原位法制备环氧化天然橡胶及其表征

采用原位反应法使天然橡胶环氧化。研究了不同浓度的甲酸、双氧水、天然橡胶胶乳、温度对环氧化反应速率、环氧化度的影响。通过对红外、核磁图谱的分析得出可能发生的副反应机理,提出了减少副反应的处理方案。结果表明:当反应温度为20～30℃,当天然橡胶干胶含量为30%,pH值约为2.0,并且H2O2、HCOOH、天然橡胶(NR)的摩尔比为1∶0.55∶1时,反应进行稳定,同时能大大减少副反应的发生。只要按不同的时间安排取样就能得到环氧化度从10%到60%的环氧化天然橡胶。

Solvent-free selective oxidation of cyclohexane with molecular oxygen over manganese oxides:Effect of the calcination temperature

The effects of calcination temperature on the physicochemical properties of manganese oxide catalysts prepared by a precipitation method were assessed by X-ray diffraction,N2 adsorption-desorption,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,O2 temperature-programmed desorption,and thermogravimetry-differential analysis.The catalytic performance of each of these materials during the selective oxidation of cyclohexane with oxygen in a solvent-free system was subsequently examined.It was found that the MnOx-500 catalyst,calcined at 500 °C,consisted of a Mn2O3 phase in addition to Mn5O8 and Mn3O4 phases and possessed a low surface area.Unlike MnOx-500,the MnOx-400 catalyst prepared at 400 °C was composed solely of Mn3O4 and Mn5O8 and had a higher surface area.The pronounced catalytic activity of this latter material for the oxidation of cyclohexene was determined to result from numerous factors,including a higher concentration of surface adsorbed oxygen,greater quantities of the surface Mn4＋ ions that promote oxygen mobility and the extent of O2 adsorption and reducibility on the catalyst.The effects of various reaction conditions on the activity of the MnOx-400 during the oxidation of cyclohexane were also evaluated,such as the reaction temperature,reaction time,and initial oxygen pressure.Following a 4 h reaction at an initial O2 pressure of 0.5 MPa and 140 °C,an 8.0% cyclohexane conversion and 5.0% yield of cyclohexanol and cyclohexanone were achieved over the MnOx-400 catalyst.In contrast,employing MnOx-500 resulted in a 6.1% conversion of cyclohexane and 75% selectivity for cyclohexanol and cyclohexanone.After being recycled through 10 replicate uses,the catalytic activity of the MnOx-400 catalyst was unchanged,demonstrating its good stability.

Strength of copolymer grouting material based on orthogonal experiment

Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of water-cement ratio （mass fraction of water to cement）, epoxy resin content, and waterborne epoxy curing agent content. By orthogonal range and variance analysis, the orders of three factors to influence the strength, the significance levels of different factors, and the optimized compound ratio scheme of copolymer grouting material mixture at different curing ages were determined. An empirical relationship among the strength of copolymer grouting material, the water-cement ratio, the epoxy resin content, and the waterborne epoxy curing agent content was established by multivariate regression analysis. The results indicate that water-cement ratio is the most principal and significant influencing factor on the strength. Epoxy resin content and waterbome epoxy curing agent content also have a significant influence on the strength. But epoxy resin content has a greater influence on the 7-day and 28-day flexural strength, and waterborne epoxy curing agent content has a greater influence on the 3-day flexural strength and the compressive strength. The copolymer grouting material with water-cement ratio of 0.4, epoxy resin content of 8% （mass fraction） and waterbome epoxy curing agent content of 2% （mass fraction） is the best one for repairing of cement concrete pavement. The flexural strength and the compressive strength have good correlation, and the ratio of compressive strength to flexural strength is between 1.0 and 3.3.

Spontaneous combustion tendency of fresh and pre-oxidized sulfide ores

Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.

