现代绿色合成化学

绿色化学越来越引起了人们的广泛关注,不少来自不同领域专家学者对其做出了卓越贡献。本文在介绍了绿色合成化学的概念、理论和特点;并总结了几种新型的合成方法。包括超临界合成法、微波合成法、等离子体合成法、超声合成法和电化学合成法等绿色合成方法,并分别对其合成的原理,特点和应用等方面进行了简要的介绍。最后,对未来绿色合成化学的发展做了展望。     

聚酰胺弹性体研究进展

综述了聚酰胺热塑性弹性体的基本结构、种类、性能及未来的研究方向,重点介绍了聚酰胺热塑性弹性体的合成方法.聚酰胺热塑性弹性体的合成方法主要包括以下几种:二元酸合成法、异氰酸酯合成法、阴离子聚合合成法、一步合成法、酯交换法、动态硫化工艺这几类合成方法.并针对每一合成方法,分别阐述了其存在的问题,并对相应的问题提出了解决方案...     

低压羰基法生产丁辛醇工艺技术进展

介绍了低压羰基法合成丁辛醇的工艺进展情况,包括戴维合成法、三菱化成合成法、巴斯夫合成法等。在比较不同工艺路线的同时,从现有的经济技术出发,提出了低压羰基法合成丁辛醇的战略思路。     

低压羰基法生产丁辛醇工艺技术进展

介绍了低压羰基法合成丁辛醇的工艺进展情况,包括戴维合成法、三菱化成合成法、巴斯夫合成法等。在比较不同工艺路线的同时,从现有的经济技术出发,提出了低压羰基法合成丁辛醇的战略思路。     

介-微孔复合分子筛的合成研究进展

本文概括了近些年介-微孔复合分子筛的合成研究工作,从两种主要的复合方式入手,综述了原位合成方法和后合成法。原位合成法主要包括单模板合成法和双模板合成法,后合成法主要介绍了孔壁晶化法、附晶生长法和微孔沸石硅源法三种代表性的合成方法。文章并分别对归属每种合成方法的具体合成方法进行了介绍,最后对介-微孔复合分子筛的合成进行了综述展望。     

萘酚的催化合成技术进展

简述了近年来一元萘酚传统合成技术的发展,包括磺化碱熔法、异丙萘法、水解法、四氢化萘法。重点介绍了一元萘酚绿色化合成工艺研究的新进展,特别是直接催化合成法和生物工程法的机理、工艺。最后对直接催化合成法的发展前景做了展望。     

丁辛醇工艺技术进展及选择

介绍了国内外合成丁辛醇的工艺技术进展情况,包括戴维合成法、三菱化成合成法、巴斯夫合成法等。在比较不同生产工艺路线的同时,从现有技术成熟角度和应用情况对比,提出了低压羰基法合成丁辛醇的选择原则。同时阐述了未来丁辛醇合成技术的发展趋势。     

微孔-介孔复合分子筛的合成研究进展

概括了近几年微孔-介孔复合分子筛的合成研究工作,主要介绍了原位合成法、后合成法和纳米组装法。原位合成法主要包括单模板合成法与双模板合成法;后合成法主要包括孔壁晶化法、附晶生长法、水热重组法、碱处理法、机械混合法与包埋法。最后对微孔-介孔复合分子筛的发展远景进行了展望。     

沸石膜合成方法研究进展

介绍了几种沸石分子筛膜的合成方法,有原位水热合成法、二次生长合成法、微波加热合成法和其他合成法。其中二次生长合成法又包括浸涂法、打磨法、旋转喷涂法和喷涂法。并介绍了相关文献研究内容。指出良好的沸石膜品质应该均匀连续、薄、定向生长。原位水热合成法只能做到使膜薄,而二次生长合成法可以做出质量合格的膜。     

苯甲醛电合成技术的新进展

简述了苯甲醛电合成的发展概况,详细地介绍了间接电合成法、成对电合成法和超声电合成法3种苯甲醛合成技术,并着重介绍了Mn3+/Mn2+电解媒质作为氧化还原电对间接电合成苯甲醛的应用情况,指出超声电合成法将是合成苯甲醛很有前景的方法。     

