水合二氧化钛晶种粒径的控制研究

硫酸氧钛溶液(简称钛液)在适当温度和水合TiO_2晶种的作用下,水解生成水合TiO_2(俗称偏钛酸)和硫酸。这是硫酸法制备钛白粉的最重要工艺过程。钛白粉的质量与用途与钛白粉的粒度和粒度分布有直接关系,因此水合TiO_2晶种粒径大小等就直接影响到最终产物     

七重水合硫酸钴的制备和性质

不久前,钱秋宇等报道了七重水合硫酸锌的制备及其热学性质,本文旨在研究其同型的七重水合硫酸钴。用 H-NMR法证明此新化合物中的氘浓度为99.7原子％,并用差热分析法测定了脱水温度的同位素效应。重水合物的制备七水合硫酸钴,北京化工厂产品,分析纯,经重结晶一次提纯。在一台北京大学自制的BD-74型X射线衍射仪上测得CuKa(波长1.5418     

硫酸的溶解热及其演示实验

硫酸有很大的溶解热,这是由于它在溶解过程中生成水合物和水合氢离子引起了能量的变化而造成的。溶解热可用系统溶解前后的焓增量△H表示,其基本数据是通过实验测定的。在25℃、常压下将1摩尔H_2SO_4与n摩尔H_2O混溶,系统这时的状态可表示为: H_2SO_4+nH_2O(?)硫酸溶液     

测定硫黄中硫的快速中和法

测定硫黄中硫的方法,中国药典采用硫酸钡重量法,样品用氢氧化钾醇溶液溶解,用过氧化氢氧化,本文仍采用药典溶样的方法,并将重量法改为中和滴定容量法,用过量的乙醇制氢氧化钾标准溶液溶样,借过氧化氢将硫氧化成硫酸根,消耗与硫等当量的氢氧化钾,剩余的氢氧化钾用标准盐酸滴定,同时做空白试验,即可求出试样中硫的含量。     

对硝基苯甲酸制备实验的改进

对硝基苯甲酸的制备实验是有机化学实验教学中氧化反应的典型代表。为了提高对硝基苯甲酸的产率、简化后处理步骤,对对硝基苯甲酸的合成条件进行了改进。探究了反应时间、反应温度和相转移催化剂对对硝基苯甲酸产率的影响。通过改变氧化剂种类、加入相转移催化剂、改变加料方式等措施有效地提高了产率。改进后产物的产率比教材中的重铬酸钠-硫酸氧化法提高了16.8%。     

D型大孔磺酸树脂催化松节油水合一步合成松油醇

以D型大孔磺酸树脂为催化剂,催化松节油水合反应一步法制备松油醇。探讨了溶剂种类、油水比、反应温度和催化剂用量等因素对松油醇产率的影响,通过单因素实验确定了适宜的反应条件为:以10.0mL异丙醇为溶剂,4.0g松节油,4.0g水,反应温度为80℃,催化剂用量为0.4g。在此条件下,松油醇产率为42.1%。催化剂重复使用3次后,松油醇的产率有所降低,将该催化剂用0.1mol/L盐酸或硫酸再生处理后催化活性恢复。该反应为一级反应,80℃时反应速率常数为0.507h-1,反应活化能为126.66kJ/mol。     

塔式法由黄铁矿制备硫酸——师范学院工业化学实验

Ⅰ实验目的: 了解塔式法制造硫酸基本原理及生产过程,并取得在实验室中以塔式法制备硫酸的实验技术。Ⅱ实验步骤和方法: (一)仪器装置:取干燥塔3,4,5平排分置,其中3和5的上口,分别装置分液漏斗9和10于其上部,干燥塔2上部装上滴液漏斗8和输水管12,并联接燃烧室(金属管或瓷管)1和干燥塔3中间,干燥塔6上部装滴液漏斗11,并联接于洗气瓶7和干燥塔5之间,洗气塔7出口处和水压抽气机相联,其装置如图2。     

