Photoelectrocatalytic production of active chlorine on nanocrystalline titanium dioxide thin-film electrodes

The production of chlorine and hypochlorite is of great economical and technological interest due to their large-scale use in many kinds of commercial applications. Yet, the current processes are not without problems such as inevitable side reactions and the high cost of production. This work reports the photoelectrocatalytic oxidation of chloride ions to free chlorine as it has been investigated by using titanium dioxide (TiO2) and several metal-doped titanium dioxide (M-TiO2) material electrodes. An average concentration of 800 mg L(-1) of free chlorine was obtained in an open-air reactor using a TiO2 thin-film electrode biased at +1.0 V (SCE) and illuminated by UV light. The M-doped electrodes have performed poorly compared with the pure TiO2 counterpart. Test solutions containing 0.05 mol L(-1) NaCl pH 2.0-4.0 were found to be the best conditions for fast production of free chlorine. A complete investigation of all parameters that influence the global process of chlorine production by the photo electrocatalytic method such as applied potential, concentration of NaCl, pH solution, and time is presented in detail. In addition, photocurrent vs potential curves and the reaction order are also discussed.     

Mechanisms of photocatalytical degradation of monomethylarsonic and dimethylarsinic acids using nanocrystalline titanium dioxide

Photodegradation mechanisms of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) with nanocrystalline titanium dioxide under UV irradiation were investigated. In the presence of UV irradiation and 0.02 g/L TiO2, 93% MMA (initial concentration is 10 mg-As/L) was transformed into inorganic arsenate, [As(V)], after 72 h of a batch reaction. The mineralization of DMA to As(V) occurred in two steps with MMA as an intermediate product. The photodegradation rate of MMA and DMA could be described using first-order kinetics, where the apparent rate constant is 0.033/h and 0.013/h for MMA and DMA, respectively. Radical scavengers, including superoxide dimutase (SOD), sodium bicarbonate, tert-butanol, and sodium azide, were used to study the photodegradation mechanisms of MMA and DMA. The results showed that hydroxyl radicals (HO*) was the primary reactive oxygen species for the photodegradation of MMA and DMA. The methyl groups in MMA and DMAweretransformed into organic carbon, including formic acid and possibly methanol, also through photochemical reactions. The results showed that nanocrystalline TiO2 can be used for the photocatalytical degradation of MMA and DMA and subsequent removal of the converted As(V), since the high adsorption capacity of the material for inorganic arsenic species has been demonstrated in previous studies.     

Adsorption of arsenic on polyaluminum granulate

The kinetics and efficiencies of arsenite and arsenate removal from water were evaluated using polyaluminum granulates (PAG) with high content of aluminum nanoclusters. PAG was characterized to be meso- and macroporous, with a specific surface area of 35 ± 1 m(2) g(-1). Adsorption experiments were conducted at pH 7.5 in deionized water and synthetic water with composition of As-contaminated groundwater in the Pannonian Basin. As(III) and As(V) sorption was best described by the Freundlich and Langmuir isotherm, respectively, with a maximum As(V) uptake capacity of ~200 μmol g(-1) in synthetic water. While As(III) removal reached equilibrium within 40 h, As(V) was removed almost entirely within 20 h. Micro X-ray fluorescence and electron microscopy revealed that As(III) was distributed uniformly within the grain, whereas As(V) diffused up to 81 μm into PAG. The results imply that As(V) is adsorbed 3 times faster while being transported 10(5) times slower than As(III) in Al hydroxide materials.     

食品添加剂二氧化钛之生产和应用

1 概述 民以食为天，我国是人口大国，也是食品消费大国。因而食品添加剂发展很快，列入GB-2760的品种已有1600种，而且逐年增加。随着国内外对环境和健康以及食品安全问题的日益重视，回归大自然，崇尚绿色消费已成为一种潮流。“天然、营养、多功能”，是我国食品添加剂的重要发展方向。食品添加剂二氧化钛是天然矿产精加工而成。无毒、无味是当今最佳的食品白色着色剂。     

改性纳米二氧化钛的性能研究

研究了改性纳米二氧化钛在乙二醇介质中的稳定性及其影响因素和应用性能.结果表明，改性纳米二氧化钛溶胶的稳定性与改性剂的用量和体系pH值有关，在大于等电点时，随体系pH值的增加，溶胶的稳定性提高.红外光谱和应用性能研究表明，由于在改性纳米二氧化钛微粒表面引入了大量的硅羟基和环氧基等基团，织物经其整理后，抗紫外线等性能的耐久性有很大提高，且随着纳米改性剂用量的增加，耐久性逐渐提高.     

