Nanocellulose encapsulated nZVI@UiO-66-NH2 aerogel for high-efficiency p-chloronitrobenzene removal with selective reduction

Abstract

A poriferous nZVI aerogel (nZVI@UiO-66-NH₂/TCNF) was elaborately constructed by in-situ deposition of nZVI on UiO-66-NH₂ and coupling with a bio-based TEMPO oxidized cellulose nanofiber (TCNF) substrate, followed by freeze-drying process for p-chloronitrobenzene (p-CNB) degradation. With degradation efficiency of above 85 % within 3 h under a wide pH range of 3–9, the nZVI@UiO-66-NH₂/TCNF aerogel presented better p-CNB removal performance than other developed aerogels. Extended to 24 h, superior p-CNB removal performance (99.83 %) and 4-chloroaniline (p-CAN) selectivity (98.84 %) were successfully achieved. This could be attributed to 1) the facilitated mass transfer via concentration-gradient driving force with buffering and drag-reducing hydrated shear layer from porous channels of hydrophilic TCNF; 2) the enhanced adhesion of p-CNB onto UiO-66-NH₂ and accelerated electron transfer by Fe-O-Zr bonds, synergistically improving the nitro- reduction of p-CNB using nZVI. This work pioneered a unique paradigm, providing nZVI with both solid bio-based moldability and highly-selective removal for the treatment of chloronitrobenzene containing wastewater.