title: Thermodynamic studies for adsorption of ionizable pharmaceuticals onto soil.
abstract: Although pharmaceutical compounds (PCs) are being used more and more widely, and studies have been carried out to assess their presence in the environment, knowledge of their fate and behavior, especially under different environmental conditions, is still limited. The principle objective of the present work, therefore, is to evaluate the adsorption behavior of three ionizable, polar compounds occurring in different forms: cationic (propranolol - PRO), anionic (sulfisoxazole - SSX) and neutral (sulfaguanidine - SGD) onto soil under various temperature conditions. The adsorption thermodynamics of these researched compounds were extensively investigated using parameters such as enthalpy change (ΔH°), Gibbs free energy change (ΔG°) as well as entropy change (ΔS°). These calculations reveal that sorption of PRO is exothermic, spontaneous and enthalpy driven, sorption of SGD is endothermic, spontaneous and entropy driven whereas sorption of SSX is endothermic, spontaneous only above the temperature of 303.15K and entropy driven. Furthermore, we submit that the calculated values yield valuable information regarding the sorption mechanism of PRO, SGD and SSX onto soils.
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland. Electronic address: joanna.maszkowska@ug.edu.pl.
authors.forename: Joanna
authors.initials: J
authors.lastname: Maszkowska
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Wagil
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Mioduszewska
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Kumirska
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Stepnowski
authors.affiliation: Department of Environmental Analysis, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Białk-Bielińska
mesh_terms: D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000032:analysis / Q000302:isolation & purification; D011433:Propranolol / Q000032:analysis* / Q000302:isolation & purification; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000302:isolation & purification; D013414:Sulfaguanidine / Q000032:analysis* / Q000302:isolation & purification; D013444:Sulfisoxazole / Q000032:analysis* / Q000302:isolation & purification; D013696:Temperature; D013816:Thermodynamics
chemical_list: D007477:Ions; D012987:Soil; D012989:Soil Pollutants; D013414:Sulfaguanidine; D013444:Sulfisoxazole; D011433:Propranolol
keywords: Beta-blockers; Ionizable compounds; Sorption; Sulfonamides; Thermodynamic