二氧化钛对卵黄高磷蛋白磷酸肽的纯化性能研究

研究了二氧化钛(Ti O2)对蛋黄蛋白中卵黄高磷蛋白磷酸肽(PPPs)的纯化性能,确定了最优纯化工艺,并对PPPs产品的持钙性能进行了研究。结果表明,在p H 4.0,吸附时间20 min,粗蛋黄多肽初始质量浓度为40mg/m L,反应温度为25℃时,Ti O2可以从粗蛋黄水解多肽中纯化得到纯度较高(N/P为5.34)且具有显著延缓钙离子沉淀效果的PPPs。同时Ti O2还具有较强的稳定性,可实现重复利用。     

聚氨酯基TiO_2隔热涂层织物

以聚氨酯为黏合剂,TiO2为功能粒子,采用涂层方法制备高性能的隔热涂层织物。讨论了TiO2用量、搅拌时间、转速、涂层厚度、焙烘温度和焙烘时间对涂层织物隔热性能和机械性能的影响。结果表明,涂层后织物的隔热性能和断裂强力显著提高,撕破强力下降。在TiO2用量18.0%,以1 500 r/min搅拌分散60 min,涂层厚度0.1 mm,140℃焙烘3 min的工艺条件下,涂层织物的隔热性能和机械性能均较好。     

魔芋凝胶食品中二氧化钛含量的测定

目的:研究一种简单快捷、方便有效、准确度高的测定魔芋凝胶食品中二氧化钛含量的方法.以便相关部门更好的对该类产品质量进行有效的监管,也有利于整个魔芋凝胶食品行业的发展和规范化;方法:魔芋凝胶食品经硫酸一硝酸一硫酸铵消化完全后,采用二安替比林甲烷分光光度法,选用388nm作为测定波长,以硫脲-V(c)作掩蔽剂,测定其二氧化钛的含量;结果:魔芋凝胶食品中的二氧化钛含量从未检出到6g/kg不等.方法重现性和回收率较为满意,RSD为1.38%,平均回收率为98.73%;结论:本法重现性好,准确度高,操作简单,对设备要求不高,既适合于检测部门对魔芋产品质量的监督检测,也适合于企业自主控制产品质量,易于广泛应用.     

二氧化氯制备系统中钛设备的选材

结合二氧化氯制备工艺对该系统中钛设备的材质选择要点进行了评述,并对相关钛设备的制造与使用注意事项进行了介绍,供设备设计与使用等参考。     

ICP-MS测定食品中的二氧化钛

建立电感耦合等离子体质谱法（ICP-MS）检测食品中二氧化钛的含量。样品经混合酸微波消解后,用电感耦合等离子体质谱仪进行食品中二氧化钛的测定。结果表明,二氧化钛在2-1000ng/mL范围内线性关系良好,相关系数0.9995,最低检出限0.5ng/mL,平均回收率109%,平均相对标准偏差3.20%。该方法简便、快捷、有较高的灵敏度、准确度、精密度和较低的检出限,适合食品中二氧化钛的测定。     

纳米锑掺杂氧化锡导电粉体的快速制备及表征

纳米锑掺杂氧化锡(ATO)以其灵敏度高、色浅透明、耐高温耐腐蚀、机械稳定性好等特点在气敏元件、导电抗静电领域、催化领域等得到了广泛的应用.本实验在共沉淀法的基础上采用特殊的组合添加剂,前驱体不需要干燥直接煅烧20 min就可以得到各项性能良好的ATO粉体,采用粒度分析仪、X衍射仪(XRD)、红外光谱仪、透射电镜(TEM)、微欧测量计等对最终粉体的性能进行了表征.结果表明:相比传统共沉淀法,该法具有快速、高效的特点,在合适添加剂作用下所制备的纳米ATO粉体一次粒径为55 nm,体积电阻率为75.93Ω.cm,晶化完整,纯度高.     

Glutamate surface speciation on amorphous titanium dioxide and hydrous ferric oxide

Hydrous ferric oxide (HFO) and titanium dioxide exhibit similar strong attachment of many adsorbates including biomolecules. Using surface complexation modeling, we have integrated published adsorption data for glutamate on HFO over a range of pH and surface coverage with published in situ ATR-FTIR studies of glutamate speciation on amorphous titanium dioxide. The results indicate that glutamate adsorbs on HFO as a deprotonated divalent anion at pH 3-5 and 0.2 micromol x m(-2) in the form of chelating-monodentate and bridging-bidentate species attached to the surface through three or four of the carboxylate oxygens, respectively. The amine group may interact weakly with the surface. However, at similar pH values and higher surface coverages, glutamate adsorbs mainly as a monovalent or divalent anion chelated to the surface by the gamma-carboxylate group. In this configuration the alpha-carboxylate and amine groups might be free to interact above the surface with the free ends of adjacent glutamates, suggesting a possible mechanism for chiral self-organization and peptide bond formation.     

