摘要
采用均匀沉淀法,以硫酸氧钛为主原料,尿素为沉淀剂宿主制备出8~30nm的TiO_2,采用X射线衍射(XRD)、透射电子显微镜(TEM)、差热—热重(DTA-TG)等分析测试手段研究了反应温度、反应时间、反应物配比、反应物浓度,煅烧时间以及煅烧温度等因素对纳米TiO_2的粒径、形貌、晶型转变的影响,结果表明:纳米TiO_2的收率随反应温度、反应物配比、反应时间的增大而增加,随反应浓度的增大减小;TiO_2的粒径随反应温度、反应浓度、煅烧温度、煅烧时间的增大而增大;TiO_2的晶型随煅烧温度的升高,由无定型转变为锐钛矿再向金红石型转变。通过正交化实验设计得出制备纳米TiO_2的最佳工艺条件为:反应温度:90℃;[TiO~(2+)]浓度:0.8mol/l;反应时间:4h;TiOSO_4/CO(NH_2)_2:1:3。通过DTA对纳米TiO_2的晶型转变进行研究,得出了在最佳工艺条件下制备出的纳米TiO_2的晶型转化温度,在470℃左右由无定型转变为锐钛矿型,在830℃左右开始由锐钛矿型向金红石型转变,这与XRD的结果完全一致。
在不同条件下对工业级TiO_2和合成的纳米TiO_2进行表面Si包覆,采用透射电子显微镜(TEM)、X光电子能谱(XPS)、X荧光光谱(XRF)等测试手段分别对包覆颗粒的表面形貌、表面组成、成膜机理、颗粒界面的化学键合进行了研究,结果表明TiO_2表面元素的Si元素是以化学键结合于TiO_2颗粒表面的,形成Ti—O—Si键;得出包覆的最佳反应条件:1、工业级TiO_2:反应温度:85℃;反应时间:5h;C_(Na_2SiO_3):0.5mol/l;反应pH:9.5;C_(TiO_2):200g/l;2、纳米TiO_2:反应温度:90℃;反应时间:1h;C_(Na_2SiO_3):0.5mol/l;反应pH:9.5;C_(TiO_2):100g/l。
Nano-TiO2 whose crystal size is from 8nm to 30nm is prepared by using homogeneous precipitation method using TiOSO4 as precursor and CO(NH2)2 as precipitator. The factors including of reaction temperature and time, TiOSO4/CO(NH2)2, [TiO2+], calcination temperature and time which have effect on production rate, crystal size and crystalline phase of nano-TiO2 are studied by XRD, TEM and DTA-TG Experimental results show that production rates of nano-TiO2 are increased with accretion of reaction temperature, TiOSO4/CO(NH2)2, reaction time and reduced with decreasing of [TiO2+]; Crystal size is largen with reaction temperature, [TiO2+], calcinations temperature and time. Crystalline phase of nano-TiO2 is transformed from amorphism to anatase, subsequently to rutile with accretion of calcinations temperature. Optimum reaction conditions are choiced by orthogonal experiments, which are that eaction temperature was 90 C, [TiO2+] is 0.8mol/l, reaction
time was 4h, TiOSO4/CO(NH2)2 was 1:3. Crystal shape changing is studied by DTA. Results which is in consistent with XRD show that crystalline phase of nano-TiO2 which is prepared in optimum reaction condition is transformed from amorphism to anatase in 470 C, from anatase to rutile in 830 C.
It is researched on SiO2-coated for TiO2 and nano-TiO2 that has been prepared in optimum reaction conditions. Characters of SiO2-coated nano-TiO2, including of crystal size, shape, mechanism,chemical bond combining and surface composing, are studied by TEM, XPS, XRF. Optimum reaction conditions are gained. For TiO2, they are that reaction temperature was 85 C, reaction time was 5h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2 was 200g/l; For nano-TiO2, reaction temperature was 90 C, reaction time was 1h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2was 100g/l.
引文
[1] 朱屯,王福明,等.国外纳米材料技术进展与应用.北京:化学工业出版社,2001:1.
[2] 高濂,郑珊,等.纳米氧化钛光催化材料及应用.北京:化学工业出版社,2001:2.
[3] 张立德,牟季美.纳米材料和纳米结构.北京:科学出版社,2001:1.
[4] 丁延伟,范崇政.纳米二氧化钛表面包覆的研究.现代化工,2001,21(7):18~22.
[5] 杨海荣,李学富,等.超微细二氧化钛.化工时刊,1996,10(3):11~14.
[6] 周晓谦,周文淮.纳米二氧化钛的光催化特性及应用进展.辽宁化工,2002,31(10):448~451.
[7] 张昭,彭少方,等.无机精细化工工艺学.北京:化学工业出版社,2002:12
[8] 陶宁,康斌,等.纳米TiO_2制备及应用技术开发.四川冶金,2002,(2):51~55.
[9] 周幸福,褚道葆,等.纳米TiO_2的制备及应用.安徽化工,2001:(6):29~31.
