纳米零价铁硫化改性对印染废水中锑的强化去除机制研究

Analysis of enhanced Sb(V) removal by sulfide modified nanoscale zero-valent iron in textile-wastewater environment

针对目前印染废水中特征污染物锑难以达标的问题,采用纳米零价铁(nZVI)并对其进行硫化改性(S-nZVI),研究了nZVI在硫化改性前后的除锑性能变化及吸附机理.表征分析显示,硫化改性后形成的FeS_(x)会使材料形成不规则的、具有复杂形态的FeS_(x)及FeO_(x)表面,增大了材料的比表面积;其次,FeS_(x)可以提高电子的转移效率,促进氧化还原反应的发生,使得少部分Sb(V)被还原为更容易沉淀的Sb(OH)_(3)或FeSbO_(3);同时由于硫元素的存在,形成的无定型态铁氧化物更为稳定,不易向结晶态转变,而无定型态铁氧化物对Sb(V)的吸附效果要远高于结晶态铁氧化物;此外,锑也可以与硫元素结合形成稳定的锑硫化合物而从废水中去除.实验结果表明,投加量为60 mg·L^(-1)的S-nZVI能够使初始浓度为200μg·L^(-1)Sb(V)的模拟印染废水和实际印染废水中总锑浓度处理至排放标准(<50μg·L^(-1)),体现出S-nZVI在印染废水除锑中具有较好的应用潜力.

Nanoscale zero-valent iron (nZVI) with relatively high affinity toward antimony (Sb) was further modified with sulfur,which was applied to increase the removal efficiency of Sb from the textile wastewater.The performance and mechanim of nZVI and sulfidized nZVI (S-nZVI) for Sb removal were studied.Multiple characterizations indicate that sulfidation could cause a irregular and complex morphology of FeS_(x)and FeO_(x)surface,increasing the specific surface area of the materials.Meanwhile,FeS_(x)could improve the electron transfer and promote the redox reactions,resulting in a partial reduction of Sb(V) to Sb(OH)_(3),which was more easily to be precipitated.Stable amorphous iron oxides with high adsorption capacity of Sb were formed in the presence of sulfur,which would not easily transform to crystalline iron oxides with relatively lower adsorption capacity.In addition,Sb could also be removed from the wastewater via the combinationd with sulfur to form a stable Sb-S compound.A dosage of 60 mg·L^(-1)S-nZVI could make both the simulated and actual Sb wastewaters (200μg·L^(-1)) reach the Sb discharge standard (50μg·L^(-1)),indicating the application potential of S-nZVI for the removal of antimony from textile wastewater.