title: Removal of diphenhydramine from water by swelling clay minerals.
abstract: Frequent detection of pharmaceuticals in surface water and wastewater attracted renewed attention on studying interactions between pharmaceuticals and sludge or biosolids generated from wastewater treatment. Less attention was focused on studying interactions between pharmaceuticals and clay minerals, important soil and sediment components. This research targeted on investigating interactions between diphenhydramine (DPH), an important antihistamine drug, and a montmorillonite, a swelling clay, in aqueous solution. Stoichiometric desorption of exchangeable cations accompanying DPH adsorption confirmed that cation exchange was the most important mechanism of DPH uptake by the swelling clay. When the solution pH was below the pK(a) of DPH, its adsorption on the swelling clay was less affected by pH. Increasing solution pH above the pK(a) value resulted in a decrease in DPH adsorption by the clay. An increase in d(001) spacing at a high DPH loading level suggested interlayer adsorption, thus, intercalation of DPH. The results from this study showed that swelling clays are a good environmental sink for weak acidic drugs like DPH. In addition, the large cation exchange capacity and surface area make the clay a good candidate to remove cationic pharmaceuticals from the effluent of wastewater treatment facilities.
authors.affiliation: Faculty of Earth Sciences, China University of Geosciences, Wuhan, Hubei, China. li@uwp.edu
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Li
authors.forename: Po-Hsiang
authors.initials: PH
authors.lastname: Chang
authors.forename: Wei-Teh
authors.initials: WT
authors.lastname: Jiang
authors.forename: Jiin-Shuh
authors.initials: JS
authors.lastname: Jean
authors.forename: Hanlie
authors.initials: H
authors.lastname: Hong
authors.forename: Libing
authors.initials: L
authors.lastname: Liao
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D004155:Diphenhydramine / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D001546:Bentonite; D004155:Diphenhydramine