Preparation and application of a novel magnetic anion exchange resin for selective nitrate removal

正A novel magnetic anion exchange resin NDM-1 was prepared through suspension polymerization and then functionalized with ammonolysis and alkylating agents.Its application for selective removal of nitrate was performed in comparison with MIEX~.The results demonstrated that NDM-1 achieved higher efficiency in nitrate removal than MIEX~ did,with or without the existence of competing anion SO_4~(2-) ascribed to its longer alkyl chains on exchange sites.Combined with the advantage of easy separation due toγ-Fe_2O_3 implanted,the magnetic anion exchange resin NDM-1 was considered to be superior to MIEX~ for nitrate removal in practical application.     

Selective removal of nitrate by using a novel macroporous acrylic anion exchange resin

An anion exchange resin NDP-5 has been prepared successfully and applied on the selective removal of nitrate from SO₄^2-/ NO₃^- binary co-existence system.The composition and morphology of NDP-5 were confirmed by FT-IR and SEM.The NDP-5 resin exhibits the completely different behavior on the adsorption capacity,adsorption kinetic and the effect of the completing anion in the absence or presence of sulfate,compared to D213.And,the resultants of kinetic are well fitted by the pseudo-first-order and pseudo-second-order models.These results are very important to develop novel resins with great features.     

Preparation of a novel magnetic resin for effective removal of both natural organic matter and organic micropollutants

A novel,bifunctional,hypercrosslinked.magnetic resin W2 was prepared using divinylbenzene(DVB) and glycidyl methacrylate(GMA) as comonomers in three steps(i.e.,suspension polymerization, amination and post-crosslinking reactions).To evaluate the adsorption of natural organic matter(NOM) and organic micropollutants(OMPs) on the obtained resin W2,two magnetic resins Wl(the precursor of W2 before post-crosslinking) and WO(the precursor of Wl before amination) were chosen for comparison.The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.     

Utilization of anion exchange resin Spectra/Gel for separation of arsenic from water

Arsenic in drinking water is one of the most challenging health hazards facing mankind today. Arsenic is a naturally occurring carcinogen and creates epidemiological problems through chronic ingestion from drinking water. Arsenic is present in water primarily as As(III) or As(V). Removal of both As(III) and As(V) from water by adsorption on strong base anion-chloride has been studied. Arsenic concentration was measured by Inductively Coupled Argon Plasma (ICP) analysis. The resin was regenerated and the adsorbed arsenic fractions were eluted by using 2 M NaCl. The effect of different parameters that influence adsorption process, such as relative arsenic and resin concentrations, retention time, and pH, were investigated. Results obtained revealed that As(III) was poorly adsorbed, whereas As(V) was successfully retained on the resin. The adsorption process was optimized by using 1 g resin for 16 ppm As(V) at pH 9 for 30 min. The removal efficiency of As(V) was 99.2%.     

阴离子交换树脂分离-原子荧光法测定色母粒中的镉

采用微波消解溶样,结合离子交换法对色母粒样品进行待测元素的提取及净化处理,利用原子荧光光度计进行镉含量的测定。研究了717型阴离子交换树脂对色母粒样品中镉的吸附及分离条件,解决了样品中铅、铜等元素的干扰问题。方法加标回收率在92.4%～117.4%之间,相对标准偏差小于3.0%。     

Exchange studies of 5-sulphosalicylic acid in amberlite IRA 401 Cl anion exchange resin

Exchange studies of 5-sulphosalicylic acid in Amberlite IRA 401 Cl anion exchange resin have been carried out at 25°C in a stirred vessel. The exchange rates have been interpreted on the basis of a simple diffusion model.     

