无机阴离子对TiO_2-膨润土紫外光降解SDBS的影响

TiO2-膨润土光催化降解水溶液中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的效率较高,Cl-、SO42-、NO3-、HCO3-、H2PO4-是水体中常见的阴离子,这些阴离子对降解效果的影响直接影响该技术的实际应用。分别投加36 mmol/L上述阴离子的钠盐到SDBS水溶液中,紫外光照射溶液2 h,比较投加与不投加的SDBS去除效果差异,结果表明:(1)水溶液中上述阴离子对TiO2-膨润土降解SDBS的效果都有不利影响,其中HCO3-影响最大,其次是H2PO4-,再次是NO3-,SO42-和Cl-。紫外光照射2 h后,投加HCO3-、H2PO4-、NO3-、SO42-、Cl-的水溶液中SDBS的浓度分别比不投加的高2.63倍、1.63倍、0.73倍、0.52倍和0.46倍。原因有三方面:这几种无机阴离子与有机分子竞争表面活性位置;在接近催化剂颗粒表面的地方产生高极性环境;溶液pH值的改变。(2)投加这些无机阴离子的溶液COD值比不投加的都高,反应2 h投加Cl-、SO42-、NO3-、HCO3-、H2PO4-分别比不投加的溶液COD值高6.62倍,0.26倍,0.03倍,0.29倍,0.45倍。

Effect of Inorganic Anion on Degradation of Sodium Dodecyl Benzene Sulfonate by TiO2-bentonite

Photodegradation of sodium dodecyl benzene sulfonate(SDBS) by TiO2-bentonite is efficient,and the inorganic anions such as Cl-,SO42-,NO3-,HCO3-,H2PO4-which usually exist in water have an effect on photodegradation efficiency of SDBS by TiO2-bentonite.36 mmol/L sodium salt of these inorganic anions was input into SDBS aqueous solution respectively,and the solutions were irradiated for 2 h with ultraviolet lamp.The difference of photodegradation results with or without the input of inorganic anions in the solution was compared.Results showed that effect of inorganic anion such as Cl-,SO42-,NO3-,HCO3-,H2PO4-on degradation of SDBS by TiO2-bentonite existed.Among which the effect of HCO3-on degradation was the most obvious,followed by H2PO4-,NO3-,SO42-,Cl-.The concentration of SDBS solutions with input of HCO3-,H2PO4-,NO3-,SO42-,Cl-increased by 2.63,1.63,0.73,0.52 and 0.46 times respectively within 2 h than that without input of the inorganic anions,which mainly depends on the competitions of surface active position between inorganic anions and organic molecules,appearance of high polarity environment near surface of catalyst particle and change of pH of solutions.Effect of inorganic anion on COD of aqueous solutions was different,within 2 h COD of aqueous solutions which had been input Cl-,SO42-,NO3-,HCO3-,H2PO4-,increased 6.62,0.26,0.03,0.29 and 0.45 times respectively than that hadn’t been put into.