Effect of the chelating agents on bio-sorption of hexavalent chromium using Agave sisalana fibers

The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocarbamide(TC), ethylenediaminetetraacetic acid(EDTA), and diphenyl carbazide(DCZ). The fiber treatments were investigated using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning electron microscope(SEM). The kinetics of chromium bio-sorption was studied in batch presses under the effect of some physicochemical factors such as the nature of chelating agent(F@UR, F@TC, F@DCZ, and F@EDTA),adsorbent dose(2–10 g·L^(-1)), chromium initial concentration(100–500 mg·L^(-1)), solution pH(1–6), and batch temperature(20 ℃–50 ℃). This study resulted in an optimum adsorption at a chromium initial concentration of 100 mg·L^(-1), at pH 2, and at 20 ℃. The obtained results showed clearly that the treatment with chelating agent boosts the adsorptive capacity of A. sisalana fibers Cr(VI) 10.9 mg·g^(-1) to 58.6 mg·g^(-1). The modeling study showed that the adsorption kinetics obey the pseudo-second-order model, with an R2 in the range of 0.991 and 0.999. The bio-sorption isotherms followed the Langmuir model; the maximum uptake capacity of(F@N, F@UR,F@TC, F@DCZ, and F@EDTA) was found to be respectively, 12.3 mg·g^(-1), 25.33 mg·g^(-1), 28.73 mg·g^(-1),42.54 mg·g^(-1), and 61.45 mg·g^(-1). The determined adsorption thermodynamics parameters such as enthalpy,free energy, and entropy showed that the adsorption process is exothermic, spontaneous, and has a stable configuration.

Adsorption of Hg(Ⅱ) from aqueous solution using thiourea functionalized chelating fiber

A fast and selective adsorbent for Hg（ll） from aqueous solutions using thiourea （TU） functionalized polypropylene fiber grafted acrylic acid （PP-g-AA）, PP-g-AA-TU fibers, was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The adsorption behavior of the functionalized chelating fibers for Hg（Ⅱ） was investigated by static adsorption experiments, and the effects of some essential factors on adsorption of Hg（Ⅱ） were examined, such as pH, initial concentration, adsorption time, coexisting cations, and temperature, The results showed that the adsorptive equilibrium could be achieved in 10 min, and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers. The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg（Ⅱ） over a wide range of pH. The adsorption isotherm can be well described with Langmuir model, with the maximum adsorption capacity for Hg（Ⅱ） up to 52.04 mg.g-1 and the removal of Hg（Ⅱ） more than 97%. The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.

Synthesis and Preparation of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea

Several kinds of chloromethyl polysulfones （CMPF） with different chlorinity and reactive groups were synthesized by Friedel.crafts reaction, which could be utilized as reactively matrix membrane materials. The CMPF hollow matrix membranes were prepared with phase inversion by utilization of CMPF/additive/DMAC casting solution and CMPF as membrane materials. It was found that the effects of additive content, bore liquid and dry spinning distance on the structure of CMPF hollow fiber matrix membrane were different. A high qualified palysulfone hollow fiber chelating membrane modified with thiourea as chelating groups was prepared using CMPF as membrane matrix materials, through the reaction between thiourea and CMPF hollow fiber matrix membrane to afford the methyl iso-thiourium polysulfone. The experimental results showed that thermal drawing could increase the mechanical properties of matrix membrane, and the thermal treatment could increase the homogeneity and stability of the structure of polysulfoue hollow fiber chelating membrane modified with thiourea.

ORGANIC CHELATING REAGENT ON REDOX ADSORPTION OF ACTIVATED CARBON FIBER TOWARDS Au^(3+)

Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.

优化等离子参数制备PP基功能纤维及其对Pb^(2+)的吸附性能

为进一步扩展熔喷聚丙烯(PP)纤维在废水重金属离子去除领域的应用,通过低温等离子技术用甲基丙烯酸缩水甘油酯(GMA)改性PP纤维得到PP接枝GMA(PP-g-GMA)纤维,探讨等离子体处理工艺参数对接枝效果的影响,继而胺化制备螯合纤维,借助红外光谱进行表征。考察溶液pH、吸附时间、初始浓度、共存离子和再生对螯合纤维吸附Pb^(2+)效果的影响。结果表明:将GMA单体接枝到熔喷PP纤维表面时,等离子体放电功率15 W、气氛压强20 Pa、放电时间3 min时最佳,接枝率最大,为6.4%;以水/N,N-二甲基甲酰胺为溶剂,二乙烯三胺(DETA)与GMA发生开环胺化反应;红外光谱分析表明成功地接枝了GMA和引入胺基。在Pb^(2+)初始质量浓度40 mg/L、pH=5、120 min时,PP-g-GMA-DETA螯合纤维对Pb^(2+)的吸附量达到最大,为31.87 mg/g;吸附过程符合准二级动力学模型,吸附等温线符合Langmuir等温吸附模型。共存离子对螯合纤维吸附Pb^(2+)影响不大,且纤维具有良好的再生性能。

