磁性市政污泥生物炭活化过硫酸盐降解水中四环素的性能和机制

Performance and Mechanisms of Magnetic Sewage Sludge Biochar-Activated Persulfate for Tetracycline Degradation in Water

摘要: 四环素(TC)本身特定的结构导致其在生物体内不易被代谢，且容易在水中积累，逐渐对环境和人类健康造成威胁。本研究以含铁市政污泥为原料制备磁性污泥生物炭(MSB)，用于水体中TC的降解性能和机制研究。应用傅里叶红外光谱(FTIR)，X射线光电子能谱(XPS)等探究反应前后MSB的理化性质；并探究了炭化温度，MSB900投加量，过硫酸盐初始浓度、共存离子等因素对MSB900活化过硫酸盐降解水中TC的影响。表征结果表明MSB900表面含有多种含氧官能团以及铁元素，且反应后含氧官能团和铁元素的含量均有明显下降。研究结果表明MSB在最佳实验条件下(炭化温度为900℃、1.33 g/L投加量、10 mmol/L过硫酸盐浓度、pH 3)对TC的降解效果最好，此时最大去除率为94.07%。此外，阴离子Cl⁻、HCO₃⁻、SO₄²⁻对TC去除率影响不显著，而金属阳离子Ca²⁺、K⁺、Mg²⁺、Na⁺有一定的抑制作用；Ca²⁺的抑制作用最强，Na⁺的抑制作用最弱。MSB900活化过硫酸盐降解水中TC的机制主要为发生了Fe²⁺/Fe³⁺循环促成了硫酸根自由基(SO₄∙⁻)与羟基自由基(∙OH)的生成。本研究表明以含铁污泥为原料制备的磁性污泥生物炭可以作为一种有效的活化过硫酸盐降解TC的环保功能材料。

Abstract: The unique structural characteristics of tetracycline render it resistant to metabolic degradation in organisms, leading to its accumulation in aquatic environments and posing a growing threat to both ecosystems and human health. In this study, magnetic sludge biochar (MSB) was synthesized from iron-rich sewage sludge to investigate its efficacy and mechanism in degrading tetracycline (TC) in aqueous solutions. The physicochemical properties of MSB were characterized using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of key parameters—including pyrolysis temperature, MSB dosage, persulfate concentration, solution pH, and coexisting ions—on tetracycline degradation were systematically evaluated. Characterization revealed that MSB900 (pyrolyzed at 900˚C) exhibited abundant oxygen-containing functional groups and iron species, although their concentrations decreased significantly after pyrolysis. Under optimal conditions (pyrolysis temperature: 900˚C, MSB dosage: 1.33 g/L, persulfate concentration: 10 mmol/L, pH 3), the degradation efficiency of TC reached 94.07%. Furthermore, common anions (Cl⁻, HCO₃⁻, SO₄²⁻) exhibited negligible effects on degradation, whereas cationic species (Ca²⁺, K⁺, Mg²⁺, Na⁺) slightly inhibited the process. Mechanistic studies indicated that TC degradation involved the redox cycling of Fe²⁺/Fe³⁺ and the synergistic action of sulfate radical (SO₄∙⁻) and hydroxyl radicals (∙OH). These findings demonstrate that iron-laden sludge-derived magnetic biochar serves as an efficient and sustainable persulfate activator for the remediation of TC-contaminated wastewater.