Maximum Cr Removal Research Articles

Removal of Cr(VI) using polyacrylonitrile/ferrous chloride composite nanofibers

Abstract Considering economic feasibility and technical effectiveness, polyacrylonitrile/ferrous chloride composite nanofibers prepared by electrospinning was used to remove the Cr(VI). Maximum removal of Cr(VI) by composite nanofibers was observed in weakly acidic environment. The analysis of the reaction kinetics revealed that the adsorption behavior seemed to follow pseudo-second-order kinetic model. Through calculating thermodynamic parameter, the adsorption reaction was proved to be an exothermic and chemical process. The PAN…Fe 1 − x Cr x (OH) 3 and PAN…Fe 1 − x Cr x (OH) x were proposed to be formed after the redox reaction was taken place. The interactive effects of coexisting ions of different metal ions like arsenic, lead and cadmium were also explored for practical consideration. The presence of these metal ions apparently decreased the efficiency of the Cr(VI) adsorption. In addition, the interactive inhibition of arsenic was more significant than other coexisting ions. It was suspected that the valence state ( e.g. , NO 3 − , SO 4 2− , Cl − , Ca 2± , Na ± and Mg 2± ) may play a crucial role during the reaction. Due to the strong electrostatic attraction, anions had the more significant attenuating effect than cations. This study is helpful not only for doping design of iron oxide nanofibers but also for practical application during advanced wastewater treatment.

Higher adsorption capacity of Spirulina platensis alga for Cr(VI) ions removal: parameter optimisation, equilibrium, kinetic and thermodynamic predictions.

This study discusses about the biosorption of Cr(VI) ion from aqueous solution using ultrasonic assisted Spirulina platensis (UASP). The prepared UASP biosorbent was characterised by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmet-Teller, scanning electron spectroscopy and energy dispersive X-ray and thermogravimetric analyses. The optimum condition for the maximum removal of Cr(VI) ions for an initial concentration of 50 mg/l by UASP was measured as: adsorbent dose of 1 g/l, pH of 3.0, contact time of 30 min and temperature of 303 K. Adsorption isotherm, kinetics and thermodynamic parameters were calculated. Freundlich model provided the best results for the removal of Cr(VI) ions by UASP. The adsorption kinetics of Cr(VI) ions onto UASP showed that the pseudo-first-order model was well in line with the experimental data. In the thermodynamic study, the parameters like Gibb's free energy, enthalpy and entropy changes were evaluated. This result explains that the adsorption of Cr(VI) ions onto the UASP was exothermic and spontaneous in nature. Desorption of the biosorbent was done using different desorbing agents in which NaOH gave the best result. The prepared material showed higher affinity for the removal of Cr(VI) ions and this may be an alternative material to the existing commercial adsorbents.

Biosorption of chromium from electroplating and galvanizing industrial effluents under extreme conditions using Chlorella vulgaris

Hexavalent chromium [Cr(VI)] is a toxic oxidized form and an important metal pollutant in the water bodies. Biosorption of chromium(VI) offers a potential alternative to conventional metal removal methods. Dried biomass of Chlorella vulgaris was used as biosorbent for the removal of Cr(VI) from electroplating and galvanizing industry effluents as a function of biosorbent dosage, contact time, pH, salinity and initial metal ion concentration. Batch experiments were conducted for biosorption and the optimum conditions were 1 g/L biomass, 4 h contact time, pH 2 and 2.893 mS/cm of electrical conductivity. The chromium biosorption was strictly pH dependent with a maximum Cr removal of 63.2 mg/L at pH 2. Highest Cr removal at a concentration of 81.3 mg/L was observed at Electrical conductivity (EC) value of 2.893 mS/cm. A comparison of Langmuir and Freundlich isotherm models revealed that Freundlich isotherm model fitted the experimental data based on R2, qmax and standard error values. The results suggest that C. vulgaris biomass could be considered a promising low-cost biosorbent for the removal of Cr(VI) from electroplating and galvanizing industry effluents.

