Green epoxidation on Ti-mesoporous catalysts

New mesoporous catalysts with a mean pore size of 65 Å have been synthesised by grafting titanium on a mesoporous silica SBA15 (Santa BArbara) by means of titanium tetrachloride in the gas phase. These catalysts have been tested for the green epoxidation of cyclooctene, cyclohexene, (R)-limonene and -pinene by hydrogen peroxide, tert-butyl hydroperoxide or cumyl hydroperoxide. The selectivity is 100% and epoxide yields can reach almost 100% in the case of organic hydroperoxides without any leaching of titanium species. Here we show that cyclohexene epoxidation could be used as the first step of a greener synthesis of adipic acid.     

Detoxification of aqueous solutions of the pesticide “Sevnol” by solar photocatalysis

The solar photodegradation of Sevnol, a commercial pesticide, based on carbaryl as active principle, was studied. Experiments have been carried out at laboratory and at pilot plant scale using titanium dioxide as catalyst. Complete dissappearance of carbaryl was achieved, while total mineralisation required longer irradiation. Active sludge respirometry showed significant detoxification of the solution. Finally, results obtained with commercial Sevnol were consistent with those of pure carbaryl, although the reaction was slower.     

光化学氧化技术去除水中有机污染物的试验研究

以自来水为试验对象，对紫外－臭氧和紫外－二氧化钛两种光化学氧化技术对水中微量有机污染物的去除进行了试验研究，结果表明两种工艺的UVA（紫外吸光度）去除率均达到80％以上，对氯仿的去除也均能达到国家饮用水标准。在此基础上，自制了一种催化剂膜，并取得了预期的处理效果，有望在新型净水技术及设备的研制和开发上得到应用。     

Azo-dyes photocatalytic degradation in aqueous suspension of TiO2 under solar irradiation

The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C₁₄H₁₄N₃SO₃Na) and orange II (C₁₆H₁₁N₂SO₄Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO₂ irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almería” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediates were found to be in lower number in respect to those obtained under artificial irradiation. In particular there were no more evidence of the presence of hydroxylated transients. The dependence of dye photooxidation rate on: (i) substrate concentration; (ii) catalyst amount; and (iii) initial pH was investigated. The influence of the presence of strong oxidant species (H₂O₂, S₂O₈²⁻) and some ions (Cl⁻, SO₄²⁻) on the process was also studied.     

SnO2/TS-1纳米材料及光催化降解工业染料研究

以SnCl_4·5H_2O为原料,钛硅分子筛TS-1为载体,采用超声溶胶-凝胶法制备了负载型催化剂SnO_2/TS-1,并对该催化剂进行X射线衍射、扫描电镜、透射电镜、比表面积等表征.以罗丹明B作为模拟废水(20 mg·L~(-1)),系统研究了催化剂SnO_2/TS-1纳米材料制备条件与影响光降解性能的主要因素,并对印染企业的实际印染染料进行降解.结果表明:在pH=7.0~8.0下,经450℃焙烧制备了球形SnO_2/TS-1(SnO_2负载量为42%)纳米催化剂,比表面积为270 m~2·g~(-1),平均孔径为46.81 nm;在高压汞灯(λ_(max)=365 nm)光照60 min,催化剂用量为30 mg的条件下,催化剂对实际应用的工业染料罗丹明B、酸性蓝、活性黑、RGFL黄、酸性红A-2BF的降解率分别为96.44%、99.85%、99.78%、96.15%、94.65%,TOC与COD的下降率分别为89.3%~96.4%和81.6%~90.4%,且催化剂稳定性较好.     

甲基橙在镧掺杂二氧化钛表面的吸附研究

以钛酸丁酯为原料,采用溶胶-凝胶法成功制备了一系列La^3＋-TiO2光催化剂。通过XRD对催化剂进行了表征,XRD光谱结果表明所制得的TiO2光催化剂晶型结构为锐钛矿型。考察了pH值对甲基橙在纯TiO2光催化剂表面的吸附以及掺杂量对吸附的影响,通过紫外-可见光吸收光谱分析得出碱性或中性条件下的吸附较好。镧（La^3＋）掺杂量的TiO2对甲基橙的吸附实验表明,La^3＋的掺杂显著提高了甲基橙在TiO2催化剂表面的吸附能力,随着La^3＋掺杂量的增加,吸附能力逐渐增强。     

Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO2 nanotubes for oil/water separation

