Changes in sulfur form during coal desulfurization with microwave:Effect on coal properties

The changes in sulfur form in coal were analyzed by sulfur K-XANES(K-edge X-ray absorption near edge structures) spectra before and after the coal microwave desulfurization in a Na OH solution. After the desulfurization, the pyritic sulfur content of coal decreased significantly from 53.6% to 39.2%, while the sulfate sulfur content increased from 17.3% to 34.6%. Only a small amount of thiophene sulfur(20.1–16.1%) was removed. Some sulfur-containing components were oxidized to sulfate sulfur. Under the optimum conditions, the ash content decreased, while the volatile content increased. The calorific value of coal slightly decreased with a slight variation in the amplitudes. The overall structure of coal did not change significantly based on Fourier transform infrared(FTIR) spectral analyses. Thus, the desulfurization of coal with microwave irradiation in a Na OH solution did not significantly change the properties of coal.

Synthesis of (Ca, Mg)-α′-Sialon-AlN-BN powders from boron-rich blast furnace slag by microwave carbothermal reduction-nitridation

(Ca, Mg)-α′-Sialon-AlN-BN powders were synthesized by the carbothermal reduction and nitridation (CRN) method using boron-rich slag, one of the intermediate products from pyrometallurgy separation of pageit, as the staring material. The influences of synthesis temperature and holding time on the phase composition and microstructure during the microwave CRN were studied by XRD, SEM and EDS. The comparison between two heating techniques, conventional and microwave heating, on the synthesized powder was presented as well. The experimental results revealed that the phase compositions and microstructures of the synthesized products were greatly affected by the synthesis temperature and holding time. With an increase in the synthesis temperature or holding time, the relative amount of α′-Sialon increased and α′-Sialon became the main crystalline phase at 1400 °C for 6 h. The synthesized products also contained AlN, BN and a small amount of β-SiC. Elongated α′-Sialon grains, short rod AlN grains, aggregate nanoscale BN grains were observed in the synthesized powders. The reaction temperature of microwave heating method was reduced by 80 °C, the reaction time was shortened by 2 h, and more elongated α′-Sialon grains with large aspect ratio were observed.

Ultra fast microwave-assisted leaching for the recovery of copper and tellurium from copper anode slime

The decomposition of copper anode slime heated by microwave energy in a sulfuric acid medium was investigated. Leaching experiments were carried out in a multi-mode cavity with microwave assistance. The leaching process parameters were optimized using response surface methodology（RSM）. Under the optimized conditions, the leaching efficiencies of copper and tellurium were 99.56% ± 0.16% and 98.68% ± 0.12%, respectively. Meanwhile, a conventional leaching experiment was performed in order to evaluate the influence of microwave radiation. The mechanism of microwave-assisted leaching of copper anode slime was also investigated. In the results, the microwave technology is demonstrated to have a great potential to improve the leaching efficiency and reduce the leaching time. The enhanced recoveries of copper and tellurium are believed to result from the presence of a temperature gradient due to the shallow microwave penetration depth and the superheating at the solid-liquid interface.

An expeditious and one-pot synthesis of unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles under microwave irradiation and solvent-free conditions

A one-pot synthesis of some unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles via cyclocondensation of benzoylhydrazines with orthoesters under solvent-free and microwave conditions are described here. The reaction is efficiently catalyzed by silica- supported sulfuric acid as it provided the title compounds in high yields and relatively short times. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reactions.

Microwave-assisted Green and Efficient Synthesis of N^6-(2-Hydroxyethyl)adenosine and its Analogues

An efficient protocol for the synthesis of N^6-（2-Hydroxyethyl）adenosine and its analogues through nucleophilic substitution was developed. All the reactions were completed in 10 rain under microwave irradiation. Using water as solvent makes our method eco-friendly and easy to handle with.

