锂电解过程中杂质元素的电化学行为

采用循环伏安法研究了锂电解过程中杂质元素的电化学行为。电解过程中杂质元素镁将优先于锂在阴极析出, 然后是金属锂的欠电位沉积形成镁锂合金, 最后才是金属锂的析出, Mg ²⁺的还原电极过程受扩散控制, 扩散系数为1.44×10 ^-5 cm ²/s;微量的Ca ²⁺即发生钙锂共沉积;在含少量氯化钠的熔盐体系中, 杂质元素钠被锂还原并形成合金, 随着电解质体系中氯化钠含量的增加, 金属锂中的钠含量有较大的增加;杂质元素铁优先于锂在阴极析出, 在阴极被还原成海绵铁使阴极钝化, 引起熔盐体系锂的析出电流急剧降低, Fe ³⁺的还原电极过程受扩散控制, 扩散系数为3.14×10 ^-5 cm ²/s。     

碳酸锂在碳酸钠溶液中的溶解度与热力学

采用等温溶解平衡法开展碳酸锂在碳酸钠溶液中(278.15～358.15 K)的溶解平衡实验研究,测定平衡体系碳酸锂溶解度和平衡溶液密度,利用E-DH方程对碳酸锂溶解度实验数据进行关联,标准偏差小于0.01;利用Connaughton方程对液相密度数据进行关联,标准偏差小于2×10^-3。实验和计算研究结果表明：在同离子和盐效应协同影响下,碳酸锂在Na₂CO₃-H₂O体系中溶解度随碳酸钠浓度增加先降低后降低趋势变缓,在278.15～358.15 K温度范围内,溶解度转变折点为碳酸钠浓度约为0.1 mol·kg^-1;通过溶解热力学计算,得到碳酸锂在碳酸钠中的溶解焓变(ΔH_d)、熵变(ΔS_d)和Gibbs自由能变(ΔG_d),结果表明溶解过程为放热、熵减的非自发过程,溶解焓变和熵变随着碳酸钠浓度增加而增加,Gibbs自由能变在0.6 mol·kg^-1出现最大值,且溶解过程为熵控制过程。研究结果将为卤水提锂碳化沉锂过程设计提供基础数据。     

湿法磷酸选择性除杂制工业级磷酸二氢铵

以湿法磷酸为原料, 通过氟化钠选择性沉淀金属离子, 使其以NaMgAl（F, OH）₆·H₂O和XMgAlF₆（X=Na ⁺、K ⁺、NH₄ ⁺）非含磷沉淀析出, 再通氨中和制得工业级磷酸二氢铵。分析了氟化钠加入量对杂质脱除（Na、K、Al、Mg、Fe和Ca等金属阳离子）及液相氟残留的影响, 结果表明氟化钠与磷酸质量比（m_NaF/m）为2.5%时, 效果较好, 此条件下制得的磷酸二氢铵纯度和五氧化二磷收率分别达到98.53%和86.2%。     

磷酸盐分步沉淀不锈钢酸洗污泥浸出液铬铁镍

不锈钢酸洗污泥含有高浓度的Fe、Cr、Ni金属离子,属于危险固体废弃物。本文对不锈钢酸洗污泥浸出液有价组分梯级分离展开研究,探讨了磷酸钠用量、浸出液初始pH、反应温度、搅拌时间对酸洗污泥中浸出液中Fe、Cr、Ni分离效果的影响。确定Cr³⁺沉淀的最佳工艺条件：P/Cr摩尔比为1.00,初始pH为1.00,反应温度为90℃,反应时间70min。Cr³⁺平均沉淀率为94.47%,Fe²⁺、Ni²⁺平均沉淀率为0.88%、0.78%。Fe³⁺优化条件为P/Fe体积比0.80、初始pH为1.00、反应温度为45℃、搅拌时间为60min,Fe³⁺沉淀率最高为99.83%、Ni²⁺沉淀率稳定在0.68%,证明了磷酸盐沉淀法可以有效分离不锈钢酸洗污泥浸出液中Fe、Cr、Ni,为不锈钢酸洗污泥铁、镍、铬分离提供理论依据和技术应用参考。     