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply andrapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrateand separate of trace amount of Au(III), Pt(IV), Pd(IV) and Ir(IV) ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0 mL/minat pH 2, and can also be desorbed with 15 mL of 4 mol/L HCl+3% thiourea from the fiber column withrecoveries of 96.5%-100%. The chelating fiber can be reused for ten times, the recoveries of theseions are still over 92%, and hundred to thousand times of excess of Fe(III), Al(III), Ca(II),Mg(II), Ni(II), Mn(II), Cu(II), Zn(II), and Cd(II) cause no interference on the determination of theanalyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The staticsaturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80 mmol/g.The relative standard deviations for the determination of 20.0 ng/mL each of Au(III), Pt(IV),Pd(IV) and Ir(IV) are in the range of 0.7%-3.0%. The recoveries for test from standard additions toreal solution samples are between 96% and 100%. The concentration of each ion in powder sampledetected by the method is in good agreement with the certified value.

Preparation and characterization of polyphenylene sulfide-based chelating fibers

A series of novel chelating fibers containing sulfur, nitrogen, oxygen heteroatoms were prepared via the functionalization of chloromethylated polyphenylene sulfide （CMPPS）. The structures, micromorpholo- gy and physicochemical properties of these fibrous adsorptive materials were characterized by FT-IR, elementary analysis, TG and SEM-EDS. The results show that chelating fibers had high functional group contents （3.94 mmol/g for thiourea, 3.85 mmol/g for mercapto, 5.00 mmol/g for methylamine and 6.07 mmol/g for ethylenediamine, respectively）. Owing to the unique matrix of polyphenylene sulfide fiber, these fibrous adsorbents possess excellent thermostability. This synthetic method proved a simple and efficient way for the preparation of chelating fibers.

Fast removal of Pb^(2+) from water using new chelating fiber modified with acylamino and amino groups

The graft copolymerization of acrylic acid（AA） onto polyethylene glycol terephthalate（PET） fiber initiated by benzoy peroxide （BPO） was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber（PET-AA） was done by changing the carboxyl group into acylamino and amino groups through the reaction with ethylenediamine.The new modified chelating fiber （NDWJN6） was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curve indicated that NDWJN6 could fastly remove Pb^（2＋） from water,and adsorption isotherm also indicated that NDWJN6 had high equilibrium adsorption capacity for Pb^（2＋）.

Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

The graft copolymerization of acrylic acid（AA） onto polyethylene glycol terephthalate（PET） fiber initialed by benzoy peroxide （BPO） was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber（PET-AA） was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber（NDWJN1） was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJNl could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJNl could be filted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion played a dominant role in the adsorption of phytic acids.

多胺型纤维素基螯合纤维的合成工艺与结构表征

将环氧活化的纤维素纤维(CPGMA)分别在水介质和二甲基酰胺(DMF)介质体系中进行多胺化有机合成反应,考察反应介质、胺浓度、反应时间、温度、液比和初始环氧基含量等对胺化反应的影响。研究结果表明:DMF作为反应介质、温度为60℃时最有利于胺化反应进行,纤维增重与胺浓度之间符合线性关系。在DMF介质中,胺化反应在1 h之内达到饱和,反应液比增大不利于胺化反应的进行,CPGMA的环氧基含量越高越有利于胺化反应进行。600℃时,CPGMA(接枝率198%)的残余量为5.1%,而胺化改性后的CPGMA-EDA残余量为16.8%,纤维热稳定性提高。固体核磁^(13)C CP/MAS NMR谱图中5′环氧基上的叔碳峰的消失及2′季碳和6′环氧基上亚甲基碳峰强度的减弱,均验证了胺化反应的成功进行。

PP-g-AA-TETA螯合纤维对Pb^(2+)的吸附

以熔喷聚丙烯(PP)纤维为基体、丙烯酸(AA)和三乙烯四胺(TETA)为功能单体,通过低温等离子接枝和胺化反应制备了PP-g-AA-TETA螯合纤维,并将其用于吸附废水中的Pb^(2+),考察了影响Pb^(2+)吸附量的主要因素和PP-g-AA-TETA的再生性能。实验结果表明:在初始Pb^(2+)质量浓度为250 mg/L、PP-g-AA-TETA加入量为10 g/L、初始溶液pH为6、吸附时间为120 min的最佳工艺条件下,PP-g-AA-TETA对Pb^(2+)的吸附量为13.46 mg/g;PP-g-AA-TETA经5次重复使用后,对Pb^(2+)的吸附量仍可达到初始值的80%以上;Na+、Mg2+和Ca2+的存在对PP-g-AA-TETA吸附Pb^(2+)的过程影响不大。PP-g-AA-TETA对Pb^(2+)的吸附过程符合准二级动力学模型和Langmuir等温吸附模型,PP-g-AA-TETA对Pb^(2+)的吸附主要是化学吸附,且为单分子层吸附,相应的饱和吸附量为15.58 mg/g。螯合配位作用是影响吸附速率的关键因素。

