Abstract：
Interaction of antibiotics with metal ions in aquatic environments, commonly occurring to form complexes, may affect the migration, transformation and reactivity of residual antibiotics. This study demonstrates the photolysis of Fe(III) by UV irradiation at pH 3.5, as an advanced oxidation process, to produce •OH for the abatement of a common broad-spectrum antibiotic compound, tetracycline (TET). The dimethylamino (-N(CH3)2) and hydroxyl (-OH) groups of TET were determined as the binding sites for the complexation with Fe(III) via a series of novel characterization approaches. The complexation stoichiometry of Fe(III)-TET complexation, including the complexation ratio, constants and percentages, was determined via a complexometric titration based on the UV differential spectroscopy. The complexation constant was determined to be 21,240 ± 1745 L·mol-1 under the designed conditions. Complexation of TET with Fe(III) enhanced its degradation in the UV/Fe(III) process, through the promotion of the •OH generation by inhibiting hydrolysis-precipitation process of Fe(III) and enhancing Fe(III)/Fe(II) cycle and the acceleration of mass transfer between •OH and TET. This finding provides new insights into the role of complexation in the fate of residual antibiotics in the UV/Fe(III) process. The reduced overall ecotoxicity during the TET abatement, evaluated by the toxicity variation through ECOSAR program, provides the UV/Fe(III) process with a theoretical feasibility for water decontamination in actual applications.
摘要：
水生环境中抗生素与金属离子的相互作用，通常形成复合物，可能会影响迁移，残留抗生素的转化和反应性。这项研究表明，Fe（III）的光解通过紫外线照射在pH3.5，作为一种先进的氧化过程，产生·OH用于消除常见的广谱抗生素化合物，四环素（TET）。通过一系列新颖的表征方法，确定了TET的二甲基氨基（-N（CH3）2）和羟基（-OH）基团作为与Fe（III）络合的结合位点。Fe（III）-TET络合的络合化学计量，包括络合比，常数和百分比，通过基于UV差示光谱法的络合滴定法测定。在设计条件下，络合常数为21,240±1745L·mol-1。TET与Fe（III）的络合增强了其在UV/Fe（III）过程中的降解，通过抑制Fe（III）的水解-沉淀过程和增强Fe（III）/Fe（II）循环来促进·OH的生成，并加速·OH和TET之间的传质。这一发现为络合在UV/Fe（III）过程中残留抗生素命运中的作用提供了新的见解。TET消减期间总体生态毒性降低，通过ECOSAR程序通过毒性变化进行评估，为UV/Fe(III)工艺在实际应用中的水去污提供了理论可行性。
