Quaternization of Porous Cellulose Beads and Their Use for Removal of Humic Acid from Aqueous Medium

Abstract

Porous cellulose beads were quaternized with glycidyltrimethylammonium chloride (GTMAC) to explore a potential use of them as an adsorbent for removal of humic acid (HA) from aqueous medium. The introduction of quaternary ammonium groups was confirmed by FT-IR and XPS analysis. The content of introduced quaternary ammonium groups increased with an increase in the GTMAC concentration. The adsorption capacity increased with a decrease in the initial pH value and attained the maximum value at pH 3 and increased with an increase in the content of quaternary ammonium groups. The removal % increased with the dose of quaternized cellulose beads at both pH 3.0 and 6.0. The adsorption process obeyed the pseudo-second order kinetic model and exhibited a better fit to the Langmuir isotherm model, suggesting that the adsorption of HA is accomplished through the electrostatic interaction between a quaternary ammonium group introduced and a dissociated carboxy group of a HA molecule. The maximum adsorption capacity obtained in this study is comparable to or higher than those published by other articles. HA loaded was completely released to NaOH solutions at higher than 100 mM to regenerate the quaternized cellulose beads. The above-mentioned results clearly show that the quaternized cellulose beads prepared in this study can be used as a regenerable adsorbent with high capacity for removal of HA from aqueous medium.

Keywords

• porous cellulose beads
• quaternization
• quaternary ammonium group
• humic acid
• adsorption
• desorption