高铁酸钾的制备与测定研究进展

近几十年来人们给予高铁酸盐高度的重视,高铁酸盐被誉为绿色氧化剂。固体高铁酸钾是最有可能商品化的一种高铁酸盐,但由于其在制备方面存在方法复杂、操作条件苛刻、产品稳定性差等问题,导致目前还没有实现工业化。针对这种情况,对国内外合成高铁酸钾的研究进展进行了综述,分析了不同制备方法的优缺点;同时对提高高铁酸钾稳定性方面的研究以及对高铁酸钾的定性定量分析方法也作了详细阐述,为实现其工业化生产提供参考。     

高铁酸盐制备方法研究进展

高铁酸盐是一种环境友好的强氧化剂,在水处理、有机合成和超铁电池等方面具有重要的潜在应用价值.综述了近20 a高铁酸盐主要合成方法的研究进展及其特点,包括:熔融法、次氯酸盐氧化法和电化学氧化法,其中电化学氧化法又包括液态高铁酸盐电合成法和固态高铁酸盐直接电合成法.指出:高铁酸钾直接电合成法以其操作简单、原材料消耗少、成本低、可循环生产、工艺绿色环保等优点而成为最有可能工业化应用的合成方法,同时指出了其发展方向.     

超声电化学耦合制高铁酸钠和高铁酸钾的工艺、方法及系统

该发明公开了一种超声电化学耦合制备高铁酸钠和高铁酸钾的工艺及方法和由隔膜电解槽、超声发生系统和直流电源等组成制备高铁酸钠和高铁酸钾的系统，属精细化工技术领域。采用隔膜式电解槽，以铁电极为阳极，不锈钢电极为阴极，将NaOH溶液分别置于隔膜电解槽的阳极室与阴极室内，     

多孔圆筒铸铁阳极电解制备高铁酸盐及其在处理有机模拟废水中的应用

引言 高铁酸盐是一种强氧化剂,可以氧化多种无机物和有机物,其被还原的产物有絮凝沉降作用,且铁元素无毒无害,可用作净水剂去除水体中的污染物[1,2].电解法[3]制备高铁酸盐是在强碱性电解质中,将牺牲铁阳极氧化成高铁酸盐,并用于处理水溶液中的污染物,操作简便,便于推广应用.本文通过改进的电解装置和选用合适的工艺条件,获得高浓度的高铁酸盐溶液,并提高了电解的电流效率.     

高铁酸盐由氢氧化铁残渣再制备及其用于水体脱色的研究

将制备高铁酸盐后所留的氢氧化铁残渣制成六氟合铁酸钾再与次氯酸钠的高碱度溶液反应，第二次生成高铁酸盐溶液。随后用制得的含氟的高铁酸盐溶液处理甲基橙有色配水，其最佳pH在7．0左右，质量浓度为20mg／L的甲基橙的水样500mL，耗用17mg的高铁酸钾，脱色率可达95％以上，处理后的水体中氟离子残留量低于国家排放标准。制得的含氟的高铁酸盐溶液作为脱色的水处理剂不会引起二次污染，工艺可行，效果良好。     

高铁酸钾的研究现状

简要介绍了高铁酸盐的研究历史、高铁酸钾的制备方法、应用领域及展望.     

高铁酸钾中总铁与高铁的测定

提出了以高氯酸代替经典方法中的二氯化汞氧化过量的氯化亚锡,重铬酸钾标准溶液滴定Fe2+的无汞盐测定高铁酸钾中全铁的新方法.用该法测定高铁酸钾中的铁含量,其相对标准偏差为0.07%,且测定结果与经典法非常一致.以亚铬酸盐氧化还原反应为基础建立了高铁酸钾中高铁酸根的滴定分析方法.对滴定分析条件进行了进一步的研究,结果表明,用氢氧根离子浓度为 16～17 mol·L-1的亚铬酸盐溶液测定高铁时,所取高铁样品的质量影响所测的高铁含量.该方法简便、快速、准确,值得应用.     

