Acid equilibrium during bioleaching of alkaline low-grade sulfide copper ore

This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.

Solid-Liquid Equilibrium of Terephthalic Acid in Several Solvents

Terephthalic acid(PTA) is practically one of the main materials of polyester. Its corresponding solid-liquid equilibrium data will provide essential support for industry design and further theoretical studies. In this work,solid-liquid equilibriums of terephthalic acid in four solvents, N,N-dimethylformamide, N,N-dimethylacetamide,dimethylsulphoxide and N-methyl-2-ketopyrrolidene, were determined in the temperature range from 293.15 K to 364.6 K by dynamic method. All these data were regressed by λh model, Wilson model and NRTL model, average absolute relative deviations of which are 1.25%, 15.02% and 7.22% respectively. It indicates that λh model is mostsuitable for description of the solid-liquid equilibrium containing PTA.

Solvent extraction equilibrium of dysprosium(Ⅲ) from nitric acid solutions with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester

In view of the importance of solvent extraction of rare earth metals with the acidic organophosphorous reagent,the development of a chemically based model applicable to high concentration is desired.In the present study,the equilibrium distribution of dysprosium(Ⅲ)between an aqueous nitric acid solution and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A)was measured in the range of an initial aqueous dysprosium(Ⅲ)concentration from 1.0×10-3to 1.0×10-1kmol/m 3and PC88A concentration from 0.16 to 0.65 kmol/m3in Shellsol D70 as the diluent.The obtained data were analyzed using the chemically based model in order to correlate the equilibrium distribution ratios.In this model,dysprosium(Ⅲ)was assumed to be extracted with the PC88A dimer as a 1:3 complex,the activities were considered for the aqueous species,and the effective concentration of the PC88A dimer was calculated using Alstad's empirical equation.As a result,the apparent extraction equilibrium constant was determined to be 253(kmol·m- 3)-2with an excellent correlation between the experiment and calculation results in the wide range of the logarithm of the distribution ratio from-2 to 3.5.In conclusion,the methodology in this model would be effective for quantitative description of solvent extraction behavior of general rare earth elements as well as dysprosium.

Adsorption of U(Ⅵ) from acid solution on a low-cost sorbent:equilibrium, kinetic, and thermodynamic assessments

In this paper,waste clay was cured with ethyl acetate to obtain treated clay(TC),which was modified with gallic acid to obtain a low-cost sorbent that was characterized by EDX,SEM,and FTIR analysis.Uranium(Ⅵ)adsorption was achieved using the batch adsorption method on the TC and gallic acid-modified treated clay(GMTC).The maximum uptakes of U(Ⅵ)on TC and GMTC were 37.2 and 193.0 mg/g,respectively.The U(Ⅵ)adsorption kinetics on the TC and GMTC sorbents were well-fitted by the pseudo-second-order mechanism,and the adsorption equilibrium followed the Langmuir model.The optimum parameters were applied to El Sela leach solution for uranium recovery.

Salt Effect on the Liquid-Liquid Equilibrium of （Water ＋ Propionic Acid ＋ Cyclohexanol） System at T=（298.2,303.2,and 308.2） K

Effects of salt and temperature on the liquid phase equilibrium of the(water + propionic acid + cyclohexanol) system were investigated.The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5,1.0,1.5,2.0,and 2.5 mol·dm3 and in absence of the salt at T=(298.2,303.2,and 308.2)K were determined.The experimental results were correlated based on the Othmer-Tobias equation and Pitzer ion-interaction model.Thermodynamic properties such as distribution coefficients and activity coefficients of propionic acid in water + cyclohexanol were determined.In addition,the separation factor,S,of the chosen solvent was obtained for the investigated system.

