新型多孔纳米钛酸锶钡的制备及其对Cd~(2+)的吸附性能

采用反相悬浮聚合溶胶-凝胶法制备了多孔纳米钛酸锶钡吸附剂,分别采用Fourier变换红外光谱、扫描电镜和X射线衍射进行表征。将该多孔纳米钛酸锶钡应用于水中镉离子的吸附,考察了吸附、洗脱条件对其吸附性能的影响,探讨了吸附热力学和动力学规律。结果表明:采用反相悬浮聚合溶胶-凝胶法合成的多孔材料,由纳米粒径的钛酸锶钡晶体组成,平均晶粒粒径为17nm。当pH值为4～7时,该吸附剂对水中的镉离子有很强的吸附能力。其吸附动力学符合Langmuir吸附等温模型和准二级动力学方程式,吸附过程的焓变为37.337kJ/mol,各温度下,Gibbs自由能变均为负值,熵变均为正,吸附活化能为32.965kJ/mol,该吸附为吸热的自发的物理过程。吸附后,该吸附剂可用1mol/L硝酸洗脱再生。     

纳米钛酸锶钡分离原子吸收法测铬酸盐转化膜中铬形态

研究了铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)的分离富集新方法。制备了纳米钛酸锶钡粉体。研究了该纳米粉体对铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)的吸附性能。结果表明:钛酸锶钡粉体为棒状,平均粒径为36 nm;当pH≤2.0时,Cr(Ⅵ)可被纳米钛酸锶钡定量吸附,而Cr(Ⅲ)不被吸附;当pH>13.0时,Cr(Ⅲ)可被定量吸附,而Cr(Ⅵ)不被吸附。采用硫酸溶液褪膜,通过改变pH,实现Cr(Ⅵ)和Cr(Ⅲ)的分离富集,用火焰原子吸收测定。建立铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)测定新方法,应用于镀锌板和镀镉板表面铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)的测定,结果满意。     

焦粉基碳吸附材料对含铜废水处理研究

用硝酸预氧化焦粉、氯化锌化学活化法制备了焦粉基碳吸附材料。静态法考察了焦粉基碳吸附材料对水中铜离子的吸附工艺参数、吸附模型、温度对吸附过程的影响。研究表明：焦粉基碳吸附材料对水中铜离子的吸附工艺参数为：铜离子溶液浓度80mg／L、吸附平衡时间50min、吸附温度为40℃、pH为5．0～6．0;该吸附过程符合Langmuir型吸附模型;温度升高有利于焦粉基碳吸附材料对铜离子的吸附,表明该吸附为吸热过程。     

PANDAN/ATP复合材料处理含Hg(Ⅱ)废水的研究

文章利用化学氧化法制备出一种新型的凹凸棒土/共聚物复合材料,并研究了其对水中汞离子的吸附性能。结果表明,该材料对废水中汞离子有优异的去除效果,吸附容量可达900 mg/g;吸附动力学过程符合准二级动力学模型,等温线符合Langmuir单层吸附模型;最佳吸附pH范围在4~9之间;氯离子对材料的吸附有很大的抑制作用。     

碳酸化对黏土质白云岩热分解产物去除水中镉离子的影响

以黏土质白云岩为原料经煅烧、碳酸化处理后,研究固液比、溶液初始pH值、反应时间、初始浓度等因素对其去除镉离子效果的影响,并对去除机理进行了探讨。结果表明:随着固液比增大,溶液中镉离子浓度先降低然后趋于稳定;煅烧-碳酸化黏土质白云岩(CCCD)去除水中镉离子受溶液初始pH值的影响较小,对不同初始pH值的镉溶液都有较好的处理效果。动力学数据表明,镉离子的去除符合准二级动力学方程(R~2≥0.996);Langmuir等温吸附模型更好地描述CCCD对镉离子的去除过程;热力学结果表明吸附类型是化学吸附。CCCD去除水中镉离子的主要作用机理是方镁石缓慢与水反应生成氢氧化镁,氢氧化镁电离产生氢氧根,使溶液的pH值升高,诱导镉离子水解,进而形成表面沉淀。     

