Sulfaclozine [HRP]

Bicarbonate, phosphate, chloride ions, and humic substances are among the constituents most widely present in natural waters. These non-target constituents can greatly affect the efficiency of advanced oxidation processes used for water decontamination due to their capacity to interfere with the adsorption of the target compounds on the surface of TiO2, absorb photons, scavenge hydroxyl radicals (center dot OH), and generate photochemical reactive intermediates. In this work, the effect of these constituents on the degradation of sulfaclozine (SCL) was monitored in three different AOPs systems: UV/TiO2, UV/K2S2O8, and UV/TiO2/K2S2O8. It was shown that bicarbonate (HCO3-) and phosphate (HPO42-) ions enhanced the degradation of SCL in UV/TiO2 and UV/TiO2/K2S2O8 systems whereas the addition of humic substances influenced these rates with a much smaller extent. On the other hand, the degradation rate of SCL in the UV/K2S2O8 system was not affected by the presence of HCO3- and HPO42- but was inhibited in the presence of humic substances. In addition, the different mechanisms that can take place in the presence of these constituents were discussed and the degradation rate enhancement in presence of HCO3- and HPO42- was attributed to the formation of new reactive species such as carbonate (CO3 center dot-) and hydroxyl (center dot OH) radicals activated by TiO2 holes (h(+)). In the presence of chloride (Cl-) and nitrate (NO3-) ions, an enhancement of SCL adsorption on the surface of TiO2 was observed. Finally, a comparative study of the degradation of SCL in river water and ultrapure water was reported.

Aim of this study was to evaluate the suitability of Daphnia curvirostris for the acute toxicity test usually performed on Daphnia magna, and to compare the sensitivity of the two species toward 10 antibacterials [enrofloxacin (EFX), ciprofloxacin(CPX), sulfaguanidine (SGD), sulfadiazine (SDZ), sulfamethazine (SMZ), sulfaquinoxaline (SQO), sulfaclozine (SCZ), sulfamerazine (SMA), sulfadimethoxine (SDM) and trimethoprim (TMP)] and some of their binary mixtures. Furthermore, a tentative prolonged-toxicity test (lasting 13 d) was settled up in order to evidence toxic responses with drug concentrations that were uneffective in the classic 48 h immobilization test. Results showed that D. curvirostris was more sensitive than D. magna to the majority of compounds (6 out of 10). Lowest 48 h EC50s, were obtained with EFX (4.3 mg L-1 in D. curvirostris) and SGD (6.2 mg L-1 in D. magna). The toxicity of paired compounds was always concentration-additive or less than concentration-additive. In the prolonged-toxicity test mortality and/or reproduction inhibition were constantly observed. It was concluded that: (1) D. curvirostris could be a suitable model for the evaluation of acute toxicity of antibacterials since its sensitivity was generally greater than that of D. magna; (2) the toxicity of EFX and SGD should be given special attention as the two compounds, in the prolonged test, showed to be active at concentrations of 0.9 mg L-1 and 2.5 mg L--1,L- respectively; (3) the concentration addition is usually a reasonable worst case estimation of the environmental impact of antibacterial mixtures. (C) 2014 Elsevier Ltd. All rights reserved.