Superior selectivity of high-frequency ultrasound toward chorine containing-pharmaceuticals elimination in urine: A comparative study with other oxidation processes through the elucidation of the degradation pathways

A critical review on the sonochemical degradation of organic pollutants in urine, seawater, and mineral water

“…Moreover, the Rk value for the ultrasonic process was higher than the obtained for the treatment of losartan using UVC/H 2 O 2 (Rk = 0.46), evidencing the sonochemical process was more selective for the degradation of this pharmaceutical in the urine matrix. Similar results to the obtained for losartan have been reported for the treatment of cloxacillin and diclofenac in synthetic fresh urine, presenting Rk values close to 0.8 [86] .…”

“…However, the sonodegradation in the real urine was slower than in distilled water or synthetic urine (i.e., the cloxacillin elimination in the actual sample had an EI < 1). Although the sono-treatment leads to partial removal of cloxacillin, this contrasts with the results for the UVC/H 2 O 2 process, which was completely inhibited (due to the high UVC absorbance of the urine sample that blocks this process), indicating that the sonochemical process is more selective than the UVC/H 2 O 2 system for the pollutant treatment in the real urine [86] .…”

“…The Rk values were explained by the authors considering that the components of the simulated fresh urine are very hydrophilic (thus, they are mainly placed in the bulk of the solution) and the pharmaceuticals losartan, diclofenac, or cloxacillin (which have a hydrophobic nature) are mainly placed in the interfacial zone that has a high concentration of sonogenerated HO* to degrade the pharmaceuticals. Consequently, sonodegradation of the pharmaceuticals was affected moderately by the urine matrix components [19] , [86] .…”

“…The sonodegradation of cloxacillin in the actual urine is slower than in distilled water due to the high content of organic substances in urine, denoted by its total organic carbon (7300 mg L −1 ), which compete with the target pharmaceutical by the sonogenerated radicals. Moreover, real urine has some surfactant substances (e.g., methionine and tyrosine), or amphiphilic metabolites (e.g., primary or secondary bile salts) that can be placed close to or inside the cavitation bubble interfering with the degradation of cloxacillin [86] .…”

“…A comparison among the compositions of mineral/bicarbonate rich-water, seawater, and fresh urine shows that the urine matrix, in addition to the inorganic salts/ions (e.g., chloride, sulfate, and/or bicarbonate), has high amounts of organic substances (e.g., urea and creatinine; which compete by the degrading radicals), whereas mineral water and seawater have a very low content of organic matter [16] , [17] , [18] , [19] , [26] , [52] , [62] , [70] , [86] . For this reason, the sono-treatment of target pollutants in the fresh urine matrix gives lower degradation efficiencies than in bicarbonate rich-water or seawater (see Table 1 , Table 2 , Table 3 ).…”