间接螯合滴定法测定硫化矿中的硫

硫的测定大都采用硫酸钡重量法和燃烧法,操作繁琐。本文采用HNO_3-KClO_3溶样,以 PbSO_4形式沉淀硫,过滤后,将硫酸铅溶于 NaAc-HAc中,直接用 EDTA 标准滴定。方法快速、简便,干扰离子少,与硫酸钡重量法比较,结果满意。

螯合沉淀法处理含铜、铅废水的研究

采用一种新型的重金属螯合剂五硫代碳酸钠(Na2CS5)处理铜铅废水。探讨五硫代碳酸钠的用量、pH、反应时间等对去除铜铅的影响。结果表明,含Cu2+和Pb2+浓度各为200 mg.L-1的混合模拟废水,当n(Na2CS5)∶n(Cu2++Pb2+)=1.5,pH 5.0,反应15 min,Cu2+和Pb2+去除率各高达99.81%和99.94%,残留的浓度各降至0.38 mg.L-1和0.12 mg.L-1,达到《污水综合排放标准》(GB8978-1996)的一级排放标准。

过氧化氢氧化硫化钠的闭系动力学行为

系统研究了过氧化氢(H_2O_2)氧化硫化钠(Na_2S)反应在封闭体系中的复杂动力学行为。通过固定两种反应物浓度,改变其中一种反应物浓度,考察了酸度、反应物浓度对硫沉淀的形成、准振荡现象的产生和反应速率的影响。结果表明:酸度越小,反应速率越慢,反应过程中产生的多硫离子被进一步氧化为无色SO_4^(2-);反之,在酸度足够大时,析出白色硫沉淀且不能被进一步氧化。H_2O_2浓度越大,反应速率越快,同时有利于硫的消耗。Na_2S浓度越大,反应过程中产生的硫沉淀越少,反应速率也越慢。酸度、H_2O_2或Na_2S浓度在某一中间值时,产生明显的准振荡现象。该研究对于减少工业和城市废水中硫化物的污染提供了一种参考思路。

高含硫气体中元素硫溶解、沉积的机理分析

元素硫的溶解与沉积是高含硫气体有别于常规气体的一个最大区别,也是高含硫气体中一个最重要的研究内容。由于富含H2S、CO2等酸性气体、元素硫能以多种形式存在于高含硫气体中。研究了高含硫气体中元素硫的溶解与沉积,主要包括溶解与沉积的机理和各种影响因素的分析,总结了在不同温度、压力和气体组成成份的条件下,硫溶解和沉淀的不同形态。

含硫气田污水三级除硫技术研究

针对高含硫气田生产污水处理难度大的特点,论文在分析研究含硫污水特性及目含硫污水除硫技术现状的基础上,构建了汽提-氧化-沉淀三级除硫工艺技术,其中汽提除硫作为一种预除硫工艺,可以将高含硫酸性污水的中硫除至300mg//L;氧化除硫可以作为中级除硫技术,根据氧化除硫的速度和效率,选择二氧化氯作为氧化除硫剂;沉淀除硫将低含硫污水中的硫除至1mg/L以下,通过实验研究选择ZnSO4作为二次脱硫沉淀药剂。论文所提出的工艺处理方法为含硫污水的处理提供了参考。

变换汽提塔顶冷凝液加药脱硫试验与研究

陕西长青能源化工有限公司600 kt/a甲醇装置采用GE水煤浆加压气化、耐硫变换工艺等,针对其变换汽提塔顶冷凝液(含硫氨水)无法用于氨法烟气脱硫系统的问题,以及变换冷凝液氨回收装置高投入和低产出的现状,借鉴污水脱硫技术,分析与探讨采用药剂氧化法或药剂沉淀法处理含硫氨水的可能性,并开展了一系列相关试验:前期探索与试验的基础上进行了含硫氨水双氧水脱硫工业试验,在H_(2)O_(2)/H_(2)S(摩尔比)为4~6时脱硫率可达90%以上;进行了脱硫氨水用作氨法烟气脱硫系统补充氨源的试验,运行一段时间后出现脱硫塔浓缩段浆液pH高于4.0、硫酸铵结晶变细不易分离等现象,对其原因进行分析并提出了后续改进意见。相较于药剂氧化法脱硫,药剂沉淀法脱硫费用更低,更广泛应用于污水处理中,对常用脱硫药剂应用于含硫氨水脱硫进行调研,初步分析认为,控制含硫氨水中NH_(3)浓度不高于1.5%的情况下,硫酸亚铁可将S^(2-)含量脱除至10 mg/L,使其满足氨法烟气脱硫系统对回收氨水的要求。

