粉煤灰合成沸石对重金属铅与镍的吸附性能研究

利用粉煤灰合成的沸石吸附混合重金属Ni~(2+)与Pb~(2+),考察吸附剂量、初始p H、反应温度与反应时间对其竞争吸附效果的影响,探讨沸石吸附Ni~(2+)与Pb~(2+)的吸附动力学。结果表明:随着吸附剂量的逐渐增大,沸石对Ni~(2+)与Pb~(2+)的吸附去除率不断提高,而单位质量吸附剂对Ni~(2+)与Pb~(2+)的吸附容量不断下降。在整个吸附过程中两种离子竞争吸附去除顺序是PbNi。初始p H值对沸石吸附Ni~(2+)与Pb~(2+)去除效果影响显著。酸性环境中沸石对混合重金属中Pb~(2+)的吸附抑制了其对Ni~(2+)的吸附。随着反应温度的上升与反应时间的延长,沸石对Ni~(2+)与Pb~(2+)的吸附去除率不断提高。沸石对Pb~(2+)的吸附去除率在各个反应温度均高于其对Ni~(2+)的去除率。沸石对混合重金属Ni~(2+)与Pb~(2+)的吸附动力学均符合准二级动力学模型。     

ZSM-5沸石对水溶液中铅离子的吸附性能

研究了ZSM-5沸石对水溶液中铅离子（Pb^2＋）的吸附性能,考察了Pb^2＋初始浓度、吸附剂用量、pH值和吸附时间等因素对吸附的影响。结果表明：ESM-5沸石对水溶液中铅离子有较好的去除效果,当其用量为40g／L时,水溶液中铅离子的吸附去除率达到96．09％;吸附过程在180min时达到吸附平衡;溶液pH值和初始浓度对水溶液中铅离子的去除也有显著的影响,中性和碱性条件下的去除率大于酸性时的去除率;平衡吸附量与吸附平衡浓度之间的关系较好符合Freundlich和Langmuir等温吸附方程所描述的规律。     

化学改性沸石对重金属离子去除的研究进展

随着工业的不断发展,重金属污染程度日益加深,严重危害人类的健康.近年来,化学改性沸石因具有较大的比表面积和较强的离子交换能力,在重金属离子处理领域被广泛应用.然而,在化学改性过程中,由于使用酸、碱、无机盐、有机试剂等改性剂,在能耗、成本以及可持续发展方面仍存在一定弊端.因此,开展沸石化学改性方法的研究,使其简单化、工业...     

Adsorptive Removal of Lead from Battery Wastewater by Coconut Coir

The sorption behavior of lead ions on coconut coir has been investigated to decontaminate lead ions from aqueous solutions. Various physico-chemical parameters were optimized to simulate the best conditions in which this material can be used as an adsorbent. Maximum adsorption was observed at 0.0001 to 0.001 mol L^?1 of acid solutions (HNO₃, HCl and HClO₄) using 0.4 g of adsorbent for 4.83 × 10^?5 mol L^?1 lead concentration in ten minutes equilibration time. The adsorption of lead was decreased with the increase in the concentrations of all the acids used. The kinetic data indicated an intraparticle diffusion process with sorption being pseudo-second order. The determined rate constant k₂ was 8.8912 g mg^?1 min^?1. The adsorption data obeyed the Freundlich isotherm over the lead concentration range of 2.41 × 10^?4 to 1.45 × 10^?3 mol L^?1. The characteristic Freundlich constants i.e., 1/n = 0.44 ± 0.02 and K = 0.184 ± 0.0096 m mol g^?1 have been computed for the sorption system. The sorption mean free energy from the Dubinin-Radushkevich isotherm is 10.48 ± 0.72 kJ mol^?1 indicating the ion-exchange mechanism of chemisorption. The uptake of lead increases with the rise in temperature (293–333 K). Thermodynamic quantities i.e., ΔG, ΔS, and ΔH have also been calculated for the system. The sorption process was found to be endothermic. The proposed procedure was successfully applied for the removal of lead from battery wastewater samples.     

