RESEARCH ARTICLE Sorption/desorption behavior of oxytetracycline and sulfachloropyridazine in the soil water surfactant system Eman M. ElSayed & Shiv O. Prasher Received: 27 June 2013 /Accepted: 22 October 2013 /Published online: 14 November 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Sorption/desorption of antibiotics, oxytetracycline (OTC), and sulfachloropyridazine (SCP) was investigated in the presence of a nonionic surfactant Brij35. Batch sorption experiments indicated that Freundlich equation fits sorption isotherms well for OTC. The sorption coefficients, K F , values were computed as 23.55 mL g -1 in the absence of Brij35 and 25.46 mL g -1 in the presence of Brij35 in the monomer form (below critical micelle concentration CMC, of 74 mg L -1 ). However, the K F values reduced to 12.76 mL g -1 in the presence of Brij35 at 2.5 g L -1 . Therefore, irrigation with surfactant-rich water may increase the leaching potential of OTC. In the case of SCP, the K F value, in the absence of Brij35, was 19.95 mL g -1 . As a result of increasing the concentration of Brij35 to 0.25 g L -1 (about 2.5 CMC), K F values first increased and reached a maximum value of 95.49 mL g -1 and then reduced to 66.06 mL g -1 , at surfactant concentration of 5 g L -1 . Unlike OTC, the presence of surfac- tant in irrigation water is likely to decrease SCP leaching. In the case of OTC, hysteresis was found at Brij35 concentra- tions below CMC. However, OTC desorbed readily from soil (no hysteresis) at Brij35 concentrations above CMC. In the case of SCP, no hysteresis was found in the presence of the surfactant, both below and above CMC. Further, the obtained values of the efficiency coefficient (E ), reveals that Brij35 had the potential to release more OTC from the soil (E >1) as compared to SCP (E <1). From these results, it can be con- cluded that regular use of manure on agricultural soils, especially in regions where poor quality irrigation water is used, can increase OTC contamination of water resources. Keywords Oxytetracycline . Sulfachloropyridazine . Non-ionic surfactant . Sorption . Desorption Introduction Recently, the release of antimicrobial agents into the environ- ment has become of great concern. Antibiotics are widely used to control disease in both humans and animals. Since antibiotics are designed to enter the body and to be excreted without metabolism, up to 90 % of these antibiotics are released in animal feces as parent compounds (Halling- Sorensen et al. 1998). Due to their high consumption rate, considerable amounts may be released into the environment and contaminate water bodies. The risk increases in the pres- ence of antibiotic resistant genes, which developed as a result of the occurrence of residues of antibiotics in different envi- ronmental matrices. Antibiotics can enter the ecosystem via two main sources: point sources, which refer to the discharge of municipal and industrial wastewater, and non-point sources which include runoff from agricultural fields or from spread- ing sewage sludge and from leaching in agricultural soils. Spreading manure as a fertilizer is a common practice. It is one of the non-point sources that introduces antibiotics into soils and groundwater and thus, leads to water quality impair- ment (Hamscher et al. 2005). Antibiotics are large molecules that are pH dependent in terms of their ionization and they can form complexes with soil minerals. These complexes can be more persistent in the environment due to their high polarity. Oxytetracycline and sulfachloropyridazine represent two major groups of antibi- otics. They are used extensively in human medicine and in concentrated animal feed operations (CAFO) as medication Responsible editor: Zhihong Xu E. M. ElSayed (*) : S. O. Prasher Department of Bioresource Engineering, 21111 Lake Shore Road, Ste Anne de Bellevue, QC H9X3V9, Canada e-mail: emisamir55@yahoo.ca E. M. ElSayed e-mail: Eman.elsayed@mail.mcgill.ca Environ Sci Pollut Res (2014) 21:3339–3350 DOI 10.1007/s11356-013-2273-x