Competitive Adsorption of Cr (VI) and Ni (II) onto Coconut Shell Activated Carbon in Single and Binary Systems

• Published in: Water, air, and soil pollution Vol. 224; no. 9; pp. 1 - 13
• Main Authors: Wu, Yunhai, Yilihan, Palizhati, Cao, Julin, Jin, Yanping
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.09.2013; Springer; Springer Nature B.V
• Subjects: Activated carbon; Adsorbents; Adsorption; Applied sciences; Atmospheric Protection/Air Quality Control/Air Pollution; Binary system; Chromium; Climate Change/Climate Change Impacts; Competition; Desorption; Earth and Environmental Science; Efficiency; Environment; Environmental cleanup; Environmental monitoring; Equilibrium; Exact sciences and technology; Experiments; Fourier transforms; Heavy metals; Hydrogeology; Infrared spectroscopy; Isotherms; Kinetics; Membrane separation; Metal concentrations; Metal ions; Metals; Nickel; pH effects; Pollution; Scanning electron microscopy; Soil Science & Conservation; Spectrum analysis; Statistical analysis; Water Quality/Water Pollution; Water treatment and pollution; X-ray diffraction; Isotherm; Desorption; Coconut shell activated carbon; Kinetics; Binary system; Nickel II; Coconut; Competitive reaction; Mutagen; Heavy metal; Trace element; Carcinogen; Shell; Pollution; Activated carbon; Poison; Teratogen; Chromium VI
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-013-1662-6

The comparative and competitive adsorption of Cr(VI) and Ni(II) in single and binary systems using coconut shell activated carbon (CSAC) was investigated. The CSAC was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM). The effects of pH, initial metal concentration, and temperature on the adsorption of metal ions were studied. Cr(VI) removal was found to be maximum (94.5 %) at pH = 2.0. While, Ni(II) removal was found to be maximum at pH = 9.0 (58.92 %). The adsorption capacity of Cr(VI) was greater than that of Ni(II) in single component system. Parameters of adsorption isotherm model, kinetics, and thermodynamics were calculated. The single ion equilibrium adsorption data were fitted to the Langmuir, Freundlich and Dubinin–Radushkevich (D-R) isotherm models. The Langmuir and Freundlich models represented the equilibrium data better than the D-R model. The result of the fitting of D-R isotherm model indicated a physical adsorption process. The adsorption kinetic data of Cr(VI) and Ni(II) were found fitting well in pseudo second-order equation both in single and binary system ( r 2  > 0.99) and intraparticle diffusion was the rate controlling step. The negative Δ G ° and the positive Δ H ° indicated the spontaneous and endothermic nature of the adsorption process. The extended Langmuir isotherm model fitted well with the competitive adsorption data of Cr(VI) and Ni(II). For the desorption experiments, EDTA showed the maximum desorption efficiency of 69 % for Cr(VI) and 81 % for Ni(II).