钼酸铅重量法测定增收钼矿中的钼

采用盐酸、硝酸等强酸分解法,使能与钼酸根生成钼酸盐沉淀的金属阳离子及与乙酸铅作用生成沉淀的钨酸根、砷酸根、磷酸根、钒酸根、铬酸根等阴离子分离.通过对酸度、介质、沉淀条件的控制,用乙酸铅沉淀方法测定增收钼矿中钼的含量.     

钼铁合金中钼的测定

钼铁合金中钼的测定是针对钼铁合金的特性,选择使用稀硝酸溶解试样,使用5％ EDTA溶液络合掩蔽多种干扰金属元素,在乙酸-乙酸铵缓冲溶液(pH =5～7)介质中,用乙酸铅溶液与钼形成钼酸铅沉淀,在箱式电阻炉中在600℃的条件下灼烧至恒重,称量.这种方法操作简单,容易掌握,分析成本低廉,准确度高,可以分析5％以上的钼.本方法可以用于实验室仲裁测定钼铁合金中的钼的含量.     

铅盐沉淀分离EDTA滴定法测定钼酸钙中氧化钙量

探讨了用乙酸铅沉淀钼与钙分离的条件。在酸性条件下加入乙酸铅后，调整酸度使钼以钼酸铅的形式沉淀，再以铜试剂使多余的铅离子和其他干扰离子沉淀而与钙分离，在滤波中以适量硫酸镁增敏，用EDTA按常法测定。方法应用于钼酸钙中乳化钙量的测定简便快速，分析结果准确可靠。     

钼酸铅重量法测定钼铁中钼的方法改进

GB/T 5059.1—2014测定钼铁中钼含量的钼酸铅重量法使用硝酸和氟化铵溶解钼铁,用氢氧化钠分离铁等干扰元素后,加Na₂EDTA进一步屏蔽干扰元素,以甲基橙指示剂和单宁指示剂确定反应终点。氟化铵遇热分解形成的氟化氢会腐蚀玻璃烧杯,且存在过滤和洗涤氢氧化物沉淀耗时长、指示剂变色不明显、所用化学试剂种类多的问题。为缩短检测时间,简化实验流程,对上述方法进行了改进:用乙酸-硝酸在50～70 ℃低温溶解钼铁试样,煮沸并蒸发至近干除去氮氧化物后,加水稀释至150 mL,加入30 mL Na₂EDTA溶液络合铁、铜等杂质离子。在乙酸-乙酸铵缓冲溶液环境下,加入120 g/L乙酸铅溶液,使钼全部形成钼酸铅沉淀。120 ℃烘干沉淀,在马弗炉中180 ℃灰化并在550 ℃灼烧后进行称重,计算钼含量。实验方法用于测定3个钼铁中钼,结果的相对标准偏差(RSD,n=5)小于0.2%;按照实验方法测定钼铁标准样品中钼,结果与标准值相一致。改进后的方法不仅解决了溶解液腐蚀玻璃烧杯的问题,而且不用氢氧化钠沉淀剂,无需使用变色指示剂,减少了实验误差,缩短了测试时间,适合生产型企业快速测定钼铁中钼含量。     

钼精矿中三氧化二铝的分析探讨

采用乙酸铅将钼精矿中钼以钼酸铅沉淀形式与三氧化二铝分离，用EDTA容量法分析三氧化二铝．消除了大量钼对分析铝的影响，能够满足快速分析的要求。     

EDTA络合连续滴定法同时测定铜精矿中高含量铅锌

建立了EDTA络合连续滴定法同时测定铜精矿中高含量铅锌的分析方法,试样以盐酸、硝酸、硫酸溶解,用氢溴酸挥发除去砷、锑和锡.硫酸铅沉淀分离铅,沉淀用乙酸-乙酸钠缓冲液溶解测定铅,滤液用氨水-氯化铵沉淀分离铁锰,用抗坏血酸、氟化钾、硫脲掩蔽Fe3+、Al3+、Cu2+等杂质,在pH=5.5～6.0的乙酸-乙酸钠缓冲液中,E...     