Kinetics of microwave heating and drying of drilling fluids and drill cuttings

Drill cutting decontamination by microwave drying has been studied over the past few years and has proved to be a promising technology. This study aimed to investigate fundamental aspects of kinetics of heating and drying of drilling fluids and drill cuttings by microwaves. The microwave heating curve of cuttings free of fluid, drilling fluids, and pure organic compounds usually used in the formulation of these fluids was evaluated to understand the behavior of each component in microwave cutting decontamination. Furthermore, commercial software was used to describe the heating kinetics of the drilling fluids used in this study. The drying kinetics of cuttings contaminated with these drilling fluids was also studied at three temperatures of control. Some classic models of conventional drying of solids were used to describe the removal kinetics of the liquid components present in contaminated cuttings (water and organic compounds). Important aspects related to the interaction of these components in the drying operation and solid heating, water evaporation, and the drag of organic compounds were investigated. Both drilling fluids showed a very similar kinetic heating. Pure organic bases did not show a significant heating. For the same drying time, the removal of paraffin is more intense than the olefin. In respect to organic component removal from cuttings contaminated with both fluids, the kinetic drying curves are similar. The Page model was the one that best describes the drying operation of drill cuttings contaminated with both drilling fluids. The microwave drying model (MDM) model is proposed in this work as a simple modification in the Henderson–Pabis model: the addition of a third parameter. The incorporation of this parameter enabled a better fit of the experimental data. Computational simulations show an electric field with symmetrical patterns for the two BR-MUL fluids analyzed.     

Effect of agronomic practices and drying techniques on nutritional and quality parameters of onions (Allium cepa L.)

The effects of four drying treatments (freeze-drying, hot air drying, oven drying, and vacuum oven drying) on the bioactive compounds (total phenolics, total flavonoids, and quercetins), color, and antioxidant capacity of organic and nonorganic onions of two varieties (Red Baron and Hyfort) subjected to two agronomic treatments (OSOP and CSCP) were investigated. The average final dry weight of the samples was 9.82?±?0.41%. After drying, there was a significant increase in total phenolics, total flavonoids, total quercetin, and antioxidant capacity in comparison with fresh onion samples, which suggested that drying can improve the extractability of phenols and accordingly the antioxidant activity of onions. Different drying techniques also resulted in different fractions of individual quercetins. Dried organic onions had higher levels of bioactive compounds and antioxidant capacity than dried nonorganic onions for a same variety. The highest antioxidant capacity displayed by freeze-dried and hot-air-dried organic Red Baron onion is in agreement with their higher phenolic and flavonoid contents compared to all other samples.     

DRYING KINETICS OF A MULTICOMPONENT MIXTURE OF ORGANIC SOLVENTS

Drying kinetics of volatile organic solvents have been examined during the drying process of a pharmaceutical coating containing a multicomponent mixture of ethyl acetate, n-heptane, propanol-2, and toluene. A complete set of experiments was performed in two drying apparatuses, a laboratory air-dryer and an oven dryer, for a wide range of drying temperature, air velocity, initial coating thickness and drying time. An empirical kinetic model is used to predict the concentration of each organic solvent in the mixture during the drying process. The results show that both drying conditions and sample characteristics affect significantly the drying rate of solvents.     

DRYING KINETICS OF A MULTICOMPONENT MIXTURE OF ORGANIC SOLVENTS

ABSTRACT

Drying kinetics of volatile organic solvents have been examined during the drying process of a pharmaceutical coating containing a multicomponent mixture of ethyl acetate, n-heptane, propanol-2, and toluene. A complete set of experiments was performed in two drying apparatuses, a laboratory air-dryer and an oven dryer, for a wide range of drying temperature, air velocity, initial coating thickness and drying time. An empirical kinetic model is used to predict the concentration of each organic solvent in the mixture during the drying process. The results show that both drying conditions and sample characteristics affect significantly the drying rate of solvents.     

