多孔型TiO2微粒的制备及其对离子型染料的吸附

Preparation of porous TiO_(2) particles and their adsorption for ionic dyes

针对印染废水中离子型染料的处理问题,提出以多孔型二氧化钛(TiO_(2))微粒为吸附剂对染料进行吸附处理。以钛酸丁酯为钛源,通过改变模板剂的种类,采用水热法制备带有不同电位的多孔型TiO_(2)微粒。借助固体表面Zeta电位测试仪、场发射扫描电子显微镜、透射电子显微镜以及X射线衍射仪对TiO_(2)的电位、形貌和晶型进行分析,通过吸附实验优化染料质量浓度和吸附剂用量,并探究TiO_(2)微粒的重复利用性能。结果表明:带正电的TiO_(2)微粒(G-TiO_(2))和带负电的TiO_(2)微粒(Y-TiO_(2))分别只对阴离子型和阳离子型染料进行吸附,遵从静电吸附机制;2种TiO_(2)微粒经过煅烧后的晶型均为锐钛矿型;在同等实验条件下,100 mg的G-TiO_(2)对100 mg/L刚果红染料的吸附率高达99.5%,100 mg的Y-TiO_(2)对20 mg/L亚甲基蓝染料的吸附率可达93.5%;在循环实验中,G-TiO_(2)对刚果红染料循环吸附4次后吸附率降低约12.6%,而Y-TiO_(2)对亚甲基蓝染料循环吸附5次后吸附率降低约17%。

Objective The utilization rate of dyes is unable to reach 100% in practical situations,which inevitably leads to residual dyes in the water discharged after dyeing,causing serious water pollution.Therefore,it is necessary to develop a water treatment technology that can effectively treat dye wastewater.Aiming at the treatment of ionic dyes in printing and dyeing wastewater,porous titana(TiO_(2))particles were used as adsorbent to adsorb dyes.Method In addition to the characteristics of stable chemical properties,low price,easy availability,and no toxicity,TiO_(2) particles also have the unique characteristic of photocatalysis.Therefore,TiO_(2) particles are often adopted to adsorb and catalyze dyes in wastewater.Through photocatalysis,the dye can be degraded,so that the TiO_(2) particles can be reused.With tetrabutyl orthotitanate as titanium source,porous TiO_(2) particles with different potentials were prepared by hydrothermal method using different templates,and then the crystal form of TiO_(2) particles was controlled by high-temperature calcination.The potential,morphology and crystal form of TiO_(2) were analyzed by solid surface Zeta potential test,field emission scanning electron microscopy(FETEM),transmission electron microscopy(TEM)and X-ray diffraction(XRD).The dye concentration and adsorbent dosage were optimized by adsorption test,and the reuse performance of TiO_(2) particles was explored.Results Positively charged TiO_(2) particles(G-TiO_(2))adsorb anionic dyes only other than cationic dyes at all,while the negatively charged TiO_(2) particles(Y-TiO_(2))only adsorb cationic dyes other than anionic dyes(Fig.3 and Fig.4).The adsorption mechanism follows the electrostatic adsorption mechanism.G-TiO_(2) has a porous spherical structure formed by the aggregation of numerous particles,about 93%of which are microspheres with a particle size of 200-500 nm.Y-TiO_(2) is in the state of fine particle aggregation,and about 91%of which are microspheres with a particle size of 50-100 nm(Fig.6 and Fig.7).The crystal forms of the two kinds of TiO_(2) particles after calcination are anatase,which have photocatalytic properties(Fig.9).Under the same experimental conditions,the adsorption rate of 100 mg/L Congo Red dye by 100 mg G-TiO_(2) can reach 99.5%,and that of 20 mg/L Methylene Blue dye by 100 mg Y-TiO_(2) can reach 93.5%(Fig.11).In the cycle experiment,the adsorption rate of Congo Red dye by G-TiO_(2) decreased by about 12.6%after four cycles,while that of Methylene Blue dye by Y-TiO_(2) decreased by about 17%after five cycles(Fig.13).Conclusion Two kinds of porous TiO_(2) particles adsorbents were prepared by changing the type of template in the hydrothermal reaction.The adsorbents not only retain the capillary adsorption of conventional porous TiO_(2) particles on dyes,but also increase the electrostatic adsorption,which can realize the rapid adsorption of ionic dyes in printing and dyeing wastewater.The adsorbents can be chemically modified subsequently to have improved photocatalytic performance,and can also be loaded on polymer films or nonwovens for specific applications.This study will provide strategic support for the treatment of ionic dye wastewater.