电解法制备高铁酸盐的研究进展

综述了电解法制备高铁酸盐的研究现状,简要介绍其制备的原理,重点探讨了高铁酸盐制备过程中影响电流效率和高铁酸盐浓度的各种因素,分析总结了提高电解过程电流效率和提高高铁酸盐浓度的方法,为高铁酸盐的工业化应用提供理论依据。未来需要努力的方向,包括电极改进、稳定剂、超声波混合使用以及高铁酸盐制备工艺的优化,在低能耗下获得高浓度的高铁酸盐工业产品。     

高铁酸钾处理多晶硅废水影响因素研究

采用高铁酸钾处理多晶硅废水,考察了初始p H、高铁酸钾投加量和反应时间对污染物去除效果的影响。结果表明,高铁酸钾通过氧化和絮凝作用去除污染物。初始p H为4时,高铁酸盐对COD和浊度的去除率最高,初始p H在5以下时高铁酸盐除F-效果好;初始p H为4、最佳投加量为500 mg/L情况下,高铁酸盐对COD的去除率达到43.4%。纳滤分析表明高铁酸盐氧化能使聚乙二醇断链降聚,改善了多晶硅废水的可生化性。     

用作饮用水处理氧化剂和絮凝剂的高铁酸钾的制备和评价Jiang，jia-Qian等（UK）Environmental Engineering Science 2001，18（5），323-328（英文）

采用一种新方法制备高铁酸钾，并评价了在水处理中的消毒／絮凝性能。结果表明，高铁酸盐在饮用水处理中可作为双功能药剂(氧化剂和絮凝剂)使用，在处理着色的地表水中，在低剂量下优十硫酸亚铁。高铁酸盐可有效地去除天然有机物(UV254)和浊度，在低剂量下杀菌率为100％。在最佳的研究条件下的处理水中，残留的铁浓度和三卤甲烷的生成低于饮用水标准。     

Analysis of Fe(Ⅵ) characteristics and its application to water treatment

Ferrate（Fe(Ⅵ)）is a new type of water treatment chemicals. From the point of view of structural chemistry,electrochemistry,thermal decomposition characteristics and stability,the physical and chemical characteristics of Fe(Ⅵ) were analyzed,and the preparation of ferrate was described. Its application to water treatment was summarized,such as pre-oxidation by ferrate,and the specific applications were outlined. The results showed that 1.0 mg / L ferrate pre-oxidation could significantly improve the effect on coagulation,Water after sedimentation and filtration turbidity removal rate reached 98.58% and 99.9% respectively. Water colority,UV₂₅₄ and other organic composite indicator were significantly decreased. At the same time,manganese and iron were also significantly reduced. In addition,ferrate pre-oxidation could effectively remove bacteria and E.coli. Finally,according to the practical situation,the paper offers advice on engineering application of ferrate.     

高铁酸盐制备影响因素研究和中试生产装置的开发

为了开发和优化高铁酸盐中试生产装置,通过小试试验对隔膜材料和生产工艺等进行了研究,结果表明,孔径小于5μm的聚偏氟乙烯膜使用寿命较长;母液循环利用提高了药剂利用率、降低制备成本;电解液NaOH不宜饱和,浓度应降低到14～ 16 mol/L; BaFeO4提取率显著高于K2FeO4,低温（5℃）、隔绝空气密封下,保存30 d以上纯度仍在50％左右.根据小试结果,开发了高铁酸盐中试生产装置,产量可达20 g/h以上,生产总成本约为6万元/t.     

