Cellulose Paper-Based Adsorbent of Heavy Metals in Water Fabricated by One-Step Ultrafast Ligation of Diazofluorene

This study outlines the development of a cellulose paper-based adsorbent, Cell-Flu, achieved by an innovative covalent ligation of 4,5-diazafluorene motifs to cellulose paper. The ultrafast approach entails the insertion of 9-diazo-4,5-diazafluorene into the O-H bonds present within the glucose units of cellulose under catalyst-free conditions. The grafting occurs in only 15 min at 25 °C through a simple impregnation strategy. Through thorough experimentation, we fine-tuned the adsorption properties of Cell-Flu in aqueous media for Ni-(II) and Cu-(II) by adjusting pH levels, contact duration, and adsorbent dose. Additionally, we describe the capability of Cell-Flu to adsorb other heavy metals like Pb-(II), Cd-(II), and Pd-(II), uncovering its broader metal removal potential. High levels of remediation, in the range of 93-98%, were obtained for all tested metals over a period of 1 to 3 h. The interaction between Cell-Flu and metal species at the equilibrium is most accurately described by the Temkin isotherm.