钼酸铵溶液的净化研究

采用硫化沉淀和离子交换法对某低品位复杂钼精矿氨浸后的钼酸铵溶液进行净化研究。研究结果表明：硫化沉淀法能够有效的沉淀钼酸铵溶液中的Cu^2＋,Fe^2＋及Pb^2＋,3种杂质离子的沉淀率分别达到99.60%,99.24%和100.00%。采用717阴树脂对硫化沉淀后的上清液进行深度净化,树脂对钼的动态饱和吸附量为125.28 g/L湿树脂。条件实验确定的离子交换最佳技术工艺条件如下：初始料液pH为9-10,钼质量浓度为11.46 g/L,流速为4 mL/min,此条件下树脂对钼的吸附效果最佳。采用5 mol/L NH4Cl和4 mol/L NH3·OH的混合液对负载钼的树脂进行解吸,解吸率可达99.85%,解吸液中钼质量浓度达167.72 g/L。

铜银中间合金中银的测定

采用硝酸溶解试样,利用硫氰酸盐沉淀滴定法测定银的含量,试验采用最佳滴定酸度和最佳指示剂用量,获得了较好的滴定终点。平行测定结果表明,铜-银中间合金中银的质量分数在2%～10%之间,银含量测定的相对标准偏差为0.277%。

Separation and enrichment of elemental sulfur and mercury from hydrometallurgical zinc residue using sodium sulfide

The separation and enrichment of mercury and the recovery of elemental sulfur from flotation sulfur concentrate in zinc pressure leaching process were carried out by sodium sulfide leaching and carbon dioxide precipitating. The results show that the leaching rate of elemental sulfur is more than 98%, and 98.13% of mercury is enriched in the residue, under the optimized conditions of sodium sulfide concentration 1.5 mol/L, liquid/solid ratio 6：1 and leaching time 30 min at room temperature. In addition, the content of mercury is enriched 5.23 times that in the leaching residue. The elemental sulfur is precipitated from leaching solution under conditions of carbon dioxide flow rate 200 mL/min and blowing time 150 min, while solution is stirred adequately. The recovery efficiency of elemental sulfur reaches 97.67%, and the purity of elemental sulfur is 99.75%, meeting the requirements of industrial first-rate product standard according to the national standard of GB/T 2449-2006 （PRC）.

2014年几道中考化学计算题的图表解法

化学计算题是中考化学的必考题,初中学生的抽象思维能力偏弱,在解答文字叙述较多的计算题时往往较难发现各物质之间的质量关系及相互转变情况。如果我们在分析过程中把题中多个数据辅以简单的图示展开,把表格不完善的数据添加补充,这样就能使有效数据显现,使题意明朗起来,学生就能快速找到突破口并顺利解答。下面就以2014年的几道中考化学计算题为例介绍如何运用图表解法解化学计算题。

Solubility Model of Thiamine Nitrate During Recrystallization Process

The concentration variations of all key components were investigated during recrystallization process of thiamine nitrate, and a mathematic model that is used to show the solubility variations of thiamine nitrate was constructed in this paper. Comparing the predicted values with those experimental results, it was concluded that the model well reflected the solubility variations of thiamine nitrate during recrystallization process. The proposed model was important to study the nucleation process and crystal growth process during recrystallization process, and also provided a beneficial method to study the solubility variations of solute during such precipita- tion process.

综合练习一参考答案

综合练习一参考答案一、二、三、抚松团四、２７．（）制Ｈ。Ｓ气体不能用稀ＨＮＯ。，应改为稀ｎ。ｓｏ。；洗气瓶Ａ与Ｂ位置不对，应对换。（２）作干燥剂吸收水蒸汽；吸收挥发出的ＨＣＩ气体，并降低ＣＩ。在水中的溶解度（３）无水氯化钙（４）黄绿色褪去，瓶壁有淡黄...

酶水解血蛋白制水解蛋白注射液

水解蛋白注射液是目前国内肠道外补充氮素营养的主要来源。虽然复方氨基酸注射液比较先进,但多种纯品氨基酸缺乏,十几种氨基酸很难备齐,且价格昂贵,故在临床上还不能广泛应用。所以研究水介蛋白还相当必要,是符合实际的。水解蛋白是个相当古老的制剂。在生产原料上,传统使用酪蛋白、纤维蛋白和大豆蛋白;在水介方法上主要采用盐酸或硫酸水介,其次则为胰酶水介。在精制脱酸时,应用钙,钡沉淀硫酸。用阴离子交换树脂脱去氯离子。酸水介方法适用于大批生产。

Modeling of the Precipitation Process in a Rotating Packed Bed and Its Experimental Validation

A mixing-precipitation model based on the modified coalescence-redispersion model was presented to describe the flow,mixing,nucleation and growth in a rotating packed bed(RPB) .The model was coupled with population balance,mass balance and crystallization kinetics.It predicted well the influence of coalescence prob-ability,which represents the mixing intensity among droplets,on the particle number density,supersaturation and mean particle size of the produced precipitates.The effects of the radial thickness of packing,liquid flow rate and rotating speed on the product particle size were also investigated.The results indicate that the needed radial length of packing is short for sparingly soluble substance precipitation(about 40-50 mm in this work) ,and the mean parti-cle size of precipitates decreases with the increase of rotating speed and liquid flow rate,respectively.The validity of this model was verified by experiment on BaSO4 precipitation in RPB.