无机固体酸催化合成乙酸乙酯

介绍了利用一水硫酸氢钠、六水三氯化铁、五水四氯化锡、十二水合硫酸铁铵和水合硫酸铁催化乙醇和乙酸制备乙酸乙酯的方法。     

电化学氟化反应1:三丙胺的电化学氟化

本文报道三丙胺在6～13伏电解电压下进行电化学氟化的实验结果。氟化产率为60%,全氟三丙胺含量为68%。研究了纯化过程中副产物的化学转化和有关组分韵化学结构。电解氟化产物以氢氧化钾-乙醇溶液处理,留有残余氢的副产物其氢原子位于邻近 N 的 C 原子上,说明电化学氟化主要按离子(EC_bEC_n)机制进行。在我们的电解氟化条件下,一些叔胺的产率较文献报道为高。     

电解法制备过二硫酸钾的微型实验研究*

采用硫酸钾-硫酸水溶液为电解液制备了过二硫酸钾。以硫酸钾和浓硫酸反应原理和硫酸氢钾溶解度为基础对电解液的配制方法进行了改进。改进后耗时少,操作简便。采用微型实验和单因素实验探讨了硫酸钾与硫酸配比、时间、电流密度、温度对过二硫酸钾制备的影响。结果表明,微型实验药品用量至少减为原来的五分之一,仪器小型化易得,节能环保,实验效果良好;制备过二硫酸钾的较适宜条件为:硫酸钾与硫酸配比50%、电解时间1.0 h、电流密度1.0 A/cm2和电解液温度-4 ℃;产率20.7%,纯度92.4%。教学改革后学生实验兴趣和主动性大增,绿色化学理念加深,设计实验和探究能力及团队意识增强。     

The electrolyte NRTL model and speciation approach as applied to multicomponent aqueous solutions of H2SO4, Fe2(SO4)3, MgSO4 and Al2(SO4)3 at 230–270 °C

This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe₂O₃) in aqueous ternary and quaternary systems of H₂SO₄, MgSO₄ and Al₂(SO₄)₃ at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H₂SO₄–MgSO₄–H₂O, H₂SO₄–Al₂(SO₄)₃–H₂O at 235–270 °C and H₂SO₄–Fe₂(SO₄)₃–H₂O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al³⁺, Mg²⁺ Fe³⁺ and SO₄²⁻, HSO₄⁻, OH⁻, H₃O⁺, respectively, as well as molecular species. The solid phases were hydronium alunite (H₃O)Al₃(SO₄)₂(OH)₆, hematite Fe₂O₃ and magnesium sulfate monohydrate (MgSO₄)·H₂O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H₂SO₄–Fe₂(SO₄)₃–MgSO₄–H₂O, H₂SO₄–Fe₂(SO₄)₃–Al₂(SO₄)₃–H₂O at 250 °C and H₂SO₄–Al₂(SO₄)₃–MgSO₄–H₂O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data.     

Three-phase extraction study of cyanex 923-n-heptane/H(2)SO(4) system

Phase behavior of the extraction system, Cyanex 923–heptane/H₂SO₄–H₂O has been studied. The third phase appeared at different aqueous H₂SO₄ concentration with varying initial Cyanex 923 concentration and temperature affects its appearance. Almost all of H₂SO₄ and H₂O are extracted into the middle phase. The H₂SO₄ concentration in the third phase increases with the increasing aqueous acid concentration (C_H2SO4,b) while the water content first increases and then reaches a constant value at C_H2SO4,b=11.3 mol l⁻¹. In the region of C_H2SO4,b higher than 5.2 mol l⁻¹, the composition of the middle phase is only related to the equilibrium concentration of H₂SO₄ in the bottom phase. H₂SO₄ and H₂O are transferred into the middle phase mainly by their coordination with Cyanex 923 when C_H2SO4,b is less than 11.3 mol l⁻¹. When C_H2SO4,b is higher than 11.3 mol l⁻¹, excess H₂SO₄ is solubilized into the polar layer of the aggregates. In the region considered, the extracted complex changes from C923 · H₂SO₄ to C923 · H₂SO₄ · H₂O and then to C923 · (H₂SO₄)₂ · H₂O.     

