| Coagulation is a traditional and simple technology in drinking water treatment and waste water treatment. The flocculants are the key of the coagulation technology and the coagulation performances largely depend on the efficiency of the flocculants. The developing of flocculants went from the traditional inorganic flocculants to the inorganic polymer flocculants, the organic polymer flocculants and the composite flocculants. Many studies have shown that conventional flocculants can efficiently remove colloidal particles through compressing the thickness of the electric double layer, charge neutralization, absorbing and bridging and enmeshment in a precipitate.Pharmaceutical and personal care products(PPCPs) are derived from the various chemicals.Due to its extensive use in our daily life and emissions, it got the formation of pseudo persistent phenomenon andattracted much attention recently by the scientific community and the public. Many PPCPs have high solubility, low molecular weight, and stable chemical property at room temperature and is not biodegradable. The removal efficiency of them by these conventional flocculants are very low.The expensive equipments and the complicated operating processes inhibit the large-scale application of the advanced oxidation process and activated carbon adsorption in practices.Ion exchange and coagulation were successfully combined to improve the removal efficiency of the low-molecular weight dissolved organic matters (DOM). Covalently bound organic silicate aluminum hybrid flocculants could be synthesized using silane coupling agents and AICl3. The inorganic and organic components were really linked together via the silicon atoms, by which some functions could be achieved. The flocculant with the function of the ion exchange could be produced by this way. With the new flocculant, the ion exchange and coagulation process could be achieved in one operation to significantly improve the removal efficiency of the DOM.In this paper, the covalently bound inorganic-organic polymer flocculant with quaternary ammonium groups(FIEX) was prepared. The FIEX can keep stable when the total aluminum (AlT) is0.2mol/L, alkalization degree Si/Al molar ratio is2.5and0.6, respectively. Compared with conventional composite flocculants, the upper limits Si/Al molar ratio and alkalization degree of covalently bound composite polymeric flocculants are improved. The Si source of FIEX were proved to be covalently bound by Al-O-Si using the IR spectroscopy. The quaternary ammonium group also could be detected.The physical-chemical characteristics of FIEX were studied. The FIEX prepared in this study all showed acidity and the solution pH increased by the Si/Al molar ratio and alkalization degree. The zeta potential value increased with the increase of Si/Al molar ratio and decrease of alkalization degree. According to the results of TEM, the sample prepared with alkalization degree formed condensed network.The FIEX can effectively remove the SA from water, which is a great advantage compared to the traditional flocculants. With the increase of Si/Al molar ratio and alkalization degree, the removal of SA by the flocculants increased. The flocculant could maintain good removal of SA in the range of solution pH studied in this paper. Besides, we found the flocculants were effective when the concentration level of SA was low. We may find good use in the drinking water treatment.Compared with PAC and PASiC, the mechanism of FIEX was studied by the jar test. The SA was combined with FIEX through the ion exchanging progress, transferred to solid phase from liquid phase and then removed in the flocculation process. This was significantly different from PAC and PASiC, which removed pollutants mainly by electricity-neutralization and adsorption-bridging actions.we did the experiment of the octanol-water partition coefficient. We found a positive correlation between the distribution ratio (Kow) and the removal efficiency of SA among the three kinds of flocculants. |
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