Kinetics and thermodynamics of rebaudioside A adsorption on a strongly acidic cation exchange resin

To explain the mechanism underlying the adsorption of stevia's polar component rebaudioside A in hydrophilic interaction liquid chromatography mode, the characteristics of rebaudioside A adsorption on various resins in an organic‐solvent‐rich system were studied. Among the tested resins, the strongly acidic cation resin FPC11 showed the best adsorption behavior for rebaudioside A. The factors affecting the adsorption kinetics of the resin for rebaudioside A are discussed. The results showed that the pseudo‐second‐order reaction model and intra‐particle diffusion model best described the adsorption kinetics of rebaudioside A on the resin. The adsorption rate was controlled by physical sorption, mainly via electron sharing or electron transfer between the adsorbent and the adsorbate. The adsorption process with multiple stages involved weak initial adsorption behavior. Thermodynamic studies showed that the adsorption of rebaudioside A on the resin was not an ideal monolayer adsorption, but mutual adsorption effects between the adsorbates. The adsorption was a spontaneous, entropy‐increasing endothermic process. The synergistic effect of hydrogen bonding and ion–dipole was a possible driving force.     

330阴离子交换树脂对草甘膦的吸附性能

采用静态吸附法研究了330阴离子交换树脂对水中草甘膦的吸附性能,并研究了吸附动力学;测定了溶液的pH值、温度、NaCl含量等因素对330树脂吸附草甘膦的影响.结果表明:330树脂对水中草甘膦的吸附速率快;在pH=2.69时对草甘膦的吸附性能最好;330树脂对草甘膦的吸附是放热、自发的过程,吸附等温线符合Freundli...     

Efficient adsorption and desorption of Cu2+ by a novel acid-resistant magnetic weak acid resin

A novel magnetic weak acid resin NDMC-1 was prepared in the presence of methyl acrylate（MA）,divinylbenzene（DVB） and titanate coupling agent（TCA） coated 7-Fe₂O₃ particles.To evaluate the adsorption of Cu²⁺ on the obtained resin NDMC-1,another two magnetic resins NDMC-0（the precursor of NDMC-1 without hydrolyzation） and NDMO-l（the synthesized weak acid resin using oleic acid coatedγ-Fe₂O₃） were chosen for comparison.The results showed that the carboxyl groups were formed after hydrolyzation,and NDMC-1 exhibited a greater adsorption capacity to Cu²⁺.The desorption experiment demonstrated that the desorption ratio at pH 2（95.14%） was greatly higher than pH 3（25.97%）.Moreover,the magnetic resin NDMC-1 was proved to be stable at pH 2,extending the application of magnetic materials which were always considered to be acid-nonresistant.     

磁性水铁矿的制备及其对二甲基亚胂酸的吸附性能

二甲基亚胂酸会对人体和环境造成严重危害。用水热法合成磁性水铁矿,对产物进行了X射线衍射分析、BET比表面积分析和磁滞回线分析,结果表明磁性水铁矿纯度较高,比表面积较大,具有较强的磁性。用磁性水铁矿作为吸附剂,考察了二甲基亚胂酸在磁性水铁矿上的吸附动力学及吸附等温线。二甲基亚胂酸在磁性水铁矿上的吸附符合准二级动力学模型,吸附速率为0.34g·mg^-1·h^-1;吸附等温线符合Freundlich模型。采用Zeta电位测定、FT-IR、SEM-EDS和XPS对吸附机理进行分析,表明磁性水铁矿通过配位络合作用和静电作用来吸附二甲基亚胂酸,在吸附过程中磁性水铁矿表面形了成Fe-O-As三元络合物。研究结果为含有二甲基亚胂酸污染物的水体处理和净化提供了新方法。     

离子交换树脂固态胺复合材料的制备、表征及CO2吸附

以离子交换树脂（D001）为载体,四乙烯五胺（TEPA）为改性剂,采用三种不同的方法制备了一系列固态胺吸附剂。采用N₂吸附-脱附、傅里叶变换红外光谱（FT-IR）、热重分析（TGA）等手段对吸附剂进行表征。在固定床反应器中考察了TEPA负载量、吸附温度、进气流量和CO₂分压等因素对CO₂吸附性能的影响。结果表明,配位法制得的固态胺吸附剂分散性和稳定性较好,且在TEPA负载量为40%,吸附温度为65℃,进气流量为40 mL/min时有最大CO₂吸附量达4 mmol/g。经过10次吸附-脱附循环实验后,CO₂吸附量下降3.98%。热力学、动力学研究结果表明,CO₂吸附是物理吸附和化学吸附的结果。     