Removal of hexavalent chromium ions using CuO nanoparticles for water purification applications

Copper(II) oxide nanoparticles were synthesized at low temperature using cold finger assisted magnetron sputtering technique and were applied as adsorbent for the rapid removal of noxious Cr(VI) ions from the solvent phase. The average size of CuO nanoparticles from TEM analysis was found to be 8nm in addition to this the BET surface area (84.327m2/g) was found to be significantly high in comparison to the previously CuO nanoparticles synthesized via green route. The synthesized CuO nanoparticles is crystalline in nature and exhibits monoclinic phase, which was confirmed using various analytical techniques such as SAED, XRD and Raman analysis. The impact of influential parameters including pH, adsorbent dose, contact time, stirring speed, initial Cr(VI) ions concentration, and temperature were optimized using batch adsorption method in order to obtain maximum removal of Cr(VI) ions. From the thermodynamic parameters, the positive value of enthalpy (ΔH) and negative value of Gibbs free energy (ΔG) indicate the endothermic and spontaneous nature of Cr(VI) ions adsorption, respectively. The adsorption kinetics data was well fitted and found to be in good agreement with the pseudo second order kinetic behaviour.

Oak (Quercus robur) Acorn Peel as a Low-Cost Adsorbent for Hexavalent Chromium Removal from Aquatic Ecosystems and Industrial Effluents

The efficiency of low-cost, abundantly available local forestry waste, oak (Quercus robur) acorn peel (OP), to remove toxic Cr(VI) from aqueous solutions was studied in a batch system as a function of contact time, adsorbate concentration, adsorbent dosage, and pH. In an equilibrium time of 420 min, the maximum Cr removal by OP at pH 2 and 10 was 100 and 97 %, respectively. The sorption data fitted well with Langmuir adsorption model. Evaluation using Langmuir expression presented a monolayer sorption capacity of 47.39 mg g−1 with an equilibrium sorbent dose of 5 g L−1 and pH 7. Uptake of Cr by OP was described by pseudo-second-order chemisorption model. ICP-OES, LC-ICPMS analysis of the aqueous and solid phases revealed that the mechanism of Cr(VI) removal is by ‘integrated adsorption and reduction’ mechanism. ESEM-EDX and XRD analysis of OP before and after adsorption also confirmed that both adsorption and reduction of Cr(VI) to less toxic Cr3+ forms followed by complexation onto the adsorbent surface contributed to the removal of Cr(VI). Consistent with batch studies, OP effectively removed (>95 %) Cr from the real water samples collected from lake and sea. The results of this study illustrate that OP could be an economical, green, and effective biomaterial for Cr(VI) removal from natural aquatic ecosystems and industrial effluents.

Removal of Cr(VI) from aqueous solution using Strychnos nux-vomica shell as an adsorbent

In the present study, the removal of Cr(VI) from aqueous solution by a Strychnos nux-vomica shell was examined in a batch study. The main process parameters such as adsorbent dose, pH, initial concentration, temperature, agitation speed and contact time were studied. The result shows that the maximum removal of Cr(VI) was observed at pH 2. The progressive changes on surface texture and the confirmation of chromium binding on adsorbent surface at different stages were obtained by the scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectrometer analysis. The equilibrium data from the biosorption study was evaluated by the use of two parameter isotherm models. Langmuir isotherm model seems to fit better with the equilibrium data. Kinetic studies were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The biosorption data were found to best fitted for pseudo-second-order kinetic model. The calculated thermodynamic parameters such as ΔG°, ΔH° and ΔS° showed that the adsorption of Cr(VI) ions onto adsorbents was spontaneous, endothermic and increased randomness in nature. The results indicate that STFS can be an effective adsorbent for the removal of Cr(VI) from aqueous solutions.

Chemical modification of expanded glass aggregate with N-Benzoyl-N′-(4-methylphenyl) thiourea (TTU) for the adsorptive removal of Cr(III) ion

In this study, the silylant agent 3-aminopropyl trimethoxysilane (APTES) was anchored on expanded glass aggregate (GA) to prepare a new adsorbent. N-Benzoyl-N′-(4-methylphenyl) thiourea (TTU) bonded to amino-functionalized GA adsorbent with reflux. Developed adsorbent (GA-APTES-TTU) was characterized using thermal analysis (TGA) and scanning electron microscopy (SEM). TGA and SEM studies indicated that modification of the glass aggregate (GA) surfaces was successfully performed. The adsorption studies exhibited that the GA-APTES-TTU could be efficiently used for the removal of Cr(III) from aqueous solutions. The effects of pH, adsorbent dosage, ion concentration, time, and temperature were investigated as adsorption parameters. The maximum removal of Cr(III) was observed at pH 4. The adsorption equilibrium was achieved in 120min and adsorption of Cr(III) followed the Langmuir isotherm model. The maximum adsorption capacity for Cr(III) was 0.4305mmol/g with GA-APTES-TTU. Thermodynamic parameters such as the standard free energy (ΔGo), enthalpy change (ΔH°) and entropy change (ΔS°) were calculated in order to explain the mechanism of adsorption process. The thermodynamic data showed that Cr(III) adsorption was spontaneous, endothermic, and a physisorption reaction. In addition, the adsorption kinetic data fitted to the pseudo-second order model.

