The removal of cobalt ion from aqueous solution by Acacia nilotica leaf carbon(HAN), is described. Effect of p H,agitation time and initial concentration on adsorption capacities of HAN was investigated in a batch mode. The adsorption process, which is p H dependent, shows maximum removal of cobalt in the p H range 5 for an initial cobalt concentration of 50 mg·L–1The experimental data have been analyzed by using the Freundlich, Langmuir,Temkin and Dubinin–Radushkevich isotherm models. The batch sorption kinetics have been tested for a pseudofirst order, pseudo-second order and Elovich kinetic models. The rate constants of adsorption for all these kinetic models have been calculated. Results showed that the intraparticle diffusion and initial sorption of Co(Ⅱ) into HAN was the main rate limiting step. The adsorption of cobalt ion was confirmed through instrumental analyses such as scanning electron microscope(SEM) and Fourier transform infrared spectroscopy(FTIR). The desorption and recycling ability of HAN were also found. We conclude that HAN can be used for the efficient removal of cobalt from aqueous solution.
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