Adsorption of copper(II) and EDTA‐chelated copper(II) onto granular activated carbons

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA‐chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA‐chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell‐based carbon exhibited a greater adsorption capacity for copper(II) than the coal‐based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4–6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA‐chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA‐chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA‐chelated copper(II) species. © 2000 Society of Chemical Industry     

Mechanisms of Cr(VI) removal from water by various types of activated carbons

The removal mechanisms of Cr(VI) from water using different types of activated carbons, produced from coconut shell, wood and dust coal, were investigated in this project. Different types of activated carbons have different surface characteristics. The coconut shell and dust coal activated carbons have protonated hydroxyl groups on the surface (H‐type carbons), while the surface of the wood‐based activated carbon has ionised hydroxyl groups (L‐type carbons). The adsorption kinetics of chromium onto the activated carbons at pH values ranging from 2 to 6 were investigated. It was found that the optimum pH to remove total chromium was 2 for wood‐based activated carbon, while for coconut shell and dust coal activated carbons, the optimum pH was around 3–4. The difference in the optimum pH for different activated carbons to remove Cr(VI) from water can be explained by the different surface characteristics and capacity of the activated carbons to reduce Cr(VI) to Cr(III). © 1999 Society of Chemical Industry     

Pentachlorophenol retention on to lignocellulosic activated carbons

The rate and equilibrium retention of pentachlorophenol, in an aqueous medium, by activated carbons obtained from peach stones and Eucalyptus globulus chips are studied and related to the chemical and textural properties of the adsorbents. E globulus‐activated carbons exhibited a higher pentachlorophenol initial retention rate, due to the higher contribution of the macropores to the porosity of these materials. However, the pentachlorophenol retention rate in activated carbons from peach stones increases to a greater extent than in E globulus with the burn‐off growth, due to the greater development of mesopores in the former. Under the experimental conditions used, the initial retention rate of pentachlorophenol in both adsorbents showed a mixed chemical and diffusional dependence, and the most important variables are the particle size of the adsorbents and the temperature of the medium. Pentachlorophenol equilibrium retention capacity depends on the apparent specific surface area, the presence of carbonylic‐like surface functional groups and the accessibility of the adsorbate to the adsorption sites. The dependence of pentachlorophenol retention capacity with the surface concentration of carbonylic functional groups suggests some chemical interactions between the aromatic pentachlorophenol ring and the carbonylic‐like surface functional groups present in the activated carbons. © 1999 Society of Chemical Industry     

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。     

Water vapour adsorption on lignin‐based activated carbons

Lignocellulosic wastes are interesting precursors for carbon products. The high amount of Na observed in kraft lignin makes it a promising precursor for the preparation of activated carbons for desiccant applications. Water adsorption capacity and kinetics of kraft lignin‐based chars and activated carbons with different burn‐off and inorganic matter content have been studied. CO₂ partial gasification of lignin char develops a wide porous structure. An increase of the micropore volume can be observed at low to medium burn‐offs. At degrees of higher activation the mesoporous structure develops. For very high burn‐off the porous structure is destroyed by coalescence of the pores and reduction of the carbon material. The carbons obtained show atomic surface concentrations of sodium from 7.6–15.4%, as revealed by XPS analysis. Water vapour adsorption isotherms have been obtained in a thermogravimetric system and have been fitted by a DS model, which properly represents the experimental data. The kinetics of water vapour adsorption follows a linear driving force mass transfer (LDF) model. The presence of sodium and oxygen surface groups on the carbon surface enhances water vapour adsorption at low relative pressure. Activated carbon produced at 41% burn‐off shows the highest water vapour adsorption at low relative pressures, as a consequence of the high sodium dispersion on its surface. The sodium dispersed over the carbon surface undergoes clustering as gasification proceeds, decreasing the number of active centres. For burn‐off higher than 41%, this behaviour produces a decrease in the water adsorbed at low relative pressures. Copyright © 2007 Society of Chemical Industry     

Kinetic,equilibrium and thermodynamic studies on removal of Cr(VI) by activated carbon prepared from Ricinus communis seed shell

A study on the removal of hexavalent chromium ions from aqueous solution by using activated carbon prepared from Ricinus communis has been done. In this process, it was carbonised and activated by treating with concentrated sulphuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments are also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data are fitted well to the Freundlich adsorption isotherm. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° are calculated, which indicated that the adsorption is spontaneous and endothermic in nature. Adsorbent used in this study is characterised by FT‐IR and SEM before and after the adsorption of Cr(VI). © 2011 Canadian Society for Chemical Engineering     