硝酸锂改性钛系离子筛的制备及其吸附性能

钛系锂离子筛具有较高的锂吸附容量和稳定性，对其制备工艺及性能进行改进研究具有重要意义。使用硝酸锂和碳酸锂混合物作为锂源，与二氧化钛在500℃下进行固相反应，生成层状钛酸锂；使用0.2 mol·L ^-1盐酸对其酸洗24 h，得到了锂离子筛吸附剂；采用X射线衍射、扫描电镜、粒度分析、N ₂吸附-脱附方法等，对其性能进行了表征；通过锂离子的吸附实验，确定了吸附和再生性能；探究了该新型吸附剂的锂离子吸附机理。结果表明：吸附过程是单分子层化学吸附；经过改性，离子筛颗粒更加细小，孔体积和比表面积更大，结构完整；在70 mg·L ^-1的Li ⁺溶液中，吸附量为25.01 mg·g ^-1，准二级吸附速率常数为0.2762 g·(mg·h) ^-1，吸附速率较之未改性提高了54.56%；该离子筛对浓度为11.6 mg·L ^-1的Li ⁺溶液，其锂去除率可以达到99.77%。     

硫酸铵法利用中低品位锂瓷土矿制备碳酸锂技术研究

针对江西宜丰地区氧化锂质量分数<2.0%以下中低品位锂瓷土矿,研究了硫酸铵法提取碳酸锂技术路线。首先,利用二步焙烧工艺,有利于脱氟、提高锂浸出率,并且能够有效防止结窑现象发生。在浸出液除杂过程中,采用成矾除铝的方法将大量溶出的铝离子转变为KAl（SO₄）₂·12H₂O、NH₄Al（SO₄）₂·12H₂O等有价值复盐,规避了传统石膏法产生的大量固废,有70%的铝离子被转变为矾盐晶体,同时带出大量的结晶水,减轻后续浓缩压力,对比传统的石膏法产生大量固废而言,其优点是显而易见的。碳化反应产品的XRD以及氧化锂含量分析表明,碳酸锂的纯度达到99%以上,全程锂收率为50%~60%。作为提锂实验对比,采用宜春414矿锂质量分数为4.0%的锂云母,由于414矿样中铝的相对含量更低,导致相同的除杂难度下得到的414矿样中浸出液锂离子浓度更高,浓缩倍数更小,414矿样的锂回收率更高。实验结果表明,中低品位锂瓷土提锂的工艺规律,通过适当改变参数,能够应用于难度更低的高品位的锂云母提锂过程。     

锰氧化物锂离子筛的掺杂改性及吸附性能研究

以二氧化锰和氢氧化锂为原料,采用高温固相法合成了锂锰氧化物前驱体,再经离子交换技术制备了锰氧化物锂离子筛并用于溶液中Li ⁺的吸附。考察了Al ³⁺和La ³⁺掺杂对锂离子筛结构、形貌和吸锂性能的影响。用粉末X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）对制备产物进行了表征。结果表明,产物为尖晶石型锰氧化物锂离子筛,呈片状形貌,分散性较均匀。Al ³⁺和La ³⁺掺杂后产物仍然保持尖晶石结构,形貌有所变化,分别呈现出不规则的立方体和纳米颗粒。吸附结果表明,掺杂后锰氧化物锂离子筛的吸附容量有所提高。     

LF精炼废渣水热浸出过程中主要矿相的溶解行为

通过水热浸出实验分别研究了精炼废渣及合成的废渣中2种主要单一矿相12CaO?7Al2O3和2CaO?SiO2的溶解行为,并将二者进行对比分析,探究了LF精炼废渣在水热浸出过程中的溶解行为。结果表明,废渣浸出过程中浸出液的pH?12,且随浸出时间增加,电导率和Ca浓度增加,Al浓度急剧下降,Si浓度低于0.1 mg/L且保持不变;12CaO?7Al2O3浸出过程中,随时间增加,浸出液pH值稳定在约11.3,浸出液中Al浓度增加,Ca浓度略微下降。2CaO?SiO2浸出液中主要为Ca2+,Si浓度低于0.6 mg/L;废渣与单一矿相浸出过程的pH值及Al, Si浓度较接近,可以通过单一矿相的溶解行为研究精炼废渣在水热浸出过程中的溶解行为,但废渣浸出液的Al和Si浓度均低于单一矿相,表明废渣中CaO等其它组分溶解抑制了12CaO?7Al2O3和2CaO?SiO2溶解。     