Accurate Determination of Moisture Content of Organic Soils Using the Oven Drying Method

The accuracy of moisture content values determined for organic soil using the oven drying method is dependent on the oven drying temperature. Some charring of the organic fraction occurs at the standard oven drying temperature of 110 ± 5°C; pore water remains in the soil when temperatures below 100°C are used. A new technique to determine the specific oven drying temperature that yields the correct value of the moisture content for organic soils is presented. Routine moisture content tests should be conducted at the standard oven drying temperature; moisture content values determined on the basis of the recommended oven drying temperature of 60°C include a larger error. A moisture content parameter is introduced to facilitate direct comparison of moisture content values calculated on the basis of different oven drying temperatures.     

Requirements of organic gels for a successful ambient pressure drying preparation of carbon aerogels

In this paper, we investigated the requirements of organic gels for a successful ambient pressure drying by analyzing the role of the strength, the pore size and the surfactant of organic gels in decreasing the drying shrinkage of organic aerogels. Experimental results showed the effect of the decrease of the surface tension, resulting from the surfactant, on the drying shrinkage was very small and negligible. The drying shrinkage depended strongly on the strength and the pore size. Subsequently, the respective role of the strength and the pore size was evaluated. It can be found that the strength plays a greater role than the pore size.     

Microwave Drying of Wood Strands

Characteristics of microwave drying of wood strands with different initial moisture contents and geometries were investigated using a commercial small microwave oven under different power inputs. Temperature and moisture changes along with the drying efficiency were examined at different drying scenarios. Extractives were analyzed using gas chromatography/mass spectrometry (GC/MS). The results showed that the microwave drying process consisted of three distinct periods (warm-up period, evaporation period, and heating-up period) during which the temperature, moisture change, and drying efficiency could vary. Most of the extractives were remnant during microwave drying. It was observed that with proper selections of power input, weight of drying material, and drying time, microwave drying could increase the drying rate, save up to 50% of energy consumption, and decrease volatile organic compound (VOC) emissions when compared with the conventional drying method.     

Optimization for Preservation of Selenium in Sweet Pepper Under Low-Vacuum Dehydration

Response Surface Methodology (RSM) was used for optimizing the drying technology of sweet pepper under low-vacuum. It was found that pH value has greater influence on the organic Se index, while drying temperature has greater effect on the chlorophyll index. The optimized parameters of drying temperature, pH value and blanching time were obtained, respectively.     

Accurate Determination of Moisture Content of Organic Soils Using the Oven Drying Method

Abstract

The accuracy of moisture content values determined for organic soil using the oven drying method is dependent on the oven drying temperature. Some charring of the organic fraction occurs at the standard oven drying temperature of 110 ± 5°C; pore water remains in the soil when temperatures below 100°C are used. A new technique to determine the specific oven drying temperature that yields the correct value of the moisture content for organic soils is presented. Routine moisture content tests should be conducted at the standard oven drying temperature; moisture content values determined on the basis of the recommended oven drying temperature of 60°C include a larger error. A moisture content parameter is introduced to facilitate direct comparison of moisture content values calculated on the basis of different oven drying temperatures.     

Microwave Drying of Wood Strands

Abstract

Characteristics of microwave drying of wood strands with different initial moisture contents and geometries were investigated using a commercial small microwave oven under different power inputs. Temperature and moisture changes along with the drying efficiency were examined at different drying scenarios. Extractives were analyzed using gas chromatography/mass spectrometry (GC/MS). The results showed that the microwave drying process consisted of three distinct periods (warm-up period, evaporation period, and heating-up period) during which the temperature, moisture change, and drying efficiency could vary. Most of the extractives were remnant during microwave drying. It was observed that with proper selections of power input, weight of drying material, and drying time, microwave drying could increase the drying rate, save up to 50% of energy consumption, and decrease volatile organic compound (VOC) emissions when compared with the conventional drying method.