Potential use of maize waste for the removal of Pb(II) from aqueous solution

Abstract

Most available technologies applied in the removal of metal contaminants in aqueous systems use the well established processes of adsorption. Adsorbents currently in use are either too expensive or not readily available for wastewater treatment. There is a need to develop new adsorbents which are readily available at low cost to remove metal contaminants in aqueous system. In this study, the authors investigated the removal of Pb(II) metal from aqueous solution by means of maize tassel powder using batch adsorption procedures. The utilization of tassels for the removal of toxic heavy metals from effluent solutions would, however, attach some economic value to this waste material. Tassel flowers were collected just prior to harvest, dried under ambient conditions, and then ground using a pestle and mortar. After particle size fractionation, the, influence of pH of the metal effluent solution, contact time and concentration of the reaction mixture, on the extent of Pb(II) ion adsorption was studied. AAS was utilized for the metal analyses. The results showed that the best adsorption (with respect to pH) was obtained from neutral pH 7, with percentage adsorptions of approximately 80% for Pb(II). Increased contact time (1 to 24 hours), indicated the establishment of equilibrium conditions between 4-24 h. It was observed that adsorption at low Pb(II) standard concentration of 5 ppm was rapid suggesting that adsorption may have been controlled by external diffusion. By increasing the concentration (from 10-20 ppm) the controlling step of adsorption was suggested to be that of internal diffusion probably within the adsorbent pores. The present study has demonstrated the usefulness of maize tassel as an adsorbent for the removal of heavy metals such as Pb(II) from aqueous solution