Removal of methylene blue by seed-watermelon pulp-based low-cost adsorbent: Study of adsorption isotherms and kinetic models

Based on the abundance of seed-watermelon pulp (SWP) in Xinjiang, China, SWP was employed to prepare low-cost adsorbent toward the removal of methylene blue (MB). The effects of contact time at different initial concentration were studied. The widely used adsorption isotherm models including Langmuir, Freundlich, and Temkin isotherms were employed to depict the adsorption process. The Langmuir isotherm was best fitted to the experimental data. Batch kinetic studies showed that an equilibrium time of 300 minutes was needed for the adsorption. The adsorption properties can be well described by pseudo-second-order kinetic model and the MB uptake was not controlled by intraparticle diffusion mechanism.     

Esterification of palmitic acid with epichlorohydrin on anion exchange resin catalyst

The esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled. The structure of synthesized ester was confirmed by FTIR and ¹H NMR analyses.      

Kinetics and mechanism of ion exchange of Fe3+, Cd2+ and Na+/H+ on Lewatite S-100 cation exchanger in aqueous and aqueous-detergent media

Sorption mechanism of Fe (III), Cd (II) and Na (I) on cation exchange resins in H-form was investigated from aqueous and aqueous-detergent media by a modified limited batch technique. The cation exchange studies involved the sorption of metallic ions onto a Lewatite S-100 exchanger. Effects of mesh size of the exchanger, temperature and detergent on the exchange rate have been investigated. The mechanisms of cation exchanges have been determined in the temperature range of 25–65°C. In all cases of the reactions ions, diffusion is found to be the rate determining step in the exchange process. The exchange rate in the exchange process was found to increase with a decrease of particle size and an increase of temperature. However, in case of the influence of detergent, the exchange reactions are dependent on the reaction technique. The effective-diffusion coefficients have been evaluated at three different temperatures. The energy barriers (ΔE_a), entropies of activation (ΔS*), (ΔH*) and (ΔG*) for various sorption systems have also been calculated. The results are discussed in terms of size and valences of the counter ions. No change in the internal structure of Lewatite S-100 is inferred due to the sorption of counter ions.     

球形纤维素磁性阴离子交换树脂的化学转化制备及特性研究

自制了大孔球形纤维素基阴离子交换树脂(PSC-AN),并利用化学转化法成功制备了大孔球形纤维素基磁性阴离子交换树脂(PSC-MAN)。对影响树脂质量磁化率的几个主要因素进行了探讨,实验确定最佳制备条件为:铁盐的配比为1∶10,EDTA的浓度为0.005 mol/L。对树脂的结构和性能进行了研究,表明化学转化法制备大孔球形纤维素基阴离子交换树脂(PSC-MAN)磁性强,在碱液中相当稳定,树脂磁化前后交换容量分别为Q前=1.33 meq/g、Q后=1.16 meq/g,即树脂基的交换容量基本不受磁化过程的影响。     

树脂分离-氢化物发生-原子荧光光谱法测定食品中无机砷、一甲基胂和二甲基胂

建立了用阴离子交换树脂分离-氢化物发生原子荧光光谱法测定食品中无机砷、一甲基胂和二甲基胂的方法.分别从样品上样条件及二甲基胂、一甲基胂、 As(Ⅲ)和As(Ⅴ)分离条件进行了优化.研究了树脂处理程序对分离的影响,并探讨了共存离子对测定砷的干扰和消除的方法.对方法的适用范围做了研究.本方法具有操作简便、快速、灵敏度高等优点.检出限(以砷计)分别为: 无机砷0.34 μg/L,一甲基胂0.57 μg/L,二甲基胂0.46 μg/L.     

