活性炭对重金属离子的吸附研究

研究了活性炭分别对铅、镉、铜及锌离子的吸附作用,研究了pH值、温度及活性炭的投加量等因素对吸附效果的影响。结果表明,当pH〉5时对四种离子的去除率均达到98％以上,能达到很好的吸附。低温有利于吸附的进行。随着活性炭的增加．重金属离子的去除率增加．而且铜离子的活性炭最佳用量是0．3000g．铅、镉和锌的活性炭最佳用量均为1．000g。随着吸附时间的增加,去除率上升。铜、铅、镉和锌离子的吸附平衡时间分别为3．5h、1h、1．5h和1．5h。铜离子的吸附符合Langmuir等温模式,而锌、铅和镉离子的吸附符合Freundlich等温模式。     

赤泥脱除废水中重金属离子的研究

为去除废水中的重金属对环境的危害,采用铝土矿经强碱浸出氧化铝后的赤泥作为废水中重金属离子的吸附剂.赤泥具有高的比表面积和孔隙率、较好的吸附性能.实验结果表明,赤泥对铅、镉、铬、锌、镍离子的对数吸附等温线都近似直线,基本符合Freundlich公式,且在室温条件下吸附就能很快达到吸附平衡,不需要温度和pH的调节.当赤泥在废水中的添加量为2.0 g/L时,铅、铬、镉的吸附率分别达到90%,94%,85%以上.赤泥对重金属离子的吸附率随废水中重金属离子初始质量浓度的增大而减小.     

四钛酸钾晶须吸附废水中重金属离子的研究

以四钛酸钾晶须(PTW)作为去除工业废水中重金属离子铅、镉的吸附剂,考察了吸附剂的用量、吸附时间和酸度对吸附效果的影响.研究结果表明:吸附效率随着吸附剂用量的增加、吸附时间的延长以及pH值的升高而提高,但吸附容量却随着吸附剂用量的增加而降低.水中铅、镉离子在PTW上的吸附可用Freundlich方程进行描述.     

木质素磺酸钠在活性炭/水界面的吸附机理

为了探究木质素磺酸钠在活性炭/水界面的吸附机理,研究了温度、pH 值、无机盐、脲以及直链醇对其吸附动力学及吸附等温线的影响.吸附动力学结果表明,木质素磺酸钠在活性炭/水界面的吸附约在10 min 内快速达到平衡;随着离子强度的增加及脲的加入吸附速率常数增大,pH值增加,吸附速率常数先增大后减小.不同pH值条件下的木质素磺酸钠在活性炭/水界面的吸附等温线符合 Langmuir 方程;随着离子强度增大、脲或直链醇的加入,吸附过程更符合 Freundlich 模型.增加离子强度、降低 pH 值及加入直链醇都可显著提高木质素磺酸钠的平衡吸附量,而脲的加入降低平衡吸附量.在中性条件下木质素磺酸钠主要通过疏水作用和氢键作用吸附在活性炭/水界面,疏水作用有利于加快吸附速率及增加吸附量,该吸附过程不受温度的影响.     

油茶果壳活性炭对铜离子的吸附性能

利用油茶壳活性炭吸附铜离子,探讨了时间、pH值、Cu(Ⅱ)初始质量浓度等因素对油茶壳活性炭吸附性能的影响;并分析了其吸附等温曲线和动力学方程。结果表明,油茶壳活性炭对铜离子吸附量可达到63.6 mg/g。油茶壳活性炭对铜离子的去除率随吸附时间的增加而增大,5 h后达到平衡;随着pH值的升高,油茶壳活性炭吸附铜离子的吸附量不断下降。油茶壳活性炭对铜离子的吸附等温数据符合Langmuir方程,吸附动力学过程可用准二级动力学模型进行模拟,相关系数为0.997 5。     

粉煤灰合成沸石对Cr3＋的吸附性能研究

利用粉煤灰合成沸石吸附重金属Cr3＋,探讨吸附剂量、初始pH值以及反应温度对Cr3＋吸附效果的影响,同时进行吸附等温线和吸附动力学的数据模拟。结果表明：沸石投加量、初始pH值以及反应温度均对Cr3＋的去除效果影响显著。随着吸附剂投加量的不断增大,Cr3＋去除效果不断提高,饱和吸附量逐渐减小。初始pH值为4时沸石吸附Cr3＋的去除率为100％。反应温度的上升不利于沸石对Cr3＋吸附,沸石对Cr3＋的吸附效果随着反应温度的升高逐渐降低。沸石吸附Cr3＋的过程符合Freundlich吸附等温式;准二级反应动力学方程能较好描述沸石对Cr3＋的吸附行为。     

