title: Impact of humic acid fouling on membrane performance and transport of pharmaceutically active compounds in forward osmosis.
abstract: The impact of humic acid fouling on the membrane transport of two pharmaceutically active compounds (PhACs) - namely carbamazepine and sulfamethoxazole - in forward osmosis (FO) was investigated. Deposition of humic acid onto the membrane surface was promoted by the complexation with calcium ions in the feed solution and the increase in ionic strength at the membrane surface due to the reverse transport of NaCl draw solute. The increase in the humic acid deposition on the membrane surface led to a substantial decrease in the membrane salt (NaCl) permeability coefficient but did not result in a significant decrease in the membrane pure water permeability coefficient. As the deposition of humic acid increased, the permeation of carbamazepine and sulfamethoxazole decreased, which correlated well with the decrease in the membrane salt (NaCl) permeability coefficient. It is hypothesized that the hydrated humic acid fouling layer hindered solute diffusion through the membrane pore and enhanced solute rejection by steric hindrance, but not the permeation of water molecules. The membrane water and salt (NaCl) permeability coefficients were fully restored by physical cleaning of the membrane, suggesting that humic acid did not penetrate into the membrane pores.
authors.affiliation: Strategic Water Infrastructure Laboratory, School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Ming
authors.initials: M
authors.lastname: Xie
authors.forename: Long D
authors.initials: LD
authors.lastname: Nghiem
authors.forename: William E
authors.initials: WE
authors.lastname: Price
authors.forename: Menachem
authors.initials: M
authors.lastname: Elimelech
mesh_terms: D057219:Biofouling; D002220:Carbamazepine / Q000737:chemistry; D006812:Humic Substances / Q000032:analysis*; D006859:Hydrogen / Q000032:analysis; D007477:Ions; D008567:Membranes, Artificial; D009038:Motion; D009995:Osmosis; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000737:chemistry; D012964:Sodium / Q000032:analysis; D012965:Sodium Chloride / Q000032:analysis; D055672:Static Electricity; D013420:Sulfamethoxazole / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D006812:Humic Substances; D007477:Ions; D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations; D014867:Water; D002220:Carbamazepine; D012965:Sodium Chloride; D006859:Hydrogen; D012964:Sodium; D013420:Sulfamethoxazole
keywords: Calcium; Forward osmosis; Fouling; Humic acid; Natural organic matter; Pharmaceutically active compounds (PhACs)