School of Environment and Resources Sciences, Shanxi University, The Laboratory of Environmental Engineering, Shanxi, 030006, China.
Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China.
Water Res. 2018 Nov 15;145:279-286. doi: 10.1016/j.watres.2018.08.008. Epub 2018 Aug 15.
Ultrasound is widely used in water and wastewater treatment. However, the influence of ultrasound on the composition and structure of dissolved organic matter (DOM) and consequently its behaviors is still unclear. In this study, the changes in proton and metal binding moieties in DOM caused by ultrasound at an environmentally relevant concentration (about 5 mg·L) were investigated using spectrophotometric titrations. The amounts of carboxylic and phenolic-like groups in DOM before and after ultrasound were quantified by the spectral parameter, Dslope (the differential slope of the Log-transformed DOM absorbance in the wavelength region of 350-400 nm) in combination with the non-ideal competitive adsorption (NICA) model. The results demonstrate that the concentration of carboxylic-like sites decreased with an increase in the ultrasound intensity at the same reaction time. However, the concentration of phenolic-like sites increased with an increase in the ultrasound intensity in most cases. The amounts of bound metal Ca(II) and Al(III) ions decreased with an increase of the ultrasound intensity due to the reduction of available total binding sites (carboxylic-like and phenolic-like groups) in the DOM after ultrasound. This study provides detailed in-situ information concerning the changes in the properties and behaviors of DOM in ultrasound, which would be useful to understand in more detail and to optimize the utility of ultrasound in water and wastewater treatment.
超声广泛应用于水和废水处理中。然而，超声对溶解有机物（DOM）的组成和结构，以及由此产生的行为的影响仍不清楚。在本研究中，使用分光光度滴定法研究了在环境相关浓度（约 5mg·L）下超声对 DOM 中质子和金属结合基团的影响。通过光谱参数 Dslope（在 350-400nm 波长区域内 DOM 吸光度的对数变换的微分斜率）与非理想竞争吸附（NICA）模型相结合，定量了超声前后 DOM 中羧酸和酚类样基团的数量。结果表明，在相同的反应时间内，随着超声强度的增加，羧酸样位点的浓度降低。然而，在大多数情况下，随着超声强度的增加，酚类样位点的浓度增加。由于超声后 DOM 中可用的总结合位点（羧酸样和酚类样基团）减少，结合的金属 Ca(II)和 Al(III)离子的浓度随着超声强度的增加而降低。本研究提供了关于超声过程中 DOM 性质和行为变化的详细原位信息，这对于更详细地理解和优化超声在水和废水处理中的应用将是有用的。