四川典型新旧磷石膏磷、氟浸出机制

探究四川省某地区磷石膏的浸出液离子成分、浸出液中磷的赋存形态,考察了环境因子对不同年龄磷石膏中磷、氟浸出的影响。结果表明,磷石膏浸出液是一种成分较为复杂的强酸性液体,主要含有SO_4^(2-)、Ca(2-)、Ca⁽²⁺⁾、SO_4(2+)、SO_4^(3-)、F(3-)、F^-、 Mg-、 Mg⁽²⁺⁾、Al(2+)、Al⁽³⁺⁾、Zn(3+)、Zn⁽²⁺⁾等阴阳离子;磷石膏浸出液中大部分磷以可溶性无机磷形态赋存,而颗粒态磷和有机磷较少;高温、低pH值环境、大粒径和较短的堆放时间均有利于磷和氟的释放;磷石膏的磷、氟释放量与水土比成正相关关系,在1 500∶1时接近平衡释放量;新磷石膏中磷和氟的释放量始终高于旧磷石膏。该研究可为磷石膏堆场的污染控制和有效管理提供理论依据。     

Fe/AC催化过氧化氢降解双酚A

传统Fenton反应存在对液相pH要求较高、Fe³⁺回收困难以及难以重复使用等问题。基于"活性离子固载化,酸性环境局部化"的设计思路,通过对活性炭(AC)表面酸化改性,制备得到载铁活性炭(Fe/AC)催化剂。研究了Fe/AC制备工艺与其性能之间的关系,结果表明,在载Fe³⁺量44.05 mg·g^-1、煅烧温度200℃的制备工艺下可得到催化活性较高、稳定性好的Fe/AC催化剂。用性能优良的Fe/AC催化H₂O₂降解双酚A(BPA),其较佳催化反应条件为:反应时间60 min、反应温度20℃、溶液pH值为4.0≤pH≤8.0、Fe³⁺/H₂O₂摩尔比为0.007～0.012、30% H₂O₂用量为0.04 ml H₂O₂·(mg BPA)^-1。本工作制备得到的Fe/AC催化剂具有较好的重复使用性能,在实际废水处理领域具有较大的应用前景。     

Ultrafiltration recovery of alginate: Membrane fouling mitigation by multivalent metal ions and properties of recycled materials

Recovery of alginate extracted from aerobic granular sludge (AGS) has given rise to a novel research direction. However, these extracted alginate solutions have a water content of nearly 100%. Alternately, ultrafiltration (UF) is generally used for concentration of polymers. Furthermore, the introduction of multivalent metal ions into alginate may provide a promising method for the development of novel nanomaterials. In this study, membrane fouling mitigation by multivalent metal ions, both individually and in combination, and properties of recycled materials were investigated for UF recovery of sodium alginate (SA). The filtration resistance showed a significantly negative correlation with the concentration of metal ions, arranged in the order of Mg²⁺ < Ca²⁺ < Fe³⁺ < Al³⁺ (filtration resistance mitigation), and the moisture content of recycled filter cake showed a marked decrease. For Ca²⁺, Mg²⁺, Fe³⁺, and Ca²⁺+Fe³⁺, the filtration resistances were almost the same when the total charge concentration was less than 5 mmol·L^-1. However, when the total charge concentration was greater than 5 mmol·L^-1, membrane fouling mitigation increased significantly in the presence of Ca²⁺ or Fe³⁺ and remained constant for Mg²⁺ with the increase of total charge concentration. The filtration resistance mitigation was arranged in the order of Fe³⁺ > Fe³⁺ + Ca²⁺ > Ca²⁺ > Mg²⁺. Three mechanisms were proposed in the presence of Fe³⁺, such as the decrease of SA concentration, change in pH, and production of hydroxide iron colloids from hydrolysis. The properties of recycled materials (filter cake) were investigated via optical microscope observation, dynamic light scattering, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The results provide further insight into UF recoveries of alginate extracted from AGS.     

Investigation of solution chemistry to enable efficient lithium recovery from low-concentration lithium-containing wastewater

In the production of lithium-ion batteries (LIBs) and recycling of spent LIBs, a large amount of low-concentration lithium-containing wastewater (LCW) is generated. The recovery of Li from this medium has attracted significant global attention from both the environmental and economic perspectives. To achieve effective Li recycling, the features of impurity removal and the interactions among different ions must be understood. However, it is generally difficult to ensure highly efficient removal of impurity ions while retaining Li in the solution for further recovery. In this study, the removal of typical impurity ions from LCW and the interactions between these species were systematically investigated from the thermodynamic and kinetics aspects. It was found that the main impurities (e.g., Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺) could be efficiently removed with high Li recovery by controlling the ionic strength of the solution. The mechanisms of Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺ removal were investigated to identify the controlling steps and reaction kinetics. It was found that the precipitates are formed by a zero-order reaction, and the activation energies tend to be low with a sequence of fast chemical reactions that reach equilibrium very quickly. Moreover, this study focused on Li loss during removal of the impurities, and the corresponding removal rates of Fe³⁺, Al³⁺, Ca²⁺, and Mg²⁺ were found to be 99.8%, 99.5%, 99%, and 99.7%, respectively. Consequently, high-purity Li₃PO₄ was obtained via one-step precipitation. Thus, this research demonstrates a potential route for the effective recovery of Li from low-concentration LCW and for the appropriate treatment of acidic LCW.     

