Study On The Preparation Of Limonite/nano-TiO₂ Photocatalyst And Treatment Of Papermaking Wastewater

Because of its stable chemical properties,high photocatalytic efficiency,low cost and nontoxicity,titanium dioxide has been the hot spot of research at home and abroad. But the traditional titanium dioxide powder has a lot of disadvantages,such as the low catalytic activity,the difficulty of separation and recovery,and what's more,it may lead to a secondary pollution.Therefore,the modification and immobilization of titanium dioxide have become a new research hot spot.In this research,Limonite was used as the carrier and Ti(OC₄H₉)₄ as the Ti source. The Limonite/TiO₂ photocatalyst had a nuclear/membrane structure was prepared by sol-gel method,and then searched the optimized preparation conditions and degradation conditions used low Concentration Wastewater of paper-making.The X-ray Diffraction(XRD) and Scanning Electron Microscopy(SEM) were used to test and analyze the experimental results,which indicated that the most optimized preparation conditions of limonite/TiO₂:reaction time 3h,reaction temperature 60℃and calcined at 500℃for 2h;the most optimized degradation conditions:the dosing quantity of photocatalyst 5g/L,the pH of Wastewater of paper-making 4.0,the decoloration rate of the wastewater treated can reach to 85%with the illumination time of 2h and the removal rate of COD attained 70%;it had been loaded with a homogeneous anatase TiO₂ film on its surface,and it had a firm nuclear/membrane structure after analyzed the results of recycled experiments,Measurement and Characterization of Limonite/TiO₂.The doping and modification of Limonite/TiO₂ for Fe³⁺ on the foundation of supported showed that Limonit/Fe³⁺TiO₂ had a better photocatalysis properties than Limonit/TiO₂.On the basis of these experiments,the decoloration rate of the wastewater treated can reach to 95%with the illumination time of 2h and the removal rate of COD_cr attained 80%,which was superior to Limonite/TiO₂.And it also had been loaded with a homogeneous TiO₂ film on its surface;Limonit/Fe³⁺TiO₂ after microwave heating could improve its adsorption capacity showed by experiment.The experiments of flocculation-photocatalystic degradation combined treatment of papermaking wastewater using the flocculant and the self-made Limonit/Fe³⁺TiO₂ photocatalyst which had the best photocatalystic effect showed that:the removal rate of COD_cr attained 94%after combined treatment and the residual COD_cr was about 183mg/L as compared with 3000mg/L of the influent, which accords with the national discharge standard.The repeated experiments showed that,under certain conditions,the cycle of repeated use is higher reactive.Flocculation- Photocatalysis combined treatment of papermaking wastewater could reach better effect,and these operations are very simple.Self-made photo-catalyst had better reuse characteristics.The low grade Limonite of rich reserves,low price and no secondary pollution,thus to cut down the operational cost, which also provided a new treatment way for papermaking wastewater.