Isobaric Vapor-Liquid Equilibrium of Binary Systems： p-Xylene ＋ （Acetic Acid, Methyl Acetate and n-Propyl Acetate） and Methyl Acetate ＋ n-Propyl Acetate in an Acetic Acid Dehydration Process

The vapor-liquid equilibrium data of four binary systems (acetic acid +p-xylene, methyl acetate +n-propyl acetate, n-propyl acetate +p-xylene and methyl acetate +p-xylene) are measured at 101.33 kPa with Ellis equilibrium still, and then both the NRTL and UNIQUAC models are used in combination with the HOC model for correlating and estimating the vapor-liquid equilibrium of these four binary systems. The estimated binary VLE results using correlated parameters agree well with the measured data except the methyl acetate +p-xylene system which easily causes bumping and liquid rushing out of the sampling tap due to their dramatically different boiling points. The correlation results by NRTL and UNIQUAC models have little difference on the average absolute deviations of temperature and composition of vapor phase, and the results by NRTL model are slightly better than those by UNIQUAC model except for the methyl acetate +n-propyl acetate system, for which the latter gives more accurate correlations.

Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

Ternary Liquid-Liquid Equilibrium for Systems of Fatty Acid Methyl Ester(Methyl Palmitate/Methyl Stearate)+Ethanol+Glycerol at Atmospheric Pressure

Liquid-liquid equilibrium data of two ternary systems methyl palmitate+ethanol+glycerol and methyl stearate+ethanol+glycerol at(318.2 and 333.2)K and atmospheric pressure were measured. The values of distribution coefficient and selectivity were calculated, which indicates that glycerol can be separated from fatty acid ester by using ethanol as an extraction solvent. The consistency of the isothermal tie-line data were checked by the Othmer-Tobias equation. The correlation coefficients R2 are higher than 0.993,9 for all the fitted curves. The NRTL activity coefficient model was applied to the correlation of the measured tie-line data. The root mean square deviation(RMSD)values are less than 0.007 for all the systems, which shows a good predictive capability of this model for such systems.

多相体系的酸碱解离平衡:气相的影响

酸碱平衡是化学教学中十分重要的内容,而在目前的教学中仅仅描述了均相溶液中的酸碱解离与pH缓冲问题,并未描述多相体系中气相成分对体系酸碱解离与pH缓冲的影响。针对该问题,本文以典型的气溶胶多相体系为例,通过对多相缓冲理论和有效解离常数pK_(a)^(*)的分析,讨论了多相体系中组分挥发性和吸湿性对体系酸碱平衡的影响,进而开拓学生思维,并为多相体系酸碱平衡的教学提供新范例。

恒浓点与水硫比

恒浓点是一系列的,共沸点只是其中之一。恒浓点为水逃逸性转折点、酸腐蚀性分界点。水硫比是H_(2)O与SO_(3)分子数量的比值,统一了气体与硫酸浓度间的关系。相对水硫比为气液平衡状态下的气相水硫比与硫酸中的水硫比之比值,随硫酸温度升高呈扇状展开。在恒浓点相对水硫比等于1;硫酸浓度低于恒浓点时相对水硫比大于1,酸中H_(2)O易逃逸;硫酸浓度越过恒浓点则相对水硫比小于1,SO_(3)更易逃逸,酸中H2O与SO_(3)的化学键弱于H_(2)O与H_(2)SO_(4)间的氢键。酸热回收第2级流下的酸与1级上塔酸混合呈区域不均,2级酸多处相对水硫比上移、气中水分含量大增而引起空间冷凝。半干法制酸用吸湿塔去除水汽,再由吸收塔完成吸收。湿法制酸亦可用两个填料塔——先吸收再吸湿。图示了两种工艺的相对水硫比与硫酸温度的关系,半干法与湿法制酸间是质的不同。

磷酸/磷酸酯基功能材料的制备及提铀性能研究

针对硝酸体系低浓度铀的吸附问题,以氯甲基化苯乙烯-二乙烯苯共聚物为骨架,以三氯化磷为功能化试剂,通过傅克烷基化反应及淬灭-水解/醇解反应,将长链羟基及烷基接枝到树脂上,从而得到分别含有磷酸和磷酸酯基功能基团的提铀树脂。通过红外光谱、元素分析、热重分析,对树脂进行了结构表征;在树脂制备过程中,考察了不同工艺参数对树脂含磷量及铀吸附性能的影响,确定了树脂合成的最优工艺参数。通过静态试验考察了pH、平衡铀浓度、吸附时间对树脂材料吸铀性能的影响,并进行了解吸剂的筛选和树脂重复使用性能的验证。结果表明:制备的磷酸酯基提铀树脂对于模拟溶液(1 mol/L HNO_(3)+1 mol/L NaNO_(3))中的低浓度铀(<20 mg/L)具有较好的吸附效果,该树脂对铀的饱和吸附容量为21.9 mg/g干树脂,吸附后残余尾液中的铀质量浓度<0.05 mg/L;以0.4 mol/L NaHCO_(3)与0.1 mol/L Na_(2)CO_(3)作为复合解吸剂,铀的解吸率为98.3%。制备的磷酸酯基提铀树脂可用于酸性硝酸体系中低浓度铀的吸附分离。