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。

偕胺肟基纤维对Sm(Ⅲ)、Nd(Ⅲ)、Pr(Ⅲ)的吸附与富集

以偕胺肟基纤维 (用 L 表示 )为吸附剂 ,对 Sm( )、Nd )、Pr( )进行螯合吸附 ,再将螯合后的纤维进行解吸 ,使稀土离子得到富集。通过实验确定出最佳吸附条件为 :温度 5 0℃、时间 30～ 6 0 m in、p H3～ 4 ;最佳解吸条件为 :0 .0 2～ 0 .0 8m ol· L- 1 HCl、室温、30～ 6 0 min。纤维 L 对 Sm( )、Nd( )、Pr( )三种离子的一次吸附的最大量分别为 2 .99、2 .86、4 .11mg· g- 1 (被吸附离子的初始浓度 C0 =0 .0 0 1mol· L- 1 )。L 对三种离子均可进行三次以上累积吸附。

偕胺肟基螯合纤维的制备

以聚丙烯腈纤维为原料,加入羟胺试剂,将腈基转变为偕胺肟基团,使聚丙烯腈纤维改性成含有偕胺肟基团的螯合纤维.探讨了聚丙烯腈纤维改性的工艺参数,结果表明:聚丙烯腈在温度为65～75℃,pH值6～7的羟胺溶液中反应3 h,螯合纤维产率最高达到41%.用傅里叶变换红外光谱(FT-IR)对螯合纤维进行了表征,部分腈基转化成了偕胺肟基团.

高分子螯合剂在重金属废水处理中的应用

综述了国内外废水处理中捕集重金属离子的各种高分子螯合剂的制备方法及应用。二硫代氨基甲酸盐衍生物对重金属具有极强的螯合能力,以氨基甲酸或其盐类高分子有机物为基质的人工合成高分子螯合剂对去除各类重金属离子有良好的效果。改性天然高分子螯合剂其原料淀粉和纤维素是一种来源既便宜又广泛的天然高分子,经改性后的产品对捕集重金属离子具有低成本、高效、低毒的优势。今后可以进一步根据物质结构与性能的关系对天然高分子进行改性,并加强其应用工艺的研究开发。

新型螯合纤维对重金属离子吸附性能的研究

本文研究了由聚(N-乙烯基甲酰胺/丙烯腈)水解得到的一种新型螫合纤维的合成、结构特征和螯合性能。这种纤维包含了高密度的螯合基像脒基、氰基和酰胺基等。研究结果显示了该纤维对金属离子有很高的束缚能力,对Cu2+,Cr3+,CO2+和Ni2+的最大吸附量分别为108.46,87.03,137.68和105.06mg/g。吸附在螫合纤维上的金属离子经洗脱后可回收,螯合纤维可以反复使用。

离子交换及多孔材料的制备与应用

离子交换和多孔材料是一类高效的吸附剂,这类新型的高效吸附分离材料具有高的比表面积或丰富的表面官能团;显示出高的吸附容量、快的吸附或脱附速度和一定的吸附选择性;可织成束、纸、布、毡等多种集合形态.本文简要地介绍了包括离子交换纤维、螯合纤维、活性碳纤维、碳气凝胶等新型离子交换和多孔材料的制备、吸附特征研究的进展,并介绍了它们在饮用水净化、环境治理、资源回收、化学工业和医疗卫生、催化剂等方面的应用.

聚乙烯醇胺肟型螯合纤维的合成及其对铜(Ⅱ)离子的吸附

本文报导通过预辐照接枝法首次合成了聚乙烯醇胺肟(PVAAO) 型螯合纤维,并且研究了影响接枝率和胺肟基因含量的因素。该纤维对铜(Ⅱ)离子的吸附容量最高达2.41毫克当量/克千纤维。

聚乙烯醇双胺肟螯合纤维的合成及其吸附性能

利用预辐照接枝法合成了聚乙烯醇双胺肟螯合纤维。研究了影响接枝率和胺肟基团含量的因素，讨论了吸附酸度、吸附时间对Ｃｕ（Ⅱ）离子吸附容量的影响。合成的聚乙烯醇双胺肟螯合纤维对Ｃｕ（Ⅱ）离子的吸附容量达１．６２ｍｍｏｌ／ｇ干纤维，在５ｍｉｎ内达到吸附平衡。

聚丙烯腈氨基膦酸型螯合纤维对汞的吸附性能

本文对氨基膦酸型螯合纤维吸附Hg（Ⅱ）离子的特性进行了研究,考察了溶液平衡pH值对吸附百分率的影响,探讨了此螯合纤维对Hg（Ⅱ）离子的吸附选择性,结果表明:该螯合纤维对Hg（Ⅱ）离子的吸附基本符合Freundlich型等温方程式,并且具有较大的螯合容量和较快的吸附速度,在较低pH值下,对Hg（Ⅱ）离子具有较高的选择性。