Punamiya Pravin, Sarkar Dibyendu, Rakshit Sudipta, Datta Rupali
Department of Earth and Environmental Studies, Montclair State University, One Normal Avenue, Montclair, NJ, 07043, USA.
Environ Sci Pollut Res Int. 2015 May;22(10):7508-18. doi: 10.1007/s11356-015-4145-z. Epub 2015 Feb 3.
In the current batch study, we investigated the effect of solution properties, competing ligands (phosphate (P(V)) and sulfate), and complexing metal (calcium (Ca(2+))) on tetracycline (TTC) and oxytetracycline (OTC) sorption by Al-based drinking water treatment residuals (Al-WTR). The sorption behavior for both TTC and OTC on Al-WTR was pH dependent. The sorption in absence of competing ligands and complexing metal increased with increasing pH up to circum-neutral pH and then decreased at higher pH. The presence of P(V) when added simultaneously had a significant negative effect (p < 0.001) on the sorption of TTC and OTC adsorbed by Al-WTR at higher TTC/OTC:P ratios. However, when P(V) was added after the equilibration of TTC and OTC by Al-WTR, the effect was minimal and insignificant (p > 0.1). The presence of sulfate had a minimal/negligible effect on the sorption of TCs by Al-WTR. A significant negative effect (p < 0.001) on the adsorption of TCs by Al-WTR was observed in the pH range below 5 and at higher TCs:Ca(2+) ratios, probably due to TCs-Ca(2+) complex formation. Fourier transform infrared (FTIR) analysis indicated the possibility of inner-sphere-type bonding by the functional groups of OTC/TTC on Al-WTR surface. Results from the batch sorption study indicate high affinity of Al-WTR for TCs in the pH range 4-8 (majorly encountered pH in the environment) in the presence of competing ligands and complexing metal.
在当前的批次研究中，我们研究了溶液性质、竞争配体（磷酸盐（P(V)）和硫酸盐）以及络合金属（钙（Ca(2+)））对基于铝的饮用水处理残余物（Al-WTR）吸附四环素（TTC）和土霉素（OTC）的影响。TTC和OTC在Al-WTR上的吸附行为均依赖于pH值。在不存在竞争配体和络合金属的情况下，吸附量随pH值升高直至接近中性pH值而增加，然后在更高pH值时下降。当同时添加P(V)时，在较高的TTC/OTC:P比例下，P(V)对Al-WTR吸附TTC和OTC具有显著的负面影响（p < 0.001）。然而，当在Al-WTR使TTC和OTC达到平衡后添加P(V)时，其影响极小且不显著（p > 0.1）。硫酸盐的存在对Al-WTR吸附四环素类药物的影响极小/可忽略不计。在pH值低于5以及较高的四环素类药物:Ca(2+)比例下，观察到Al-WTR对四环素类药物吸附有显著的负面影响（p < 0.001），这可能是由于四环素类药物与Ca(2+)形成了络合物。傅里叶变换红外（FTIR）分析表明，OTC/TTC的官能团在Al-WTR表面可能形成内球型键合。批次吸附研究结果表明，在存在竞争配体和络合金属的情况下，Al-WTR在pH值4 - 8范围内（环境中主要遇到的pH值）对四环素类药物具有高亲和力。
