Tuning and Characterizing Nanocellulose Interface for Enhanced Removal of Dual-Sorbate (AsV and CrVI) from Water Matrices

Cellulose nanofiber (CNF) is one of the emerging green candidates for the various domains due to its sustainability, abundance availability, and high surface area. However, its effectiveness in the environmental aspect of toxic heavy metal removal required improvement by tuning the interface between CNF and heavy metals, and by understanding removal mechanisms. Herein, we synthesized four types of surface-functionalized CNF from waste coffee-filters for enhanced uptake of As-V and Cr-VI in the different water matrices. Among them, Fe3+-cross-linked CNF-Fe2O3 (FF) and mussel-inspired dopamine conjugated CNF (DP) demonstrated significant performance in water treatment for As-V and Cr-VI, respectively, than commercial activated carbon based adsorbents. Combined X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS) spectroscopy, and data fitting elucidated the complexation mode of As-V and Cr-VI to each CNF derivative which suggested that As-V binds through a bidentate-binuclear complex and that Cr-VI binds to catecholic OH as a trinuclear complex. Simultaneously, the transformation of harmful Cr-VI into nontoxic Cr-III was observed in DP which supports their potential practical applications. Taken together, our comprehensive data not only provide the material fabrication, interface behavior, and impact of water quality parameters in simulated and real contaminated waters but also explore the holistic understanding of the heavy metal removal mechanism and adsorbate-adsorbent interfacial interaction of these novel CNF derivatives.