Selective exchange of alkali metal ions on EAB zeolite

EAB zeolite was successfully prepared and applied to selective adsorption of Li^(+),Na^(+)and K^(+)ions.The physical and chemical properties of the adsorbent were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),scanning electron microscope(SEM)and thermogravimetry(TG)methods.The ion exchange behaviours for Li^(+),Na^(+)and K^(+)ions in monomcomponent and multicomponent solutions were studied.In independent ion exchange,the ion exchange capacities ratiosα(/Na/Li)andα(K/Li)were 3.8 and 6.2,respectively.In competitive ion exchange,the selectivitiesβ(Na/Li)andβ(K/Li)increased with the initial concentrations and reached 409 and 992 when the initial concentrations was 100 mmol/L.The thermodynamic study results showed that Gibbs free energy change(ΔGΘ)of ion exchange reaction between Li-EAB and K^(+)was-34.96 kJ/mol,indicating that ion exchange of K^(+)ions was more energetically favourable than Li^(+)ions.The calculation results showed that the energy barriers of ion exchange increased in the order K^(+)Na^(+)<Li^(+).The study shows that EAB zeolite is potential to be used in the separation of alkali ions.

Kinetic modeling of adsorption of vanadium and iron from acid solution through ion exchange resins

This study assessed the adsorption process and the reaction kinetics involved in the selective recovery of vanadium from an acid solution containing iron as an impurity.Four commercial resins were studied:Lewatit^(®)MonoPlus TP 209 XL,Lewatit^(®) TP 207,Dowex^(TM)M4195(chelating resin)and Lewatit^(®) MonoPlus S 200 H(strong cationic exchange resin).To investigate the effect of time on the adsorption process,batch experiments were carried out using the following initial conditions:pH 2.0,298 K,and a proportion of 1 g of resin to 50 mL of solution.The variation of pH over time was analyzed.Chelating resin released less H+ions as the adsorption occurred,resulting in a lower drop of pH when compared to S 200 H resin.Ion adsorption by the resins was also evaluated through FT-IR and SEM−EDS before and after the experiments.Among the evaluated kinetic models(pseudo-first order,pseudo-second order,Elovich and intraparticle diffusion models),the pseudo-second order model best fits the experimental data of the adsorption of vanadium and iron by all of the four resins.M4195 resin showed the highest recovery of vanadium and the lowest adsorption of iron.Kinetic data,which are fundamental to industrial processes applications,are provided.

ADSORPTION OF HUMIC SUBSTANCES BY MACRO WEAKLY BASIC IONEXCHANGE RESIN AND THEIR EFFECTS ON REMOVAL OF Cu^(2+) AND Pb^(2+)

Adsorption of humic, tannic and gallic acids by a macro weakly basic ion-exchange resin JN-01 was studied. The adsorption capacity of this resin for gallic and tannic acids is much higher than that for humic acid, which can be explained on the basis of both their molecular size and ionization degree. Furthermore, humic acid is separated into different components with molecular weight in the range from 2000 Da to 100000 Da by ultra-filter, and their adsorption isotherms on resin JN-01 indicate that humic acid＇s molecular weight is an important factor which makes significant influence on adsorption. Finally, changes in the amount of Cu^2＋ and Pb^2＋ adsorbed on resin JN-01 as a function of the concentration of each of these three acids were studied. A large increase in the heavy metal ions uptake is observed in the presence of humic substance, such advantages are due to the interactions between the heavy metal ions and the unbound functional groups of the adsorbed organic acids.

STUDY ON THE PHYSICAL CHEMICALPROPERTIES OF FFA-1 ION EXCHANGE FIBER

The physical and chemical properties of FFA-1 ion exchange fiber have beencharacterized with IR spectrum. thermal analysis and SEM means. The PH titrationcurve, swelling rate, mechanical properties, resistance drop of filter layer as well asthe dynamic adsorption for SO2 was determined These experiments provided theessential parameters for the practical application of FFA-1 material in adsorption oftoxic gases.

