Sorption of sulfadiazine on Brazilian soils.

Antimicrobials, among them sulfonamides are widely used in veterinary medicine and can contaminate the environment. The degree to which antimicrobials adsorb onto soil particles varies widely, as does the mobility of these drugs. Sulfadiazine (SDZ) was used to study the adsorption-desorption in Brazilian soil-water systems, using batch equilibrium experiments. Sorption of SDZ was carried out using four types of soils. Adsorption and desorption data were well fitted with Freundlich isotherms in log form (r>0.999) and (0.984<r<0.999), respectively. An adsorption-desorption hysteresis phenomenon was apparent in all soils ranging from 0.517 to 0.827. The experimental results indicate that the Freundlich sorption coefficient (K(F)) values for SDZ ranged from 0.45 to 2.6 μg(1-1/n)(cm(3))(1/n)g(-1).