Research On Removal Of Typical Antibiotics From Aqueous Solution By Peroxymonosulfate Oxidation Activated With Ferrous/Hydroxylamine

Sulfamethoxazole?SMX?,trimethoprim?TMP?and ofloxacin?OFL?are broad spectrum antibiotics.The harm of these three antibiotics on the natural environment and biological health can not be ignored because it is easy to accumulate in organism and hard to be degrade by microorganisms.These three antibiotics are detected at a higher frequency in surface water,therefore,it is great significance to explore an effective,economical and applicable technology to remove the three antibiotics.Advanced oxidation technology based on SO₄^·-and·OH has potential of application and development in the field of water treatment.In this study,hydroxylamine hydrochloride?NH₂OH?was introduced to the system based on the oxidation of peroxymonosulfate?PMS?activated by ferrous(Fe²⁺),which meant a coupling(Fe²⁺/NH₂OH/PMS)system was established.In this study,the sewage from the secondary sedimentation tank of Wenchang wastewater treatment plants?WWTP?was collected and used as the wastewater sample.The degradation efficiencies of the three antibiotics were investigated.Furthermore,the effects of pH,adding mode of PMS and Fe²⁺,and COD of wastewater on the degradation of the three antibiotics were also investigated in the coupling system.Furthermore,the degradation mechanism of the three antibiotics was speculated and the applicability of the system was analyzed.The results of kinetic studies showed that the coupling system with 50?M of Fe²⁺,0.4m M of NH₂OH,2mM of PMS exhibited a better oxidation removal rate for the three antibiotics?3mg/L?in the wastewater.The removal rate of SMX,TMP,and OFL were 85.60%,30.46%and 68.96%,respectively.The degradation efficiency of the three antibiotics increased graduallyand kept stable at 10 min.compared to the Fe²⁺/PMS system,the removal rate of SMX,TMP,and OFL in the Fe²⁺/NH₂OH/PMS system were increased 63%,18%and50%.The removal of the three antibiotics in the coupling system was fitted with the pseudo-second-order kinetics model.The results of influence factors indicated that the removal of three antibiotics was affected by the solution pH,the adding mode of PMS and Fe²⁺,and the COD of wastewater.With the increase of pH from 3.0 to 7.6,the degradation rates of the three antibiotics were decreased and the maximum removal was all obtained at pH=3.The removal rates of SMX,TMP,and OFL were 89.96%?38.56%and 100%respectively in the Fe²⁺/NH₂OH/PMS system.The effect of pH on the degradation of OFL wasmore serious than SMX and TMP.When the PMS and Fe²⁺were added in a continuous mode or in batch mode,the removal rateof every antibiotics was almost the same within 10 min,however,the degradation speed of every antibiotics was obviously changed by four different dosing modes.The removal speed was the fastest when PMS and Fe²⁺were added in the batch mode.The degradation efficiency of the three antibiotics was reduced with the increase of COD concentration in the wastewater.The mechanism of the degradation of antibiotics was further speculated.Hydroxylation and bond cleavage of the molecular and oxidation of the functional group were proposed as the major degradation mechanism of the three antibiotics in coupling system.Applicability analysis showed that chemical oxygen demand,ammonia nitrogen and total nitrogen were further removed during the degradation of three antibiotics in the coupling system,the removal rate was 24.68%?42.98%and 57.34%,respectively.The residues of the coupling system were environment friendly.The research would provide an important reference for the advanced treatment of SMX,TMP and OFL via the Fe²⁺/NH₂OH/PMS system.