Effect of pH and temperature on the ion‐exchange isotherm of Cd(II) and Pb(II) on clinoptilolite

The ion‐exchange equilibrium of Pb(II) and Cd(II) on clinoptilolite from different deposits was studied in this work. The Langmuir isotherm fitted the ion‐exchange equilibrium data of both ions better than the Freundlich isotherm. The capacity of the natural zeolite to exchange Cd(II) and Pb(II) increased, augmenting the solution pH. This behaviour was attributed to the interactions between the ions in solution and the surface charge of the zeolite. Moreover, the capacity of the natural zeolite to exchange Cd(II) and Pb(II) was increased when the temperature was raised from 15 to 35 °C. This tendency was explained by assuming that the ion exchange was an endothermic reaction. The selectivity of the zeolite for the metal cations decreased in the following order: Pb(II) > Cd(II). This order was not modified while reducing the solution pH, but the zeolite selectivity was increased. At pH 2 the selectivity of the zeolite for Pb(II) was nearly three times larger than at pH 4. Copyright © 2006 Society of Chemical Industry     

Removal of Fluoride from Water by Metal Ions (Al3+, La3+ and ZrO2+) Loaded Natural Zeolite

Abstract

In this study, the ion exchange of metal ions (Al³⁺, La³⁺ and ZrO²⁺) on modified zeolites was carried out using batch method. Fluoride removal from water using Al³⁺‐, La³⁺‐ and ZrO²⁺‐ exchanged zeolite was subsequently investigated to evaluate the fluoride sorption characteristics of the sorbents. Natural zeolite samples (<45 µm) were pre‐conditioned with HNO₃ solution (ZEO‐1), NaNO₃ solution (ZEO‐2), and deionized water (ZEO‐3) before loading Al³⁺, La³⁺, and ZrO²⁺ on zeolite. ZEO‐1 type zeolite had a higher capacity than ZEO‐2 and ZEO‐3 type zeolites. Metal exchange capacities are 0.233, 0.089, 0.090 mmol/g for ZrO²⁺‐, La³⁺‐, and Al³⁺‐ exchanged zeolite (ZEO‐1), respectively. Equilibrium isotherms fitted well to Langmuir and Freundlich models. Percent removal of fluoride from aqueous solution containing 2.5 mg F/L was 94% using metal loaded zeolite (ZEO‐1 type) at an adsorbent concentration of 6.00 g/L.     

The Effect of Zeolite Fixed Bed Depth on Lead Removal from Aqueous Solutions

Abstract

The effect of zeolite bed depth on lead removal from aqueous solutions by the column method has been examined. The results indicate that the increase of bed depth delays the breakthrough point and exhaustion point, and increases the contact time of the zeolite – lead solution, and the height of the mass transfer zone, h_z. The increase of the bed depth lowers the effect of axial dispersion on the mass transfer process. In order to predict the time necessary for exceeding the defined effluent concentration for a constant bed depth, the bed depth service time (BDST) approach has been used. Experimentally obtained breakthrough curves for the flow rate of 1 ml/min were used to derive the BDST approach equations. These equations were successfully used for modelling of the system for flow rates of 2 and 3 ml/min. The BDST equations have yielded modelled linear equations used for calculation of h_z. The increase of the flow rate increases h_z, which indicates that the zeolite–solution contact time is not sufficient. This may be attributed to the affect of axial dispersion on mass transfer on the solid-liquid interface.     

Mechanism of the Adsorption of Ammonium Ions from Aqueous Solution by a Chinese Natural Zeolite

Abstract

The adsorption of ammonium ions onto a Chinese natural zeolite in an agitated batch adsorber was studied. A trial‐and‐error non‐linear method was developed to examine two widely used isotherms, the Langmuir and Freundlich. The data gained from the adsorption system fitted the Freundlich isotherm better. An ion exchange model, describing the relationship among the total metal ions in the solution, NH₄ ⁺ removed from the solution, and ions initially released from the zeolite, was developed for the adsorption system. In addition, a parameter of the ion exchange potential was defined to describe the adsorption mechanism. Ion exchange was the main mechanism that accounted for the adsorption of ammonium ions onto the Chinese natural zeolite.     

