title: Effect of pH on transport of Pb2+, Mn2+, Zn2+ and Ni2+ through lateritic soil: column experiments and transport modeling.
abstract: This study investigated the effects of pH on the transport of Pb2+, Mn2+, Zn2+ and Ni2+ through lateritic soil columns. Model results by fitting the symmetric breakthrough curves (BTCs) of bromide (Br-) with CXTFIT model suggested that physical non-equilibrium processes were absent in the columns. The heavy metal BTCs were, however, asymmetrical and exhibited a tailing phenomenon, indicating the presence of chemical non-equilibrium processes in the columns. The retardation factors of Pb2+ were the largest of the four metal ions at both pH 4.0 (33.3) and pH 5.0 (35.4). The use of Langmuir isotherm parameters from batch studies with HYDRUS-1D did not predict the BTCs well. Rather the two-site model (TSM) described the heavy metal BTCs better than the equilibrium linear/nonlinear Langmuir model. The fraction of instantaneous sorption sites (f) of all four metal ions on the lateritic soil was consistently about 30%-44% of the total sorption sites.
authors.affiliation: National Center of Excellence for Environmental and Hazardous Waste Management (NCE-EHWM), Chulalongkorn University, Bangkok 10330, Thailand. lertc77@yahoo.com
authors.forename: Srilert
authors.initials: S
authors.lastname: Chotpantarat
authors.forename: Say Kee
authors.initials: SK
authors.lastname: Ong
authors.forename: Chakkaphan
authors.initials: C
authors.lastname: Sutthirat
authors.forename: Khemarath
authors.initials: K
authors.lastname: Osathaphan
mesh_terms: D000327:Adsorption; D001965:Bromides / Q000032:analysis; D055598:Chemical Phenomena; D003198:Computer Simulation; D005843:Geography; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000032:analysis*; D008906:Mining; D008956:Models, Chemical; D009038:Motion; D012987:Soil / Q000737:chemistry*; D013696:Temperature; D013785:Thailand
chemical_list: D001965:Bromides; D019216:Metals, Heavy; D012987:Soil