微波－气相－热压法分解高纯铂的研究

本文研究了微波气相热压法新技术分解高纯铂在密闭的聚四氟乙烯高压罐中，以微波瞬间加热混合酸产生的高压、纯净蒸气分解金属铂，此法避免了酸中杂质的沾污以制备供高纯铂分析的试液，提高了痕量杂质分析的准确度和降低检测限     

水中痕量苯酚的微波萃取气相色谱分析

A method of microwave-assisted extraction and gas chromatography for determination of trace phenol in water was established.The conditions of microwave extraction and derivation were optimized.Acetone-cyclohexane(1∶1) mixture was used as extracting agent for water sample containing phenol and acetic anhydride was employed for the direct acetylation of phenol.Petroleum ether was used as the extracting agent to extract the derivative of phenol.Detection was carried out in GC-FID equipped with DB-17(30 m×0.53 ...     

微波氯化分解氟碳铈矿的研究

采用微波加热技术氯化分解四川冕宁60%品位的氟碳铈精矿(含氟碳铈矿57.78%,氟碳钙铈矿33.86%),利用无水MgCl₂作为氯化剂,活性炭作为辅助剂,实现了微波场中空气气氛下氟碳铈精矿的无氧化焙烧分解。通过热重-差热分析(TG-DSC)、 X射线衍射(XRD)、扫描电镜(SEM)和能谱(EDS)分析等检测手段,阐明了微波氯化分解氟碳铈精矿的无氧化反应机理,得到了主要以氯氧化稀土(REOCl)和氟化镁(MgF₂)为主的微波焙烧矿。通过实验,确定了微波氯化分解工艺的最佳参数：微波功率1200 W,焙烧温度800℃,焙烧时间30 min,矿盐比(氟碳铈精矿∶无水氯化镁∶活性碳)为1∶0.25∶0.18。在此条件下,氟碳铈精矿的分解率为96.23%,酸浸液中氟的浸出率只有23.35%,铈的氧化率小于0.6%。     

气相色谱-质谱法研究敌百虫在气相色谱分析过程中产生的分解产物

利用气相色谱-质谱联用技术对敌百虫在气相色谱分析过程中产生的分解产物进行定性研究。通过质谱解析鉴定出敌百虫的分解产物有三氯乙醛、磷酸二甲酯和敌敌畏。研究了气相色谱条件如进样口温度、柱温升温速率、进样方式对敌百虫分解产物的影响。实验结果表明:这3种因素对敌百虫的稳定性均有不同程度的影响,其中进样口温度是导致敌百虫分解的主要因素,进样口温度越高,敌百虫的分解量就越大。     

沉积物中多糖的微波消解及气相色谱分析

建立了采用硫酸体系微波消解沉积物中多糖,乙酰化后用气相色谱同时分离测定7种单糖的分析方法。考察了温度和微波消解时间对多糖水解效率的影响,实验表明在100℃下消解60min达到最高效率。将水解得到的单糖还原并乙酰化,采用HP-5石英毛细管柱(30m×0.32mm,0.25μm)为色谱柱,利用气相色谱法对7种单糖进行分离测定,总分析时间32min。用保留时间定性,内标法(以各个单糖的标样峰面积/内标样峰面积)进行定量。加样回收率为63%～106%,重现性测定平均相对标准偏差(RSD)为6.7%。实验结果表明本法是一种快速、有效测定沉积物中糖类物质组成的方法。     

生物样品中多氯联苯的微波皂化萃取气相色谱法测定

以KOH－甲醇－正己烷为皂化萃取溶剂,利用微波皂化萃取－气相色谱法测定了生物样品中的多氯联苯（PCBs）,实现了在皂化的同时对待测物的萃取。方法的检出限为质量分数6.25×10     

微波辅助萃取-气相色谱测定土壤中多氯联苯

建立了微波辅助萃取-气相色谱-微电子捕获检测土壤样品中6种多氯联苯(pcb28, pcb52, pcb101, pcb138, pcb153和pcb180)的方法. 确定了以V(20 mL丙酮):V(正己烷)＝1:1混合溶剂作萃取剂, 萃取温度110 ℃, 仪器功率800 W, 微波萃取5 min的样品前处理条件, 并用柱温程序优化了GC-μECD分析条件. 方法的检出限为0.027～0.087 ng/g; 相对标准偏差为3.4%～7.6% (n=6); 加标平均回收率79.8%～91.1%. 可用于土壤环境中多氯联苯的监测分析.     

微波皂化萃取气相色谱法测定生物样品中的多氯联苯

１引言 多氯联苯（ＰＣＢｓ）的性质稳定、毒性大,贻贝等海洋生物能摄取和富集海水中的ＰＣＢｓ,因此研究其中ＰＣＢｓ的测定具有重要意义。生物样品中 ＰＣＢｓ的测定一般要进行预分离处理,索氏萃取分离 ＰＣＢｓ耗时至少８ｈ,加碱皂化生物组织再以液－液萃取提取ＰＣＢｓ需要在沸水浴中回流１～２ｈ,微波直接革取能有效地分离环境样品中的ＰＣＢｓ。本文利用微波皂化萃取（ＭＡＳＥ）气相色谱法（ＧＣ）测定生物样品中的多氯联苯,实验以未受ＰＣＢｓ污染的淡水鱼为空白,用正交试验系统优化了微波功率、微波加热时间、皂化及萃取溶…     

