Adsorption characteristic of As(III) on goethite waste generated from hydrometallurgy of zinc.

Abstract

In this paper, goethite waste from hydrometallurgy of zinc was used as a raw material for arsenic adsorbent preparation. The goethite waste adsorbent (GWA) was characterized with scanning electron microscope (SEM), X-ray powder diffraction (XRD), and particle size distribution analysis. The adsorption of As(III) on GWA was studied as a function of contact time, pH, and coexisting anions. The safety of GWA usage in the wastewater treatment process was assessed by toxicity characteristic leaching procedure (TCLP) tests. The equilibrium adsorption data fitted well with the Langmuir isotherm model, and the maximum adsorption capacity of As(III) on GWA was 51.47 mg.g-1. GWA showed higher adsorption capacity at weak alkaline pH values (7.0-9.5). The coexisting PO43- and SiO32- presented significant adsorption competition with As(III) in aquatic systems. No significant heavy metals leaching was observed for GWA and As(III) loaded GWA in TCLP tests, which implied the safety of GWA as an adsorbent for arsenic containing wastewater treatment.