金属离子对水热法制备半水硫酸钙晶须的形貌及粒径的影响

以二水硫酸钙为原料,采用水热法制备了半水硫酸钙晶须。通过单因素实验得出制备半水硫酸钙晶须的较优工艺条件为：反应温度120℃、料浆质量分数2%、反应时间2h、搅拌速度200r/min,此时所得晶须产物平均直径2.4μm,长径比103.9,晶须呈长针状、规则统一,分散性好。探讨了K⁺、Mg²⁺、Cu²⁺、Fe³⁺、Al³⁺对较优工艺条件下制备的半水硫酸钙晶须形貌及粒径的影响,结果表明：金属离子对晶须产物形貌及粒径有显著影响。其中低浓度的Mg²⁺、Cu²⁺有助于获得小直径、高长径比的晶须产物;Al³⁺、Fe³⁺对晶须的生长有较强的抑制作用,特别是低浓度的Al³⁺、Fe³⁺使得晶须的形貌发生明显的变化,导致长径比较低;除K⁺外,金属离子浓度越高,所得晶须产物直径越大,长径比越小,并发生团聚现象,晶须由针状变为短棒状,分散性变差。同时探讨了金属离子的作用机理。     

高铁煤矸石酸浸液合成氧化铁红的实验研究

以高铁煤矸石为原料,先用硫酸酸浸的方法获得含有铝离子的硫酸铁溶液;采用分步沉淀的方法,使Fe3+完全转化为氢氧化铁凝胶而与Al³⁺分离;再将获得的氢氧化铁凝胶烘干后高温煅烧;最后将煅烧产物磨粉过筛,获得了氧化铁红。确定了合成氧化铁红的工艺条件是：酸浸液中铁离子的浓度为0.31 mol/L;分离Fe³⁺与Al³⁺时,氢氧化钠溶液的浓度为1 mol/L,且控制终点pH在3.0左右;干凝胶焙烧温度为800 ℃,时间为60 min。XRD及化学分析结果表明：所得产物为氧化铁红,符合GB/T 1863-2008《氧化铁颜料》的相关要求。     

Self-assembly of metal-cholesterol oxidase hybrid nanostructures and application in bioconversion of steroids derivatives

A cholesterol oxidase (COD) was hybridized with Ca²⁺, Zn²⁺, Al³⁺, Fe²⁺ and Mn²⁺. After precipitation with PO₄^3– at 4 °C for 72 h, the resulting pellets were freeze-dried. In scanning electron microscopy assays, the metal-COD complexes revealed flower-like or granular structures after hybridization. Fourier transform infrared spectroscopy assay revealed the characteristic peaks of both the enzyme and metal materials. X-ray diffraction analysis indicated that COD was encapsulated in CaHPO₄·2H₂O-, Zn₃(PO₄)₂·4H₂O-, AlPO₄-, FeP₄- and Mn₃(PO₄)₂·3H₂O-based nanostructures, respectively. Differential scanning calorimetry assay indicated significant increases in thermo-denaturation temperatures from 60.5 °C to 167.02 °C, 167.02 °C, 137.70 °C, 172.85 °C and 160.99 °C, respectively. Using steroid derivatives as substrates, this enzyme could convert cholesterol, pregnenolone, dehydroepiandrosterone, ergosterol, b-sitosterol and stigmasterol to related single products. Hybridization in metal-based nanostructures could significantly enhance the initial conversion ratio and reaction stability of the enzyme. In addition, substrate selectivity could be affected by various metal materials. Briefly, using Ca²⁺, Zn²⁺, Al³⁺, Fe²⁺ and Mn²⁺ as hybrid raw materials could help to encapsulate COD in related metal-enzyme nanostructures, and could help to promote the stability and tolerant properties of the enzyme, while also enhancing its catalytic characteristics.     

