Institute of Environmental and Analytical Sciences, Henan Joint International Research Laboratory of Environmental Pollution Control Materials, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China.
Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300350, China; Department of Hydrology, University of Bayreuth, Bayreuth D-95440, Germany.
Sci Total Environ. 2019 May 20;666:94-102. doi: 10.1016/j.scitotenv.2019.02.242. Epub 2019 Feb 17.
The impact of low-molecular weight organic acids (LMWOAs) on the transport of graphene oxide (GO) nanoparticles in saturated quartz sand was investigated. The different LMWOAs such as acetic acid, glycolic acid, malonic acid, and tartaric acid were used in experiments. The effects of LMWOAs on the transport of GO were markedly dependent upon organic acid species. In general, the transport enhancement effects followed the order of tartaric acid > malonic acid > glycolic acid > acetic acid, the regular pattern might be related to amount and type of functional groups of LMWOAs. Additionally, the different enhanced ability of LMWOAs was determined by their molecular weight. In the presence of Na, the main deposition mechanism was ascribed to steric hindrance and competition between LMWOA and GO for deposition sites on grain surfaces under acidic conditions (i.e., pH 4.0 and 5.0). Batch adsorption experiments indicated the extents of competitive adsorption between LMWOAs and GO on quartz sand. In addition, the DLVO theory was not applicable to describe the transport of GO in the presence of LMWOAs at pH 5.0. Nevertheless, electrostatic and steric repulsion, existing between GO and sand grains, were the most important deposition mechanisms under the neutral condition (i.e., pH 7.0). When Ca was the main cation in the background solution, the transport enhancement effects followed quite similar order to those of Na, mainly due to different complexing strength of organic acids.
研究了低分子量有机酸 (LMWOAs) 对饱和石英砂中氧化石墨烯 (GO) 纳米颗粒传输的影响。实验中使用了不同的 LMWOAs，如乙酸、甘醇酸、丙二酸和酒石酸。LMWOAs 对 GO 传输的影响明显取决于有机酸的种类。一般来说，传输增强效应的顺序为酒石酸>丙二酸>甘醇酸>乙酸，这种规律可能与 LMWOAs 的官能团数量和类型有关。此外，LMWOAs 的不同增强能力取决于它们的分子量。在存在 Na 的情况下，主要的沉积机制归因于在酸性条件下（即 pH 值为 4.0 和 5.0），LMWOA 和 GO 之间的空间位阻和竞争导致沉积位点上的 LMWOA 和 GO 的沉积。批处理吸附实验表明了 LMWOAs 和 GO 在石英砂上的竞争吸附程度。此外，DLVO 理论不适用于描述在 pH 值为 5.0 时存在 LMWOAs 的 GO 的传输。然而，在中性条件下（即 pH 值为 7.0），GO 和砂粒之间存在静电和空间排斥，这是最重要的沉积机制。当 Ca 是背景溶液中的主要阳离子时，增强效果的顺序与 Na 相当相似，主要是由于有机酸的络合强度不同。