电化学合成法制备高铁酸盐的研究进展

高铁酸盐是公认的“绿色”化学试剂,但制备成本过高大大限制了它的应用。电解法制备高铁酸盐以其工艺简单,原料消耗少而成为最可能商业化生产的方法。本文从电解槽结构、阳极材料组成、电解液的组成和浓度、电流密度、电解时间等各个方面阐述了影响电流效率和高铁酸盐产品浓度的因素。阳极室体积减小、电流密度和电解时间适当增加,可使Na2FeO4产品的浓度加大。阳极材料比表面积大,含有碳、硅的铸铁比纯铁活性高。新发展起来的惰性阳极法值得深入研究。电解液组分为氢氧化钠,浓度约为14mol/L时电流效率较高,电解液中添加适当的氧化剂或腐蚀性离子有助于减少阳极钝化和稳定高铁酸根离子。交直流叠加的加电方式有利于缓解阳极钝化现象。文章指出,未来需要设计新型合理的电解槽结构和研发新的生产工艺,降低电耗和电解液浓度,提高电流效率,最终达到长时间连续生产高浓度高铁酸盐的目的。     

Treatment and reuse of dyeing effluents by potassium ferrate

The use of potassium ferrate, K₂FeO₄, an environmentally-friendly chemical reagent containing iron in the + 6 oxidation state, has been investigated as a new approach for dyeing wastewater purification.The performance of this product, alone or in combination with a cationic organic polymer and/or power ultrasound, was compared to the traditional biological activated sludge process and a tertiary treatment featuring ozonation.Experimental tests showed that, thanks to its unique properties (high redox potential and simultaneous generation of ferric coagulating species), potassium ferrate can be successfully used in dyeing wastewater treatment. In fact, treatment with ferrate at the optimal dose of 70 mg/L as Fe(VI) was found to allow a high removal efficiency of relevant parameters such as turbidity, total suspended solids and chemical oxygen demand (COD).Whilst potassium ferrate alone had a minor effect on colour, the combination of ferrate with the organic polymer allowed a good decolourisation: this suggested the eventual application of this combined process for reuse of dyeing wastewater, resulting in environmental and economic benefits. The possibility of reusing the purified effluent in textile processes that do not require softened water was demonstrated through dyeing tests.     

Electrosynthesis of ferrate in a batch reactor at neutral conditions for drinking water applications

We report on the electrochemical generation of ferrate species in a batch reactor at neutral conditions (pH ～7) using boron‐doped diamond (BDD) electrodes and Fe (III) salts for applications in drinking water treatment. The impact of several relevant variables, including current density (5–55 mA cm^?2), pH (5–8), and type and concentration of the dissolved iron salts on the production of ferrates were examined. In addition, linear sweep voltammetry (LSV) studies were conducted using buffered electrolytes with and without the presence of iron (III) to decouple the parasitic oxygen evolution reaction. The LSV measurements in the presence of iron (III) and with a neutral electrolyte exhibit oxidation peaks centered ～2.0 V (versus SHE), indicating the production of ferrates at this pH. The rate of ferrate generation is not strongly affected by the pH condition (≤ 20 %); however, current density and the source of iron were found to have a higher impact on the production rate of ferrates. The efficacy of the process was higher using FeCl₃ instead of other sources of iron such as Fe₂O₃ and FeO(OH). The batch reactor results were successfully interpreted by a simple model that considered the kinetics of the ferrate generation and degradation reactions.

     

不同浓度Fe-H2O体系的溶解组分 优势区域图和Pourbaix图

对25 ℃、总铁浓度分别为1.0×10-2 mol/L和1.0×10-5 mol/L时的Fe-H2O体系可能存在的组分做了热力学和电化学分析,计算了各溶解组分的浓度,运用浓度比较法为判据,确定液相和液相、液相和固相以及各固相之间的分界线,绘制了不同浓度时Fe-H2O体系溶解组分的优势区域图和Pourbaix图。对比发现,在一定的温度和压力下,总铁浓度对Fe3+、Fe（OH）2+、HFeO2和FeO2-的优势区域影响不大,但对Fe2+、HFeO2-、Fe（OH）+的优势区域影响明显。随着总铁浓度的减小和碱化程度的逐步加强,Fe（OH）2和Fe3O4会发生一系列复杂的质子化作用。总铁浓度越高,多核组分Fe（s）、Fe3O4（s）、Fe（OH）2（s）和FeOOH（s）的稳定区域越大,性质越稳定。     

The cyclic voltammetric study of ferrate(VI) formation in a molten Na/K hydroxide mixture