Biodiesel Production from Waste Cooking Oil Using Sulfuric Acid and Microwave Irradiation Processes

A comparative study of biodiesel production from waste cooking oil using sulfuric acid (Two-step) and microwave-assisted transesterification (One-step) was carried out. A two-step transesterification process was used to produce biodiesel (alkyl ester) from high free fatty acid (FFA) waste cooking oil. Microwave-assisted catalytic transesterification using BaO and KOH was evaluated for the efficacy of microwave irradiation in biodiesel production from waste cooking oil. On the basis of energy consumptions for waste cooking oil (WCO) transesterification by both conventional heating and microwave-heating methods evaluated in this study, it was estimated that the microwave-heating method consumes less than 10% of the energy to achieve the same yield as the conventional heating method for given experimental conditions. The thermal stability of waste cooking oil and biodiesel was assessed by thermogravimetric analysis (TGA). The analysis of different oil properties, fuel properties and process parametric evaluative studies of waste cooking oil are presented in detail. The fuel properties of biodiesel produced were compared with American Society for Testing and Materials (ASTM) standards for biodiesel and regular diesel.

Microwave promoted one-pot synthesis of 3-(2′-amino-3′-cyano-4′-arylpyrid-6′-yl)coumarins

A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR, ^1H NMR, and mass spectral data.

Optimization of Process Parameters of Continuous Microwave Drying Raspberry Puree Based on RSM and ANN-GA

To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexes(average temperature,average moisture content,average retention rate of the total anthocyanin content,temperature contrast value,and moisture dispersion value)were investigated via the response surface method(RSM)and the artificial neural network(ANN)with genetic algorithm(GA).The results showed that the microwave intensity and drying time dominated the changes of evaluation indexes.Overall,the ANN model was superior to the RSM model with better estimation ability,and higher drying uniformity and anthocyanin retention rate were achieved for the ANN-GA model compared with RSM.The optimal parameters were microwave intensity of 5.53 W•g^(-1),air velocity of 1.22 m·s^(-1),and drying time of 5.85 min.This study might provide guidance for process optimization of microwave drying berry fruits.

Microwave absorption properties regulation and bandwidth formula of oriented Y_(2)Fe_(17)N_(3-δ)@SiO_(2)/PU composite synthesized by reduction-diffusion method

As concepts closely related to microwave absorption properties,impedance matching and phase matching were rarely combined with material parameters to regulate properties and explore related mechanisms.In this work,reduction–diffusion method was innovatively applied to synthesize rare earth alloy Y_(2)Fe_(17).In order to regulate the electromagnetic parameters of absorbers,the Y_(2)Fe_(17)N_(3-δ)particles were coated with silica(Y_(2)Fe_(17)N_(3-δ)@SiO_(2))and absorbers with different volume fractions were prepared.The relationship between impedance matching,matching thickness,and the strongest reflection loss peak(RLmin)was presented obviously.Compared to the microwave absorption properties of Y_(2)Fe_(17)N_(3-δ)/PU absorber,Y_(2)Fe_(17)N_(3-δ)@SiO_(2)/PU absorbers are more conducive to the realization of microwave absorption material standards which are thin thickness,light weight,strong absorbing intensity,and broad bandwidth.Based on microwave frequency bands,the microwave absorption properties of the absorbers were analyzed and the related parameters were listed.As an important parameter related to perfect matching,reflection factor(√ε_(r)/μ_(r))was discussed combined with microwave amplitude attenuation.According to the origin and mathematical model of bandwidth,the formula of EAB(RL<-10 dB)was derived and simplified.The calculated bandwidths agreed well with experimental results.

Microwave Synthesis and Crystal Structure of Bis{2-[(2,4-dichloro-phenylimino)methyl]-4,6-diiodo-phenol}-copper(Ⅱ)

Bis{2-[（2,4-dichloro-phenytimino）-methyl]-4,6-diiodo-phenol}-copper（II） （1） has been synthesized and its structure determined by X-ray diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 14.7558（17）, b = 20.770（2）, c = 20.3260（19） A, β = 90.6110（10）°, V= 6229.2（11） A3 and Z = 8. The Cu atom is surrounded by two O atoms and two N atoms from two 2-[（2,4-diehloro-phenylimino）-methyl]-4,6-diiodo-phenol molecules to form a tetrahedral coordination environment. The complex is linked into a column by weak intermolecular interactions.