Characterization and application of biomass gasifier waste material for adsorptive removal of Cr (VI) from aqueous solution

This study was performed to investigate the latent potential of biomass gasifier waste material (BGWM) as an adsorbent for removal of Cr (VI) from aqueous solution. The present work also proposes an alternate use of gasifier refuge BGWM with great economic feasibility. The effects of initial pH, BGWM concentration, Cr(VI) concentration, temperature and contact time were investigated on the removal of Cr (VI) from aqueous solution. The maximum removal of Cr (VI) was found to be 99.67% at optimum condition of initial pH 2, contact time 80 min, initial Cr (VI) concentration 10 mg L−1, adsorbent dose 5 g L−1, agitation speed 120 rpm, and temperature 35°C. The adsorbent was characterised by SEM, EDX, XRD, BET and FTIR analysis to get important information about its effective application for Cr (VI) removal. The BET surface area of 165.287 m2 g−1 for BGWM was found comparable to that of commercial silica. Batch adsorption experiments showed that pseudo‐second‐order kinetics model and Langmuir isotherm model fitted the adsorption data very well. Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of Cr (VI) adsorption onto BGWM. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 95–102, 2016

Evaluation of performance of Planococcus sp. TRC1 an indigenous bacterial isolate monoculture as bioremediator for tannery effluent

An indigenous bacterial isolate Planococcus sp. TRC1 was found to tolerate Cr(VI) solution up to 500 mg/L concentration when grown in mineral salt media. Gene sequencing of the isolated strain using 16S rDNA technique and phylogenetic analysis confirmed that the species was 96% close to Planococcus maritimus (KP8). Studies on cell dynamics in batch bioreactor showed the maximum specific cell growth rate (μmax) to be 0.276 h−1. Removal of Cr(VI) was observed to be dependent on initial chromium concentration and the maximum removal of Cr(VI) (75 ± 3%) was obtained at 25 mg/L Cr(VI) solution for an incubation period of 72 h. Above this value, the removal of Cr(VI) was declined. Scanning electron microscope and Fourier transform infrared spectroscopic studies indicated that the Cr(VI) removal took place by the adsorption process on the cell outer membrane. It is observed that the adsorption process follows the Freundlich adsorption isotherm (R2 = 0.987). Planococcus sp. TRC1 reduced 80 ± 5% chemical oxygen demand (COD) of tannery effluent (COD 7,270 ± 45 mg O2/L) within 48 h of batch treatment. The elimination of cytotoxicity and genotoxicity imparted by the raw tannery effluent and Cr(VI) solution after bacterial treatment is an important observation which reflects the eco-friendly behavior of the Planococcus sp. TRC1 mediated tannery effluent and aqueous Cr(VI) solution treatment. The results revealed the applicability of Planococcus sp. TRC1 in both tannery waste and Cr(VI) reduction without affecting our environment.

Biosorption of Hexavalent Chromium from Aqueous Medium with the Antibiotic Residue

The antibiotic residue was used as a biosorbent for Cr (VI) aqueous solution to investigate its Cr (VI) removal capacity. The effect of experimental parameters, such as pH, sorbent dosage, initial metal concentration and contact time were examined and the optimal experimental conditions were determined. The results showed that 88.61 and 95.07% of Cr (VI) was removed by using the raw and acid-treated antibiotic residue powder as biosorbent. Maximum removal of Cr (VI) ions in aqueous solution was observed at pH 1.0. Biosorption kinetic data were properly fitted with the pseudo-first order kinetic model. The adsorption process followed the Langmuir isotherm adsorption model. Thermodynamic parameters of the adsorption process, such as ΔG°, ΔH° and ΔS°, were calculated and the results indicated that the overall adsorption process were feasible, spontaneous in nature. Finally, the removal mechanism is discussed by deduction from the experimental results, FTIR and SEM images. The adsorption of Cr (VI) coexists with the redox process and the antibiotic residue powder is a potential biosorbent which could be used in treatment of chromium contaminated wastewater.