Water Effect on Amine-Modification of Adsorbents for Separation of CO_2/N_2

The adsorption of CO2can be enhanced through loading amines on adsorbents,therefore,the separation of CO2from other gases is promoted.Water plays an important role in this process.Water increases both the adsorption amount of CO2and the separation coefficient with N2for all amines loaded.However,the effect of loading trialkylamines is not remarkable in the absence of water.The effect of loading dialkylamine does not depend on water,but the adsorbent cannot be regenerated at ambient temperature.In comparison,an adsorbent loading trialkylamine can be regenerated at ambient temperature even in the presence of water with fairly good stability.

Self-reaction of initial active groups in coal

For further understanding of self-heating of coal, we tested the reactions of seven different ranks of coal under inert atmosphere. In the test, 50-gram of coal sample ranged from 0.18 mm to 0.38 mm was put into a special designed copper reaction vessel and let pure nitrogen to flow into the coal sample from the bottom at a rate of 100 mL/min. The programmed temperature enclosure was run at a programmed rate of 0.8 ~C/min. The concentration of the carbon oxides and the coal temperature were tested. The results show that the coal reactions under inert atmosphere can generate CO and C02. The reactions under inert atmosphere are affected by coal ranks, initial pore structure of coal and sulfur content. For low ranks of coal, the productions of carbon oxides are piecewise. The coal temperature is lower than the surrounding temperature throughout the reactions under inert atmosphere, but it rises quickly and reaches a crossing point temperature in the later stage under dry-air atmosphere. Based on the analysis, it indicates the self-reaction of initial active groups exists in the self-heating of coal besides the reactions in the two parallel reactions model. Spontaneous combustion of coal is due to both the oxidation heat accumulation and the chain reaction. A new reaction model of self-heating of coal was orooosed.

Deep removal of copper from cobalt sulfate electrolyte by ion-exchange

SP-C was applied for the removal of Cu^2＋ from simulated cobalt sulfate electrolyte containing Co2＋ 50 g/L and Cu2＋ 0.5-2.0 g/L. Experimental conditions included pH of 2-4, temperature of 20-60℃ and contact time of 10-40 min. The investigation demonstrated that SP-C had recommendable efficiency in adsorbing Cu2＋ from the electrolyte with 25- to 100-fold of Co2＋ The optimal adsorption conditions of SP-C were pH of 4, contact time of 30 min and ambient temperature. The study also showed that the loaded resin could be effectively eluted with 2.0 mol/L H2SO4 solution at a contact time of 40 min; the peak concentration of Cu2＋ in the eluate was about 35 g/L. The sorption characteristics of Cu2＋ by SP-C could be described by Langrnuir isotherm and the pseudo second-order kinetic equation. Infrared spectra showed that nitrogen atoms in the functional group coordinated with Cu2＋ to form coordination bands.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.

Characteristics of Cyanate Ester and Fluorenyl Epoxy-Based Polymer-Ceramic Composites

In the field of highly integrated printed circuit board （PCB）, the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate material with low moisture absorption and high glass transition temperature （Tg） simultaneously, a fluorenyl ＂Cardo＂ epoxy was incorporated into novolac cyanate ester resin. As an optimum curing agent for the fiuorenyl epoxy, methyl nadic anhydride （MNA） was selected. Silica powders as fillers were added into the resin composition. The partial replacement of the cyanate ester resin with the fluorenyl epoxy could reduce the moisture absorption with keeping high glass transition temperature over 300 ℃. The laminate, which was fabricated from prepregs made with 40 wt% silica-filled resin composition and glass fabric, showed high Tg of 317 ℃ and low moisture absorption of 0.57%.

Environmental life cycle assessment of Indian coal-fired power plants

Coal is the backbone of the Indian power sector. The coal-fired power plants remain the largest emitters of carbon dioxide, sulfur dioxide and substantial amounts of nitrogen oxides, which are associated with climate and health impacts. Various CO2 mitigation technologies （carbon capture and storage--CCS） and SO2/NOx mitigation technologies （flue gas desulfurization and selective catalytic reduction） have been employed to reduce the environmental impacts of the coal-fired power plants. Therefore, it is imperative to understand the feasibility of various mitigation technologies employed. This paper attempts to perform environmental life cycle assessment （LCA） of Indian coal-fired power plant with and without CO2, SO2 and NOx mitigation controls. The study develops new normalization factors for India in various damage categories, using the Indian emissions and energy consumption data, coupled with the emissions and particulate emission to come up with a final environmental impact of coal-fired electricity. The results show a large degree of dependence on the perspective of assessment used. The impact of sensitivities of individual substances and the effect of plant efficiency on the final LCA results is also studied.