The electrochemical synthesis of ferrate(VI) was studied in a molten salt environment as a function of temperature (170–200 °C). A eutectic NaOH–KOH melt was selected as the most appropriate system for this purpose. Cyclic voltammetry was used to characterize the processes taking place on the stationary iron electrode. The anodic current peaks corresponding to the ferrate(VI) production as well as cathodic current peaks corresponding to the ferrate(VI) reduction appeared to be strongly dependent on the temperature at which the experiment was performed. Ferrate(VI) formation by anodic oxidation of the iron electrode in the molten electrolyte during the batch electrolysis was confirmed for the first time by visible and Mössbauer spectroscopy. The maximum current efficiency of Fe(VI) formation reached during galvanostatic batch electrolysis has attained 72%. It was reached at the temperature of 170 °C.     

Affinage electrolytique des ferronickels

Electrorefining of ferronickels is possible in a cell without diaphragm with the electrolyte CaCl₂ 5 M at 98°C.Behavior of the following impurities have been studied: Ag(I), Au(III), Bi(III), Cd(II), Co((II), Cu(I), Fe(II), Hg(II), Ni(II), Pb(II), Pd(II), Sb(III) and Sn(II).The electrochemical system Ni(II)/Ni(O)is much more reversible in this electrolyte and the only other electrochemical system which appears at the same potential is Cu(I)/Cu(O).Ferronickels of 23.2;72.2 and 94.4% in nickel have been refined in this medium without purification of the electrolyte. Nickel of a purity between 98.7 and 99.7% is obtained.In order to increase the nickel purity and for continuous operation of the method a purification of the electrolyte is necessary. Two methods are proposed: anion exchange resin and liquid—liquid extraction with tri-n-butyl phosphate (TBP).Partition coefficients and ion-exchanger capacities are given for following impurities: Fe(III), Fe(II), Co(II), Cu(II), Mn(II), Zn(II), Cr(III) and Pb(II).Percent extracted by TBP for following impurities are given: Fe(III), Fe(II), Co(II), Cu(II), Zn(II), Mn(II), Cr(III), Pb(II), Al(III), Bi(III), Sb(III) and Sn(IV).A continuous purification of the electrolyte by ion-exchange has been done in the refining of a ferronickel 94.4% in nickel. Nickel obtained is 99.74%.CaCl₂ 5 M appears to be a good electrolyte for electro-refining of nickel.     

磁性胺肟基功能化CMC对铀酰离子的吸附行为研究

采用两步法合成磁性胺肟基功能化CMC（简称PAO/CMC/Fe3O4）,用批示法研究了PAO/CMC/Fe3O4对U（Ⅵ）的吸附行为,考察了pH值、吸附时间、吸附剂用量等对吸附效果的影响.结果表明,PAO/CMC/Fe3 O4对U（Ⅵ）的吸附容量大,速度快,最大吸附容量119.21 mg/g,30 min左右达到吸附平衡,平衡数据符合Langmuir等温方程,符合伪二阶动力学吸附模型,说明PAO/CMC/Fe3O4对U（Ⅵ）的化学吸附过程是速率控制步骤.     

高铁酸钾氧化去除水中甲萘酚的研究

新兴有机污染物在传统的污水处理厂处理过程中难以完全去除,如果进入到水环境中,不仅影响水质,而且对水生态系统和人类健康具有潜在的风险。高铁酸钾在水处理领域被称为环境友好型的多功能水处理剂,其氧化降解新兴有机污染物的研究备受关注。本文采用高铁酸钾(K2FeO4)氧化降解甲萘酚水溶液,研究表明,甲萘酚水溶液浓度为10 mg/L时,初始pH=12~13,高铁酸钾与甲萘酚的质量比8∶1,反应时间10 min,温度25℃为最优反应条件,甲萘酚去除率达到89.6%左右。通过对反应产物的分析,推测甲萘酚首先被高铁酸钾氧化为1,2-萘二酚,再进一步被氧化开环生成终产物。