沉淀剂对铜锰复合氧化物变换催化剂构效的影响

以CuSO4.5H2O和MnSO4.H2O为原料,KOH和NaOH为沉淀剂制备了铜锰复合氧化物,考察了其变换反应催化性能,利用XRD、低温氮气吸附法、TG、H2-TPR等对所合成样品进行了表征。以KOH和NaOH为沉淀剂所得沉淀终产物的物相组成和织构明显不同,分别为层状结构碱式硫酸铜Cu4SO4(OH)6.H2O及无定形锰氧化物和Cu2+1O和Mn3O4混合物。两种物相组成和织构完全不同的沉淀终产物焙烧后都生成Cu1.5Mn1.5O4固熔体,在变换反应条件下均转化为Cu和MnO,但其催化性能却有明显差异。以NaOH为沉淀剂,得到以Cu2+1O和Mn3O4复合体为主的沉淀终产物,焙烧及还原后保持了较高的织构稳定性,提高了样品的活性和热稳定性。而以KOH为沉淀剂得到以层状结构碱式硫酸铜Cu4SO4(OH)6.H2O和无定形锰氧化物为主的沉淀终产物,在焙烧过程发生的演变极其复杂,削弱了铜锰组分协同效应,造成其活性和热稳定性极差。研究结果表明,NaOH作沉淀剂所制备样品的织构稳定性、催化活性显著高于以KOH作沉淀剂所制备样品,且热稳定性良好。     

Spectrophotometric investigation of the nature and stability of silver(II) in acidic sulphate media

A spectrophotometric study of silver(II) in sulphuric acid solution indicates the formation of two sulphate complexes, in the range 4–18M H₂SO₄, with absorbance peak maxima at 361 and 260 mμ, respectively. In 15M H₂SO₄ the molar absorptivity of silver(II) is 3.11 × 10⁴ at 361 mμ. Kinetic studies of the reduction of silver(II) by the solvent suggest a rate-determining step first order in silver(II) and yield a pseudo first-order rate constant of 1.9 × 10⁻¹min⁻¹. Further studies as a function of H₂SO₄ concentration show that the specific decomposition rate of the two complexes is identical and that changes in H₂SO₄ concentration only serve to shift the concentration equilibrium between the two complexes.     

Mechanism of Lithium and Cobalt Recovery from Spent Lithium-ion Batteries by Sulfation Roasting Process

Different from the traditional pyrometallurgical recovery process of Li and Co from spent lithium-ion batteries, a new recovery method for Li and Co was established by converting LiCoO₂ into water-soluble metal sulfates by roasting a mixture of LiCoO₂ and NaHSO₄·H₂O. The evolution law of the mixture with increased roasting temperature was investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), in situ X-ray diffraction(XRD), XRD, and X-ray photoelectron spectroscopy(XPS). The results show that the phase transition of LiCoO₂ mixed with NaHSO₄·H₂O with increased temperature proceeded as follows:LiCoO₂, NaHSO₄·H₂O→LiCoO₂, NaHSO₄→Li_1-xCoO₂, LiNaSO₄, Na₂S₂O₇, Na₂SO₄→Li_1-xCoO₂, Co₃O₄, LiNaSO₄, Na₂SO₄→Co₃O₄, LiNaSO₄. The reaction mechanism of this roasting process may be as follows:LiCoO₂+NaHSO₄·H₂O→1/2Li₂SO₄+ 1/2Na₂SO₄+1/3Co₃O₄+1/12O₂+3/2H₂O, Li₂SO₄+Na₂SO₄=2LiNaSO₄.     

Ferroelectricity based on coordination compound： Transition metal Co（Ⅱ） sulfates templated by homochiral 2-methylpiperazine （C5H14N2）[ Co（H2O）6]（SO4）2

Reacting homochiral （R）-2-methylpiperazine with cobalt sulfate heptahydrate by the solution method in the presence of concentrated sulfuric acid （H2SO4） yielded two coordination compounds （C5H14N2） [CO（H2O）6]（SO4）2 （1 and 2）. They are polymorphs, but their hydrogen bonds structure differ significantly. Both 1 and 2 crystallize in chiral space group P21 which is related with point group C2, and experimental results suggest that 1 displays ferroelectric behaviors.     

