Abstract:
Organoclays were prepared from sodium-rich bentonite and quaternary ammonium cations (QACs) at loading levels of 0.5, 1.0 and 1.5 times the bentonite}s cation exchange capacity (CEC). In this study, two QACs with similar number of carbon in molecules but different molecular structure, Dodecyl pyridinium chloride (DPC) and Dodecyltrimethylammonium bromide (DTAB) were chosen. The raw water used was collected from three main water treatment plants in Bangkok Metropolitan Areas (BMA). Natural organic matters (NOM) removal from raw waters and trihalomethanes (THMs) removal from chlorinated raw waters were studied in batch adsorption experiments. The correlation between NOM surrogates with trihalomethanes formation potential (THMFP) were also investigated. From batch adsorption studies, organoclays were unable to remove NOM but could effectively adsorbed THMs from water. The lower molecular weight and higher polarity of THMs made them more suitable for partitioning into organoclays. Adsorption of THMs by DPC-bentonite was well fitted with Langmuir isotherm and Adsorption of THMs by DTAB-bentonite was well characterized by linear adsorption model. TOC and DOC were well correlated with THMFP.