镁铝离子共存硅酸体系的聚合行为

通过对镁铝离子共存硅酸体系中硅酸胶凝时间、单硅酸聚合反应速率以及凝胶热性能的研究,得出：在pH<;4的微酸性条件下,硅酸体系的胶凝时间随镁铝离子共存浓度的增大而减小,且铝离子在对硅酸体系的促凝过程中起主要作用。镁铝离子共存硅酸体系的单硅酸反应速率常数比不含金属离子硅酸体系的有所增大,计算得出MA_0.1+0.1硅酸体系的单硅酸平均速率常数为：k₀=7.28×10^-4,k₁=5.62×10^-4。镁铝离子共存硅酸体系凝胶的晶化转变温度与晶型转变温度,相较于不含金属离子硅酸体系的均有所降低,根据热重曲线计算出MA_0.1+0.1硅酸体系水合二氧化硅的化学式为：SiO₂·0.556 H₂O。     

硫酸锌溶液脱除钙镁试验及生产应用

某硫酸锌生产厂,由于原料氧化锌矿中钙镁含量较高,用硫酸浸出后的硫酸锌溶液中钙镁含量也较高,导致生产的硫酸锌产品钙镁含量偏高,主含量偏低,影响了硫酸锌产品质量。对氢氟酸沉淀法脱除硫酸锌溶液中的钙镁离子进行了试验研究及生产应用。用氢氟酸作为沉淀剂,在较低温度和较高pH条件下可有效脱除硫酸锌溶液中的钙镁离子,并能控制氟在溶液中的累积,使制得的硫酸锌产品质量得以提高。     

固相法制备掺杂型高色度CoxM1-xAl2O4/高岭土复合颜料

为了制备低成本、高色度的钴蓝颜料,本文以高岭土为载体,以Al₂O₃和Co₃O₄为主要原料,通过引入ZnO、CaO及MgO不同金属氧化物,采用固相法制备了高色度(Co_xM_1-xAl₂O₄)/高岭土复合颜料(M为Ca²⁺、Mg²⁺或Zn²⁺)。系统考察了研磨时间、煅烧温度、煅烧时间和不同金属氧化物掺量对复合颜料呈色性能的影响规律。研究表明,在煅烧温度1 200 ℃、研磨时间12 h和n(Co²⁺)/n(M²⁺)为3:2时,制得的复合颜料具有最好的呈色性能(L^*=53.68,a^*=7.58,b^*=-62.89)。同时,引入不同的金属元素,可实现对复合颜料颜色的调控,引入Ca²⁺后,所制备的Co_xCa_1-xAl₂O₄复合颜料偏红相,而引入Zn²⁺后,所制备的Co_xZn_1-xAl₂O₄复合颜料偏绿相。通过相关表征,提出了复合颜料的呈色机理,在颜料制备过程中,引入与Co²⁺离子半径接近的Mg²⁺或Zn²⁺,Mg²⁺或Zn²⁺可进入CoAl₂O₄的四面体配位中,部分替代Co²⁺,形成MgAl₂O₄-CoAl₂O₄或ZnAl₂O₄-CoAl₂O₄的固溶体,而引入离子半径较大的Ca²⁺,形成CaAl₂O₄和CoAl₂O₄的均相混合物。最后,将制得复合颜料应用到有机硅耐热涂料中,可以明显提高有机硅涂料的热稳定性。     

Selective removal of iron(III) from highly salted chloride acidic solutions by solvent extraction using di(2-ethylhexyl) phosphate

Metal ions including Fe³⁺, Ca²⁺, Mg²⁺, Ni²⁺, Co²⁺ and Cu²⁺ are commonly found in the leaching solution of laterite-nickel ores, and the pre-removal of Fe³⁺ is extremely important for the recovery of nickel and cobalt. Di(2-ethylhexyl)phosphate acid (D2EHPA) showed high extraction rate and selectivity of Fe³⁺ over other metal ions. The acidity of the aqueous solution is crucial to the extraction of Fe³⁺, and the stoichiometry ratio between Fe³⁺ and the extractant is 0.86:1.54. The enthalpy for the extraction of Fe³⁺ using D2EHPA was 19.50 kJ/mol. The extraction of Fe³⁺ was ≥99% under the optimized conditions after a three-stage solvent extraction process. The iron stripping effects of different reagents showed an order of H₂C₂O₄>NH₄HCO₃>HCl>NaCl>NaHCO₃>Na₂SO₃. The stripping of Fe was ≥99% under the optimized conditions using H₂C₂O₄ as a stripping reagent.