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Influence of ultrasound on the properties of dissolved organic matter with regards to proton and metal ion binding moieties
- Liu, Hailong, Chen, Guohao, Liu, Lei, Yan, Mingquan
- Water research 2018 v.145 pp. 279-286
- absorbance, adsorption, aluminum, binding sites, calcium, dissolved organic matter, ions, models, moieties, wastewater treatment, wavelengths
- 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−1) 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, Dslope350-400 (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.