[10] 方世杰,徐明霞.纳米TiO_2光催化剂的制备方法.硅酸盐通报,2002,21(2):38~42.
[11] 孟季如,赵磊,等.无机非金属纳米微粒的制备方法.化工新型材料,2000,(4):23~27.
[12] Maira A J, Yeung K L et al. Size effects in gasphase photo-oxidation of trichhoroethylene using nanometersized TiO_2 cataly. 2000, 192:185.
[13] 张启超,杨隽,等.胶溶法制备超微粒二氧化钛.重庆大学学报,1989,12(4):10.
[14] 王晓慧,王子忱.胶溶法合成TiO_2超微粒子.材料科学进展.1992:6(6):533~537.
[15] 李晓娥,祖庸.纳米二氧化钛的制备.现代化工,1999,19(11):42.
[16] 李晓娥,祖庸,等.溶胶-凝胶法合成纳米二氧化钛中催化剂的研究.河北化工,1997(2):10~12.
[17] 曹建军,王兰武,等.锐钛型纳米二氧化钛的制备与应用.攀钢技术,2002:25(2):15~19.
[18] H-K P, Young-T M, Do-K K. Formation of monodispersed spherical TiO_2 powders by thermal hydrolysis of ri(SO_4)_2. J. Am .Ceram. Soc. 1996, 79 (10):2727~2732.
[19] 张汝水,刘宏英,等.均匀沉淀法制备纳米TiO_2及其在环保方面的应用.
环境化学,1999.18(6):579~583.
[20] 雷闫盈,俞行.均匀沉淀法制备纳米二氧化钛工艺条件研究.无机盐工业,2001,33(2):3~5.
[21] 赵旭,王予忱,等.球形二氧化钛的制备.功能材料.2000:31(3):303~305.
[22] 唐波,葛介超,等.金属氧化物纳米材料的制备新进展.化工进展,2002,21(10):707~712.
[23] Li G L, Mang G H. Sybthesis of nanometer sized TiO_2 particles by mieroe mulsion method. Nano Structure Materials, 1999,11(5) : 663.
[24] 施利毅,胡莹玉,等.微乳液反应法合成二氧化钛超细粒子.功能材料,1999,30(5);495~497.
[25] 蒋卫中,范山湖,等.表面活性剂对纳米TiO_2制备及其光催化活性的影响(Ⅰ).中山大学学报,2001,40(2):58~61.
[26] 林安,程学群,等.纳米二氧化钛表面化学改性及在涂料中的应用.材料保护,2002:35(11):6~7.
[27] 邓祥义,胡海平.纳米粉体材料的团聚问题及解决措施.化工进展,2002,21(10):761~762.
[28] 丁延伟,范崇政.纳米二氧化钛表面包覆的研究.现代化工,2001,21(7):17~22.
[39] 崔爱莉,王亭杰,等.TiO_2颗粒表面包覆SiO_2纳米膜的动力学模型.高等学校化学学报,2000,21(10):1560~1562.
[30] 邵艳群,唐电.纳米级二氧化钛的表面包覆技术.中国粉体技术,1999,5(5):18~21.
[31] 鄢程,李竟先,等.纳米TiO_2颗粒的表面改性研究进展,陶瓷学报,2002,23(1):62~66.
[32] 张淑霞,李建保,等.TiO_2颗粒表面无机包覆的研究发展.化学通报.2001:(2):71~75.
[33] 覃操,王亭杰,等.液相沉积法制备TiO_2颗粒表面包覆SiO_2纳米膜.物理化学学报,2002,18(10):884~889.
[34] 孙秀果,林玉龙,等.SiO_2包覆纳米TiO_2的初步探讨.纳米材料与结构,2002,(10):23~26.
[35] 沙利,王训,等.Fe(Ⅲ)对纳米TiO_2光化学活性影响研究.现代化工,2000,20(1):37~39.
[36] 周铭.纳米二氧化钛研究进展.涂料工业,1996,(4):36~39.
[37] 王卫红,刘长生,等.纳米二氧化钛表面包覆改性及光催化性能研究.武汉化工学院学报,2003,25(1):59~72.
[38] 李晓娥,邓红,等.纳米TiO_2粉体的表面有机处理研究.西北大学学报,2002,32(5):523~525.
[39] 徐存英,段云彪,等.纳米二氧化钛的表面改性研究.云南化工,2000,27(5):6~7.
[40] 李正安.二氧化钛表面处理技术进展.现代涂料与涂装,1996,(4):30~31.
[41] 崔爱莉,王亭杰,金涌.SiO_2和Al_2O_3在TiO_2表面的成核包覆与成膜包覆.化工冶金,1999,20(2):178~181.
[42] 王乃忠,腾兰珍.水处理理论基础.成都:西南交通大学出版社,1998:102~103.
[43] Her R K. US 2 885 366, 1959
[44] Her R K. The Chemistry of Silica. New York:Wiley Pubication Inc.,1979:127.