Magnetic vinylphenyl boronic acid microparticles for Cr(VI) adsorption: Kinetic, isotherm and thermodynamic studies

Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate(EG)–vinylphenyl boronic acid(VPBA)) [m-poly(EG–VPBA)], produced by suspension polymerization and characterized, was found to be an efficient solid polymer for Cr(VI) adsorption. The m-poly(EG–VPBA) microparticles were prepared by copolymerizing of ethylene glycol dimethylacrylate (EG) with 4-vinyl phenyl boronic acid (VPBA). The m-poly(EG–VPBA) microparticles were characterized by N2 adsorption/desorption isotherms, electron spin resonance (ESR), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), elemental analysis, scanning electron microscope (SEM) and swelling studies. The m-poly(EG–VPBA) microparticles were used at adsorbent/Cr(VI) ion ratios. The influence of pH, Cr(VI) initial concentration, temperature of the removal process was investigated. The maximum removal of Cr(VI) was observed at pH 2. Langmuir isotherm and Dubinin–Radushkvich isotherm were found to better fit the experiment data rather than Fruendlich isotherm. The kinetics of the adsorption process of Cr(VI) on the m-poly(EG–VPBA) microparticles were investigated using the pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models, results showed that the pseudo-second order equation model provided the best correlation with the experimental results. The thermodynamic parameters (free energy change, ΔG0 enthalpy change, ΔH0; and entropy change, ΔS0) for the adsorption have been evaluated.

Acid and Alkali Modified Cow Hoof Powder as Adsorbents for Chromium (VI) Removal from Aqueous aqoues phase

A B S T R A C T In this work, the feasibility of batch studies using hydrochloric acid modified cow hoofs (HCH), citric acid modified cow hoofs (CACH) and sodium hydroxide modified cow hoofs (SCH) for removing Cr (VI) from aqueous solution were investigated. Equilibrium data at four different temperatures (25, 35, 45 and 55 0 C), by contacting Cr (VI) solution at different concentrations with CACH, HCH and SCH were also conducted. The results of this study showed that SCH recorded higher percentage Cr (VI) removal than both HCH and CACH. The pH of 2 was required for maximum removal of Cr (VI) by the three biosorbents. The data obtained for both CACH and SCH were best fitted by Langmuir model while the data obtained for HCH were best fitted by Freundlich model. Thermodynamic parameters for the removal of Cr (VI) revealed the process to be spontaneous and exothermic for HCH and SCH but endothermic for CACH. Therefore, the removal of Cr (VI) from wastewater using these low-cost biosorbents (particularly HCH and SCH) would be economically feasible.

Biosorption of Hexavalent Chromium Using Bark of <i>Cassia spectabilis</i>

Biosorption is a relatively new process that has proven very promising in the removal of heavy metal contaminants from aqueous solutions. The biosorption of Cr(VI) from aqueous solution using bark of Cassia spectabilis has been investigated in a batch system. The effect of various parameters such as pH, contact time, adsorbent dosage and initial concentration of Cr(VI) on the biosorption process were studied. The maximum removal of Cr(VI) was observed at pH 1.0. The Study indicated that both biosorption and bioreduction were involved in removal of Cr(VI). The sorption equilibrium exhibited a better fit to the Langmuir isotherm than Freundlich isotherm. The maximum biosorption of Cassia spectabilis bark to remove Cr(VI) was 12.865 mg/g. The dimensionless equilibrium parameter, RL, signifies a favorable adsorption of Cr(VI) on the adsorbent and is found to be 0.441 (0 < RL<1). Pseudo first-order and second order kinetic models were used to evaluate the mechanism of adsorption. Kinetic evaluation of the experimental data showed that the biosorption process follows pseudo- second order kinetic model. Keywords : Hexavalent chromium; Biosorption; Cassia spectabilis bark; Adsorption isotherm; Adsorption kinetic

Decontamination of Cr(VI) and Mn(II) from aqueous media by untreated and chemically treated banana peel: a comparative study