Commercial indium-tin oxide glass:A catalyst electrode for efficient N_(2)reduction at ambient conditions

The typical Haber technical process for industrial NH_(3)production involves plenty of energy-consumption and large quantities of greenhouse gas emission.In contrast,electrochemical N_(2)reduction proffers environment-friendly and energy-efficient avenues to synthesize NH_(3)at mild conditions but demands efficient electrocatalysts for the N_(2)reduction reaction(NRR).Herein we report for the first time that commercial indium-tin oxide glass(ITO/G)can be used as a catalyst electrode toward artificial N_(2)fixation,as it demonstrates excellent selectivity at mild conditions.Such ITO/G delivers excellent NRR performance with a NH_(3)yield of 1.06×10^(-10) mol s^(-1) cm^(-2) and a faradaic efficiency of 6.17%at-0.40 V versus the reversible hydrogen electrode(RHE)in 0.5 M LiClO4.Furthermore,the ITO/G also possesses good electrochemical stability and durability.Finally,the possible reaction mechanism for the NRR on the ITO catalysts was explored using first-principles calculations.

Effect of CaO composition on oxidation and burning behaviors of AM50 Mg alloy

Oxidation and burning behaviors were studied for CaO added AM50 Mg composites which were manufactured by conventional melting and casting processes without SF6 protective gas. CaO added AM50 Mg composites show the stable oxidation resistance, while AMS0 Mg alloys show the poor oxidation resistance. The effects of CaO addition on the burning resistance under ambient, nitrogen and dry air atmospheres were examined for CaO added AM50 Mg composites. With increasing CaO addition, the burning temperature increases under ambient, nitrogen and dry air atmospheres. The burning temperatures of small test specimen under all conditions greatly increase even by 0.3% CaO （mass fraction） addition into AM50 Mg alloys.

Firework Induced Large Increase in Trace Gases and Black Carbon at Dibrugarh, India

Religious, occasional and annual fire work festivals worldwide are found to introduce high concentrations of pollutant gases and particulate matter into the atmosphere. These in turn alters the air quality of a region in the short and long time scales and affect human health adversely. The effect of fireworks on short-term variation in air quality of an urban location Dibrugarh, set amidst the rural environment of north-east India, was assessed from the ambient concentrations of 03, SO2, NOx, CO and BC （black carbon） during the Diwali festival during Nov. 13-14, 2012. The firework activity in general peaks during evening to midnight hours. Substantial increase in concentrations of O3, SO2, NOx, CO and BC was observed during the peak hours of firework activity （16：00 h to 22：00 h） in the Day 1 and Day 2 of the Diwali festival. However, the increase in concentrations from the background level was found to be highest on the post-Diwali day due to their accumulation in the atmosphere. The firework activity has not affected the regular diurnal pattern of the measured species during this episode.

Fruit protected cultivation in China

Protected fruit cultivation in China has developed very quickly from the early 1990s, and now it is an important branch in fruit cultivation. A brief review including fruit species, developing history, growing area, output, and distribution in the whole country is made in the paper. Characteristics of the dominant kinds of greenhouse, environmental control methods, and standards of temperature, humidity, light and CO2 for different fruit species are presented. Information on varieties, growing benefits, special management practices and other aspects of the main fruit species used for protected cultivation are also presented.