Ammonia Removal from Aqueous Solutions by Iranian Natural Zeolite

Abstract

The capability of Iranian natural clinoptilolite for ammonia removal from aqueous solutions has been thoroughly studied. Both batch and continuous (column) experiments were carried out. The viability of this natural zeolite in reducing the leakage of ammonia to the environment through waste water streams was a main focus of this research. Through the batch experiments, the effect of process variables such as the size of zeolite particles, pH, and ammonia concentration of the feed solution on the kinetics of ammonia uptake were investigated. Ammonia removal occurred rapidly and within the first 15 minutes of contact time, a major part of ammonia was removed from the solution. An adsorption capacity about 17.8 mg NH₄ ⁺/g zeolite at feed ammonia concentration of 50 mg/L was obtained and the optimum range for pH was achieved about 5.5–7.6. The adsorption capacity of clinoptilolite in the continuous mode was about 15.16 and 15.36 mg NH₄ ⁺/g zeolite for the original and regenerated types of clinoptilolite, respectively, where feed ammonium concentration was 50 mg/L. Increasing the feed ammonium concentration to 100 mg/L did not reduce the capability of the column for its ammonium removal and up to a bed volume (BV) of 85, there was only less than 1 mg/L ammonium in the column outlet. Presence of cations such as Ca²⁺, Mg²⁺ and Na⁺ in the feed solution reduced the clinoptilolite adsorption capacity to about 11.68 mg NH₄ ⁺/g zeolite. Regeneration experiments were carried out using concentrated sodium chloride solutions, as well as tap water. Where tap water was used as the regenerant, gradual release of ammonium from exhausted clinoptilolite was observed.     

Removal of Lead (II) Ions from Aqueous Solution Using Eggplant Peels Activated Charcoal

The eggplant peel activated charcoal (EPPAC) was investigated as an adsorbent for the removal of lead II ions from aqueous solution. Three methods were tested for the production of eggplant peel activated charcoal (EPPAC) from eggplant peel charcoal (EPPC), yielding three different products; EPPAC-1, EPPAC-2, and EPPAC-3. The difference among the three methods lies in the primary physical mixing of the EPPC with the activating agent (potassium hydroxide) before heating the mixture in a furnace for activation. The removal efficiency of lead II ions by the three adsorbents was 57.7%, 70.0%, and 60.0% for EPPAC-1, EPPAC-2, and EPPPAC-3, respectively. The optimized activation parameters for EPPAC-2 were: activation time 2 hours, activation temperature 700°C, and activation ratio 1:2 (EPPAC: KOH). Scanning electron microscopy (SEM) revealed that EPPAC-2 has the most porous structure. The surface area of EPPAC-2 was measured to be 739 m²/g. Adsorption kinetics of lead (II) is best described by the pseudo-second-order kinetic model with second order rate constant of 1.70 × 10^?3 g/mg.h at room temperature. The adsorption of lead on EPPAC-2 is found to follow the Langmuir isotherm with a maximum adsorption capacity of 1.4 × 10² mg/g.     

铜离子和镍离子对绿泥石的抑制作用及机理

通过浮选实验、动电位测量、ICP离子浓度测试及溶液化学计算,研究铜离子和镍离子对绿泥石浮选的影响,并考察其作用机理.结果表明,绿泥石具有一定的天然可浮性,一定pH值条件下铜离子和镍离子能够水解生成亲水的氢氧化物沉淀,通过静电作用吸附在绿泥石表面,抑制绿泥石的浮选;在较高pH条件下,生成的氢氧化物沉淀与绿泥石表面电性相同,吸附量较少,抑制效果较弱.     

