title: Chromate transport through columns packed with surfactant-modified zeolite/zero valent iron pellets.
abstract: Chromate transport through columns packed with zeolite/zero valent iron (Z/ZVI) pellets, either untreated or treated with the cationic surfactant hexadecyltrimethylammonium (HDTMA), was studied at different flow rates. In the presence of sorbed HDTMA, the chromate retardation factor increased by a factor of five and the pseudo first-order rate constant for chromate reduction increased by 1.5-5 times. The increase in rate constant from the column studies was comparable to a six-fold increase in the rate constant determined in a batch study. At a fast flow rate, the apparent delay in chromate breakthrough from the HDTMA modified Z/ZVI columns was primarily caused by the increase in chromate reduction rate constant. In contrast, at a slower flow rate, the retardation in chromate transport from the HDTMA modified Z/ZVI columns mainly originated from chromate sorption onto the HDTMA modified Z/ZVI pellets. Due to dual porosity, the presence of immobile water was responsible for the earlier breakthrough of chromate in columns packed with zeolite and Z/ZVI pellets. The results from this study further confirm the role of HDTMA in enhancing sorption and reduction efficiency of contaminants in groundwater remediation.
authors: Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53141, USA. li@uwp.edu
authors: Zhaohui
authors: Z
authors: Li
authors: H
authors: H
authors: Kirk Jones
authors: Pengfei
authors: P
authors: Zhang
authors: Robert S
authors: RS
authors: Bowman
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D002840:Chromates / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D017641:Zeolites / Q000737:chemistry*
chemical_list: D002593:Cetrimonium Compounds; D002840:Chromates; D013501:Surface-Active Agents; D017641:Zeolites; D007501:Iron; D000077286:Cetrimonium