Arsenate Removal by Iron-Modified Ion Exchange Fiber

The adsorption characteristics of arsenate on ion exchange fiber(IEF) and iron-modified ion exchange fiber(FeIEF) were evaluated.Batch adsorption experiments were conducted to study the arsenate adsorption effect by varying contact time,pH,and coexisting anions.Adsorption capacity was found to increase by increasing the contact time and acidic conditions were favorable for arsenate adsorption on IEF and Fe-IEF.Arsenate adsorption data were better consistent with Freundlich equation than Langmuir equation.The maximum monolayer adsorption capacities were 285 and 333 mg/g at 25℃ for IEF and Fe-IEF respectively.The adsorption kinetics was found to follow the pseudo-first-order kinetic model.The existence of HCO 3-,PO34-,SO24-,SiO23-,and NO 3-decreased the arsenate adsorption capacity on IEF.Cl-and F-had little influence on it.When FeIEF was adopted,the effects of HCO 3-,SO24-,Cl-,SiO23-,and NO 3-were negligible,while PO43-could still markedly decrease the adsorption capacity and F-had inhibitory effect on arsenate adsorption.Fe-IEF can be used as a highly selective and efficient sorbent for removal of arsenate from aqueous solutions.

EFFECTS OF COMPOSITION AND STRUCTURE OF ALGTNATES ON ADSORPTION OF DIVALENT METALS

Results of a series of experiments(on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of different composition and block structure) conducted in this systematic study of the effects of the composition and structure of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of the M/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu2+ ion decrease with the increase of the G-block or the average length of the G-block (NG) and the total adsorption capacity of alginic acid is found to vary in the same order as the FMM(diad frequency) in alginate in the mixed solution of Sr2+, Ba2+ and Cd2+.

硫酸镁和硫酸铵浸矿对离子吸附型稀土与重金属的释放与影响机理

传统的硫酸铵与新型的硫酸镁是目前离子吸附型稀土矿原位浸矿主要的浸矿剂,除了关注稀土的浸取效率,稀土浸取过程中是否会引起伴生重金属的释出而对地下水环境造成影响是值得关注的问题。为此,以江西龙南稀土矿为研究对象,对比研究硫酸镁和硫酸铵浸矿剂条件下,pH、固液比及浸矿剂浓度对稀土及Pb、Mn、Cd等金属离子释放与变化的影响。结果表明:稀土浸出率和重金属受pH影响较大,其次是固液比和浸矿剂浓度。pH对浸出液中金属释放影响程度从大到小为:Pb>Mn>Cd。根据微观表征,浸出前后稀土矿中的主要矿物相组成未发生明显变化,高岭石、钾长石等矿相表面的Mn、Fe等重金属通过离子交换作用进入浸出液。整体上,硫酸铵较硫酸镁对RE 3+的释放迁移影响更显著,可能加剧重金属离子的释放,造成地下水中重金属的超标。

富咪唑型多孔左旋聚乳酸纳米纤维膜制备及其双重净水性能

为开发具有油水分离和吸附重金属离子双重功能的新型膜材料,利用静电纺丝技术制备左旋聚乳酸(PLLA)纳米纤维膜,再依次采用溶剂诱导结晶和1-(3-氨基丙基)咪唑(API)修饰改性得到富咪唑型多孔PLLA纳米纤维膜,并对其微观形貌、化学基团构成、力学性能和润湿性能进行测试与表征,研究了该纳米纤维膜的油水分离性能和对铜离子的吸附性能。结果表明:当丙酮与水体积比为10∶1、丙酮/水混合溶液用量为0.4 mL/(mg纤维)、处理时间为150 s时,溶剂诱导结晶处理所得PLLA纳米纤维膜中多孔纤维的形貌最佳;API修饰改性并未对多孔纤维的形貌和直径产生过多影响,改性后PLLA纳米纤维膜表面出现的咪唑和酰胺基团能够有效改善其润湿性能,使静态水接触角下降了15.6°;与未改性PLLA纳米纤维膜相比,所制得富咪唑型多孔PLLA纳米纤维膜的脆性有所增加,但其断裂强度仍能达到未改性的PLLA纳米纤维膜断裂强度的96.6%,整体力学性能保持良好;利用该纳米纤维膜可实现有效油水分离,分离通量为1044.9 L/(m^(2)·h),分离效率可达99.1%,且其对铜离子吸附性能良好,在pH值为6的铜离子溶液中接触24 h后,对铜离子吸附量可达41.46 mg/g。