Amidoximation of Cyano Group for Chelating Ion Exchange of Some Heavy Metal Ions from Wastewater

Ion exchange behavior of some heavy metal ions, Pb²⁺, Ni²⁺, and Cd²⁺, onto amidoximated polyacrylonitrile based Ce(IV) phosphate was investigated. Polyacrylonitrile based Ce(IV) phosphate was prepared and followed by functionalization of the cyano group to amidoxime group with hydroxylamine. The amidoximated resin was characterized using FT-IR and SEM. Removal of Pb²⁺, Ni²⁺, and Cd²⁺ ions from aqueous solution was examined by studying some factors using the batch technique such as effect of pH, contact time, initial metal ion concentration, and temperature. Some kinetic and isotherm models had been applied. The calculated amount of the sorbed values in case of the pseudo-second-order model are closer to the experimental data than that of the pseudo-first-order model, and with a correlation coefficients R² > 0.99. Therefore, the sorption of the three metal ions can be approximated more favorably by the pseudo-second-order model. The sorption process obeys the Freundlich isotherm model. The sorption has an endothermic nature which is indicated by the positive value of the enthalpy change, ΔH, the high positive values of the entropy change, and ΔS show the increased randomness at the solid/solution interface. The obtained negative values of free energy change, ΔG, indicate the feasibility and the spontaneous nature of the sorption process.     

Removal of Copper (II) and Nickel (II) Ions from Aqueous Solutions by a Composite Chitosan Biosorbent

Abstract

A composite chitosan biosorbent (CCB) was prepared by coating chitosan on to ceramic alumina. The adsorption characteristics of the sorbent for copper and nickel ions were studied under batch equilibrium and dynamic flow conditions at pH 4.0. The equilibrium adsorption data were correlated with Langmuir, Freundlich, and Redlich‐Peterson models. The ultimate monolayer capacities, obtained from Langmuir isotherm, were 86.2 and 78.1 mg/g of chitosan for Cu(II) and Ni(II), respectively. In addition, dynamic column adsorption studies were conducted to obtain breakthrough curves. After the column was saturated with metal ions, it was regenerated with 0.1 M sodium hydroxide. The regenerated column was used for a second adsorption cycle.     

The Adsorption of Arsenic Ions Using Beidellite,Zeolite, and Sepiolite Clays: A Study of Kinetic,Equilibrium and Thermodynamics

Arsenic contamination in drinking water resources is a global problem; therefore, its removal from drinking water has become an important sustainable matter. The adsorption process can be more cost-effective and applicable, especially, if the absorbents used in the process are low-cost natural geo-materials. Beidellite, zeolite, and sepiolite are inexpensive and natural minerals available locally, modified, and used as adsorbents for the removal of arsenic ions from aqueous solutions in batch experiments. The kinetics of the adsorption process was separately tested for the pseudo-first order and pseudo-second order reactions and intra-particle diffusion models. The rate constants of adsorption for all these kinetic models were calculated. The comparison among the models showed that the pseudo second-order model best described the adsorption kinetics. Applied to the experimental equilibrium, at different temperatures were the Langmuir and Freundlich isotherm models. The Langmuir isotherm was used to calculate the adsorption capacities (Q°) of minerals for arsenic ions. The adsorption capacities of these three modified minerals, at different temperatures, ranged from 476 to 841 µg/g. Thermodynamic studies showed that the arsenic uptake reactions by minerals were endothermic and spontaneous in nature. Bottled spring water containing arsenic, sold in markets, was used to conduct the arsenic adsorption study beidellite, zeolite, and sepiolite, minerals which efficiently removed the arsenate ions from the bottled drinking water. The use of modified beidellite, zeolite, and sepiolite as adsorbents in the arsenic ion removal processes is possible, based on the optimum parameters found.     

