Abstract: Oxytetracycline is widely used in animal husbandry and aquaculture because it can effectively inactivate Gram-positive and Gram-negative bacteria. However, 50%~80% of oxytetracycline is not fully absorbed and utilized, and enters the environmental units such as surface water, groundwater, and soil through sewage discharge, surface runoff, and landfill leachate in the form of livestock parent or metabolite. Therefore, it is urgent to take fast and efficient means to deal with oxytetracycline pollution. Photocatalytic technology is widely used in organic compounds due to its low energy consumption, high removal rate, low cost, and ability to convert organic pollutants into harmless small molecular organic compounds. Among the existing photocatalysts, tungstate photocatalysts stand out due to their wide absorption wavelength range, narrow band gap, and high stability. The natural semiconductor mineral wolframite was used as a photocatalyst for the degradation of oxytetracycline in wastewater. The effects of solid-liquid ratio, light intensity, and initial concentration on the degradation of oxytetracycline were investigated while the degradation mechanism and pathway were analyzed. The results showed that wolframite had a promising degradation effect on oxytetracycline under visible light, and the removal efficiency of oxytetracycline could reach 94.3% at 120 min under the conditions of concentration of 15 mg/L, pH=4.5, the solid-liquid ratio of 1.0 g/L and light intensity of 60 W; The degradation of oxytetracycline by wolframite is in accordance with the primary kinetic reaction law. The results of the quenching experiment and electron paramagnetic spectroscopy showed that hydroxyl radical (?OH) and superoxide anion radical (?O2-) were the main active oxidizing species causing oxytetracycline degradation, which degraded 20.4% and 10% oxytetracycline at 120 min, respectively. The results of liquid chromatography-mass spectrometry showed that oxytetracycline was degraded into intermediates through hydroxylation, demethylation, and decarbonylation, which was beneficial to the industrial application of wolframite in antibiotic treatment.

Key words: Wolframite, Oxytetracycline, photocatalysi, mechanism, Pathway

摘要： 采用天然半导体矿物黑钨矿作为光催化剂用于降解废水中的土霉素。研究了固液比、光照强度、初始浓度对土霉素降解的影响，并解析了降解机理和路径。结果表明，可见光下黑钨矿对土霉素具有较好的降解效果，在浓度为15 mg/L、pH=4.5、固液比为1.0 g/L、光照强度60 W的条件下，120 min时土霉素的去除效率可以达到94.3%，黑钨矿对于土霉素的去除速率符合一级动力学反应规律。淬灭实验和电子顺磁光谱结果表明羟基自由基(?OH)和超氧阴离子自由基(?O2-)是导致土霉素降解的主要活性氧化物种，分别在120 min时降解了20.4%和10%的土霉素。液相色谱-质谱联用显示土霉素经过羟基化、去甲基化、和脱羰化降解为中间产物，使其化学毒性下降，有利于工艺在抗生素处理中的工业化应用。

关键词: 黑钨矿, 土霉素, 光催化, 机理, 路径