金属镓生产工艺及离子交换装置的结构设计优化定型

本文介绍了树脂吸附法离子交换技术从拜耳法种分母液中提取镓的机理和该技术的核心设备——离子交换装置的工艺及结构设计,并结合离子交换装置在生产应用中存在的问题及原因分析,提出优化改进措施。该装置工艺、结构定型后,在多家氧化铝企业推广应用,效果良好。为利用树脂吸附法离子交换技术提取金属镓的核心装备的设计提供了重要的参考,同时,也为湿法冶金行业大型离子交换装置的设计提供借鉴。

污水处理中离子交换树脂对重金属的吸附特性与再生机理分析

离子交换树脂作为一种重要的污水处理材料,在吸附重金属方面发挥着关键作用。本文通过分析其吸附特性和再生机理,探讨了其在环境保护领域的潜在应用。研究表明,离子交换树脂的结构和动力学参数对重金属吸附效果具有重要影响。此外,再生方法的选择和优化也对树脂的长期应用起着至关重要的作用。

重金属废水处理技术及设备的研究

在工业生产、矿山开发、农业活动及城市生活等人类活动中通常会排放含有重金属离子的废水。这类废水具有毒性高和难降解性等特点,若未经处理而直接排放,会对周边生态环境造成严重污染,重金属离子易通过食物链传递,对人类健康造成不利影响。基于此,本文综述了处理含有重金属离子废水的技术、设备和工艺流程,以期为重金属废水的处理提供基础理论。

改性聚丙烯腈纤维对铅镉汞离子的吸附性能研究

以改性聚丙腈纤维(简称改性纤维,用L表示)为吸附剂,对水溶液中的重金属离子Pb2+、Cd2+、Hg2+进行螯合吸附。实验证明,L对它们有很强的吸附能力,通过实验确定出L对各离子吸附的最佳条件参数:温度、时间、pH值、离子浓度等;并发现L对Pb2+、Hg2+有累积吸附作用;吸附后的纤维可以反复再生使用,并找出再生的最佳条件。而且,在一定的浓度范围内三种离子的吸附都能符合Freundlich型等温方程式。

离子交换纤维吸附儿茶素的热力学

采用自制离子交换纤维对儿茶素的吸附特性进行了研究,在温度为286～328K和研究的浓度范围内,离子交换纤维对儿茶素吸附平衡数据符合Langmuir和Freundlich吸附等温方程.Freundlich吸附等温线和等量吸附焓表明:离子交换纤维对儿茶素吸附是吸热过程.对儿茶素在离子交换纤维上的吸附焓、自由能、吸附熵的计算表明,该离子交换纤维对儿茶素的吸附没有化学键生成,并对吸附行为作了合理解释.

离子交换纤维对偏二甲肼的吸附性能

以火箭推进剂主要成分偏二甲肼为研究对象,通过配制模拟水样,采用强酸阳离子交换纤维对其中的偏二甲肼进行吸附,研究了偏二甲肼在离子交换纤维上的等温吸附线、吸附动力学和动态吸附,并将其动态吸附效果与732强酸阳离子交换树脂进行了对比.结果表明,强酸阳离子交换纤维对偏二甲肼的吸附以液膜扩散为主,符合Boyd液膜扩散方程.在291K和研究的浓度范围内,离子交换纤维对偏二甲肼的吸附符合Freundlich等温吸附方程.动态吸附结果表明,离子交换纤维对偏二甲肼的交换吸附速率大于离子交换树脂.离子交换纤维柱的利用率高,相同条件下的处理量是树脂的3.86倍.

