Lead desorption from modified spent grain
(School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China)
Abstract: Lead-loaded modified spent grain regenerated by desorption process was investigated. HCl, H2SO4, H3PO4, NaOH, NaCl and ultrapure water were chosen as desorption agents to treat lead-loaded modified spent grain for 30 min. The structures and components of regenerated modified spent grain before and after adsorbing Pb(Ⅱ) were investigated using scanning electron microscopy(SEM), energy-dispersive analysis of X-ray(EDAX) and Fourier transform infrared spectrometry(FTIR). The results indicate that lead-loaded modified spent grain treated in 0.1 mol/L HCl exhibits higher elution efficiency (86.44%) as compared with other agents. The enrichment of carboxyl and hydroxyl groups susceptible to combine with Pb(Ⅱ) are observed in the regenerated modified spent grain, which may result in high re-absorption efficiency of Pb(Ⅱ). Moreover, C—Cl, N—H, C—N and O—H (polysaccharides) also play an crucial role in Pb(Ⅱ) binding to regenerated modified spent grain.
Key words: Pb(Ⅱ); spent grain; desorption; re-adsorption; mechanism