Tentative Study on a New Way of Simultaneous Desulfurization and Denitrification

Thiobacillus denitrificans, a kind of autotrophic facultative bacteria, can oxidize sulfide into elemental sulfur or sulfate when nitrate was adopted as its electron accepter and carbon dioxide as its carbon resource under anoxic or anaerobic environment. In this way, nitrate is converted into nitrogen. In addition, ThiobaciWus denitrificans can accumulate sulfur extracellularly. In this study, in a process of simultaneous desulfurization and denitrification, a strain of Thiobacillus denitriificans is employed as sulfur-producer in the treatment of wastewater containing sulfide and nitrate. The key factors affecting this process are investigated through batch tests. The experimental results indicate that the sulfide concentration and the ratio of sulfide to nitrate (S2-/NO3-) in the influent are the key factors, and their suitable values are suggested to be 5/3 and no more than 300mg·L-1, respectively, in order to achieve high conversion of sulfur.

Propene and CO oxidation on Pt/Ce-Zr-SO_4^(2-) diesel oxidation catalysts:Effect of sulfate on activity and stability

Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improved the catalytic activity significantly.When using Pt/Ce-Zr-SO_4^（2-） with 10 wt%SO_4^（2-）,the temperature for 90%conversion of propene and CO decreased by 75℃ compared with Pt/Ce-Zr.The conversion exceeded 95%at 240℃ even after 0.02%sulfur dioxide poisoning for 20 h.Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO_4^（2-） support,and the increased number of Pt particles built up more Pt^（-）-（SO_4^（2-））^（-） couples,which resulted in excellent activity.The increased total acidity and new Bronsted acid sites on the surface provided the Pt/Ce-Zr-SO_4^（2-） with good sulfur resistance.

微波-炭还原法处理二氧化硫(SO_2)的研究

本文报道一种不用催化剂采用微波－炭还原技术处理二氧化硫（SO2）的新方法。讨论了气体流量、反应器温度、微波功率和施加微波时间对二氧化硫和活性炭发生还原反应的影响。比较了连续施加微波和间歇施加微波两种方式下二氧化硫与活性炭发生化学反应转化为无公害的二氧化碳（CO2）气体和单质硫（S）的效率。研究结果表明，微波功率和反应器的类型及升温速率对二氧化硫的去除率影响较大。在连续施加微波时，二氧化硫的去除率可达95％以上，此外还对二氧化硫与活性炭反应后的产物进行了表征。

微波消解-吸附柱分离-离子色谱法测定钢样中微量硫

建立了用微波消解样品，活性氧化铝吸附柱分离，离子色谱法测定钢中微量硫的新方法。钢样经过王水／HF／H2O2溶解和微波消解，样品中的硫转变为硫酸根离子，消解液流经吸附柱，硫酸根离子与其他金属离子分离后，用离子色谱测定硫酸根。考查了淋洗液的组成、浓度及流速对分离和测定的影响。在实验条件下，方法的线性范围为0．2～100μg／mL，检出限为0．2μg／mL。用于测定标准钢样中硫的含量，平均相对标准偏差为3．3％～6．7％（n=5），适合于大批样品的测定。

苯并咪唑-2-硫的无溶剂微波合成

以多聚磷酸(PPA)作催化剂,在无溶剂微波照射下,用邻苯二胺与硫脲合成苯并咪唑2硫,为合成目标产物提供了一种新方法,与常规合成法相比,反应时间由2～3h缩短至6～10min.正交试验结果表明影响因素的影响顺序为:微波功率>催化剂用量>原料配比>照射时间;最优化工艺条件是:邻苯二胺与硫脲的摩尔比为1∶2,微波功率为126W,微波照射时间为6min,催化剂用量为7mL.通过数字熔点仪、红外光谱仪、核磁共振谱仪对合成的产物进行表征.

