溶胶-凝胶法合成TiO2/活性炭光催化剂及联用超声技术还原铬(Ⅵ)和铜(Ⅱ)废水

Sol-gel preparation of TiO2/AC photocatalysts and ultrasound reduction of chromium(Ⅵ) and copper(Ⅱ) wastewater

  • 摘要: 以钛酸四丁酯为钛源, 活性炭(AC)为载体, 采用溶胶-凝胶法合成TiO2/AC复合体, 利用TGA-DSC、 SEM、 XRD、 DRS(漫反射光谱)及FTIR对复合体表面结构、 光谱特征、 晶体结构进行表征分析, 并通过AAS(原子吸收分光光度计)测定铬(Ⅵ)、 铜(Ⅱ)离子浓度以探讨超声-TiO2光催化还原去除率。研究表明: 溶胶-凝胶法制备的TiO2/AC在290℃处由板钛矿型向锐钛矿型转变, 500℃下焙烧催化活性最高; TiO2/AC复合体分散性能好、 团聚尺寸低、 比表面积大, 其接触界面处有C—O—Ti键生成; 经光催化动力学研究发现, 光催化吸附还原机制符合一级动力学方程ln(c0/c)=kt及Langmuir-Hinshelwood吸附理论。对比无超声光催化, 超声-光催化技术对铬(Ⅵ)、 铜(Ⅱ)的还原去除率分别提高了39.32%和52.95%; 催化剂循环使用3次后, 超声-光催化还原铬(Ⅵ)、 铜(Ⅱ)的去除率仍能达到70.61%和75.30%。

     

    Abstract: TiO2/AC composites were prepared via the sol-gel method from a carrier of activated carbon (AC) and Ti(OBu)4. Photocatalysts were characterized by TGA-DSC, SEM, XRD, diffuse reflectance spectroscopy (DRS) and FTIR. The ultrasound-TiO2 photocatalytic reduction removal rate by determination concentration of chrome(Ⅵ) and copper (Ⅱ) was also studied by atomic absorption spectrophotometer (AAS). The results show that TiO2/AC prepared by sol-gel method transforms from rutile into anatase at the temperature of 290℃ and shows the highest catalytic activity at 500℃. TiO2/AC composites which formed C—O—Ti between the AC bulk and TiO2 has good dispersion, low agglomeration and high surface area. The mechanism of photocatalytic reduction and adsorption follows the first order kinetics equation ln(c0/c)=kt and Langmuir-Hinshelwood adsorption. Compared with the no-ultrasound, the reductive removal rate of Cr(Ⅵ) and Cu(Ⅱ) can be improved by 39.32% and 52.95% using ultrasound-photocatalytic technology. Cr(Ⅵ) and Cu(Ⅱ) removal rate is 70.61% and 75.30% even when the catalysts are recycled three times.

     

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