Relationship between breakthrough curve and adsorption isotherm of Ca(Ⅱ) imprinted chitosan microspheres for metal adsorption

In this work, an equilibrium-dispersion model was successfully established to describe the breakthrough performance of Ca(II) imprinted chitosan (Ca(II)-CS) microspheres packed column for metal adsorption, and the assumptions of Langmuir isotherms and axial dispersion controlled mass transfer process were confirmed. The axial dispersion coefficient in Ca(II)-CS microspheres packed column was found to be almost proportional to the linear velocity and fit for prediction through single breakthrough test. Sensitivity analysis for breakthrough curve indicated the axial dispersion coefficient as well as Langmuir coefficient was sensitive variable for deep removal requirement. The retrieval of the adsorption isotherms of Ca(II)-CS microspheres from breakthrough curve was fulfilled by model ing calibration. A strategy based on the correlation between adsorption isotherms and breakthrough performance was further proposed to simplify the column adsorption design using absorbents with smal/uniform size and fast adsorption kinetics like Ca(II)-CS microspheres to cut down the gap between lab and industry.     

Cd(II)掺杂TiO2多孔纳米晶膜电极 的表征及其光电化学行为

利用X射线粉末衍射法和原子力显微镜对镉掺杂的TiO     

羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)、Cd(Ⅱ)吸附性能研究

以CO2为活化剂制备羊骨炭,在不同溶液pH、初始浓度、活性炭投加量等条件下,通过动态吸附试验考察羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)和Cd(Ⅱ)的吸附规律,并用Langmuir和Freundlich吸附等温模型对其吸附性能进行了分析。结果表明,当羊骨炭对Pb(Ⅱ)、Cr(Ⅵ)和Cd(Ⅱ)的最佳吸附量分别为:4.2 mg/g、0.07 mg/g和2.7 mg/g时,吸附液的pH值Pb(Ⅱ)、Cd(Ⅱ)为7～8、Cr(Ⅵ)为酸性pH<6;羊骨炭的投加量分别为:0.2、0.7、0.03 g;最佳初始浓度分别为:60 mg/L、15 mg/L、30 mg/L。羊骨炭对3种离子的吸附行为基本符合Langmuir吸附等温模型和Freundlich吸附等温模型,计算得四种离子的最大吸附量分别为:4.854、1.247、0.402 mg/g。     

Zn-MOF-74对Cd(Ⅱ)的吸附性能及机理研究

研究了新型吸附材料Zn-MOF-74对水体中重金属Cd(Ⅱ)的吸附性能和吸附机理。结果表明,吸附过程较好地符合Langmuir模型、Temkin模型、D-R模型和准二级动力学模型,最大吸附量为16.77 mg/g;吸附过程为物理吸附和化学吸附共同作用,且为自发的放热反应。采用Zn-MOF-74处理0.5 mg/L的含镉废水,有效时长可达36.25 h,Cd(Ⅱ)去除率>90%;NaCl溶液的解吸率可达到85%。吸附位点主要集中在孔道中,有静电作用、化学作用和氢键作用。     

改性泥炭对Pb(Ⅱ)和Cd(Ⅱ)的单一及竞争吸附研究

以强碱改性泥炭,研究改性泥炭对Pb~(2+)、Cd~(2+)的吸附效果及竞争吸附机制。结果表明,改性泥炭对Pb~(2+)、Cd~(2+)具有显著的吸附效果,吸附容量分别由118,64 mg/g提高到225,95 mg/g;FTIR分析表明,吸附过程为Pb~(2+)、Cd~(2+)与—OH、—COO-、C—H等官能团的络合作用或者离子交换作用。当吸附时间为70 min,pH在4～8,改性泥炭添加量分别为0.8,1.6 g/L时,可达到高效与经济双层效益。竞争吸附中,Pb~(2+)、Cd~(2+)的吸附容量均低于单一离子时的吸附容量,且竞争吸附能力Pb~(2+)Cd~(2+)。     

