MoS_(2)强化Fe^(2+)活化单过硫酸盐去除磺胺甲恶唑和还原六价铬的研究

Improved removal of sulfamethoxazole and Cr(Ⅵ) by the addition of MoS_(2) into the Fe^(2+)/PMS process

采用二硫化钼(MoS_(2))作为助催化剂加入到亚铁离子(Fe^(2+))/单过硫酸盐(PMS)体系,去除溶液中的磺胺甲恶唑(SMX)和还原六价铬(Cr(Ⅵ)),分别对SMX及SMX与Cr(Ⅵ)共存情况下的去除效果进行研究,并考察了MoS_(2)、Fe^(2+)、PMS、SMX投加量对SMX和Cr(Ⅵ)去除效果的影响.结果表明,在[MoS_(2)]_(0)=0.9 g·L^(-1),[Fe^(^(2+))]_(0)=0.3 mmol·L^(-1),[PMS]_(0)=1 mmol·L^(-1),[Cr(Ⅵ)]_(0)=100μmol·L^(-1),[SMX]_(0)=25μmol·L^(-1),初始pH为3.0的条件下反应30 min时,SMX的去除率和Cr(Ⅵ)的还原率分别达到98.8%和99.2%;实验中MoS_(2)和Fe^(2+)浓度与Cr(Ⅵ)还原率呈正相关,而PMS浓度过高则会抑制Cr(Ⅵ)的还原;MoS_(2)/Fe^(2+)/PMS体系下Cr(Ⅵ)的还原机理不仅与MoS_(2)还原生成的亚铁离子有关,Cr(Ⅵ)也能够被MoS_(2)或PMS直接还原.EPR实验表明,MoS_(2)/Fe^(2+)/PMS体系中主要的自由基是SO4·-和HO·.

The simultaneous removal of sulfamethoxazole(SMX) and reduction of Cr(Ⅵ) in Molybdenum sulfide/ferrous ion/peroxymonosulfate(MoS_(2)/Fe^(2+)/PMS) process was studied. In the meantime, some influencing factors, such as the dosages of MoS_(2), Fe^(2+), PMS and SMX, were also investigated. The results show that the removal of SMX and the reduction of Cr(Ⅵ) were 98.8% and 99.2%, respectively, at the optimal pH(3.0) under the conditions of reaction time of 30 minutes, MoS_(2) dosage of 0.9 g·L^(-1), Fe^(2+) dosage of 0.3 mmol·L^(-1), PMS dosage of 1 mmol·L^(-1), and initial SMX and Cr(Ⅵ) concentrations of 25 μmol·L^(-1) and 100 μmol·L^(-1). The reduction of Cr(Ⅵ) increased with the elevation of MoS_(2) or Fe^(2+) concentration, while excessive PMS inhibited the removal of Cr(Ⅵ). Fe^(2+) benefit the reduction of Cr(Ⅵ), while the Cr(Ⅵ) could be inhibited by the increased initial SMX concentration and PMS dosage. The analysis of electron paramagnetic resonance(EPR) has proven that both sulfate and hydroxyl radicals are the dominant reactive species in the MoS_(2)/Fe^(2+)/PMS process.