纳米钛酸锶钡对牛血清白蛋白的吸附行为

以硝酸钡、硝酸锶和钛酸四正丁酯为原料,采用柠檬酸络合溶胶-凝胶法制备纳米钛酸锶钡(nano-barium-strontium titanate,n-BST)粉体。用X射线衍射、透射电子显微镜和Fourier变换红外分析表征n-BST粉体的结构与性能。研究n-BST粉体对牛血清白蛋白(bovine serum albumin,BSA)的吸附行为,考察吸附条件和洗脱条件,并分别用红外光谱和紫外光谱以及荧光光谱分析吸附作用和解吸过程对BSA结构的影响。结果表明:当介质的pH=4.10时,n-BST对BSA具有很强的吸附能力,其吸附行为符合Langmuir吸附等温方程式和HO准二级动力学模型,吸附过程的焓变ΔH=-13.30kJ/mol,自由能变(ΔG)和熵变(ΔS)均为负值,吸附活化能Ea=16.18kJ/mol,该吸附过程是以氢键作用力为主的自发放热过程。被吸附的BSA可用pH=7.54的缓冲溶液完全洗脱。吸附过程和洗脱过程没有明显改变BSA的结构。     

磁性纳米颗粒去除饮用水中铬和镉离子性能的初步研究

基于表面修饰的四氧化三铁磁性纳米材料具有高比表面积、高吸附能力及吸附速度快等优点。研究了Fe_3O_4磁性纳米材料的制备及表面修饰条件,及其对饮用水中微量铬和镉离子的吸附、脱附性能。结果表明,在氨水浓度为0.5 mol/L时,采用化学共沉淀法制备的四氧化三铁磁性纳米颗粒产率最大;十二烷基磺酸钠浓度为300 mg/L,与四氧化三铁磁性纳米颗粒配比为2∶3,溶液pH为5.0,表面修饰的四氧化三铁磁性纳米颗粒对重金属镉和铬离子有显著的去除能力,对镉和铬离子的饱和吸附量分别为3.09,2.11 mg/g,在pH为7时,其对镉和铬离子的解析率分别为79%,60.5%。所制备材料的平衡吸附量与平衡质量浓度之间符合Langmuir和Freundlich等温吸附方程。     

淀粉/二氧化硅微球对水中重金属离子的吸附性能

利用土豆淀粉、玉米淀粉、正硅酸乙酯为原料,氨水为催化剂,通过溶胶-凝胶法制备了淀粉/二氧化硅复合微球,研究了该复合微球对水中铅离子的吸附性能。结果表明,在弱碱性条件下,淀粉/二氧化硅复合微球对水中铅离子表现出良好的吸附性能,其对铅离子的吸附行为符合Langmuir模型和Freundlich模型,对铅离子的饱和吸附量为31.34 mg/g。动力学研究表明,淀粉/二氧化硅复合微球对铅离子的吸附符合拟二级动力学模型,在淀粉/二氧化硅复合微球的活性点上的化学反应为吸附控制步骤。     

磁性纳米颗粒去除饮用水中铬和镉离子性能的初步研究

基于表面修饰的四氧化三铁磁性纳米材料具有高比表面积、高吸附能力及吸附速度快等优点。研究了Fe_3O_4磁性纳米材料的制备及表面修饰条件,及其对饮用水中微量铬和镉离子的吸附、脱附性能。结果表明,在氨水浓度为0.5 mol/L时,采用化学共沉淀法制备的四氧化三铁磁性纳米颗粒产率最大;十二烷基磺酸钠浓度为300 mg/L,与四氧化三铁磁性纳米颗粒配比为2∶3,溶液pH为5.0,表面修饰的四氧化三铁磁性纳米颗粒对重金属镉和铬离子有显著的去除能力,对镉和铬离子的饱和吸附量分别为3.09,2.11 mg/g,在pH为7时,其对镉和铬离子的解析率分别为79%,60.5%。所制备材料的平衡吸附量与平衡质量浓度之间符合Langmuir和Freundlich等温吸附方程。     