完全不互溶双液系的蒸气压*

对完全不互溶双液系的饱和蒸气压进行了实验研究与理论讨论,认为完全不互溶双液系的平衡蒸气压随两组分相互溶解度减小而趋于但总是小于两纯组分的饱和蒸气压之和;当完全不互溶两液相一起静置时,上层液体能有效但不能完全阻止下层液体的挥发,这种阻止作用源于缓慢溶解、扩散和挥发这些动力学过程;提出了阻止下层液体挥发的方法,即用与之完全不互溶且密度小的液体来覆盖,并且2种液体充满容器,阴凉处密闭静置保存。     

液相微波介电加热法制备纳米粒子的研究进展

随着纳米科技的飞速发展,合成纳米材料的新方法层出不穷。在这些新方法当中,液相微波介电加热法近年来得到了飞速的发展,引起了科学界越来越多的关注。本文介绍了近年来液相微波介电加热法制备纳米粒子的一些研究进展,主要是该方法在制备金属、过渡金属氧化物和金属硫族化合物纳米粒子中的应用,并且对该领域未来的发展作了一些展望。     

Vapor Pressure Determination by Pressure DSC

A new pressure DSC module (Mettler DSC27HP) and its abilities for vapor pressure determination in the range of subambient pressure to 7 MPa are presented. To compare the new to an established method, vapor pressures of caffeine, naphthalene and o-phenacetin have been determined both by pressure DSC and the Knudsen effusion cell method. These results, including the derived heats of evaporation and heats of sublimation, are compared to literature values. This revised version was published online in July 2006 with corrections to the Cover Date.     

秸秆中钾的溶出工艺研究

采用单因素实验法考查了微波功率、固液比、消解时间等条件对钾溶出率的影响。优化得出较适钾的溶出工艺条件:微波功率为中高火,液固比35,消解时间60 s,在此条件下,微波溶出钾量为秸秆量的3.057%。     

微波加热法快速合成T型分子筛

由于具有高的水热稳定性和优良的孔道结构．T型分子筛已成为一种高选择性的催化剂．在低碳化合物的催化和重整等方面有较多的应用。近年来．报道采用晶种法在无机多孔陶瓷支撑体上制备的T型分子筛膜．在脱除有机物／水混合物中的水时．表现出优异的渗透汽化分离性能。然而，提高T型分子筛膜的致密性和生长速率仍是亟待解决的问题。T型分子筛的合成研究较少．制备过程均采用普通加热（Conventional Heating．CH）法。在无模板剂的条件下．T型分子筛的结晶区间较窄，结晶速率慢．合成时间通常需要6d以上。     

微波加热制备空心和锯齿形貌Bi_2Te_3晶体(英文)

Well-crystallized Bi₂Te₃ hollow spheres and nanosaws were prepared by microwave heating. Both the ionic liquid and the microwave heating play important role in the formation of the above nanostructures. Hollow spheres can not be obtained only by electronic stove heating, while the addition of ionic liquid leads to fast preparation of nanosaws structure under microwave heating conditions. The similar experimental results have been observed in the preparation of Bi₂S₃, Sb₂S₃ and Bi₂Se₃ nanostructures.     

Cooperative Ligands in Dissolution of Gold

Development of new, environmentally benign dissolution methods for metallic gold is driven by needs in the circular economy. Gold is widely used in consumer electronics, but sustainable and selective dissolution methods for Au are scarce. Herein, we describe a quantitative dissolution of gold in organic solution under mild conditions by using hydrogen peroxide as an oxidant. In the dissolution reaction, two thiol ligands, pyridine-4-thiol and 2-mercaptobenzimidazole, work in a cooperative manner. The mechanistic investigations suggest that two pyridine-4-thiol molecules form a complex with Au⁰ that can be oxidized, whereas the role of inexpensive 2-mercaptobenzimidazole is to stabilize the formed Au^I species through a ligand exchange process. Under optimized conditions, the reaction proceeds vigorously and gold dissolves quantitatively in two hours. The demonstrated ligand-exchange mechanism with two thiols allows to drastically reduce the thiol consumption and may lead to even more effective gold dissolution methods in the future.     

微波场中T型分子筛的合成及晶化研究

研究了微波场中T型分子筛的结晶过程。考察了微波加热体系中合成参数如合成时间、溶胶组成、反应压力和模板剂用量对分子筛晶化的影响。微波加热的主要优点是减少合成时间,无模板剂的溶胶在普通加热条件下的晶化时间需要120 h,而在微波场中则仅需要20～25 h。另一方面,由于微波的快速加热特性促进了稳定相钙十字沸石的生成,从而减小了次稳定相T型分子筛的结晶区间。在未添加模板剂条件时,100 ℃下微波水热合成T型分子筛的结晶区间为：20≤n_SiO2/n_Al2O3≤22和0.31≤ n_M2O/n_SiO2≤0.33(其中M₂O=Na₂O+K₂O, n_Na/n_K=3和n_M2O/n_SiO2=11.70)。在普通加热和微波加热合成体系中,添加模板剂均能扩大结晶区间,同时还可以进一步减少合成时间。     

Kinetics study on the dissolution of UO_2 particles by microwave and conventional heating in 4 mol/L nitric acid

The dissolution of UO2 particles in 4 mol·L-1 nitric acid medium at temperatures of 90-110℃ by mi- crowave heating and conventional heating has been investigated, respectively. It is found that the dissolution ratios of UO2 particles by microwave heating were 10%-40% higher than that by conven- tional heating. Kinetics research shows that the dissolution of UO2 particles in 4 mol·L-1 nitric acid is controlled by the diffusion control model for microwave heating and by the surface reaction control model for conventional heating. The diffusion control model for the dissolution of UO2 particles by mi- crowave heating could be explained by the diffuseness on the surface of UO2 particles.