Mn/γ-Al_2O_3纳米颗粒催化双氧水降解水溶性PVA废弃面料

Degradation of Water Soluble PVA Waste Fabrics by Hydrogen Peroxide Catalyzed by Mn/γ-Al_2O_3 Nanoparticles

采用浸渍-煅烧法制备得到Mn/γ-Al_2O_3纳米颗粒,并通过BET、SEM-EDS等方法对其进行表征,此外还考察了煅烧温度、双氧水投加量、催化剂投加量,以及PVA面料初始浓度和初始pH等因素对Mn/γ-Al_2O_3催化双氧水氧化降解PVA废弃面料的效果。实验表明:适当提高煅烧温度和双氧水投加量均可促进PVA废弃面料在水相条件下的降解,而提高PVA面料初始浓度不利于提高PVA的降解彻底度。本实验条件下,当PVA面料初始浓度在5%以下,初始pH=3,双氧水投加量为120 mL/L,催化剂投加量为1g/L,反应温度为80℃,溶液中PVA的浓度下降率在90%以上,且经GPC分析,降解产物粘均分子量在1千左右,分子量下降率为99%。通过过滤-煅烧的方法还可以将Mn/γ-Al_2O_3纳米颗粒进行回收再利用,在4个使用循环中,Mn/γ-Al_2O_3均表现出良好的催化效率。

Mn/γ-Al_2O_3 nanoparticles were obtained by a wet impregnation-calcination method and characterized by using BET and SEM-EDS methods. Besides, the effects of the calcination temperature, H_2O_2 dosage, the catalyst dosage, the initial concentration of PVA fabrics and the initial pH value on the degradation of PVA waste fabrics by hydrogen peroxide catalyzed by Mn/γ-Al_2O_3 were investigated. The results show that the proper increase of calcination temperature and H_2O_2 dosage will promote the degradation of PVA in aqueous phase, while the increase of the initial concentration of PVA fabrics is not conductive to the thorough degradation of PVA.Under the experimental conditions, when the initial concentration of PVA fabrics is below 5%, the initial ph value is 3, the H_2O_2 dosage is 120 ml/L, the catalyst dosage is 1 g/L and the reaction temperature is 80℃, the concentration of PVA will decrease at a rate of over 90%. And the GPC analysis shows that the viscosity average molecular amount of the degradation product is about 1000, and the decrease rate of molecular amount is 99%.The Mn/γ-Al_2O_3 nanoparticles can be recycled with the method of filtration-calcination and the Mn/γ-Al_2O_3 shows good catalyst effect in four cycles.