改性碳纳米管对水中铜离子的去除作用

采用次氯酸钠氧化法改性碳纳米管,用于吸附水溶液中铜离子。结果表明,改性碳纳米管对水中铜离子的去除效果明显高于未改性的碳纳米管,纯化的碳纳米管对水中铜离子的吸附在60 min左右达到平衡;溶液pH值对水中铜离子的去除有较大的影响。吸附等温线既符合Langmuir吸附等温式,又符合Freundlich等温式。     

不同热解温度生物炭对溶液中镉的吸附性能研究

以玉米秸秆、枫杨树枝、花生壳为生物质材料,分别在450、550、650℃下,对3种生物质材料进行厌氧热解制备了9种生物炭,对溶液中的Cd2+进行吸附试验,研究了pH、生物炭投加量、吸附时间和Cd2+初始质量浓度对Cd2+吸附效果的影响。结果表明,吸附过程与Langmuir、Freundlich和准一级动力学方程拟合的相关性较好。pH对吸附的影响较大,吸附率与生物炭的投加量呈正比,650℃制备的3种生物炭的吸附能力更强,花生壳生物炭对溶液中的Cd2+具有更好的吸附能力。     

Sacrificial template-directed synthesis of mesoporous manganese oxide architectures with superior performance for organic dye adsorption

Mesoporous MgO architectures were successfully synthesized by the direct thermal transformation of the sacrificial oxalate template. The as-prepared mesoporous architectures were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption-desorption techniques. The MgO architectures showed extraordinary adsorption capacity and rapid adsorption rate for removal of Congo red (CR) from water. The maximum adsorption capacity of the MgO architectures toward CR reached 689.7 mg g(-1), much higher than most of the previously reported hierarchical adsorbents. The CR removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The superior adsorption performance of the mesoporous MgO architectures could be attributed to the unique mesoporous structure, high specific surface area as well as strong electrostatic interaction.     

花生壳活性炭的表征,表面改性及吸附脱除水中Pb2+离子

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell (PAC) was used for the removal of Pb2 from aqueous solution. The impacts of the Pb2 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Boehm titration. The textural properties (surface area, total pore volume) were evaluated from the nitrogen adsorption isotherm at 77K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon (GAC) showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% (by mass)] modified PAC has larger adsorption capacity of Pb2 from aqueous solution (as much as 35.5mg.g1). The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

Studies on two‐dimensional coordination polymer cadmium phosphate and its high efficient adsorption of Pb(II) ions from aqueous solutions

The two‐dimensional coordination polymer cadmium phosphate with the morphology of rectangle layers was prepared by solid‐state template reaction at room temperature, and was characterized by XRD, FTIR, and TEM techniques. The as‐synthesized sample is a layered cadmium phosphate material, in which the structure is poly (CdPO₄^?) anion framework with ammonium ions and water species residing in the space between the layers, and cadmium ions are coordinated by the phosphate oxygen atoms. This article also presents the adsorption of Pb(II) ions from aqueous solution on the as‐synthesized coordination polymer cadmium phosphate, and the results showed that this inorganic polymer adsorbent had good adsorption capacity. It could reach to the saturation adsorption capacity within an hour, and its excellent adsorption capacity for Pb(II) was 5.50 mmol/g when the initial solution concentration was 1.68 × 10³ μg/mL at T = 278K. Moreover, the adsorption kinetics and adsorption isotherms were studied, it revealed that the adsorption kinetics can be modeled by pseudo second‐order rate equation wonderfully. The apparent activation energy (E_a), ΔG, ΔH, and ΔS were 3.16 kJ mol^?1, ?13.97 kJ mol^?1, ?11.84 kJ mol^?1, and 7.66 J mol^?1 K^?1, respectively. And it was found that Langmuir equation could well interpret the adsorption of the as‐synthesized coordination polymer cadmium phosphate for Pb(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effect of pH control on synthesis of Sr doped barium titanate nanopowder by oxalate precipitation method

Sr substituted BaTiO₃ (BST) nanopowders were prepared using oxalate co-precipitation methods. During synthesis, oxygen was applied to the oxalate solution in order to control the oxidation states of Ti. Control of pH in the solution results in different crystalline phases of the powders after calcination; pure perovskite BST was obtained in the powder prepared at pH 3 solution, while perovskite BaTiO₃ (BTO) and impurities were observed in powders prepared at pH 1 solution. Phase transformation from amorphous to crystalline BST during heat treatment was discussed by different analysis technique. Also, morphology and elemental distribution of the pure BST was investigated.     

