Advanced BiVO4-deoxygenated lignocellulosic photocatalyst for effective degradation of organic and heavy metal pollutants in aqueous system.

Abstract

Bismuth vanadate (BiVO₄) is a common photocatalyst for water remediation, yet its powder form renders difficulty to disperse, recycle and regenerate, limiting photodegradation efficiency. In this study, a lignocellulosic-templated BiVO₄ photocatalyst was fabricated from BiVO₄ precursor and lignocellulose using a simple vacuum impregnation (w/o heat treatment on wood template). Results showed that the modified template retained original hierarchical structure with an increased specific surface area and reduced hemicellulose content, leading to a promising template for uniform distribution of BiVO₄. Moreover, compared to untreated, heat treatment cleaved acetyl groups in the hemicellulose chain, broke down fatty ether bonds, and oxidized lignin side chains, resulting in no disruption to the catalysis of BiVO₄. The BiVO₄-pyrolyzed lignocellulosic photocatalyst achieved remarkable degradation efficiencies of 90.03 % (approximately 7-fold increase compared to untreated) for RhB, and complete degradation of Cr (VI) within 60 min. Furthermore, the efficiency remained >80 % after seven cycles. The mechanism was hypothesized that BiVO₄ and template play distinct roles, as deoxygenated lignocellulosic template only acts as a carrier for BiVO₄ growth, and BiVO₄ serves as the photocatalyst. However, untreated template can react with BiVO₄ and impair photocatalytic efficiency. The BiVO₄-pyrolyzed lignocellulosic photocatalyst hold great promise for the remediation of aqueous contaminants.