Adsorption capacity of lead on holocellulose aerogels synthesized from an alkali hydroxide — urea solution

Abstract

This study investigated adsorption characteristics of lead on bead-type holocellulose aerogels synthesized from wood fiber by using an alkali hydroxide — urea solution. The synthesized holocellulose aerogels were classified into two groups for comparison according to the source of the precursor hydrogel, a dissolved upper layer and a precipitated bottom layer of hydrogel solution, formed during the synthesis procedure. As the equilibrium concentration of lead in the solution was increased, the amount of lead adsorbed on the holocellulose aerogel increased, eventually reaching a maximum. As the pH was increased, the adsorption capacity of lead also increased. The adsorption rate rapidly increased during the earlier 10 min period and then asymptotically approached equilibrium. However, as the lead concentration in the water was increased, the time required for achieving equilibrium also increased due probably to the dynamic exchange of lead molecules during the adsorption process. The lead adsorbed to the aerogels was visually identified by using Scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) analyses. This study suggests that the holocellulose aerogel can be potentially used in many water treatment applications targeting heavy — metal, including lead, removal.