碱性条件下NaY分子筛水热交换反应的研究

对碱性条件下的分子筛离子水热交换反应进行了研究。结果表明,离子交换反应为吸热反应,交换反应等温线为d型,交换反应为一级反应,表观活化能Ea为10．05kJ／mol。     

钛柱撑蒙脱石对镍离子和锰离子的吸附机理

以钠基蒙脱石(Na-MMT)、钛酸四丁酯作基质材料,通过溶胶-凝胶法制备了钛柱撑蒙脱石(Ti-MMT)。利用XRD、FTIR及SEM对Ti-MMT进行了结构表征,考察了不同吸附条件对Ti-MMT吸附Ni~(2+)和Mn~(2+)的影响,并重点分析水溶液pH对Ti-MMT Zeta电位及吸附的影响,探究了Ti-MMT吸附Ni~(2+)和Mn~(2+)的机理。结果表明:Ti-MMT具有较大的晶面间距(d001=2.94 nm);pH对吸附Ni~(2+)与Mn~(2+)有较大影响,去除率随初始水溶液pH增加而提高。在pH=7,Ni~(2+)和Mn~(2+)初始质量浓度为50 mg/L,Ti-MMT投加量分别为5和9 g/L时,Ni~(2+)在318 K下吸附120 min,吸附量可达9.46 mg/g,去除率可达94.59%,Mn~(2+)在328 K下吸附180 min,吸附量可达4.82mg/g,去除率可达86.73%。此外,Ti-MMT对两种离子的吸附都更符合Temkin等温吸附模型及拟二级动力学模型,吸附过程受液膜扩散、颗粒内扩散等环节控制,且以离子交换的化学吸附为主。热力学分析表明,Ti-MMT对Ni~(2+)的吸附属于自发吸热熵增过程,而Mn~(2+)属于吸热熵增的非自发过程。     

磁性X沸石的合成及其性能

采用水热合成法,在X型沸石的晶化原料液中加入磁核合成了磁性沸石,对合成产物进行了结构性能测试. 结果表明,产物为X型沸石结构,具有较好的磁性能和吸附性能. 饱和磁化强度为3.7 emu/g,在磁场作用下,磁性沸石在30 min内完成与母液的分离,产物的比表面积为571.5 m2/g,铅离子吸附量为196.8 mg/g.     

HPb59-1铅黄铜电镀黑镍工艺

介绍了以HPb59-1铅黄铜标准螺钉电镀黑镍的全部工艺过程。基材经过化学除铅后电镀锌-镍作为阻挡层,再电镀锌作为打底层,最后电镀黑镍。采用此工艺获得的螺钉螺纹牙丝不发黄,镀出的黑镍层均匀、黝黑,能够满足HB5039-92中抗变色标准要求,具有良好的消光性能和吸幅比。     

Preparation of Pectin-Based Biosorbents for Cadmium and Lead Ions Removal

The optimal formation conditions of pectin-based, as well as new hybrid pectin-guar gum, biosorbents were found. The lead affinity for obtained biosorbents was very strong even in solution of pH = 1, in opposite to cadmium, which was adsorbed from solutions of pH ≥ 2. The sorption capacities in the studied conditions were about 0.6 and 0.8 mmol/g for cadmium and lead, respectively. The cadmium removal could be fast and it is almost quantitatively desorbed using 0.25 M HNO₃, while desorption of lead required 1 M HNO₃ to achieve a removal efficiency of ca. 75% from pectin-based beads. The possibility of biosorbents’ reuse was also proved. Addition of guar gum to pectin biosorbent did not change its sorption properties significantly.     

Removal of lead(II) from water using activated carbon developed from jujube stones,a low-cost sorbent

The preparation of activated carbon from jujube stones with H₂SO₄ activation and its ability to remove lead from aqueous solutions were reported in this study. The surface structure of the activated carbon was characterized by various physico-chemical methods. Sorption studies were carried out by varying the initial metal ion and the pH: the amount of sorbed Pb(II) ions increased with increasing pH and initial Pb(II) ions concentration. The removal of lead ions was rapid and the kinetic of sorption can be well described by pseudo-second order modelling. The Langmuir model conveniently fits the data of isotherm experiments and the monolayer sorption capacity of Pb(II) ions was determined as 71.43 mg/g at pH 6.0 and 25°C. These results showed that activated carbon prepared from jujube stones could be considered for application as a potential sorbent for the removal of lead from wastewaters.