Titanium tetrachloride for silver nanoparticle-humic acid composite contaminant removal in coagulation-ultrafiltration hybrid process: floc property and membrane fouling

Zhao, Yanxia; Sun, Yangyang; Tian, Chang; Gao, Baoyu; Wang, Yan; Shon, Hokyong; Yang, Yanzhao

Titanium tetrachloride for silver nanoparticle-humic acid composite contaminant removal in coagulation-ultrafiltration hybrid process: floc property and membrane fouling

2017

Titanium-based coagulation is expected to achieve both efficient water purification and sludge recycling. This study is the first attempt to use titanium tetrachloride (TiCl₄) for silver nanoparticle (AgNP)-humic acid composite contaminant removal in a coagulation-ultrafiltration (C-UF) process, where characterization of flocs and membrane fouling under varied coagulant dose, initial solution pH, and AgNP concentration conditions are the main contents. Results suggested that the TiCl₄ achieved high AgNP removal in the form of silver nanoparticle through adsorption and sweep flocculation and simultaneously exerted additional 68.2 % higher dissolved organic carbon removal than Al₂(SO₄)₃. The TiCl₄ produced larger and stronger flocs but with weaker recoverability and less compact degree than did Al₂(SO₄)₃. Floc properties were independent of AgNP concentration except floc fractal dimension, which was negatively correlated with AgNP concentration. The TiCl₄ precoagulation caused less membrane fouling within wider pH range than Al₂(SO₄)₃ did in the C-UF process. Incorporation of AgNPs during the TiCl₄ pretreatment process facilitated the mitigation of membrane fouling, which was, however, negligibly influenced by AgNP concentration in the case of Al₂(SO₄)₃.

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