Highly efficient removal of cadmium (II) ions using cellulose-based monolith with a hierarchically porous structure fabricated through phase separation method

In this study, a functionalized cellulose-based monolith was utilized as a highly efficient adsorbent to remove heavy metal ions. Firstly, cellulose-based monolith (CE MONOLITH) was obtained via combination of thermally induced phase separation and post-alkaline hydrolysis. Afterwards, the functionalized monolith (EDTA-CE MONOLITH) was prepared through esterification with ethylenediaminetetraacetic dianhydride. The fabricated EDTA-CE MONOLITH showed a hierarchically porous morphology containing macro- and mesopores simultaneously with an excellent compressive strength, which was extremely suitable for heavy metal removal. The porous structure and chemical properties of CE MONOLITH and EDTA-CE MONOLITH were characterized through SEM, N-2 adsorption/desorption isotherm, FT-IR, elementary analysis, EDS, and XPS. Finally, the batch and fixed-bed column experiments were performed to evaluate the adsorption behaviors of EDTA-CE MONOLITH for Cd2+. The results revealed that EDTA-CE MONOLITH exhibited a relatively fast Cd2+ adsorption rate with a maximum adsorption capacity of 110.1 mg/g. And EDTA-CE MONOLITH could be regenerated easily and displayed excellent reusability without significant loss of absorption capacity. The fixed-bed column adsorption implied that EDTA-CE MONOLITH showed high efficiency for Cd2+ adsorption. Therefore, the EDTA-CE MONOLITH fabricated in this work had large potential to be used as an efficient adsorbent for the removal of heavy metal ions in wastewater treatment.