (4.0 mol/L HNO(3)) or alkaline media (pH 11.0), the adsorbent had a sound Cr(VI) uptake capacity (ca. 22 and 30 mg/g, respectively), and the adsorption followed Langmuir mode. The results indicated that this adsorbent, prepared via a convenient approach, is applicable for removing heavy-metal-ion pollutants (e.g. Cr(VI)) from waste waters.

Removal of Cr(VI) by thermally activated weed Salvinia cucullata in a fixed-bed column

The present study evaluates the feasibility of using a thermally activated fresh water weed in removing Cr(VI) from wastewater through column studies. The effect of flow rate, bed height and Cr(VI) concentration of the feed solution on the adsorption capacity of the activated weed was investigated. The adsorption capacity increased with decrease in both flow rate and bed height but increased with an increase in initial adsorbate concentration. Four different kinetic models, such as. Adams-Bohart, Bed Depth Service Time (BDST), Thomas and Yoon-Nelson models were first applied to the experimental data to predict the breakthrough curve and to determine the characteristic parameters of the column useful for designing large-scale column studies. Different statistical methods such as Sum of the Square of the Error (SSE), Sum of the Absolute Error (SAE), Average Relative Error (ARE), Average Relative Standard Error (ARS) and regression coefficient, were applied to evaluate the prominent and unique characteristic features of the experimental and predicted parameters under the respective models to find out the best fit. The performance stability of the adsorbent was tested by continuous adsorption-desorption studies.