Commercial steel wool for reduction of hexavalent chromium in wastewater: batch kinetic studies and rate model

Abstract We report on the role of ester bonds in the enhanced removal of hexavalent chromium from water using cotton fibers coated with chitosan. Adsorption capacities up to five times higher than those of the unmodified fibers were observed when the cotton fibers were exposed to an NaOH, followed by citric acid (0.97 M), and a chitosan solution (2%). We found that the use of NaOH favors the formation of ester bonds over amide bonds on the surface of the cotton fibers. This increase in the surface density of ester bonds generates an increase in the amount of exposed amino groups from the chitosan, hence increasing the removal capacity of the modified fibers. Experimental results also reveal that the adsorption is induced by the electrostatic attraction between the protonated amino groups on the surface and the negatively charged chromium ions in the water. Adsorption isotherms and kinetic studies indicated that the adsorption process fits the Langmuir and the Freundlich isotherm models as well as the pseudo-first and pseudo-second order kinetic models. These results can open a new avenue for the manufacturing of fibers with enhanced removal capacities for hexavalent chromium.

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Optimization for Reduction/Precipitation Treatment of Hexavalent Chromium

Water Science & Technology ◽

10.2166/wst.1994.0495 ◽

1994 ◽

Vol 29 (9) ◽

pp. 275-284 ◽

Cited By ~ 15

Author(s):

J. W. Patterson ◽

E. Gasca ◽

Y. Wang

Keyword(s):

Wastewater Treatment ◽

Hexavalent Chromium ◽

Treatment Plant ◽

Kinetic Studies ◽

Critical Parameters ◽

Sodium Metabisulfite ◽

Treatment Optimization ◽

Total Chromium ◽

Manufacturing Operations ◽

Treatment Train

This paper describes wastewater treatment optimization studies performed on an industrial wastewater generated in Boston, Massachusetts, USA. The manufacturing plant generates hexavalent chromium [Cr(VI)] wastewater as a result of chromating brass, bronze and copper parts produced in the manufacturing operations. The facility utilizes a continuous flow treatment train, involving segregated Cr(VI) reduction with sodium metabisulfite (Na2S2O5) under acidic conditions, followed by combined wastestream two-stage pH adjustment, metals precipitation, and clarification before discharge to the municipal sewer. The objectives of the studies were to define and evaluate critical parameters, such as pH and oxidation reduction potential (ORP) for hexavalent and total chromium control and to perform treatability studies to optimize the performance of the wastewater treatment plant (WWTP). The treatability studies included Cr(VI) reduction versus Na2S2O5 dosage evaluations and corresponding chromium reduction kinetic studies, and trivalent chromium hydroxide precipitation. The Cr(VI) reduction experiments and chromic hydroxide precipitation studies were performed for three different wastewaters collected from within the manufacturing process; a high, typical, and dilute strength wastewater.

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Removal of hexavalent chromium from aqueous solution by a novel biosorbent Caryota urens seeds: equilibrium and kinetic studies

Desalination and Water Treatment ◽

10.1080/19443994.2015.1134355 ◽

2016 ◽

Vol 57 (50) ◽

pp. 23940-23950 ◽

Cited By ~ 6

Author(s):

E. Suganya ◽

S. Rangabhashiyam ◽

A.V. Lity ◽

N. Selvaraju

Keyword(s):

Aqueous Solution ◽

Hexavalent Chromium ◽

Kinetic Studies

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Adsorption of Hexavalent Chromium from Aqueous Solution Using Chemically Activated Carbon Prepared from Locally Available Waste of Bamboo (Oxytenanthera abyssinica)

ISRN Environmental Chemistry ◽

10.1155/2014/438245 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 27

Author(s):

Tamirat Dula ◽

Khalid Siraj ◽

Shimeles Addisu Kitte

Keyword(s):