甲基丙烯酸水溶液萃取分离液液相平衡数据测定与关联

针对甲基丙烯酸(MAA)与水(H_(2)O)形成共沸混合物、MAA水溶液分离难的问题,开展了MAA水溶液提纯过程萃取剂筛选、MAA H_(2)O萃取剂三元液液相平衡数据测定与关联等研究。通过对甲苯、正己烷、环己烷、邻苯二甲酸二丁酯(DBP)4种萃取剂的萃取效率进行考察,确定DBP为综合性能最优的萃取剂。测定了常压条件下20、30、40℃时H_(2)O MAA DBP三元体系的液液相平衡数据,实验结果通过了Hand方程和Othmer Tobias方程对相平衡数据的一致性验证,线性相关性系数R^(2)值超0.99。使用UNIQUAC模型来拟合实验数据得到三组分二元交互作用参数,模型预测值与实验值的均方根偏差小于0.07,表明实验数据及拟合参数均有较高的准确性,为DBP应用于工业MAA水溶液提纯过程开发提供基础。

Extraction Equilibria of Trimellitic and [ 1,1′-Biphenyl]-2,2′-dicarboxylic Acid with 1-Octanol, 50%TBP, and 10%TRPO in Kerosene

探索从氧化提取芳香的酸产品的可行性煤，二芳香的酸， trimellitic 并且[1,1联本基] -2,2-dicarboxylic 酸，当溶质，和酸的抽取平衡与 1-octanol 被学习，被选择，在煤油的50% tributyl 磷酸盐( TBP )，并且在煤油的10% trialkylphosphine 氧化物( TRPO )。结果证明抽取的度[1,1 联本基]-2,2-dicarboxylic 酸比为所有溶剂的 trimellitic 酸的大，并且有 TRPO 的抽取能力是比有 TBP 的那个更有效的。芳香的 polyacid 的抽取行为与羧基的酸的不同，并且有 TBP 和 TRPO 的芳香的酸的反应抽取功能不象羧基的酸的一样有效。1-octanol 能被用来搬迁[1,1 联本基] 从 trimellitic 酸的混合的 -2,2-dicarboxylic 酸并且[1,1 联本基]-2,2-dicarboxylic 酸。因为弱氢契约协会存在在之间哦在在芳香的酸的 1-octanol 和 COOH，引得出的选择[1,1 联本基] 到 trimellitic 酸的 -2,2-dicarboxylic 取决于 stoichiometric 比率。

Relative Basicity of Trioctylamine to Carboxylic Acid in Selected Organic Diluents

trioctylamine ( TOA )的相对盐基度，pK_(一，噻开黑)在 protic polar diluent ( 1-octanol )， non-protic polar diluent [甲基.异丁基酮( MIBK )]并且惰性diluent ( CCl_4 )为pK_的 11 单音羧基的酸，和依赖被决定(一，噻开黑)在溶质和diluent 的性质上，类型被讨论。结果显示出那pK_(一，噻开黑)与溶质由半中立化决定羧酸在为 fixedTOA 集中的 l-octanol】MIBK】CCl_4 的顺序，并且它与与提取的溶质(酸味和 hydrophobicity )的二个参数增加 carboxylicacid.Compared 的酸味和 hydrophobicity 增加，pK_(一，噻开黑)对 acid.A 的 hydrophobicity 更敏感代表在明显的抽取平衡(K_( 11 ))和系统性质之间的关系的数学方程(pK_(一，噻开黑)并且 pK_a )被建议：Ig K_(11 )=2pK_( 一，噻开黑)- pK_a.It 被证明抽取平衡 ofmono 羧基的酸能被上述方程与合理精确性预言。

Measurement and Correlation for Solubility of Adipic Acid in Several Solvents

Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure sol-vents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by λ h, NRTL, Wilson, and the modified Wilson models. For the study of six, λ h, NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the λ hmodel is the most suitable for description of the solid-liquid equilibrium containing adipic acid.

