闪速氢化制备纳米TiO2-x及其对砷离子吸附特性的研究

Arsenic pollution has seriously threatened the eco-safety. Developing nanomaterials with high efficient arsenic adsorption has been a cutting-edge task and nano titanium dioxde of them has been the one of most potential materials. However, how to improve its catalysis oxidation and adsorption abilities for As (III) is one of key scientific points for the new TiO2-base absorbents. Preparation of nano TiO2-x by flash hydrogenation of nano TiO2/H2TiO3, to increase disorder degree on surface, visible light adsorption ability and improve its catalysis oxidation ability and adsorption capacity of TiO2-based adsorbent for its application on arsenic adsorption in water, are proposed in this project. The main research work includes the influences on physical and chemical properties of nano TiO2-x sample of different factors in flash hydrogenation process, oxygen removal kinetics of different precursors, Asn+ oxidation and adsorption performance, Asn+ adsorption kinetics, desorption and recycling performance of nano TiO2-x. The two scientific problems would be solved, one is the controlling mechanism to synthesis different nonstoichiometric TiO2-x and another is the establishment of arsenic adsorption kinetic model of TiO2-x. With completing the above research, some kinetic models, concerned about hydrogenation and oxygen removal, of different precursors would be set up and Asn+ oxidation and adsorption properties of nano TiO2-x would be discovered. Consequently, the flash hydrogenation process of nano TiO2/H2TiO3 to prepare nano TiO2-x will be developed which will be significantly helpful to the exploration of new arsenic adsorbents.

砷污染已严重威胁生态安全，开发高效的砷吸附材料是国际研究的前沿课题，纳米二氧化钛已成为最具潜力的砷吸附新型材料之一。但如何增强TiO2对水体中As(III)的氧化能力，成为亟待解决的科学问题。项目提出闪速氢化还原处理纳米TiO2/H2TiO3制备纳米TiO2-x，使其表面结构无序度增加、可见光吸收能力增强，提高其催化氧化和吸附能力，从而应用于Asn+的氧化和吸附。重点研究多种因素对TiO2-x样品理化性质的影响，前驱体的失氧动力学，TiO2-x对Asn+氧化、吸附性能和动力学以及纳米TiO2-x对Asn+的脱附和循环吸附性能。解决闪速制备TiO2-x相的调控机制和TiO2-x对Asn+的吸附动力学模型两大科学问题；建立相应前驱体脱氧过程的动力学模型，揭示TiO2-x对Asn+的氧化、吸附特性，形成闪速氢化钛（氢）氧化物制备纳米TiO2-x的新方法，为新型砷吸附剂的开发提供重要参考。

随着含砷矿产资源的开发与利用，水体砷污染已对生态安全构成重大威胁。开发高效砷吸附材料是国际研究的前沿课题，纳米二氧化钛已成为最具潜力的砷吸附材料之一。如何增强TiO2对水体中As(III)的氧化吸附能力是提升钛氧化物砷吸附材料性能的科学关键。项目提出闪速氢化制备纳米TiO2-x材料的新思路，自行研制了闪速氢化还原装置。重点研究了不同前驱体及其物相、气氛、温度、停留时间等参数对还原产物颜色、粒径、物相、形貌以及光吸收特性等的影响规律；考察了典型样品的砷离子吸附性能，重点研究了可见光、水样pH值、纳米TiO2-x添加量、初始Asn+浓度、温度等不同条件下对Asn+的氧化、吸附行为的影响规律。结果表明：以偏钛酸作为前驱体，当氢化处理温度在600~1200 ℃时，物相为TiO2，当处理温度达1500 ℃时，物相转变变为Magnéli phase相亚氧化钛（TinO2n-1）；以P25作为前驱体，经闪速氢化处理后可形成核壳结构的Magnéli phase相亚氧化钛材料；以比表面积为260 m2/g的纳米TiO2为前驱体，闪速氢化处理后获得了比表面积为220.27 m2/g的纳米TiO2-x粒子。纳米TiO2-x粒子上发现的氧空位浓度最高为41.4%，最低为26.8%。TiO2-x纳米粒子具有快速氧化和吸附As3+离子的能力，以偏钛酸为前驱体制备的TiO2-x纳米粒子在180 min内就能达到平衡，其吸附容量为13.2 mg/g，对As(III)和As(Ⅴ)离子的吸附都符合拟二阶动力学模型；以大比表面积TiO2为前驱体闪速制备的TiO2-x纳米粒子，10min内砷吸附即可达到平衡，比现有报道快150倍，As(III)吸附容量可达31.6 mg/g，对As(III)-无光系统的吸附符合Freundlich模型；对As(III)-有光系统和As(Ⅴ)的吸附符合Langmuir模型。项目研究形成了闪速氢化处理钛氢（氧）化物制备纳米TiO2-x的新方法；揭示了TiO2-x纳米颗粒对Asn+的氧化、吸附特性，建立了TiO2-x光催化氧化吸附Asn+的动力学模型，为新型高效的砷吸附剂提供重要的参考。项目执行过程中发表论文8篇，申请和授权4件，支撑培养了国家级、省级高端人才4人次，晋升职称2人，参加国内外学术交流14人次。