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Chromate Transport through Surfactant‐Modified Zeolite Columns
Author(s) -
Li Zhaohui
Publication year - 2006
Publication title -
groundwater monitoring and remediation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 47
eISSN - 1745-6592
pISSN - 1069-3629
DOI - 10.1111/j.1745-6592.2006.00091.x
Subject(s) - chromate conversion coating , chemistry , pulmonary surfactant , desorption , zeolite , inorganic chemistry , bromide , adsorption , counterion , cationic polymerization , ion , organic chemistry , corrosion , catalysis , biochemistry
Remediation of ground water containing anionic contaminants presents a great challenge. Because of its low cost, surfactant‐modified zeolite (SMZ) has been studied for >10 years for potential uses as permeable barrier materials to remove anionic contaminants from water. In this study, zeolite aggregates with particle size of 3.4 to 4.8 mm were modified by hexadecyltrimethylammonium (HDTMA) bromide, a cationic surfactant, to a surfactant loading level of 80 mmol/kg and a concurrent counterion bromide loading level of 34 mmol/kg. While no retardation of chromate transport was observed for unmodified columns, a retardation factor of 60 was found for chromate transport through the SMZ columns. Slow but persistent desorption of HDTMA occurred throughout the chromate transport experiment. Accompanying HDTMA desorption, slow release of counterion bromide and chromate also occurred. After the sorbed chromate was fully released when the columns were flushed with 400 pore volumes of water, a second pulse of chromate input was initiated. However, the chromate retardation factor was reduced to 5, indicating a loss of 90% of its functionality for chromate retardation, which is attributed to a change in the surfactant surface configuration from an admicelle formation to a monolayer. The results indicate that caution should be exercised when using SMZ as permeable barrier materials for remediating anion‐contaminated ground water.