Investigation on the adsorption characteristics of pharmaceuticals and personal care products on polyethylenimine-alginate-activated carbon composite fiber

A new fibrous adsorbent, a composite of polyethylenimine, alginate, and activated carbon was developed for the removal of ionic and non-ionic pharmaceutical and personal care products (PPCPs) from aqueous phases. The adsorbent was conceptually designed to strongly adsorb charged and neutral PPCPs and to have a fibrous form for easy recovery after use. Instrumental analysis, isotherms, and modeling studies were used to characterize the adsorbent. The instrumental analysis provided the morphological properties, functional groups, and surface charges, and the isotherm study assisted in determining the adsorption affinity (K_d) of the adsorbent for various PPCPs. The measured ranges of log K_d were 1.22–1.82 for cations, 0.32–1.03 for anions, and 0.85–1.31 for non-ions. In addition, the effects of salts and wastewater on adsorption were examined. The results reveal that overall, the adsorbent has higher adsorption in salt-containing solutions and wastewater than pure water. In the modeling study, the quantitative structure-adsorption relationship was modeled to help rapidly estimate the K_d of any PPCPs. The developed model was highly predictable, i.e., R² of 0.892–0.894 and a standard error in log units of 0.150–0.151. Notably, the modeling study revealed that ionic and hydrogen-bond interactions were the primary adsorption interactions for the adsorbent.