改性泥炭对Pb(Ⅱ)和Cd(Ⅱ)的单一及竞争吸附研究

以强碱改性泥炭,研究改性泥炭对Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附效果及竞争吸附机制。结果表明,改性泥炭对Pb(2+)的吸附效果及竞争吸附机制。结果表明,改性泥炭对Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾具有显著的吸附效果,吸附容量分别由118,64 mg/g提高到225,95 mg/g;FTIR分析表明,吸附过程为Pb(2+)具有显著的吸附效果,吸附容量分别由118,64 mg/g提高到225,95 mg/g;FTIR分析表明,吸附过程为Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾与—OH、—COO-、C—H等官能团的络合作用或者离子交换作用。当吸附时间为70 min,pH在4～8,改性泥炭添加量分别为0.8,1.6 g/L时,可达到高效与经济双层效益。竞争吸附中,Pb(2+)与—OH、—COO-、C—H等官能团的络合作用或者离子交换作用。当吸附时间为70 min,pH在4～8,改性泥炭添加量分别为0.8,1.6 g/L时,可达到高效与经济双层效益。竞争吸附中,Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附容量均低于单一离子时的吸附容量,且竞争吸附能力Pb(2+)的吸附容量均低于单一离子时的吸附容量,且竞争吸附能力Pb⁽²⁺⁾>Cd(2+)>Cd⁽²⁺⁾。     

Zn(Ⅱ)-EDTA和Cd(Ⅱ)-EDTA在草酸根掺杂溴化银颗粒乳剂中的增感效应

使用反馈式微机控制双注乳化仪,在晶体生长过程特定时间内,加入一定量的草酸盐,制得了草酸根离子处于晶体次表面的立方体溴化银微晶乳剂,并对其进行传统的硫加金化学增感、Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感以及光谱增感.对实验过程的考察和感光性能的测试结果表明,Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA对细微粒溴化银颗粒乳剂均有显著的增感效应;Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感可在传统硫加金增感基础上与光谱增感协同作用,三者具有兼容和可加和性;Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感可在传统硫加金增感与光谱增感协同作用的基础上,与草酸根内部掺杂增感兼容,实现四者的协同作用,而不引起乳剂灰雾增加.     

竹炭对水溶液中Cu(Ⅱ)、Cd(Ⅱ)的吸附性能研究

研究了竹炭对溶液中Cu2+、Cd2+的吸附性能,考察了吸附时间、溶液pH值、吸附温度和溶液初始浓度对吸附效果的影响,同时研究了活性炭对Cu2+、Cd2+的吸附性能。结果表明,竹炭能有效吸附水溶液中的Cu2+、Cd2+,且单位吸附量均随时间的延长而增加,均在14 h左右达到平衡,吸附速度快于活性炭;相同pH值条件下,竹炭的单位吸附量明显高于活性炭,吸附效果最佳的pH值分别为3.8左右和7.5左右;当吸附温度为15,25,45℃时,竹炭对Cu2+的最大吸附量分别为4.13,4.45,4.23 mg/g,而竹炭对Cd2+的最大吸附量分别为0.81,1.05,2.01 mg/g。竹炭对Cu2+、Cd2+的吸附均符合Freundlich方程和Langmuir方程。     

Static magnetic field-assisted synthesis of Fe_3O_4 nanoparticles and their adsorption of Mn(Ⅱ) in aqueous solution

A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD,TEM,SEM,VSM and BET.The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe_3O_4 nanoparticles but improved the crystallinity.The morphology of Fe_3O_4 nanoparticles was varied from random spherical particles to rod-like cluster structure.The VSM results indicated that the saturation magnetization value of the Fe_3O_4 nanoparticles was significantly improved by the magnetic field.The BET of Fe_3O_4nanoparticles prepared with the magnetic field was larger than the control by 23.5%.The batch adsorption experiments of Mn(Ⅱ) on the PMF and AMF Fe_3O_4 nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased.At pH 8,the Mn(Ⅱ) adsorption capacity for the PMF and AMF Fe_3O_4 was reached at 36.81 and 28.36 mg·g~(-1),respectively.The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe_3O_4.The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(Ⅱ) from aqueous solution.     

