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891.
TiO_2纳米膜上吸附态甲基橙的光催化降解反应活性研究 总被引:10,自引:2,他引:10
以反胶束溶液不同陈化是间及涂膜次数制备了三种TiO_2纳米膜,用XRD,SEM 和AFM方法考察了这些膜的形态结构特征,以吸附态甲基橙为模型反应物,研究 TiO_2纳米膜的光催化降解活性,并以AM1分子模拟计算探讨了甲基橙分子在不同膜 上可能的吸附态,及其与光催化降解的关联。结果表明,膜A最薄,膜上纳米粒子 分布均匀,表面平滑,甲基橙分子可能主要以端基方式吸附,这种吸附对分子骨架 化学键的影响较小,且不利于表面羟基对底物分子的进攻,结果反应活性低。膜B 最厚,对光的透过率最低,膜上纳米粒子分布很不均匀,表面缺陷结构丰富,对甲 基橙的吸附强,甲基橙分子主要以平卧式吸附,从而削弱了分子中的N=N双键,有 利于表面痉基对底物分子的进攻,光催化反应活性最高。膜C的厚度和粒子分布的 均匀性介于膜A和膜B之间,甲基橙分子可以两种方式吸附光催化反应的活性介于膜 A和膜B之间。 相似文献
892.
杂多酸/聚乙烯醇复合膜的制备及光催化性能研究 总被引:2,自引:0,他引:2
合成了过渡金属取代的硅钨酸盐K6SiM(H2O)W11O39(M=Co、Ni、Cu,简称为SiMW11),利用硅钨酸(H4SiW12O40·nH2O,简称为SiW12)与SiMW11做母体,分别将它们负载于聚乙烯醇(polyvinyl alcohol,PVA)上,制成一系列杂多酸/聚乙烯醇复合膜光催化剂,利用IR、SEM进行了表征.以高压汞灯为光源,分别研究了SiW12/PVA、SiCoW11/PVA、SiNiW11/PVA、SiCuW11/PVA复合膜对有机染料甲基橙的光催化脱色,它们都具有很高的催化活性,60 min内对甲基橙的脱色率均可达到90%以上,其中SiW12/PVA复合膜效果最好,12 min内脱色率达100%.提高SiW12负载量可有效提高膜的光催化活性,当SiW12与PVA质量比为1:1时催化活性最高. 相似文献
893.
在pH 6.20的KH2PO4-Na2HPO4缓冲溶液中,吖啶橙(AO)与一定浓度的十二烷基苯磺酸(SDBS)发生荧光增强反应,当在该体系中加入有机磷农药后,在λex=494 nm处荧光强度明显下降,其降低程度与有机磷农药的加入量呈良好的线性关系,线性范围和检出限分别为0.020~0.28 mg/L、0.020 mg/L。据此建立了测定有机磷农药残留总量的新方法。该方法用于大米和土壤中有机磷农药残留总量的检测,回收率在92.1%~96.8%之间,RSD在2.8%~4.3%之间。 相似文献
894.
895.
研究了吐温20(Tween20)存在下,铝与二甲酚橙(XO)的显色反应,建立了分光光度法测定微量铝的新方法.结果表明,在pH=3.13的乙酸-乙酸钠缓冲介质中,铝与XO及吐温20反应生成有色络合物,络合物的最大吸收波长位于511 nm处, 表观摩尔吸光系数ε为1.99×10~4 L·moL~(-1)·cm~(-1),在10 mL溶液中,铝量在2.2~15.1 μg范围内符合比耳定律,检出限为0.0018 μg/mL.方法应用于茶叶、沙棘叶中铝的测定,样品加标回收率为96%~102.6%. 相似文献
896.
Roberta Eliane Santos Froes Waldomiro Borges Neto Nilton Oliveira Couto e Silva Rita Lopes Pereira Naveira Clésia Cristina Nascentes José Bento Borba da Silva 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
A method for the direct determination (without sample pre-digestion) of microelements in fruit juice by inductively coupled plasma optical emission spectrometry has been developed. The method has been optimized by a 23 factorial design, which evaluated the plasma conditions (nebulization gas flow rate, applied power, and sample flow rate). A 1:1 diluted juice sample with 2% HNO3 (Tetra Packed, peach flavor) and spiked with 0.5 mg L− 1 of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Sn, and Zn was employed in the optimization. The results of the factorial design were evaluated by exploratory analysis (Hierarchical Cluster Analysis, HCA, and Principal Component Analysis, PCA) to determine the optimum analytical conditions for all elements. Central point condition differentiation (0.75 L min− 1, 1.3 kW, and 1.25 mL min− 1) was observed for both methods, Principal Component Analysis and Hierarchical Cluster Analysis, with higher analytical signal values, suggesting that these are the optimal analytical conditions. F and t-student tests were used to compare the slopes of the calibration curves for aqueous and matrix-matched standards. No significant differences were observed at 95% confidence level. The correlation coefficient was higher than 0.99 for all the elements evaluated. The limits of quantification were: Al 253, Cu 3.6, Fe 84, Mn 0.4, Zn 71, Ni 67, Cd 69, Pb 129, Sn 206, Cr 79, Co 24, and Ba 2.1 µg L− 1. The spiking experiments with fruit juice samples resulted in recoveries between 80 and 120%, except for Co and Sn. Al, Cd, Pb, Sn and Cr could not be quantified in any of the samples investigated. The method was applied to the determination of several elements in fruit juice samples commercialized in Brazil. 相似文献
897.
A simple and sensitive method for the determination of patulin in fruit juice and dried fruit samples was developed using a fully automated method consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–mass spectrometry (LC–MS). Patulin was separated within 5 min by high-performance liquid chromatography using a Synergi MAX-RP 80A column and water/acetonitrile (80/20, v/v) as the mobile phase. Electrospray ionization conditions in the negative ion mode were optimized for MS detection of patulin. The pseudo-molecular ion [M−H]− was used to detect patulin in selected ion monitoring (SIM) mode. The optimum in-tube SPME conditions were 25 draw/eject cycles of 40 μL of sample using a Carboxen 1006 PLOT capillary column as an extraction device. The extracted patulin was readily desorbed from the capillary by passage of the mobile phase, and no carry-over was observed. Using the in-tube SPME LC–MS with SIM method, good linearity of the calibration curve (r = 0.9996) was obtained in the concentration range of 0.5–20 ng/mL using 13C3-patulin as an internal standard, and the detection limit (S/N = 3) of patulin was 23.5 pg/mL. The in-tube SPME method showed >83-fold higher sensitivity than the direct injection method (10 μL injection volume). The within-day and between-day precision (relative standard deviations) were below 0.8% and 5.0% (n = 6), respectively. This method was applied successfully for the analysis of fruit juice and dried fruit samples without interference peaks. The recoveries of patulin spiked into apple juice were >92%, and the relative standard deviations were <4.5%. Patulin was detected at ng/mL levels in various commercial apple juice samples. 相似文献
898.
899.
900.
采用火焰原子吸收法检测了36例胆汁运流性胃炎病人和30例健康对照者血清和胃液中微量元素Zn、Cu、Fe、及Ca的含量。结果显示,胆汁返流组血清Zn、Cu、Fe含量均明显低于对照组;胃液中Zn、Cu、含量则明显高于对照组;血清和胃液中Ca含量在2组间未见明显差异。该研究为开展胆汁返流性胃炎的病因学和治疗学研究提供了有益的资料。 相似文献