羽毛纤维对废水中重金属离子的吸附性能研究

利用禽类羽毛纤维作为吸附剂,吸附溶液中的重金属离子Cu~(2+)、Zn~(2+)、Ni~(2+)、Pb~(2+)、Cr~(6+)。考察温度、pH值、吸附剂投加量、重金属离子初始浓度等对羽毛纤维吸附效果的影响并建立吸附等温线。结果表明,羽毛纤维能吸附重金属离子,随着温度、吸附剂投加量的增大,重金属离子初始浓度的降低,羽毛纤维对重金属离子的吸附率逐渐提高。随着pH值的升高,羽毛纤维对Cu~(2+)、Zn~(2+)、Ni~(2+)、Pb~(2+)的吸附率提高,对Cr~(6+)的吸附率降低。羽毛纤维对Cu~(2+)、Zn~(2+)、Ni~(2+)、Pb~(2+)吸附符合Freundlich吸附等温模型。羽毛纤维对重金属离子的吸附能力顺序为Pb~(2+)>Cu~(2+)>Zn~(2+)>Ni~(2+)>Cr~(6+)。     

土壤对重金属Cu(Ⅱ)、Cd(Ⅱ)的吸附研究

采用等温吸附平衡法研究了土壤对重金属Cu2+和Cd2+的吸附,研究了浓度、搅拌时间、静置时间以及pH对土壤吸附铜和镉影响。结果表明,土壤对铜的吸附量大于镉,土壤对重金属吸附的最佳条件是搅拌15 min,静置20 min,pH为7.0,初步确定土壤对铜和隔的吸附属于Freundlich吸附。     

果壳活性炭对废水中苯酚的吸附特性

研究了果壳活性炭对废水中苯酚的吸附特性,考察了接触时间、温度、pH值对吸附效果的影响,绘制了吸附等温线和动力学曲线。试验结果表明:果壳活性炭对苯酚的吸附约6 h即已趋于平衡,去除率达到96.63%。该吸附过程受温度影响不显著;溶液pH值对吸附量影响较大,酸性至中性条件下苯酚的吸附效果更佳。在给定吸附剂浓度条件下,Langmuir和Freundlich吸附等温式均能较好拟合平衡吸附数据,动力学试验数据则与Lagergren准二级动力学方程的拟合度最佳。     

泥炭吸附法去除废水中重金属

介绍了天然廉价矿物泥炭的物理化学性质,综述了泥炭的改性方法及其对多种重金属离子的吸附容量．分析了pH、改性方法、竞争离子浓度等因素的影响。并对泥炭吸附重金属离子的机理和规律进行了总结．其吸附机理有离子交换、络合、表面吸附、化学吸附等四种,吸附一般符合Langmuir吸附等温式或Freundlich吸附等温式。最后展望了泥炭在重金属废水处理中的应用前景,提出了一些建议。     

改性活性炭吸附重金属镉的技术与机理

镉污染对饮用水安全造成了严重的威胁。活性炭吸附是水处理中最重要的处理方法之一,但是对镉等重金属的吸附较弱,通过改性可以改变活性炭的表面特性,从而促进对重金属的吸附。该文对活性炭进行了混酸氧化改性,臭氧氧化改性和乙二胺氨基化的改性,零电荷点和表面官能团大大发生变化,混酸改性后的零电荷点最低。通过吸附动力学的研究发现混酸改性的活性炭（Ac-0）对镉的吸附效果最好,且更加符合二级动力学的吸附模型。对AC-0活性炭进行了不同pH下吸附热力学的研究,结果表明吸附等温线用Freundlich的热力学模型拟合比较好,并且pH越大越有利于镉的吸附,pH对Ac-O吸附镉效果的影响试验也表明,由于零电荷点的影响,在pH小于9的情况下,随着pH的升高静电吸引力越强。     

Kinetic and equilibrium modeling of liquid‐phase adsorption of lead and lead chelates on activated carbons

The sawdust (SD) waste generated in the timber industry was converted to a low‐cost activated carbon (SDAC) using a simpler and cheaper activation process, single‐step steam pyrolysis activation. The possibility of utilizing SDAC for the removal of lead (Pb(II)) in the absence of ligands and nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) chelated Pb(II) complexes from the liquid phase was examined and the results were compared with those for commercial activated carbon (CAC). SDAC shows a high adsorption capacity for Pb(II) and Pb(II) chelates compared with CAC. The extent of adsorption of Pb(II) and Pb(II) chelates on activated carbons was found to be a function of solution pH and species distribution of Pb(II) and Pb(II) chelates. The optimum pH range for the removal of Pb(II) in the absence of ligands by SDAC was 6.5–8.0, whereas its maximum removal by CAC was observed at pH 6.5. In the presence of ligands, the extent of Pb(II) adsorption was enhanced in the pH range 2.0–5.0 and was reduced significantly in the pH range 6.0–8.0. The maximum uptake of Pb(II) chelates for both carbons was observed at pH 5.0. Kinetic models such as pseudo‐first‐order, pseudo‐second‐order and pore diffusion were tested to investigate the adsorption mechanism. Batch kinetic studies showed that the adsorption of Pb(II) from aqueous solutions with and without ligands could be best described by a psuedo‐first‐order model for both carbons. The effect of pH on the adsorption isotherms of Pb(II) and Pb(II) chelates was also investigated. The applicability of the Langmuir and Freundlich isotherms, established for various initial concentrations of the adsorbate and for different pH values, was tested at 30 °C. Copyright © 2003 Society of Chemical Industry     