水合MnO_2强化FeCl_3共沉降去除水中微量Cd(Ⅱ)

采用烧杯混凝实验,分别以实验室配水和松花江水为本底,研究了水合二氧化锰强化三氯化铁共沉降去除水中微量镉的效能。详细探讨了影响水合二氧化锰强化三氯化铁共沉降去除水中微量镉的主要因素。结果表明:两种水质条件下,水合二氧化锰均可强化FeCl3混凝去除水中的微量镉,镉的去除率明显高于单纯FeCl3混凝。水体pH值、浊度、腐殖酸等水质参数对于水合二氧化锰强化三氯化铁共沉降去除水中微量镉的效能有不同程度的影响。其中水体pH值对水合二氧化锰强化三氯化铁共沉降去除水中微量镉的影响十分显著,Cd(Ⅱ)的去除效果随着水体pH增加显著升高。     

Kinetic and equilibrium studies of Pb(II) and Cd(II) removal from aqueous solution onto colemanite ore waste

The adsorption characteristics of Pb(II) and Cd(II) onto colemanite ore waste (CW) from aqueous solution were investigated as a function of pH, adsorbent dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the adsorption isotherms. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The adsorption capacity of CW was found to be 33.6 mg/g and 29.7 mg/g for Pb(II) and Cd(II) ions, respectively. Analyte ions were desorbed from CW using both 1 M HCl and 1 M HNO₃. The recovery for both metal ions was found to be higher than 95%. The mean adsorption energies evaluated using the D-R model indicated that the adsorption of Pb(II) and Cd(II) onto CW were taken place by chemisorption. The thermodynamic parameters (ΔG^o, ΔH^o and ΔS^o) showed that the adsorption of both metal ions was feasible, spontaneous and exothermic at 20-50 °C. Adsorption mechanisms were also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The kinetic results showed that the adsorption of Pb(II) and Cd(II) onto CW followed well pseudo-second order kinetics.     

Adsorption of Ni(II) and Co(II) Using Microballoons Containing Mg-Silicate and CYANEX923 Prepared by the Emulsion Liquid Membrane System

Abstract

The Mg-silicate microballoons containing CYANEX923 were prepared by W/O/W emulsion. The diameter of obtained micro-sphere particles was ～10 µm and shell thickness was 2 µm. The adsorption of Co(II) and Ni(II) from aqueous solutions using prepared micro-sphere particles was investigated. Experiments were carried out as a function of solute concentration and temperature (25–60°C). Several kinetic models were used to test the experimental rate data and to examine the controlling mechanism of the adsorption process. Equilibrium adsorption data were analyzed using Langmuir isotherm model. The results indicated that prepared micro-sphere particles can be used as an efficient adsorbent for the removal of Ni(II) and Co(II) from aqueous solution.     

Preconcentration of Heavy Metals and Matrix Elimination using Silica Gel Chemically Modified with 2,3‐Dihydroxybenzaldehyde

Abstract

Many direct methods cannot easily be used to measure analytes such as Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) ions in sea and river water since these elements are present at very low concentration and the sample has a very complex matrix. In this study a method was developed to preconcentrate these ions by solid phase extraction within a column system using a newly synthesised 2,3‐dihydroxy benzaldehyde modified silica gel (SGDHB). Different parameters, such as pH, resin amount, eluent type, eluent volume, sample flow rate, preconcentration factors, and resin capacity were determined for the preconcentration of metal ions with the resin. Samples (125–500 ml) containing metal ions were passed through the column filled with SGDHB resin so that metal ions were retained on the column. The preconcentrated analytes were then eluted with 15 mL of 0.1 M HCl. The metal concentrations in the eluate were measured by FAAS. A sample and eluent flow rate of 1.12 and 0.56 ml/min respectively was used. Estimates of accuracy, precision, and detection limits were determined. In addition, analysis of the CRM LGC 6156 harbor sediment was undertaken, using the resin to isolate the analytes from potential interferences. Good agreement with certified values was obtained, indicating that the method is equally applicable to the analysis of water samples and to digests of solid materials.     