离子交换纤维对葛根素动态吸附和解吸的研究

目的:为了规范中药生产、提高纯度和疗效,开展用离子交换纤维(IEF)提取葛根素的研究。方法:通过系统研究IEF对葛根素动态吸附和解吸的机制和行为,来确立IEF提取纯化葛根素的最佳工艺参数。结果:研究表明IEF的吸附量和解吸量与上柱液浓度、流速、pH值有关。用乙醇可以将吸附的葛根素迅速解吸下来。结论:用IEF提取、分离葛根素的方法是可行和有意义的。

强碱阴离子交换纤维对活性染料的吸附性能研究

采用聚丙烯强碱阴离子交换纤维对活性艳黄等几种活性染料进行静态吸附、动态吸附和再生实验,并与同类型树脂相比较。结果表明,强碱阴离子交换纤维对活性艳黄的吸附曲线符合Langmuer等温方程,吸附反应以液膜扩散为主,反应速率随温度和pH值的升高而增加,并且远大于树脂的吸附反应速率。动态吸附表明,强碱阴离子交换纤维对活性艳蓝、活性艳黄和活性艳红的吸附处理量依次增大。利用硝酸乙醇混合溶液再生,再生效率85.7%,纤维能够反复多次使用,可以作为活性染料废水的脱色剂使用。

离子交换纤维对葛根素静态吸附和解吸作用的考察

目的考察离子交换纤维对葛根素的静态吸附和解吸作用。方法将离子交换纤维预处理并制得饱和吸附纤维后，分别考察温度、pH值对葛根素静态吸附和解吸的影响，由此确定离子交换纤维提取纯化葛根素的影响因素和程度。结果离子交换纤维的吸附量和解吸量与葛根素溶液的温度、pH值和相互作用时间有关，作用时间越长、pH值越大，吸附量则越大；在pH值为9、作用时间为40min时，最佳吸附温度为70℃；在一定的pH值条件下，用乙醇可以将吸附在离子交换纤维上的葛根素迅速解吸下来；最佳的醋酸解吸剂的浓度为2mol·L^-1，最佳静态解吸温度控制在40～60℃。结论用离子交换纤维提取纯化溶解在乙醇中的葛根素的方法是可行的；本方法为葛根素的分离提纯开辟了新的途径，奠定了新的基础，对中药标准化生产具有重要意义。

离子交换纤维分离混合氨基酸的性能研究

对新研制的强酸型离子交换纤维PP-g-St-SO3H和两性离子交换纤维PP-g-4VP-SO3H分离混合氨基酸的性能进行研究,并与相应的离子交换树脂进行比较。结果表明在相同分离操作条件下,所制备的阳离子交换纤维PP-g-St-SO3H和两性离子交换纤维PP-g-4VP-SO3H对混合氨基酸的分离性能比通用732#树脂好。两性离子交换纤维还具有洗脱容易,洗脱液用量少的特点。在合适条件下,PP-g-St-SO3H纤维分离组氨酸和谷氨酸的分辨率达1.87。PP-g-4VP-SO3H两性纤维分离丙氨酸和谷氨酸的分辨率达2.69。

含偕胺肟基螯合纤维吸附、还原Au^(3+)的研究(Ⅰ)——含偕胺肟基螯合纤维对Au^(3+)的吸附行为

研究了含偕胺肟基螫合纤维对Au^(3+)的吸附特征及影响吸附量的因素。结果表明,含偕胺肟基螫合纤维对Au^(3+)的吸附量极高,而且将所吸附的Au^(3+)还原成单质金;在含Au^(3+)、Cu^(2+)+、Zn^(2+)和Cr^(3+)的溶液中,对Au^(3+)具有相当高的吸附选择性。提高偕胺肟基在螯合纤维中的含量及吸附温度和Au^(3+)的初始浓度等均有利于提高吸附量。

离子交换纤维对重金属的吸附研究

采用自制强酸性阳离子交换纤维对镉、铅离子的吸附性能进行了初步研究。实验结果表明 ,强酸性阳离子交换纤维对镉、铅离子具有较好的吸附能力 ,其最大吸附容量分别为 2 0 6.6mg g和 10 5 .5mg g ;吸附速度快 ,2 0min即可达到平衡。用Langmuir方程对其吸附等温线进行回归 。