Investigation of adsorption of lead,mercury and nickel from aqueous solutions onto carbon aerogel

Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm³) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H⁺ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry     

Effect of Complexation on the Adsorption of Cadmium by Activated Carbon

Abstract

The adsorption of Cd²⁺ in the absence and presence of two chelating agents was examined as a function of pH. Fits of the data to the Freundlich and Langmuir equations were compared as were results with Zn and Pb using four different activated carbons. In general, adsorption increased with increasing pH and was not extensive, particularly for Cd. At low cadmium to carbon ratios, EDTA appeared to enhance adsorption. With more realistic loadings, when competition for surface sites is greatest, the presence of EDTA is shown to be detrimental to the process. 1,10-Phenanthroline, the second chelating agent studied, was more effective for promoting the removal of Cd. The uncomplexed Cd and Cd-EDTA systems were best described by the simple Langmuir adsorption isotherm. The adsorption of 1,10-phenanthroline and its Cd complex were modeled using a modified form of the Langmuir equation.     

Adsorption of lead(II) from aqueous solution by activated carbon prepared from Eichhornia

Activated carbon prepared from Eichhornia was used for the adsorptive removal of Pb(II) from aqueous solution. As the raw material for the preparation of the activated carbon is an aquatic weed, the production of this carbon is expected to be economically feasible. Parameters such as agitation time, metal ion concentration, adsorbent dose and pH were studied. Adsorption equilibrium was reached in 100 min for a solution containing 15 mgdm^?3 and 125 min for solutions containing 20 and 25 mgdm^?3 Pb(II), respectively. Adsorption parameters were determined using both Langmuir and Freundlich isotherm models. The adsorption capacity was 16.61 mgg^?1 at pH 3.0 for particle sizes of 125–180 µm. Pb(II) removal increased as the pH increased from 2 to 4 and remained constant up to pH 10.0. Desorption studies were also carried out with dilute hydrochloric acid to recover both carbon and Pb(II). Quantitative desorption of Pb(II) from carbon indicates that adsorption of metal ion is by ion exchange. © 2002 Society of Chemical Industry     

Removal of copper,cadmium, and chromium from wastewater by modified wheat bran using Box–Behnken design: Kinetics and isotherm

In this work, copper, cadmium, and chromium were removed using hydrochloric acid-treated wheat bran as an adsorbent. Experiments were carried out in batch adsorption mode. Box–Behnken design of response surface methodology was used to determine the effect of initial metal concentration, pH, temperature, and adsorbent dose on removal efficiency of copper, cadmium, and chromium. Analysis of variance results are shown for all the three heavy metal, and the effect of the parameters is discussed. The optimum initial metal concentration, pH, temperature, and adsorbent dose were found to be 90.58 mg/L, 6, 35.9°C, and 2.39 g, respectively. Pseudo-second-order kinetic model was found to be the best suitable model for adsorption rate. The isotherms of adsorption data were analysed using various adsorption isotherm models such as Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherms. It was found that Langmuir and Temkin isotherms represent the equilibrium data for these heavy metal removals.     

Physical and chemical characteristics of polymer-based spherical activated carbon and its ability to adsorb organics

The characterization of a polymeric spherical activated carbon (PAC) was performed by comparing its adsorption, porosity, functional groups and some of the physical properties with a commercial spherical activated carbon (CAC). The PAC was about 4 times superior to the CAC with respect to the mechanical strength. The micropore volume of the PAC was about 5% smaller than that of the CAC. The maximum methylene blue adsorption values of the PAC and the CAC were 32 and 14 mg g⁻¹, respectively, which indicated low mesopore volumes as consistent with the values of BJH volume. This resulted in the low butane working capacity values for both activated carbons. Adsorption parameters for the Langmuir and the Freundlich isotherm models were determined for all organic substances tested. Both isotherms were suitable models to analyze the equilibrium data for the removal of all organics. However, the Langmuir model fitted better than the Freundlich model and the adsorption capacities of the PAC were somewhat higher than those of the CAC. The chemical properties of the activated carbons, the pH of solutions and the substituents on absorbates have an effect on adsorption of the organics tested.     

Coniferous Wood Sawdust-based Activated Carbons as Adsorbents Obtained with the Use of Microwave Radiation

Activated carbons were prepared by physical and direct activation of sawdust pellets coming from coniferous trees, with the use of microwave radiation. The activated carbons obtained were used as adsorbents for the removal of methylene blue (MB) from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of each activated carbon sample was determined. The effects of activation procedure as well as adsorption tests parameters i.e., temperature, pH, initial methylene blue concentration, and contact time on the sorption capacity of each activated carbon were investigated. The kinetic models for MB adsorption on the activated carbons were also studied. Better fit to the experimental data was obtained with the Langmuir isotherm than Freundlich one, for all samples.     

苯酚在活性炭上吸附平衡模型的研究

本文研究了苯酚在活性炭上的吸附特性,并发现在低pH,低温度下有利于活性炭吸附苯,研究表明Freundlich模型能较好描述吸附过程,并得到了在考虑温度,pH值影响情况下苯酚的Freundlich模型表达式。