Removal of arsenic from acid wastewater via sulfide precipitation and its hydrothermal mineralization stabilization

To achieve a safe treatment of arsenic-containing acid wastewater,a new process was proposed,including arsenic removal via sulfide precipitation and hydrothermal mineralization stabilization.Under optimal conditions of sulfide precipitation,99.65%of arsenic from wastewater was precipitated in the form of amorphous As2S3.The As leaching concentration of amorphous As2S3 in TCLP(toxicity characteristic leaching procedure)test was up to 212.97 mg/L,therefore,hydrothermal mineralization was adopted to improve the stability of amorphous As2S3.The results showed that the As leaching concentration of mineralized As2S3 was only 4.82 mg/L.Furthermore,the amorphous As2S3 could be transformed into crystallized As2S3(orpiment)in the presence of mineralizer Na2SO4.Simultaneously,the As leaching concentration of crystallized As2S3 was further reduced to 3.86 mg/L.Hydrothermal mineralization was an effective method for the stabilization of As2S3.Therefore,this process has a greater application in the treatment of arsenic-containing wastewater.

Separation and recovery of copper in Cu-As-bearing copper electrorefining black slime by oxidation acid leaching and sulfide precipitation

A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.

Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite(MPr)to treat heavy metal ions in wastewater.Ultrasonic technology was introduced to assist MPr to recover the copper ions.XPS result proves that CuS products exist on the surface of MPr.XRD and SEM results show that the CuS on the particles’surface is stripped under ultrasonic condition.The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model.The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off.The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr;by controlling the amount of MPr,the removal rates of copper and arsenic in copper smelting dust leachate exceed 99%and 95%,respectively.

Recovery of magnetite from FeSO_4·7H_2O waste slag by co-precipitation method with calcium hydroxide as precipitant

Proper utilization of the FeSO4·7H2O waste slag generated from TiO2 industry is an urgent need, and Fe3O4 particles are currently being widely used in the wastewater flocculation field. In this work, magnetite was recovered from ferrous sulphate by a novel co-precipitation method with calcium hydroxide as the precipitant. Under optimum conditions, the obtained spherical magnetite particles are well crystallized with a Fe304 purity of 88.78%, but apt to aggregate with a median particle size of 1.83 μm. Magnetic measurement reveals the obtained Fe304 particles are soft magnetic with a saturation magnetization of 81.73 A-m2/kg. In addition, a highly crystallized gypsum co-product is obtained in blocky or irregular shape. Predictably, this study would provide additional opportunities for future application of low-cost Fe3O4 particles in water treatment field.

Production and characterization of alkaline extracellular lipase from newly isolated strain Aspergillus awamori HB-03

A strain HB-03 to produce alkaline extracellular lipase was isolated from oil-rich soil samples and identified as Aspergillus awamori. The growth conditions and nutritional factors for lipase production by strain HB-03 were optimized, and the maximum lipase production of （45.9±2.3） U/mL was obtained at 30 ℃ and pH 7.0 after 36 h using olive oil （1%） and sucrose （0.5%） as carbon sources and combination of peptone （2%）, yeast extract （0.5%） and ammonium sulfate （0.1%） as nitrogen sources. The lipase was purified to homogeneity with 10.6-fold, 18.84% yield and a specific activity of 1 862.2 U/mg using ammonium sulfate precipitation followed by SephadexG-75 gel filtration chromatography. The purified lipase with molecular mass of 68 ku was estimated by SDS-PAGE. The optimum pH and temperature for the purified lipase were found to be 8.5 and 40 ℃, respectively. The lipase kept more than 80% of activity in pH 7.0-10.0 and temperatures up to 45 ℃. The metal ions of Mn2＋, Ba2＋ significantly enhanced the lipase activity, whereas Cu2＋, Fe3＋ and Mg2＋ strongly reduced the lipase activity. The Km and Vmax values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mrnol/L and 60.6 mmol/（L.min）, respectively. The results show that this novel lipase has potential industrial applications.

Electrodeposition of Pyrite Thin Films for Solar Cell

Formation of pyrite (FeS 2) films through electrodeposition from aqueous solutions which contain different source materials has been investigated. Na 2S 2O 3·5H 2O is used as sulfur source material, FeSO 4·7H 2O, FeCl 2·4H 2O and FeCl 3·6H 2O are used as iron source materials respectively. The samples are annealed in N 2 atmosphere at 400 ℃ and 500 ℃ respectively. From XRD (X-ray diffraction) patterns of the films, it is found that there are peaks of FeS 2, FeS and Fe 7S 8 in all films, but there are sharp and more peaks characterizing FeS 2 in the film from Na 2S 2O 3 +FeSO 4 than other films, and 400 ℃ is the more suitable temperature than 500 ℃ for annealing the samples in N 2 atmosphere. In addition, one solution can be used repeatedly.