Sorption and Leaching Behaviors of Quaternary Ammonium Compounds in Paddy Soil

WANG Xiong-ke;XIANG Lei;ZHENG Mei-jie;MO Ce-hui;LI Yan-wen;ZHAO Hai-ming;CAI Quan-ying;LI Hui;Guangdong Provincial Engineering and Technology Research Center for Environmental Pollution Control and Remediation Materials,School of Environment,Jinan University;Department of Environmental Engineering,Jinan University;

quaternary ammonium compounds;;sorption;;soil column leaching;;paddy soil;;organic pollutants

Sorption and leaching behaviors of three typical quaternary ammonium compounds(QACs), i.e. dodecyl trimethyl ammonium chloride(DTAC), cetyl trimethyl ammonium bromide(CTAB), and didecyl dimethyl ammonium chloride(DDAC), in paddy soil were investigated using batch sorption and soil column leaching experiments. Sorption kinetics of three QACs followed pseudo-second-order kinetics.The organic carbon partition coefficients(Koc)of these QACs, ranging from 3056 m L·g-1 to 36 245 m L·g-1, had significantly positive relationship with their molecular weight and carbon chain lengths, indicating that the sorption of QACs decreased in order of DDAC >CTAB >DTAC. DDAC and CTAB were pollutants with high sorption abilities, while DTAC with moderate sorption ability. In leaching water of p H7,three QACs had low leaching abilities, with leaching rates ranging from 27% ~41% and being negatively correlated with their molecular weight and carbon chain lengths. Migration of three QACs(20 mg·kg-1)significantly enhanced in acidic leaching water(p H=4)and organic matter-removed paddy soil, with leaching rates ranging from 42%~63% and 58%~74%, respectively.