Activated Carbon ◽

Hexavalent Chromium ◽

Freundlich Isotherm ◽

Kinetic Studies ◽

Batch Adsorption ◽

Koh Activation ◽

Order Kinetic ◽

Oxytenanthera Abyssinica ◽

Equilibrium Data ◽

Order Kinetic Model

This study reports on the adsorption of Hexavalent Chromium from aqueous solutions using activated carbon prepared from bamboo (Oxytenanthera abyssinica) waste by KOH activation heating in an electrical furnace at 1073 K for 3 hrs. Batch adsorption experiments were also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption on the surface of BWAC was feasible, spontaneous in nature, and exothermic between temperatures of 298 and 318 K. The equilibrium data better fitted the Freundlich isotherm model for studying the adsorption behavior of Hexavalent Chromium by BWAC. IR spectrum for loaded and unloaded BWAC was obtained using FT-IR spectrophotometer. Adsorption efficiency and capacity of Hexavalent Chromium were found to be 98.28% at pH 2 and 59.23 mg/g at 300 K.

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Adsorption of hexavalent chromium ions from aqueous solutions using nano-chitin: kinetic, isotherms and thermodynamic studies

Water Practice & Technology ◽

10.2166/wpt.2021.007 ◽

2021 ◽

Vol 16 (2) ◽

pp. 436-451

Author(s):

Meghdad Sheikhi ◽

Hassan Rezaei

Keyword(s):

Aqueous Solutions ◽

Correlation Coefficient ◽

Hexavalent Chromium ◽

Contact Time ◽

New Technology ◽

Kinetic Studies ◽

Chromium Vi ◽

Effects Of Ph ◽

Pseudo Second Order ◽

Adsorbent Dose

Abstract Treatment of the industrial wastewater before discharging into aquatic ecosystems using a new technology such as nanotechnology seems necessary. There are different methods for the removal of the heavy metals in the wastewater. In this study, nano-chitin was purchased from the Nano-Novin Polymer Company and used as an adsorbent for the removal of chromium (VI) ions from aqueous solution in a batch system. The effects of pH, temperature, contact time, concentration, and adsorbent dose were investigated. According to the results, the optimum conditions of adsorption occurred at pH = 6, temperature = 25 °C, 60 minutes contact time, and 0.6 g·L−1 adsorbent dose. Investigation of equilibrium isotherms showed that the isotherm fitted the Freundlich model with a correlation coefficient of R2 = 0.9689. The pseudo second-order model with the larger correlation coefficient had a greater fitness against experimental data in the kinetic studies. Thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy were calculated, which indicated spontaneous, endothermic, and random processes, respectively. Given the good results of this project, nano-chitin can be suggested as a novel adsorbent which is highly capable of adsorbing hexavalent chromium from aqueous solutions.

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Application of Factorial Design for the Optimization of Hexavalent Chromium Removal Using a New Low-cost Adsorbent: Adsorption Isotherms, Thermodynamic and Kinetic Studies

Biointerface Research in Applied Chemistry ◽

10.33263/briac121.12471262 ◽

2021 ◽

Vol 12 (1) ◽

pp. 1247-1262

Keyword(s):

Aqueous Solution ◽

Activated Carbon ◽

Experimental Design ◽

Hexavalent Chromium ◽

Low Cost ◽

Research Work ◽

Kinetic Studies ◽

Factorial Experimental Design ◽

Initial Ph ◽

Adsorbent Dose

This research work involved using factorial experimental design techniques to investigate the adsorption of hexavalent chromium from an aqueous solution on medlar activated carbon. A 24 full factorial experimental design was employed to determine the optimum values and degree of importance of parameters: pH, initial Cr (VI) concentration, adsorbent dose, and contact time at two levels. The optimized conditions for hexavalent chromium Cr (VI) removal were at initial pH 1.5, 5 mg.L−1Cr (VI), adsorbent dose 6 mg, and 60 min adsorption time. The results predicted a good agreement between the predicted values (R2= 0.9909), as obtained by the model, and the experimental value (R2= 0.9977). The main effects and interaction effects were analyzed using analysis of variance (ANOVA), F-test and P-values to define the most important process variables affecting Cr (VI) adsorption. The most significant variables were therefore the pH of the solution and the adsorbent dose. Therefore, the present results demonstrate that medlar activated carbon should be regarded as a low-cost alternative for removing Cr (VI) from an aqueous solution. The adsorption data were evaluated by Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. The results showed that the Langmuir isotherm model best describes the equilibrium adsorption with a high correlation coefficient.

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