EDTA返滴定法测定铅玻璃中铅

采用氢氟酸-盐酸-硝酸-高氯酸溶解样品,硫酸铅沉淀分离,在氨水-EDTA介质中溶解硫酸铅沉淀,在乙酸-乙酸钠缓冲体系下,以二甲酚橙为指示剂,乙酸铅返滴定测定铅含量,优化了沉淀陈化时间、氨水加入量、微沸时间以及乙酸-乙酸钠缓冲溶液加入量等实验条件,建立了采用EDTA返滴定法测定铅玻璃中铅的方法。实验方法用于测定铅玻璃中铅,结果的相对标准偏差(RSD,n=11)为0.32%。按照实验方法对铅玻璃样品进行加标回收试验,回收率为99.5%~102.0%。     

从铀钼合金燃料中选择性分离铀、钼试验研究

研究了以硝酸溶液为沉淀剂,从U-10%Mo合金中选择性沉淀分离铀和钼,考察了硝酸浓度、硝酸过量系数对铀、钼分离的影响。试验结果表明:在n(HNO3)/n(Mo)一定条件下,硝酸浓度对铀溶解率影响较小;随n(HNO3)/n(Mo)增大,铀溶解率增大至95.2%,钼沉淀率先降低后升高,铀钼分离系数(β)先减小后增大;[HNO3]≥12 mol/L时,n(HNO3)/n(Mo)≥94有利于铀钼分离,且工艺上容易实现。     

硫氰酸盐光度法测定钼精矿中的钨

实验采用盐酸+硝酸溶解钼精矿,然后用氨水溶解钨酸,再用硝酸铅沉淀基体钼,过滤分离,然后用硫氰酸盐光度法测定钨。在实验中着重考虑溶解试样,然后用硝酸铅能很好的除去基体钼,又用碱化溶液时主体杂质铁离子的沉淀夹带其他杂质离子,从而达到与钨沉淀分离。通过对不同含量的钼精矿中钨的测定,测定结果与原子吸收光谱法相符,相对标准偏差为0.160%~6.285%(n=6)。     

铅锌矿中铅锌快速连续测定

采用盐酸、硝酸、硫酸分解试样,铅形成硫酸铅沉淀而与锌分离.以慢速滤纸过滤,滤液用EDTA络合滴定分析法测定锌量;沉淀以HNO3(1+1)溶解后,在pH5.5～6.0的乙酸-乙酸钠缓冲溶液中,以二甲酚橙为指示剂,用EDTA标准溶液滴定铅量.     

实验室废旧贵金属材料中铂的回收利用

实验室使用的含铂耗材会因为长时间使用形成损耗、变性或功能失效,长期搁置或丢弃造成极大的浪费,工业上常使用硼氢化钠作还原剂还原回收铂。实验依据硼氢化钾相比硼氢化钠具有分解温度高、稳定性好、在使用过程中较安全的特性,与氯化铵相结合利用二次沉淀法,以实验室含铂废旧耗材为原料,建立了硼氢化钾还原-氯化铵沉淀法回收铂的方法。为了获得纯净的金属铂,实验采用硝酸分离杂质元素,王水溶解铂,反复用盐酸驱赶氮氧化物,使铂充分转化为氯铂酸。在40℃、5%(V/V)盐酸介质中用硼氢化钾还原氯铂酸及少量难溶于王水的氧化铂,再用王水溶解铂黑并完全转化为氯铂酸,氯铂酸与过量的氯化铵形成黄色氯铂酸铵沉淀,陈化过夜。选择分段缓慢升温分解氯铂酸铵,在750℃和900℃煅烧,分别获得松散的金属铂粉和较致密的金属铂。两次沉淀溶液中残余的铂离子均小于20μg/mL。回收铂的纯度不小于99.9%,回收率大于99.5%。     

Biogeochemical Evaluation of Mechanisms Controlling CaCO3(s) Precipitation in Landfill Leachate-Collection Systems

A common failure mode for landfills is clogging of the leachate-collection system. The reduction in hydraulic conductivity associated with clogging causes a buildup of leachate head on the underlying liner, potentially increasing advective contaminant transport from the landfill and contaminating adjacent groundwater. In this paper, the biogeochemical model CCBATCH is used to link a primary cause of leachate collection system failure—CaCO3(s) precipitation?to anaerobic degradation of volatile fatty acids (VFAs) in column reactors used to study the clogging phenomena. One key to applying CCBATCH correctly was dividing the VFA conversion into two steps: conversion of propionate to acetate, carbonic acid, and methane; and acetate conversion to methane and carbonic acid. The primary driver for CaCO3(s) precipitation in the columns was acetate fermentation to CH4 and H2CO3, which increased the total carbonate concentration in the leachate and shifted the acid/base control to a weaker acid system, which caused an increase in solution pH. A second key to proper modeling was adding CO2(g) gas transfer to CCBATCH. The modeling results indicate that the kinetics of CO2(g) gas transfer was a key control over leachate chemistry once acetate fermentation was nearly complete. These results suggest that the best approach for the long-term control of CaCO3(s) clogging may be to enhance CO2(g) gas transfer from the leachate while buffering the leachate pH to near neutral. Taken together, these actions should decrease the yield of CaCO3(s) precipitated per mass of acetate removed.     