Preparation and characterization of Type II anion exchange membranes from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)

To separate hydrophilic anions from hydrophobic ones, Type II PPO-based anion exchange membranes were developed. Different from Type I (with both trimethylbenzylammonium and triethylbenzylammonium groups), Type II has an excellent hydrophobicity modifier as fixed groups: dimethyethanolammonium groups, which were introduced into PPO (poly(2,6-dimethyl-1,4-phenylene oxide)) by following benzyl bromination of PPO and subsequent quaternary amination with a dimethylethanolamine (DMEA) aqueous solution. The membrane's intrinsic properties are dependent on DMEA concentration and amination temperature. The optimum conditions for membrane preparation are as follows: amination temperature 70 °C, time 30–48 h, and DMEA concentration 1:3–1:5 (v/v, DMEA to water). The obtained Type II anion exchange membranes had an IEC of 1.5 mmol/g dry membrane, water content of 30%, and membrane area resistance of 30 Ω cm². The introduced dimethyethanolammonium groups can block hydrated anions from the access to membranes but let hydrophobic anions transport; hence, an effective separation between hydrophilic and hydrophobic anions can be achieved during electro-membrane operation.     

CMC-Na辅助磁性Fe3S4纳米复合物的合成及其吸附与吸波性质研究

以羧甲基纤维素钠(CMC-Na)为模板,采用简单温和的水热法制备了一种薄片状含碳Fe3S4纳米复合物,并探讨了反应时间和反应温度的影响。采用X射线衍射、扫描电镜、透射电镜、FT IR、振动磁强计和UV-Vis对材料进行了表征。结果表明,这种纳米复合材料在常温下具有较好的吸波性质和对污水中亚甲基蓝染料的吸附作用。     

Reactive blue 19 adsorption behaviors of magnesium hydroxide modified biochar derived from the traditional Chinese medical residual

This study examined the reactive blue 19 (RB-19) adsorption behaviors of magnesium hydroxide modified biochar (MBC) derived from the traditional Chinese medical residual. The obtained MBC was characterized using Scanning Electron Microscope (SEM), Fourier Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The static adsorption experiment was carried out to investigate the adsorption properties. The results indicated that pH 4 was best for the adsorption removal of RB-19 in the pH range of 4–9. Compared with the pseudo-first-order model and Elovich model, the pseudo-second-order equation was best to describe the adsorption process (R² > 0.995). The Langmuir model was better than the Freundlich model to fit the experimental data (R² > 0.990). The intra-particle diffusion model showed that film diffusion and intra-particle diffusion were involved in the adsorption process. Thermodynamic parameters showed that the RB-19 adsorption by MBC was spontaneous and endothermic. The adsorption mechanism might include electrostatic interaction, pore filling, and hydrogen bond, and the MBC was a promising adsorbent.     

Kinetics and thermodynamics of bromophenol blue adsorption by a mesoporous hybrid gel derived from tetraethoxysilane and bis(trimethoxysilyl)hexane

A mesoporous hybrid gel is prepared with tetraethoxysilane (TEOS) and bis(trimethoxysilyl)hexane (TSH) as precursors without using any templating agent. Nitrogen sorption, TG-DTA, FTIR, and point of zero charge (PZC) measurement are used to characterize the gel. The gel has a specific surface area of 695 m(2) g(-1) with a pore size of 3.5 nm, a pore volume of 0.564 cm(3) g(-1), and a point of zero charge (PZC) of 6.2. The kinetics and thermodynamics of bromophenol blue (BPB) adsorption by the gel in aqueous solution are investigated comprehensively. The effects of initial BPB concentration, pH, ionic strength, and temperature on the adsorption are investigated. Kinetic studies show that the kinetic data are well described by the pseudo-second-order kinetic model. Initial adsorption rate increases with the increase in initial BPB concentration and temperature. Adsorption activation energy is found to be 62.5-67.5 kJ mol(-1) depending on the initial BPB concentration. Internal diffusion appears to be the rate-limiting step for the adsorption process. The equilibrium adsorption amount increases with the increase in the initial BPB concentration, solution acidity, and ionic strength, but decreases with the increase in temperature. The thermodynamic analysis indicates that the adsorption is spontaneous and exothermic. The adsorption isotherms can be well described with Freundlich equation indicating the heterogeneity of the hybrid gel surface. Electrostatic and hydrophobic interactions are suggested to be the dominant mechanism for adsorption.