食品添加剂二氧化钛和纳米二氧化钛对大鼠肝脏DNA损伤作用的评价

目的 利用哺乳动物体内碱性彗星试验,评价食品添加剂二氧化钛和纳米二氧化钛对大鼠肝脏细胞DNA的损伤作用。方法 依据哺乳动物体内碱性彗星试验指南（OECD TG489）,将雄性SD大鼠随机分成9组,每组5只。食品添加剂二氧化钛设1 000、500、250 mg/kg·BW 3个剂量组,阴性对照为纯水;纳米二氧化钛设500、150、50 mg/kg·BW 3个剂量组,阴性对照为0.8%吐温+3%FBS。通过灌胃方式给予,每日1次,共15 d;同时设置阳性对照组,阳性物甲基磺酸乙酯（EMS）仅在第14、15天每日灌胃一次给予,剂量为200 mg/kg·BW·d。末次灌胃6 h后,麻醉条件下取大鼠肝脏,制备成单细胞悬液后涂片,经裂解、解旋、电泳、染色等步骤,进行彗星图像分析。结果 食品添加剂二氧化钛和纳米二氧化钛各剂量组大鼠肝脏细胞的尾部DNA含量百分比与相应阴性对照组相比均无显著性差异（P>0.05）,而EMS组大鼠肝脏细胞的尾部DNA含量百分比与阴性对照组比较均具有显著差异（P<0.01）。结论 在本实验条件下,食品添加剂二氧化钛和纳米二氧化钛均未诱导大鼠肝脏细胞的DNA损伤。     

纳米二氧化钛整理剂的研制和应用

通过调整一系列的配方,从中选择最佳的分散剂配比,从而制得透亮、均匀、分散性和稳定性都很好的纳米二氧化钛整理剂,并在织物上应用,结果表明此整理剂有突出的抗紫外、抗静电性能。     

纳米二氧化钛在山羊绒针织物上的应用

综合溶胶-凝胶法、乙酰丙酮和硝酸的抑制水解作用、微乳法表面活性剂的分散效果制得纳米二氧化钛溶胶.采用浸压法,用制得的纳米二氧化钛溶胶处理经过氧化-丝胶处理过的山羊绒针织物,并通过正交试验得到最佳的整理工艺:纳米二氧化钛溶胶的浓度为0.706 mg/ml,处理温度45℃,时间35 min,经测试山羊绒针织物的抗静电性能得到了一定的改善.     

Adsorption characteristics of various proteins to a titanium surface

Adsorption characteristics of 18 proteins, with different sizes and isoelectric points, to a titanium oxide surface were studied. The adsorption isotherms were categorized based on protein type and pH: type 1, irreversible adsorption; type 2, Langmuir-type reversible adsorption; and type 3, reversible and irreversible adsorption. Most of the proteins tested were irreversibly adsorbed in the pH range of 3-8, whereas most adsorbed reversibly at pH 8.5-9.4. Protamine, with a pI value of 12, adsorbed reversibly in the pH range of 3-9. pH values that gave maximal sums of irreversibly and reversibly adsorbed proteins were in the pH range of 3-8 and tended to increase slightly with the pI value of the corresponding protein. pH values that gave maximal quantities of irreversibly adsorbed protein ranged between 4-6 and were nearly independent of pI.     

Adsorption of arsenic from water using activated neutralized red mud

In this paper activated seawater-neutralized red mud, herein referred to as activated Bauxsol (AB), is used as a novel adsorbent for removing inorganic arsenic (As) from water. The adsorption of As onto AB is studied as a function of contact time, particle size, pH, initial As concentration, AB dosage, and temperature. Kinetic data indicate that the process pseudoequilibrates in 3 and 6 h for As(V) (arsenate) and As(III) (arsenite), respectively, and follows a pseudo-first-order rate expression. Within the range tested, the optimal pH for As(V) adsorption is 4.5, and close to 100% removal can be achieved irrespective of the initial As(V) concentration. Desorption of As(V) is greatest at pH 11.6 where a maximum of 40% can be achieved. In contrast, the optimum pH for As(III) removal is 8.5, and the removal efficiency changes with the initial As(III) concentration. The adsorption data fit the Langmuir isotherm and its linearized form well, with thermodynamic data indicating the spontaneous and endothermic nature of the process. The FITEQL (V.4) and PHREEQC (V.2) computer programs are used to predict As(V) adsorption at various pH values (based on diffuse double layer models). The modeling results fit the experimental results very well and indicate that surface complexation modeling is useful in describing the complex AB surface during the adsorption process. This study shows that As(III) needs to be oxidized to As(V) for a favorable removal using AB and that AB can be a very efficient unconventional adsorbent for removing As(V) from water.     

二氧化钛纳米材料印花探讨

在涂料印花体系中加入二氧化钛纳米材料,可产生消光作用。通过实验对黏胶长丝针织物进行消光印花,确定了达到最佳印制效果的纳米二氧化钛浓度为25g(/100g)和焙烘温度130℃。