铜钼精矿制取钼酸铵试验研究

铜钼精矿氧化焙烧-二段氨浸得到铜钼氨溶液,通过考察净化剂用量、时间、温度对净化过程的影响,净化得到的钼酸铵溶液酸沉得到的四钼酸铵符合国标二级品的标准要求。     

Molybdenum in Nb-C alloys

The effects of molybdenum alloying additions to niobium on the carbide phases and their precipitation behavior were investigated. The experimental alloys included Nb-0.1C, Nb-15Mo-0.1C, and Nb-30Mo-0.1C. After selected heat treatments the microstructural changes were determined by metallography and the carbide phases were extracted and identified by X-ray diffraction and chemical analysis. The results are essentially in agreement with recent phase diagram determinations. Additions of 30 wt pct Mo appears to slightly increase the solubility of carbon in niobium at temperatures around 1650°C. The solubility of molybdenum in Nb₂C is very small. Discontinuous precipitation of β-Nb₂C was found to occur in the Nb-30Mo-0.1C alloy during annealing at 1200°C. The important, overall effect of molybdenum in Nb-C alloys is to decrease the rate of niobium carbide precipitation so that appreciable carbon supersaturation can be achieved even after comparatively slow furnace cooling.     

硅钼蓝分光光度法测定六硼化镧中酸溶硅的研究

LaB6经稀硝酸分解,在0．1mol／L硫酸介质中,正硅酸与钼酸铵生成黄色的硅钼杂多酸,提高硫酸浓度至1．2mol／L以消除磷、砷的干扰,用抗坏血酸将硅钼黄还原成硅钼蓝,考察了分光光度法的最大吸收波长为660nm;该方法适宜于LaB6中硅含量的测定;加标回收率及精密度实验都符合实验要求。     

柠檬酸掩蔽钨硫氰酸盐光度法测定钨铁中钼量

详细地研究了用硫氰酸盐光度法测定钨基试样中钼量的方法。采用过氧化钠分解试样后,干过滤使铁、锰等与钨钼分离,用柠檬酸络合钨,于约1 1mol/L的硫酸介质中,以铜盐为催化剂,硫脲为还原剂,用硫氰酸盐光度法测定钼量。分析结果令人满意。     

硝酸铅容量法测定钼精矿中钼量

通过选择适量的硝酸铅标准溶液，使钼呈钼酸铅沉淀，用EDTA反滴定法测定钼精矿中的钼量。方法结果准确，重现性好。     

微合金钢中钛析出相的氯化钾-柠檬酸体系提取及各相的分离测定

对含钛微合金钢的钛相进行分离和测定,建立了一种快速分离微合金钢中钛析出相的定量方法。通过优化试验选择75g/L氯化钾溶液-5g/L柠檬酸-去离子水体系代替传统的甲醇电解液提取微合金钢中钛析出相,于0℃电解可以克服低温电解速度慢的问题。用2.4mol/L HCl分解细粒碳化钛,1mol/L HNO₃分解粗粒碳化钛,硝酸和过氧化氢分解氮化钛,采用电感耦合等离子体原子发射光谱法(ICP-AES)测定各相中钛的含量。差减法得到固溶钛以及用碳硫分析仪测定残渣中硫含量换算得到硫化钛含量。细粒碳化钛占钛相的34.27%,粗粒碳化钛占钛相的22.38%,氮化钛占钛相的14.68%,硫化钛占钛相的6.29%,固溶钛占钛相的16.78%。方法的钛析出相回收率为94.41%。     

A simple method for extracting DNA from old skeletal material

Extraction of DNA from old skeletal material is of great importance in the identification of human remains, but is particularly difficult because the methods currently employed, especially those using phenol/chloroform, are not always satisfactory. A simple technique based on the removal of non-nucleic acid material by salting out (precipitation) with saturated sodium acetate is described; the presence of DNA in the extract being confirmed by amplification of selected sequences of the HLA-DRB1 gene using the polymerase chain reaction (PCR). The method was applied to fresh bone (five femoral heads and six vertebral bodies) and to bone from two forensic cases, 3 and 9 months post-mortem, respectively. Parallel extractions using the phenol/chloroform technique were performed on all samples in order to compare the efficiency of the two methods. Using sodium acetate precipitation, amplifiable DNA was consistently extracted from fresh bone, as well as from the two forensic cases. With the phenol/chloroform method, amplification was successful in only 7 out of 11 instances with the fresh bone samples and failed in both forensic cases. The studies also showed that an effective way of removing PCR inhibitors is to subject the extract to agarose gel electrophoresis, isolate the high molecular weight area and re-extract the DNA from the gel by boiling. It was concluded that the sodium acetate method is a valid alternative to established techniques for extracting DNA from bone and that it offers the advantages of being simple, quick, inexpensive and avoids using hazardous reagents.