Solubility of Glutaric Acid in Cyclohexanone,Cyclohexanol,Their Five Mixtures and Acetic Acid

By using the laser-monitoring technique,solid-liquid equilibrium data of glutaric acid in cyclohexanol,cyclohexanone,their five mixed solvents and acetic acid were measured within the temperature range from 292.15K to 354.60K by dynamic method.Empirical formula and λh equation were used to correlate the solubilities of glutaric acid in eight solvents.The maximal average relative deviations were 1.15% and 2.20% by using the em-pirical formula and λh equation to correlate the solubility data.The results showed that the empirical formula and λh model could correlate the solubility data of glutaric acid in eight solvents.In addition,the solubility data of glutaric acid in five mixtures(cyclohexanone+cyclohexanol)could be predicted with the NRTL equation utilizing the pa-rameters of the binary systems.The total average relative deviation was 3.60%.The results indicate that the NRTL equation could well predict the solubilities of glutaric acid in the mixed solvents of cyclohexanone and cyclohexanol.

Solubilities of Isophthalic Acid in Acetic Acid ＋ Water Solvent Mixtures

The solubilities of isophthalic acid(1) in binary acetic acid(2)+water(3) solvent mixtures were determined in a pressurized vessel.The temperature range was from 373.2 to 473.2K and the range of the mole fraction of acetic acid in the solvent mixtures was from x2 = 0 to 1.A new method to measure the solubility was developed,which solved the problem of sampling at high temperature.The experimental results indicated that within the temperature range studied,the solubilities of isophthalic acid in all mixtures showed an increasing trend with increasing temperature.The experimental solubilities were correlated by the Buchowski equation,and the calculate results showed good agreement with the experimental solubilities.Furthermore,the mixed solvent systems were found to exhibit a maximum solubility effect on the solubility,which may be attributed to the intermolecular association between the solute and the solvent mixture.The maximum solubility effect was well modeled by the modified Wilson equation.

Behaviour of Tributylamine as Entrainer for the Separation of Water and Acetic Acid with Reactive Extractive Distillation

A new separation method, reactive extractive distillation, was put forward for separating water and acetic acid. The separation mechanism was analyzed through infrared spectra technique. Isobaric vapor-liquid equilibrium (VLE) data at 101.33 kPa for the binary or ternary systems consisting of water, acetic acid and tributylamine were measured. The activity coefficients were correlated by using Wilson, NRTL, and UNIQUAC Equations.The VLE experiment showed that tributylamine could enhance the relative volatility of water to acetic acid. An extractive distillation experiment was carried out and proved that tributylamine was a good extractive solvent.

Extraction Behavior and Wastewater Treatment of Amino Sulfonic Acid with Alamine 336

p-Amino benzene sulfonic acid (PABSA) is selected as the solute with amphoteric functional group, Lewis acid and Lewis base, to be separated from its dilute solutions. An aliphatic, straight chain amine, Alamine 336, is used as the extractant, and kerosene, 1-octanol, chloroform, butyl acetate and benzene as the diluent. The effects of pH value of solution, extractant concentration, salt and types of diluent on the distribution coefficient, D, are studied. There is a peak of D value with pH value of solution, the polar diluents are favorable for extracting PABSA, and the salt in aqueous phase reduces values of D apparently. The extraction equilibrium is described using the mass action law, and the calculated data according to the proposed model agree with the experimental data well. Further, the extraction behavior for other amino benzene sulfonic acids, 1-amino-8-naphtol-3,6-disulfonic acid (H acid) and 4,4′-diaminostilbene-2,2′-disulfonic acid (DSD acid), is investigated in a wide pH value region. Finally. H acid and DSD acid are successfully removed from wastewater by the extraction with Alamine 336.