载银二氧化钛光催化杀菌性能的研究

以偏钛酸为前驱体,浸渍一定浓度的硝酸银溶液,用热沉积法制备出载银二氧化钛。用XRD测定载银二氧化钛的结构,扫描电镜观测形貌,研究了载银量、光强、二氧化钛浓度、细菌浓度对光催化杀菌的影响。结果表明:制备的粉体为超细锐钛矿型二氧化钛,颗粒为均匀的类球形,粒度约为100～200nm。在二氧化钛颗粒上负载约1.6%的银可以扩展光源利用范围至可见光,光催化作用与银协同杀菌;但银量过高,则主要体现银的杀菌效果。光强增加,杀菌效果提高;二氧化钛的浓度为1.5g/L时杀菌效果最好;细菌浓度低于106细胞/mL时,载银二氧化钛杀菌率可以达到90%以上。     

Effect of thermal treating temperature on characteristics of silver-doped titania

The silver-doped titania antibacterial agent was synthesized by mixing silver nitrate and the precursor of titania. Effects of thermal treatment on the properties of the silver-doped titania powders were investigated by thermal gravimeter/differential thermal analyzer（TG/DTA）, scanning electron microscope（SEM）, and X-ray diffractometer（XRD）, respectively. The results show that the anatase phase forms in titania when the powder is calcined at 400℃. With the increase of the calcination temperature from 400 to 700℃ , the grains of titania agglomerate and the particle size increases from 14 to 23 nm, and the specific surface area decreases from 63 to 38m^2g. As the powder is calcined at 700℃, titania starts to transform from anatase to futile phase. The release rate of silver ion of powder treated at the relatively low temperature is larger than that of powder treated at the relatively high temperature. The antibacterial tests show that the antibacterial activity of silver-doped titania powders is excellent against E.coli and S. aureus, and the antibacterial activity of powders weakens with the increase of the calcination temperature.     

Preparation of titanium dioxide/silver sulfate powder and its antibacterial activity

Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2 SO4. The granularity of the particles increases from 10.7 nm to 28.7 nm with the temperature of heat-treatment increasing from 300 ℃ to 800 ℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0× 10-4- 1.5 × 10-4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500 ℃. But when the temperature is beyond 600 ℃ the MiCs increase quickly, which shows the inferior antibacterial performance.     

气相色谱法测定塑料复合食品包装袋中的溶剂残留

采用气相色谱法对10种不同的塑料复合食品包装袋中可能残留的溶剂如甲苯、二甲苯(邻、间、对)、丙酮、乙醇、乙酸乙酯、丁酮、正丁醇、乙酸丁酯进行分析。方法采用HP-5色谱柱分离,氢火焰离子检测器FID检测,结果显示10种溶剂分离效果好,线性相关性高,样品加标回收率中苯系物介于78%~80%,其他溶剂介于86%~94%,最低检出限可达0.003 mg/m2。     

Preparation of doping titania antibacterial powder by ultrasonic spray pyrolysis

Doping titania powders were synthesized by ultrasonic spray pyrolysis method from an aqueous solution containing H2TiF6 and AgNO3. The effects of the processing parameters on particle size distribution, structure, and morphology of doping particles were investigated. The results show that aggregation-free spherical particles with average diameter of 200-600 nm are obtained and the particle size of the powder can be controlled by adjusting the concentration of solution. The experimental approach indicates that the size and the value of standard deviation of particle size increase from 210 nm to 450 nm and from 0.46 to 0.73 respectively with the increase of the titanic ion concentration from 0.05 to 0.4 mol/L. Composite TiOF2 is obtained when the pyrolysis temperature is set to be 400 ℃. With increasing pyrolysis temperature from 400 ℃ to 800 ℃, the crystal size of titania powders increases from 14.1 to 26.5 nm and TiOF2 content of powder decreases dramatically. The property of ion released from powder is affected significantly by the pyrolysis temperature, and the amount of fluorine ion and silver ion released from powder decrease with increasing pyrolysis temperature. The optical property of doping titania powders is not affected by pyrolysis temperature. Antibacterial test results show that composite powders containing more fluorine ions exhibit stronger antibacterial activity against E.coli.