Macrokinetics of Ethylene Epoxidation over A-type Silver Catalyst

By taking the surface chemical reactions as the rate-controlling step, a possible reaction mechanism for ethylene epoxidation to synthesize ethylene oxide over the A-type silver catalyst was developed, while it was assumed that the epoxidation reaction would take place between ethylene and the un-dissociated adsorbed oxygen O2 a on the solo active sites, while the deep oxidation would occur between ethylene and the dissociated adsorbed oxygen Oa on the adjacent multi-active sites. In order to describe the effect of 1,2-C2H4Cl2(EDC) inhibitor on the ethylene epoxidation process, the reversible reactions between EDC and vinyl chloride(VC) on the active sites of silver catalyst was introduced. According to the assumed mechanism, the hyperbolic macro-kinetic model of ethylene epoxidation over the A-type silver catalyst was established, and the macrokinetic experiments were carried out in an internal-recycle gradientless reactor operating at a pressure of 2.1 MPa and a temperature in the range of 217.8—249.0 ℃, with the gas composition(molar fraction) consisting of 15.82%—34.65% C2H4, 2.55%—7.80% O2, 0.88%—6.15% CO2, 0.15—2.61 μmol/mol of 1,2-C2H4Cl2 and 0.14—1.28 μmol/mol of C2H3 Cl. By means of the Simplex Optimal Method, the parameters of the macrokinetic models were estimated. Statistical test showed that the macrokinetic models developed for the A-type silver catalyst agree well with the experimental results.

Pyropia yezoensis can utilize CO_2 in the air during moderate dehydration

Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentrations （（600-700）×10^-6 and （40-80）×10^-6, named Group I and Group II respectively） were investigated. The thalli of Group I had a significantly higher effective photosystem II quantum yield than the thalli of Group II at 71% absolute water content （AWC）. There was little difference between thalli morphology, total Rubisco activity and total protein content at 100% and 71% AWC, which might be the basis for the normal performance of photosynthesis during moderate dehydration. A higher effective photosystem I quantum yield was observed in the thalli subjected to a low CO2 concentration during moderate dehydration, which might be caused by the enhancement of cyclic electron flow. These results suggested that P. yezoensis can directly utilize COz in ambient air during moderate dehydration.

A review of chemical absorption of carbon dioxide for biogas upgrading

Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these techniques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research.

Atmospheric Pollution due to Road Traffic Case of the Greater Casablanca Region

In the Greater Casablanca, road transport is the second largest emissions source of gaseous pollutants and particles after the industry [ 1 ]. The emitters are mobile and include different categories of vehicles in circulation, in the road network of the region [2]. Air emissions from road transport considered in this study are the exhaust emissions from combustion of fuel during vehicle movement. This is mainly SO2 （sulfur dioxide）, NOx （nitrogen oxides）, CO （carbon monoxide）, CO2 （carbon dioxide）, SP （suspended particulate） [3], VOC （volatile organic compounds）, benzene, lead Pb and cadmium. These emissions depend mainly on the technology of the vehicle （type, fuel, engine size, and age）, the vehicle speed, the engine temperature and ambient temperature [4].

A Molecular Dynamic Modelling of Cross-Linked Epoxy Resin Using Reactive Force Field： Thermo-Mechanical Properties

The reactive force field was used to study the molecular dynamics of cross-linked EPON 862 （diglycidyl ether of bisphenol-F） and DETDA （diethylene toluene diamine） system in order to predict its thermo-mechanical behavior under different loading conditions. The approach for building the EPON 862/DETDA structures, cross-linking, and equilibration of the systems, and the evaluation of the models are presented. The mechanical properties such as Young＇s and shear moduli, Poisson ratio, and yields strength as well as thermal properties such as glass transition temperature and coefficient of thermal expansion are predicted. The results are in close agreement with both experimental data and simulated results in literature.

Formation of copper oxide nanowires and nanoparticles via electrospinning

Copper oxide nanowires and nanoparticles were fabricated through electrospinning followed by calcinations in different heating conditions.It was found that the solution viscosity and environment humidity had great impact on the morphologies of precursor nanowires,and the parameters of heat treatment,including final temperature and heating rate,significantly affected the product morphologies.