反相微乳液聚合

介绍了反相微乳液聚合方法的建立及体系组成、乳化剂选择、聚合过程及聚合物的表征、聚合反应动力学及机理,以及反相微乳液聚合的特点及应用。指出,提高反相微乳液聚合体系中的固含量将是今后的重点及难点。     

丙烯酰胺/DBMA反相共聚物乳液粒子形态及大小的研究

阳离子型聚丙烯酰胺共聚物具有广泛的用途 ,本文以 SPAN80作为乳化剂 ,偶氮二异丁基脒盐酸盐 ( AIBA )作为引发剂 ,通过反相乳液聚合合成了丙烯酰胺 /N ,N -二甲基 N -丁基 -N -甲基丙烯酰氧乙基溴化铵 ( DBMA)反相共聚物乳液。研究了 DBMA用量、乳化剂用量 ,引发剂用量及反应条件等对反相共聚物乳液粒子形态及大小的影响。结果表明 ,反相共聚物乳液粒子的形态呈规整性球状结构 ,其大小随反应条件的不同而发生变化     

智能印迹聚合物及其外场强化的识别机制研究进展

智能印迹聚合物在外部环境刺激下对模板分子具有响应性分子识别吸附能力,在吸附分离、药物传递、检测、固相萃取、催化等应用领域有着广阔的前景。本文首先对分子印迹聚合物进行了综述并指出在外场强化过程中常规分子印迹聚合物很难通过改变结合位点来控制结合特性的问题,针对这个问题进而提出具有柔性位点的智能响应型印迹聚合物。随后以具有不同响应功能的智能印迹聚合物为出发点,对磁、热、光、pH、生物大分子等单因子及双重因子响应功能印迹聚合物在外场强化过程中的响应与识别机制分别进行分析与总结,并综述了近些年来这些智能印迹聚合物在不同应用领域中相关研究工作进展。最后,基于不同响应功能的智能印迹聚合物的现状问题,对智能印迹聚合物在材料制备与理论两方面分别进行了展望。     

Structural Pitstops and Turnoffs on the Way to the Birefringent 2-D Layer Structure $$\{\hbox{(tmeda)M[Hg(CN)}_{2}]_{2}\}[\hbox{HgCl}_{4}]$$ (M=Cu,Ni)

The reaction of N,N,N′,N′-tetramethylethylenediamine (tmeda) and NiCl₂ with the soft, Lewis acidic Hg(CN)₂ and HgCl₂ in ethanol formed the 2-D layer structure {(tmeda)Ni[Hg(CN)₂]₂}[HgCl₄] (1), isostructural to the Cu(II) analogue. Complex 1 crystallizes in the tetragonal, non-centric m space group and contains a 2-D cationic layer of {(tmeda)Ni[Hg(CN)₂]₂}²⁺ units in which the six-coordinate Ni(II) centres are bridged by four Hg(CN)₂ groups and capped by a tmeda ligand. This array is interspersed with a layer of [HgCl₄]²⁻ anions, which form bridging Hg–Cl bonds with the Hg(CN)₂ units. The formation of 1 is very sensitive to reaction conditions; the addition of water to the mixture yields the related “structural pitstop” 2-D array {(tmeda)Ni(H₂O)[Hg(CN)₂]}{[Hg(CN)Cl]₂Cl₂}·H₂O (2), in which the halide migration among Hg(II) centres is incomplete. The larger zero-field splitting D-values of 6.91(1) cm⁻¹ for 1 vs. 2.85(4) cm⁻¹ for 2 indicate that some weak antiferromagnetic interactions are likely present in 1. The reaction of tmeda/Cu(ClO₄)₂·6H₂O with Hg(CN)₂ yields [Cu(tmeda)(μ-OH)(ClO₄)]₂[Hg(CN)₂(H₂O)₂][Hg(CN)₂] (3) which is composed of [Cu(tmeda)(μ-OH)(ClO₄)]₂ dimers in which the anions cis-bridge the copper(II) centres in the axial positions as well as bind to two adjacent Hg(CN)₂ moieties; the perchlorate anion is acting as a rare η⁴–μ₄–ClO₄ ligand. N-cyano interactions also exist between the Hg(II) centres; overall, a 2-D corrugated sheet structure which stacks via Cl–O–Hg bridges to yield a 3-D array is formed. The χ_M T value for 3 decreases with decreasing temperature; a maximum in χ_M vs. T at 20 K is also observed. This is consistent with antiferromagnetic interactions within the copper(II) dimer, which were fit with the Bleaney-Bowers model to yield J=−23.1(1) cm⁻¹, g=2.113(5) and a paramagnetic impurity P=0.017(1).Special Issue to honour Professor Richard J. Puddephatt