Removal of Cu²⁺ from aqueous solutions by the novel modified bagasse pulp cellulose: Kinetics, isotherm and mechanism

This study designed and synthesized a novel cellulose-based heavy metal adsorption material. One kind of bagasse pulp cellulose was pretreated under microwave 200 W for 3 min before the epoxidation, amination and ultrasonic enhancement sulfonation reaction. Heavy metal adsorption groups N and S were grafted onto the bagasse pulp cellulose. Furthermore, the effects of solution pH, adsorption temperature, adsorbent dosage, Cu(2+) concentration, and adsorbent recycling on adsorption capacity were investigated. Under the optimum condition, the adsorption amount of Cu(2+) was 35.2mg/g adsorbent. Compared with other cellulose-based adsorbents, this kind of adsorbent could be easily prepared and effectively recycled. Except for the normal fitting of adsorption process with the Langmuir isotherm adsorption model, Freundlich isotherm adsorption model and secondary adsorption kinetics model, the solid-liquid phase adsorption mechanism was also introduced to explain the Cu(2+) adsorption process. Three consecutive stages were deeply discussed and verified, where the surface diffusion and particle internal diffusion process were the primary along with a quick adsorption of the adsorbate onto the in-hole surface of the cellulose-based adsorbent.