Au-loaded ZnO immobilized cellulose-derived carbon beads for enhanced photocatalytic degradation of tetracycline.

The elimination of tetracycline antibiotics from aqueous environments remains a significant challenge. In this work, Au-loaded ZnO immobilized cellulose-derived carbon beads (Au/ZnO@C) composite materials, with varying Au molar ratios, were synthesized through a one-pot approach. The Au/ZnO@C composite featured a metal-semiconductor architecture built from Au nanoparticles deposited on ZnO. The introduction of Au nanoparticles can modify the interfacial electronic structure of ZnO and promote charge transfer between Au and ZnO. Meanwhile, using cellulose-derived carbon beads as a carrier effectively suppressed the aggregation of Au/ZnO particles, addressing a key limitation in ZnO-based photocatalysts. Compared to bare carbon beads and ZnO@C, Au/ZnO@C exhibited better photocatalytic degradation performance. Among all samples, Au(1%)/ZnO@C showed the best catalytic performance, achieving a degradation efficiency of 87.62% for tetracycline. The degradation kinetics were well described by the Langmuir-Hinshelwood model, exhibiting a first-order behavior and an optimal apparent rate of 0.00729 min-1. Mass spectrometry analysis revealed that tetracycline was progressively transformed into small-molecule intermediates during the degradation process.