含磷活性炭作为双电层电容器电极材料的电化学性能

采用磷酸活化和磷酸改性制备了不同种类的含磷活性炭,采用元素分析、X射线光电子能谱(XPS)和氮气吸附等手段分析了活性炭的元素含量、表面化学性质和孔隙结构,采用恒电流充放电、循环伏安和交流阻抗分别考察了活性炭在KOH和H_2SO_4电解质溶液中作为超级电容器电极材料的电化学性能,采用自由截距多元线性回归拟合统计分析研究了活性炭电极比电容量的影响因素,应用三电极体系分析了磷元素对活性炭电化学性能的影响机理。研究结果表明,活性炭掺杂的磷引入了赝电容,提高了活性炭电极的比电容量,磷元素含量为5.88%(w)的活性炭的比电容量在0.1 A·g~(-1)下达到185 F·g~(-1)。统计分析结果显示,活性炭的中孔有利于电解质离子向微孔内的扩散。在6 mol·L~(-1)KOH电解质溶液中,孔径在1.10-1.61 nm、2.12-2.43nm及3.94-4.37 nm范围内是电解质离子在活性炭孔隙内部形成双电层的主要场所;在1 mol·L~(-1)H_2SO_4电解质溶液中,孔径在0.67-0.72 nm范围内有利于双电层电容的形成。     

燃烧与催化气化灰中铝溶出行为的研究

实验对比了燃烧灰与负载Na_2CO_3催化气化灰中Al的溶出行为,考察了Na_2CO_3负载量(0-15%,质量分数)和温度(600-1 000℃)对催化气化灰中主要矿物组成与Al溶出行为的影响。同时,采用XRD分析了燃烧灰、催化气化灰以及酸浸残渣的主要组成。结果表明,燃烧灰的主要组成为莫来石,而催化气化灰的主要组成为硅铝酸钠((Na_2O)_(0.33)NaAlSiO_4)。6 mol/L硫酸、60℃和30 min浸取条件下,燃烧灰的浸出率只有40%,而Na_2CO_3负载量为10%的催化气化灰的浸出率达到88%。催化气化灰更易于回收灰中的Al。     

Modelling of calcium sulphate solubility in concentrated multi-component sulphate solutions

The chemistry of several calcium sulphate systems was successfully modelled in multi-component acid-containing sulphate solutions using the mixed solvent electrolyte (MSE) model for calculating the mean activity coefficients of the electrolyte species. The modelling involved the fitting of binary mean activity, heat capacity and solubility data, as well as ternary solubility data. The developed model was shown to accurately predict the solubility of calcium sulphate from 25 to 95 °C in simulated zinc sulphate processing solutions containing MgSO₄, MnSO₄, Fe₂(SO₄)₃, Na₂SO₄, (NH₄)₂SO₄ and H₂SO₄. The addition of H₂SO₄ results in a significant increase in the calcium sulphate solubility compared to that in water. By increasing the acid concentration, gypsum, which is a metastable phase above 40 °C, dehydrates to anhydrite, and the conversion results in a decrease in the solubility of calcium sulphate. In ZnSO₄–H₂SO₄ solutions, it was found that increasing MgSO₄, Na₂SO₄, Fe₂(SO₄)₃ and (NH₄)₂SO₄ concentrations do not have a pronounced effect on the solubility of calcium sulphate. From a practical perspective, the model is valuable tool for assessing calcium sulphate solubilities over abroad temperature range and for dilute to concentrated multi-component solutions.     

Supported liquid membranes (SLM) for recovery of bismuth from aqueous solutions

In this study, the extraction of Bi(III) from synthetic solutions of 2 M H₂SO₄/0.5 M HCl by supported liquid membranes (SLM) using tri-n-octylphosphine oxide (Cyanex 921) as extractant is reported. First, the nature of the Bi(III)/Cyanex 921 solvates extracted to organic phase (in a solvent extraction system) was determined by the slope method. It was found that Bi(III) reacts with 2 molecules of Cyanex 921 to form the solvate BiCl₃·2Cyanex 921. In the recovery of Bi(III) by the SLM system, parameters that influence extraction efficiency were evaluated, including: support, feed solution and stripping solution nature, and extractant concentration in the organic phase which impregnates the support. Results indicate that Cyanex 921 dissolved in kerosene is not able to extract Bi(III) from H₂SO₄ media. Moreover, transfer of H₂SO₄ was observed. HCl addition to the feed solution up to a maximum concentration of 0.5 M increases Bi(III) extraction. Further increase in HCl concentration causes a decrease in Bi(III) transfer. Likewise, the concentration of Cyanex 921 in the SLM organic phase which produced the maximum Bi(III) extraction was found to be 0.3 M. The performance of H₂O and 0.2 M H₂SO₄ as stripping solutions was evaluated, and it was found that only H₂SO₄ enabled Bi(III) transfer.