Preparation of composite soybean straw-based materials by LDHs modifying as a solid sorbent for removal of Pb(II) from water samples

Abstract

In this study, the nanocomposites from biomass (soybean straw) and layered double hydroxides (LDHs), denoted as B/LDHs, were fabricated using the mechanical- hydrothermal method. The obtained B/LDHs nanocomposites were characterized by TEM, SEM, FT-IR, and N2 adsorption-desorption techniques. Adsorption of the heavy-metal ions Pb(II) on the B/LDHs was determined at 25°C and pH 6.0 using a batch technique. The experimental results demonstrated that biomass contributed to the sorption process. The pseudo-second-order, Langmuir, and Freundlich models well fitted the sorption process, indicating chemisorption and monolayer adsorption were the main adsorption mechanisms. Meanwhile, it is found that there is an obvious effect of adsorbent concentration in the studied adsorption system. In comparison with soybean straw and Mg-Al LDHs, the B/LDHs nanocomposites exhibit significantly enhanced sorption capacities. It is evident from this study that the construction of B/LDHs nanocomposites is an effective strategy for improving the sorption capacity of LDHs, and the modified LDH-based adsorbent shows a good potential in the removal of heavy metals from water. More importantly, it solves the problem of a large number of agricultural waste disposals. And, it achieved the goal of a win-win situation.