フォトフェントン反応によるスルファメトキサゾールの分解と無機化

摘要

フォトフェントン反応を用いたSMX(スルファメトキサゾール)の分解および無機化実験を行った。初期全鉄イオン濃度が16mg·L~(-1)，初期過酸化水素濃度が500mg·L~(-1),主波長を352nmとする紫外線照射下で，初期SMX濃度176mg·L~(-1)を5minで完全に酸化分解できた。40minで初期TOC(全有機炭素）濃度83mg·L~(-1)の65%を無機化できた。初期全鉄イオン濃度が5mg·L~(-1)以下では，濃度の上昇に伴いSMXの分解速度定数は上昇したが，それ以上では上昇しなかった。反応中の有機酸濃度の経時変化を測定することにより，OHラジカルとの反応性が低い有機酸が系内に蓄積することを確認した。また，実排水中における夾雑物質とSMXのOHラジカルとの反応速度定数の比較により，実環境中の濃度が極低濃度である医薬品成分の場合，夾雑物質の影響を大きく受ける可能性が示唆された。%Degradation and mineralization of sulfamethoxazole by the photo-Fenton reaction (Fe~(2+)/H_2O_2/UV) were investigated. It was found that 176mg·L~(-1) sulfamethoxazole was completely degraded by the photo-Fenton reaction in 5 min with an initial total iron ion concentration of 15mg·L~(-1) and an initial hydrogen peroxide concentration of 500mg·L~(-1) under ultraviolet light irradiation. About 65% mineralization of the initial total organic carbon concentration of 83 mg·L~(-1) was achieved in 40 min. Under the initial total iron ion concentration of 5 mg·L~(-1), the degradation rate constant of sulfamethoxazole (SMX) increased with the initial total iron ion concentration. However, over the initial total iron ion concentration of 5 mg·L~(-1), the degradation rate constant of SMX did not increase with the initial total iron ion concentration owing to scavenger effects. From the results of the measurement of the organic acid concentration during the sulfamethoxazole degradation and mineralization by the photo-Fenton reaction, organic acids were found to accumulate in the solution. The comparison between the reaction rate constants of SMX and coexisting substances in real sewage revealed that degradation of micropollutants such as Pharmaceuticals could be significantly affected by matrix effects.