Green and Economical Synthesis of Bi2WO6-Doped Geopolymers and Their Visible-Light Catalytic Degradation Mechanism Toward Tetracycline Hydrochloride

To address the environmental threats posed by antibiotic residues in water and the engineering bottlenecks of traditional powder photocatalysts—such as high cost, complicated preparation processes—a novel Bi2WO6-doped geopolymer composite photocatalytic material was successfully constructed through a facile and green synthesis strategy, utilizing low-cost and readily available geopolymers as the supporting matrix. The adsorption and degradation performance of this material toward tetracycline hydrochloride (TC), a typical antibiotic in aquatic environments, was systematically evaluated under visible-light irradiation. Experimental results demonstrate that the composite system exhibits a synergistic effect of adsorption enrichment by geopolymers and in situ photodegradation by Bi2WO6. Under the optimized conditions of merely 4% Bi2WO6 loading, catalyst dosage of 1 g/L, and an initial pH of 8.0, the degradation efficiency of TC reached 82.7% after 300 min of visible-light illumination. Even in real and complex water matrices, the material maintained a stable microstructure and highly efficient targeted removal capability. Radical scavenging experiments confirmed that the highly oxidative photogenerated holes (h+) generated by Bi2WO6 and the superoxide radicals (O2−) derived from the reduction of dissolved oxygen are the primary active species governing the efficient decomposition of TC. This study not only ameliorates the agglomeration tendency of pure-phase Bi2WO6 but also, by virtue of its inexpensive raw materials, facile synthesis process, and excellent adaptability to the weakly alkaline environments of actual water sources, provides a highly feasible strategy for the future low-cost, large-scale remediation of realistic aquatic environments and the treatment of industrial antibiotic wastewater.