A Sorbent Based on Liquor Distillers’ Grains for the Removal of Pb(II) and Cr(III) from Aqueous Solution

A new sorbent based on liquor distillers’ grain for removal of Pb(II) and Cr(III) from aqueous solution has been systematically studied. Comparison of the adsorption potential of the sodium hydroxide modified (MLDG) and raw (RLDG) liquor distillers’ grain for the removal of Pb(II) and Cr(III) ions has been done by considering the effects of the following parameters: pH, dosage, contact time and initial concentration of metal ions. The samples were examined by particle size analyzer, specific surface area analyzer, SEM, FTIR, Zeta potential measurement and XPS. Results showed that MLDG has rougher surface and looser structure than RLDG and the -OH and -COOH are the main functional groups involved in the adsorption. The MLDG exhibited higher adsorption capacities on heavy metal ions than RLDG. The maximum adsorption capacities of MLDG were 44.13 mg g-1 for Pb(II) and 19.80 mg g-1 for Cr(III) while those of the RLDG were 11.69 mg g-1 for Pb(II) and 6.38 mg g-1 for Cr(III). Furthermore, the equilibrium sorption data are well demonstrated by Langmuir model and the kinetics adsorption data was well fitted to the pseudo-second-order equation. The results showed that sodium hydroxide modified liquor distillers’ grains is a promising sorbent for the removal of heavy metal ions.