The use of exhausted olive cake ash (EOCA) as a low cost adsorbent for the removal of toxic metal ions from aqueous solutions

The removal characteristics of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution by exhausted olive cake ash (EOCA) were investigated under various conditions of contact time, pH, initial metal concentration and temperature. Batch kinetic studies showed that an equilibrium time of 2 h was required for the adsorption of Ni(II) and Cd(II) onto EOCA. Equilibrium adsorption is affected by the initial pH (pH₀) of the solution. The pH₀ 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by EOCA. The adsorption test of applying EOCA into synthetic wastewater revealed that the adsorption data of this material for nickel and cadmium ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of nickel and cadmium ions adsorbed by EOCA were 8.38 and 7.32 mg g⁻¹, respectively. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (ΔG°) and the enthalpy change (ΔH°) showed that the process was feasible and endothermic respectively. As the exhausted olive cake is discarded as waste from olive processing, the adsorbent derived from this material is expected to be an economical product for metal ion remediation from water and wastewater.     

Cadmium removal byJuniperus monosperma: The role of calcium oxalate monohydrate structure in bark

This study suggests that calcium oxalate monohydrate overJuniperus monosperma bark is an ion-exchangeable site for cadmium adsorption on the basis of its cadmium adsorption behavior and surface characterization. Cadmium adsorption behavior showed that juniper bark had a higher cadmium adsorption capacity (84.6 Μmol Cd g^-1 at pH 5) than juniper wood (32.0 Μmol Cd g⁻¹ at pH 5), and that the base-treatment improved the cadmium adsorption capacity of only juniper wood. This difference between juniper bark and wood might have originated from different cadmium binding sites. In calcium displacement, the cadmium uptake onto juniper bark was identical to the amount of calcium ions displaced, which indicated that calcium played an important role in cadmium adsorption onto juniper bark. X-ray diffraction (XRD) results gave evidence that only juniper bark contained the structure of calcium oxalate monohydrate. Furthermore, cadmium adsorption decreased the intensity of the characteristic XRD peaks for calcium oxalate monohydrate. In diffuse reflectance infrared Fourier transform (DRIFT) spectra, existence of oxalate on juniper bark was proven again and interpretation on IR band of carbonyl groups matched significantly the cadmium adsorption behavior.     

Adsorption of heavy metals by brewery biomass

In this work, biosorption of lead, copper and cadmium by waste brewery yeast has been studied. The adsorption capacity for lead, copper and cadmium on the biomass increased with the increasing temperature and the maximum uptakes were 0.465 mmolPb/g (96.4 mg/g), 0.769 mmolCu/g (48.9 mg/g) and 0.127 mmolCd/g (14.3 mg/g) at 308 K. The Langmuir isotherm, favorable type, and the pseudo second-order kinetic model represent our experimental data very well. The heat of biosorption was evaluated from the Langmuir isotherm equation, and the biosorption of lead, copper and cadmium was endothermic reaction.     

Peanut Shell Activated Carbon： Characterization,Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.     

Surface functionalized carbon microspheres for the recovery of copper ion from refinery wastewater

Micro-sized carbon spheres (CNS) were synthesized by hydrothermal process from glucose solution at 443.15 K and two different reaction times. The synthesized CNS samples were surface functionalized with hydroxyl (-OH) functional groups using NaOH treatment, and were tested in batch adsorption to remove heavy metal ion (Cu²⁺) from aqueous solutions. Experimental results revealed that CNS contains mostly amorphous carbon. NaOH functionalized CNS had significantly higher adsorption capacity of copper ～170×10^?3 Kg Cu²⁺/Kg-CNS as compared to the untreated CNS. The adsorption isotherms were well fitted by the Langmuir isotherm equation. The surface morphology of the native and functionalized CNS samples was characterized by a number of techniques and based on which the adsorption of copper ion was discussed.