ICP-AES法检测硫磺熏蒸前后金银花中金属元素及微量元素

目的测定硫磺熏蒸前后中药金银花中金属元素和微量元素。方法采用微波消解法进行样品前处理,再经电感耦合等离子体发射光谱(ICP-AES)法测定金属元素及微量元素。结果中药金银花中Al、Fe、Mn、Zn、Cu等元素含有量丰富,硫磺熏蒸后金银花中S、Al元素的含量有显著升高(P<0.05),并伴有铬残留量的增加。结论硫磺熏蒸工艺能导致金银花中S元素量升高和铬残留的增加,测定金银花中金属元素及微量元素对于全面和客观评价其质量具有积极现实的意义。

微波辅助酸消解ICP-OES同时测定硫醇甲基锡中硫和锡的含量

硫醇甲基锡因其卓越的稳定性、良好的透明性、优异的兼容性和耐候性,目前是聚氯乙烯（PVC）加工过程中效果最好、使用最广泛的一类热稳定剂,其中硫和锡的含量是影响其质量和性能非常重要的指标,因此发展同时测定硫和锡的分析方法具有十分重要的意义。电感耦合等离子体原子发射光谱法（ICP-OES）因其检出限低,线性范围宽,干扰小,可多元素同时分析,样品通量高,已被广泛用于复杂样品的分析。微波消解做样品前处理可大幅缩短消化时间,且样品和试剂的使用量少,相对于传统的敞开消解法,还可减少挥发性元素的损失。我们建立了一种微波辅助酸消解-ICP-OES同时测定硫醇甲基锡中的硫和锡的新方法,该方法简单、快速、准确、绿色、样品用量少。采用DX-181样品,通过与化学分析方法的测试结果相比较,优化了微波辅助酸消解体系和消解时间。在消解体系为HNO3-HCl-HClO4（v/v/v=9∶3∶1）,消解时间为10min的优化条件下,分别用标准加入法和标准曲线法测定了DX-181样品中硫和锡的含量,测定结果无显著性差异,与化学方法测定参考值的相对偏差均小于2%。最后选择标准曲线法测定了元素含量分别为高、中、低的三个样品（DX-181,DX-990,DX-960）,相对偏差小于3%,加标回收率在99%~102%之间,结果令人满意。

高硫炼焦煤微波-KMnO_4协同脱硫实验研究

选用新阳高硫炼焦原煤,研究在微波-KMnO4协同作用下煤中有机硫的脱除效果,考察了微波辐照功率、辐照时间、KMnO4用量和稀硝酸用量对脱硫率的影响;以均匀化实验设计开展实验,选用DPS软件对实验结果进行逐步回归分析,创建最优回归方程,并对回归方程进行模型优化,获得了实验条件选取范围内微波-KMnO4协同法脱硫效果的最优实验条件组合;采用XPS对实验前后煤中有机硫组分进行分析,得出不同类型有机硫组分在微波-KMnO4协同作用下的脱除情况.

微波消解-ICP-AES法测定铁矿中P和S

采用微波加热 ,在高温高压下酸消解样品 ,应用电感耦合等离子体原子发射光谱法 (ICP- AES)同时测定铁矿中杂质元素 P和 S。选用紫外区谱线 P178.2 2 1nm、S180 .6 6 9nm,避免了基体中大量存在的 Fe、Si、Al、Cu、Mn、Ca等元素的光谱干扰。通过用纯氮吹扫光谱仪光路的方法消减空气中氧对紫外线的吸收 ,获得了足够的灵敏度。该方法简便、快速、稳定可靠 ,P、S检出限分别为 0 .0 6 7、0 .0 78μg· m L-1,回收率为89.6 %— 10 0 .7% ,RSD为 1.35 %— 5 .0 5 % ,线性范围为 0 .1— 2 0 0 μg·m L-1。

煤微波法脱硫过程中铁-硫化合物的变化

在不加浸提剂和通以氮气(含氧约1%)条件下,用2.45GHz微波照射约100s,东林煤(D)和鱼田堡煤(Y)的脱硫率均可达到20%以上。照射后进一步用5%的过量稀盐酸处理,脱硫率可高达68%。穆谱分析麦明,D、Y均含黄铁矿和硫酸亚铁,D还存在少量黄钾铁矾。经微波照射,黄铁矿转变成磁黄铁矿和陨硫铁,硫酸亚铁可能转变成其它铁相,其程度随着脱硫深度的变化面变化。用稀酸处理几乎可以除尽煤中磁铁矿和陨硫铁。因而微波照射与酸洗结合将是一种有效的脱硫方法。