Untreated banana peels (UTBPs), alkali-hydrolyzed banana peels (AlBPs), acid-hydrolyzed banana peels (AcBPs), and bleached banana peels (BBPs) were used as adsorbents separately for the removal of Cr(VI) and Mn(II) from aqueous solution during batch experiments. Different parameters like pH, temperature, contact time, adsorbent dose, and initial concentration were studied. The maximum removal capacities for Cr(VI) were UTBP (45%), AlBP (87%), AcBP, (67%) and BBP (40%). While for Mn(II), the maximum removal capacities of theses adsorbents were UTBP (51%), AlBP (90%), AcBP (74%) and BBP (67%) at optimum conditions. The maximum removal of Cr(VI) and Mn(II) was obtained at initial concentration 3 mg/L, adsorbent dose of 4 g/L, pH 6, and contact time 60 min. It was noted that the metal ions removal capacity of these adsorbents was AlBP > AcBP > UTBP > BBP, which indicated that chemical treatment of banana peels enhances the biosorption of metal ions. This study showed that chemically treated banana peel can be used as suitable and cost-effective adsorbent for the removal of Cr(VI) and Mn(II) ions from aqueous solutions.

Removal of Heavy Metals Cr (VI), Cd (II) and Ni (II) from Aqueous Solution by Bioabsorbtion of Elaeagnus Angustifolia

The problem of removing pollutants from water is an important process and is becoming moreimportant with the increasing of industrial activities. One of the most important environmental problems iswater resources pollution by Heavy metals. Bioabsorbtion is affordable adsorbents for the removal of heavymetals from aqueous solutions. This study explores the adsorption potential of Cr (VI), Cd (II) and Ni (II) by Elaeagnus angustifolia fruit powder in aqueous solution. The influences of several main parameters such as pH value of solution, sorbent amount, initial metal ion concentration, and contact time in batch experiments have been studied. The adsorption was depended on pH, adsorbent dosage, and contact time. Maximum removal of Cr (VI), Cd (II) and Ni (II) were obtained 7.19mg/g, 2.42 mg/g and 1.97 mg/g respectively. Adsorption isotherms were compared with both Langmuir and Freundlich adsorption models. The experimental data best fit with the Langmuir isotherm model. Experimental results show natural biosorbent was effective for the removal of pollutants from aqueous solution.

Use of modified wheat bran for the removal of chromium(VI) from aqueous solutions

Novel adsorbents, wheat bran (WB) and modified wheat bran (M-WB) with tartaric acid were developed and Cr(VI) adsorption was investigated by changing various parameters. The adsorption increased with contact time and become optimum at 180min for WB and 200min for M-WB. When the pH of the solution phase increased, some of toxic Cr(VI) reduced into less toxic Cr(III) on the WB surface. The maximum removal of Cr(VI) from the solution having an initial Cr(VI) concentration of 200mgL−1 was obtained at pH 2.0 as 51.0% and 90.0% for WB and M-WB, respectively. Isotherm data of Cr(VI) adsorption on WB and M-WB was described by the Freundlich adsorption model. The adsorption capacity of 4.53mg of Cr(VI)/g for WB and 5.28mg of Cr(VI)/g for M-WB was obtained at pH 2 and 2.2 respectively.

Removal of hexavalent chromium from aqueous solution by granular and powdered Peganum Harmala

In this paper, batch removal of hexavalent chromium from aqueous solutions by granular and powdered seeds of Peganum Harmala was investigated. The Peganum Harmala seeds were collected and after beating slowly, separating and cleaning the Harmala seeds done using a sieve. Batch adsorption studies were performed in 100ml Erlenmeyer flasks inside an incubator container. The main process parameters considered were pH, initial Cr(VI) concentration for PPH and GPH, adsorbent dose, and contact time. Cr(VI) was measured at a wavelength of 540nm using a UV–vis T80+ spectrophotometer. The adsorption data were fitted well by Freundlich isotherm. The result shows that the maximum removal of Cr(VI) was observed at pH 1.5 for both adsorbents. Also, by increase adsorption dose, adsorption capacity of Cr(VI) decreased but the chromium adsorption rate increased. The mount of adsorbed Cr(VI) onto both adsorbents increased with an increase in the contact time but by increases initial concentration of Cr(VI), the mount of adsorbed Cr(VI) onto both adsorbents decreased. The results indicate that the powdered Peganum Harmala can be effective adsorbent than the granular Peganum Harmala for the removal of Cr(VI) from aqueous solution.

