Thermodynamic studies for adsorption of ionizable pharmaceuticals onto soil

• Published in: Chemosphere (Oxford) 2014-09, Vol.111, p.568-574
• Main Authors: Maszkowska, Joanna, Wagil, Marta, Mioduszewska, Katarzyna, Kumirska, Jolanta, Stepnowski, Piotr, Białk-Bielińska, Anna
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Beta-blockers; Biological and physicochemical properties of pollutants. Interaction in the soil; Endothermic reactions; Entropy; Exact sciences and technology; Hydrogen-Ion Concentration; Ionizable compounds; Ions - analysis; Ions - isolation & purification; Mathematical analysis; Pollution; Propranolol - analysis; Propranolol - isolation & purification; Soil (material); Soil - chemistry; Soil and sediments pollution; Soil Pollutants - analysis; Soil Pollutants - isolation & purification; Sorption; Spontaneous; Sulfaguanidine - analysis; Sulfaguanidine - isolation & purification; Sulfisoxazole - analysis; Sulfisoxazole - isolation & purification; Sulfonamides; Temperature; Thermodynamic; Thermodynamics
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2014.05.005

•Adsorption thermodynamics of three ionizable, polar compounds were analyzed.•Clear differences were observed in sorption thermodynamics depending on ionic form.•Sorption mechanisms of PRO, SGD and SSX were demonstrated. 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.