Design of amphoteric MOFs-cellulose based composite for wastewater remediation: Adsorption and catalysis

Water pollution remains a serious problem for aquatic organism and human beings. Developing an efficient material which can simultaneously remove and convert pollutants into low or no harmful compounds is an essential issue. Targeting at this goal, a multifunctional and amphoteric wastewater treatment material of Co-MOF and functionalized cellulose-based composite (CMC/SA/PEI/ZIF-67) was designed and prepared. Carboxymethyl cellulose (CMC) and sodium alginate (SA) were selected as support to construct an interpenetrating network structure and made it crosslinked with polyethyleneimine (PEI) for further in situ growth of ZIF-67 with good dispersion. The material was characterized using an appropriate set of spectroscopic and analytical techniques. When applied in the adsorption of heavy metal oxyanions with no adjustment of pH, the adsorbent could completely decontaminate Cr(VI) at both low and high initial concentrations with good reduction rates. The adsorbent maintained good reusability after five cycles. Meanwhile, the cobalt species of CMC/SA/PEI/ZIF-67 can activate peroxymonosulfate to generate high oxidizing substances (such as SO₄^-· and ·OH^- radicals) to degrade cationic rhodamine B dye within 120 min, thus indicating the amphoteric and catalytic nature of our CMC/SA/PEI/ZIF-67 adsorbent. The mechanism of the adsorption and catalytic process was also discussed based with the assistance of different characterization analysis.