Adsorption studies of chromium (VI) removal from water by lanthanum diethanolamine hybrid material

In the present research work, lanthanum diethanolamine hybrid material is synthesized by co-precipitation method and used for the removal of Cr(VI) from synthetic dichromate solution and hand pump water sample. The sorption experiments were carried out in batch mode to optimize various influencing parameters such as adsorbent dose, contact time, pH, competitive anions and temperature. The characterization of the material and mechanism of Cr(VI) adsorption on the material was studied by using scanning electron microscope, Fourier transform infrared, X-ray diffraction, Brunauer–Emmett–Teller and thermogravimetric analysis–differential thermal analysis. Adsorption kinetics studies reveal that the adsorption process followed first-order kinetics and intraparticle diffusion model with correlation coefficients (R2) of 0.96 and 0.97, respectively. The adsorption data were best fitted to linearly transformed Langmuir isotherm with correlation coefficient (R2) of 0.997. The maximum removal of Cr(VI) is found to be 99.31% at optimal condition: pH=5.6 of the solution, adsorbent dose of 8 g L−1 with initial concentration of 10 mg L−1 of Cr(VI) solution and an equilibrium time of 50 min. The maximum adsorption capacity of the material is 357.1 mg g−1. Thermodynamic parameters were evaluated to study the effect of temperature on the removal process. The study shows that the adsorption process is feasible and endothermic in nature. The value of E (260.6 kJ mol−1) indicates the chemisorption nature of the adsorption process. The material is difficult to be regenerated. The above studies indicate that the hybrid material is capable of removing Cr(VI) from water.

Synthesis, performance, and nonlinear modeling of modified nano-sized magnetite for removal of Cr(VI) from aqueous solutions

Contamination of water bodies with toxic and non-biodegradable heavy metals is a serious environmental problem. Chromium is a very important contaminant in soil, industrial waste, groundwater, and surface water sources. This study was conducted to assess hexavalent chromium (Cr(VI)) adsorption onto modified magnetite nanoparticles from aqueous solution. The effects of adsorbent dose, pH, contact time, initial Cr(VI) concentrations, adsorption capacity, and modeling of kinetic and isotherm adsorption of Cr(VI) were investigated. Modified magnetite nanoparticles were synthesized by using a co-precipitation method, and its structural and textural properties were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum removal of Cr(VI) was achieved at pH 4.0. A contact time of 60 min was required to reach the equilibrium. Experimental data were fitted with different nonlinear isotherm and kinetic models. The results showed that the adsorption data were fitted well by the Redlich and Peterson and Freundlich isotherm models. The kinetic data were best fitted to pseudo-second-order kinetic model. The results indicate that modified nano-sized magnetite could be employed as adsorbent for the removal of Cr(VI) in aqueous environments effectively.

Biosorption of Cr(VI) and Zn(II) ions from aqueous solution onto the solid biodiesel waste residue: mechanistic, kinetic and thermodynamic studies

In this present study, the biosorption of Cr(VI) and Zn(II) ions from synthetic aqueous solution on defatted J atropha oil cake (DJOC) was investigated. The effect of various process parameters such as the initial pH, adsorbent dosage, initial metal ion concentration and contact time has been studied in batch-stirred experiments. Maximum removal of Cr(VI) and Zn(II) ions in aqueous solution was observed at pH 2.0 and pH. 5.0, respectively. The removal efficiency of Cr(VI) and Zn(II) ions from the aqueous solution was found to be 72.56 and 79.81%, respectively, for initial metal ion concentration of 500 mg/L at 6 g/L dosage concentration. The biosorbent was characterized by Fourier transform infrared, scanning electron microscopy and zero point charge. Equilibrium data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models and the best fit is found to be with the Freundlich isotherm for both Cr(VI) and Zn(II) metal ions. The kinetic data obtained at different metal ion concentration have been analysed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion models and were found to follow the pseudo-second-order kinetic model. The values of mass transfer diffusion coefficients (De) were determined by Boyd model and compared with literature values. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were analysed using the equilibrium constant values (Ke) obtained from experimental data at different temperatures. The results showed that biosorption of Cr(VI) and Zn(II) ions onto the DJOC system is more spontaneous and exothermic in nature. The results indicate that DJOC was shown to be a promising adsorbent for the removal of Cr(VI) and Zn(II) ions from aqueous solution.