GO/TiO₂ membrane was prepared by assembling GO nanosheets and TiO₂ nanotubes. The intercalation of TiO₂ nanotubes enlarged the space of GO interlayers and modified the surface morphology. Hydrophilic/underwater superoleophobic property of GO/TiO₂ membrane was obtained. Water permeability, hydrophilicity, oleophobicity and antifouling ability of GO-based membrane were all enhanced by intercalating TiO₂ nontubes. Membrane technology for oil/water separation has received increasing attention in recent years. In this study, the hydrophilic/underwater superoleophobic membrane with enhanced water permeability and antifouling ability were fabricated by synergistically assembling graphene oxide(GO) nanosheets and titanium dioxide (TiO₂) nanotubes for oil/water separation. GO/TiO₂ membrane exhibits hydrophilic and underwater superoleophobic properties with water contact angle of 62° and under water oil contact angle of 162.8°. GO/TiO₂ membrane shows greater water permeability with the water flux up to 531 L/(m²·h·bar), which was more than 5 times that of the pristine GO membrane. Moreover, GO/TiO₂membrane had excellent oil/water separation efficiency and anti-oil-fouling capability, as oil residual in filtrate after separation was below 5 mg/L and flux recovery ratios were over 80%.The results indicate that the intercalation of TiO₂ nanotubes into adjacent GO nanosheets enlarged the channel structure and modified surface topography of the obtained GO/TiO₂ membranes, which improved the hydrophilicity, permeability and anti-oil-fouling ability of the membranes, enlightening the great prospects of GO/TiO₂ membrane in oil-water treatment.     

A holistic approach to achieving energy efficiency for interoperable machining systems

In the twenty-first century, the continuous demand in energy resource has put sustainability on the agenda of many businesses. This is particularly true for the manufacturing industry, where a large amount of energy is consumed to sustain daily operations. This paper studies energy-efficient computer numerical control machining systems. To achieve overall energy efficiency in machining systems, several activities are involved as in the proposed research framework of a global energy-efficient machining system (GEMS). These activities are described as modules, i.e. energy monitoring, energy analysis and optimisation, energy-based optimal control and energy-enriched database. In a GEMS, one critical issue is data interoperability. Seamless data sharing enables collaboration for improving energy efficiency. Using the EXPRESS language, energy data models are proposed for each module in the GEMS, and integrated with the existing STEP-NC (STandard for Exchange of Produce-compliant Numerical Control) standards. Two case studies are presented to demonstrate how the proposed data models may be used. One study updates an existing production file to include general energy information for auditing or reviewing purposes; the other study maintains machine tool energy profiles in a database. Many other energy-efficient activities, e.g. online energy optimisation, can be realised with the proposed data models. The present study proved that interoperable energy information can enhance the energy-efficient performance of a machining system.     

Computational energy estimation tools for machining operations during preliminary design

The aim of this paper is to develop computational machining energy estimation tools during the early design stage of product development. In the preliminary or embodiment design, a product's shape and materials are determined. At this stage, it is crucial for a designer to be able to compare alternative designs and materials based on many different criteria, such as cost, functionality, energy, etc. Automated tools for estimating energy consumption that could later be used to integrate with CAD/CAM systems are in demand. This study presents computational tools for estimating the energy consumption of machining operations during the early design phase. The computational tools utilize a preliminary computer representation of a product (CAD model), its material and candidate machining operations to automatically analyse and estimate a range of energy consumption during machining operations. Detailed steps for computing turning and milling energy consumption are presented. Case studies of both parts and assemblies were conducted to test the validity of the tools and to evaluate the performance of the tools. Environmental impacts such as carbon weight will also be estimated. The computation tools will assist users with little knowledge about energy computations to estimate energy consumption during the design stage. Such energy estimation can be used to redesign parts and assemblies, leading to the development of products with reduced machining energy. The computation tools are part of a larger research on estimating energy consumption throughout a product's life cycle.     

V2O5-TiO2-AlF3/Al2O3催化臭氧化2,4-滴丙酸的氧化效能

为了提高有机物的臭氧化降解效率,工作中利用浸渍法制备了一种新型的三组分催化剂(记为V2O5-TiO2-AlF3/Al2O3)。催化臭氧化降解2,4-滴丙酸的实验结果表明,该催化剂能有效提高臭氧化的效率,体系可能遵循羟基自由基的作用机理。利用相对法计算结果表明,与单独臭氧化相比,V2O5-TiO2-AlF3/Al2O3催化臭氧化体系具有更大的Rct值。重复实验结果表明,该催化剂具有相对较好的稳定性。以上研究结果对推广催化臭氧化技术在实际废水处理中的应用具有重要的实际意义。