Adsorption of tetracycline onto goethite in the presence of metal cations and humic substances.
Adsorption of tetracycline onto goethite in the presence of metal cations and humic substances.
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DOI：
10.1016/j.jcis.2011.05.051
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发表时间：
2011-09
影响因子：
9.9
通讯作者：
Yanping Zhao;Jinju Geng;Xiaorong Wang;X. Gu;Shixiang Gao
中科院分区：
文献类型：
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作者：
Yanping Zhao;Jinju Geng;Xiaorong Wang;X. Gu;Shixiang Gao
四环素，最广泛使用的抗生素之一，针铁矿上的吸附作为一个功能的pH值，金属阳离子，和腐殖酸（HA）在pH值范围3-10进行了研究。浓度为0.01 M的五种背景电解质阳离子（Li+、Na+、K+、Ca 2+和Mg 2+）在研究的pH范围内对四环素吸附几乎没有影响。而二价重金属离子Cu 2+对吸附有明显的促进作用，且Cu 2+浓度越高，吸附越强，说明两种阳离子的吸附机理可能不同。背景电解质阳离子几乎不干扰四环素和针铁矿表面之间的相互作用，因为它们只形成弱的外层表面络合物。而Cu ~（2+）能与针铁矿形成强而专一的内球表面络合物，从而起到桥离子的作用，形成针铁矿-Cu ~（2+）-四环素表面络合物，从而增强了对四环素的吸附。在不同pH条件下，HA对四环素的吸附效果不同。在酸性条件下，HA的存在显著增加了四环素的吸附。结果表明，重金属阳离子和土壤有机质对四环素在土壤环境中的迁移有很大影响，并最终影响其暴露浓度和对生物的毒性。
Adsorption of tetracycline, one of the most widely used antibiotics, onto goethite was studied as a function of pH, metal cations, and humic acid (HA) over a pH range 3–10. Five background electrolyte cations (Li+, Na+, K+, Ca2+, and Mg2+) with a concentration of 0.01 M showed little effect on the tetracycline adsorption at the studied pH range. While the divalent heavy metal cation, Cu2+, could significantly enhance the adsorption and higher concentration of Cu2+, stronger adsorption was found. The results indicated that different adsorption mechanisms might be involved for the two types of cations. Background electrolyte cations hardly interfere with the interaction between tetracycline and goethite surfaces because they only form weak outer-sphere surface complexes. On the contrary, Cu2+could enhance the adsorption via acting as a bridge ion to form goethite–Cu2+–tetracycline surface complex because Cu2+could form strong and specific inner-sphere surface complexes. HA showed different effect on the tetracycline sorption under different pH condition. The presence of HA increased tetracycline sorption dramatically under acidic condition. Results indicated that heavy metal cations and soil organic matters have great effects on the tetracycline mobility in the soil environment and eventually affect its exposure concentration and toxicity to organisms.