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Synthesis of zinc oxide-goethite composite and its performance on the adsorption of arsenite in aqueous media

DE Egirani , NR Poyi, N Wassey

This paper investigated the synthesis of Zinc oxide-Pary Mountain Mine (PMM)-goethite composite and its performance in the adsorption of arsenite. The trimetric approach was used in the synthesis and characterization was carried out using usual laboratory procedures. Batch mode techniques at ambient temperature were used to test the adsorption of arsenite on zinc oxide PMM coated goethite. The mechanism of the reaction indicated less than one proton coefficient of 0.74, an intraparticle diffusion that was controlled by a boundary layer with a slope of 1.13-3 (mg-1) min0.5, and an intercept C that was 9.96. The mass transfer rates were 3.608-6 cm2hr-1, 1.958-6 cm2hr-1 and 0.7521-6 cm2hr-1. There was an enhancement of the mass transfer of adsorbate to the external layer of the adsorbent. The capacity of adsorption increased with increase in contact time. The first part of the linear plot may be linked to larger numbers of active adsorption sites. The aging reaction provided the different magnitude of adsorption capacity. Based on pH variability, the adsorption efficiency of the zinc oxide-goethite composite was 93.05%.