In Situ Growth of ZnAl-LDH on Biomass Carbon for Highly Efficient Photodegradation of Malachite Green (MG) From Water

As a renewable new material with high void ratio, large adsorption surface area, and high adsorption rate, biomass carbon (BC) is a promising adsorbent, which has received wide attention for the degradation of dyes. However, physical adsorption cannot completely remove dyes, and there is also the risk of secondary pollution. ZnAl-layered double hydroxide (ZnAl-LDH) is a semiconductor photocatalyst with abundant active sites and excellent degradation efficiency. In this paper, we have designed a ZnAl-layered double oxide@biomass carbon (ZnAl-LDO@BC) formed by in situ grown LDH on the waste poplar wood as a synergistic adsorption and photocatalytic system. BC as a support could enhance the dispersity of layered double oxide (LDO), whereas LDO could provide photodegradation function to BC. Our studies indicate that the prepared ZnAl-LDO@BC presents lower bandgap energy, higher surface area, and lower complexation efficiency of holes and electrons than delignified biomass (DB). As a result, ZnAl-LDO@BC increased the removal rate of malachite green (MG) to 85.8%, which is 3.5 times higher than DB. The maximum removal rate was close to 98%, and the removal capacity was 1954 mg g⁻¹ under an initial concentration of 200 mg L⁻¹ of MG dye, and the possible mechanism of MG degradation was also investigated. In this study, the conversion of agroforestry wastes into high-value materials applied to dye degradation provides a new pathway for the production of stable, sustainable, and superior photocatalytic material.