Preparation and characterization of polymer‐based spherical activated carbons with tailored pore structure

A series of spherical activated carbons (SACs) with different pore structure were prepared from divinylbenzene‐based polymer through CO₂ activation. The effect of activation temperature and retention time on the yield and textural properties of the resulting SACs were studied. The SACs were characterized by N₂ adsorption, X‐ray diffraction, scanning electron microscopy, and aqueous adsorption assays. Either increasing activation temperature or extending retention time decreases the yield of SACs. The BET surface area and pore volume increase with activation temperature and reach a maximum at 1000°C and then decrease at higher activation temperatures. At 1000°C, BET surface area, total pore volume, and mesopore pore volume increase with retention time from 0.5 to 2 h, and meanwhile micropore volume decreases. The micropores are gradually widened into mesopores with increasing activation temperature or extending retention time. SEM and XRD analyses of SAC10 verify the presence of developed porous structure composed of disordered micrographite stacking. Aqueous adsorption assays indicate that SACs have good adsorption capacity for phenol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Adsorption of sulfur dioxide onto activated carbons prepared from oil‐palm shells impregnated with potassium hydroxide

Adsorption of sulfur dioxide (SO₂), a gaseous pollutant, onto activated carbons prepared from oil‐palm shells pre‐treated with potassium hydroxide (KOH) impregnation was studied. Experimental results showed that SO₂ concentration and adsorption temperature affected significantly the amount of SO₂ adsorbed and the equilibrium time. However, sample particle sizes influenced the equilibrium time (due to effect of diffusion rate) only. Desorption at the same temperature of adsorption and a higher temperature of 200 °C confirmed the presence of chemisorption due to pre‐impregnation. Impregnation with different activation agents was found to have limited effect on the inorganic components of the sample. Compared with the activated carbon pre‐treated with 30% phosphoric acid (H₃PO₄) that had larger BET and micropore surface areas, the sample impregnated with 10% KOH had a higher adsorptive capacity for SO₂, which was closely related to the surface organic functional groups of the sample. In general, the activated carbon prepared from oil‐palm shell impregnated with KOH was more effective for SO₂ adsorption and its adsorptive capacity was comparable to some commercial activated carbons. © 2000 Society of Chemical Industry     

Adsorption of selected environmentally important metals by poultry manure‐based granular activated carbons

Water quality and public health impacts of mass produced poultry manure have prompted the need for viable conversion and reuse solutions. Conversion of poultry manure to value‐added granular activated carbons for environmental remediation can be such a solution. The objective of this study was to compare the effectiveness of poultry manure‐based carbons for the adsorption of selected metal ions (copper, cadmium, nickel, zinc) from solutions containing individual ions or the four metal ions present together. Adsorption properties for poultry manure‐based carbons were compared with those of two commercial carbons, PūR RF and Minotaur, and carbons from three traditional precursors, coal, coconut and wood. Pelletized samples were pyrolyzed at 700 °C for 1 h followed by 800 °C steam activation at 1, 3 and 5 mL min^?1 water flow rate, for 30 and 45 min, under nitrogen. The carbon's ability to adsorb the metals was influenced by the activation strategy, increasing for longer activation times and higher water flow rates, in the presence of a single metal solution. Saturation conditions were achieved at 20 mM and, at 5 mM , almost all metal ion in solution was adsorbed, except for nickel. Carbons showed similar affinity towards copper, cadmium and zinc, individually. However, when in competition, at 5 mM of each metal, manure‐based carbons showed a preference for Cu²⁺ followed by Zn²⁺ and Cd²⁺. Poultry manure‐based carbons outperformed all reference carbons and PūR RF, and, except for Ni²⁺, Minotaur was also outperformed. Experiments showed that the highest removal rate in a competition situation was obtained for broiler‐cake carbon activated for 45 min at 3 mL min^?1, with 93.1%, 50.9% and 85.2% for copper, cadmium and zinc ions, respectively. Published in 2005 for SCI by John Wiley & Sons, Ltd.     

The effect of mechanical grinding on the mesoporosity of steam‐activated palm kernel shell activated carbons

BACKGROUND: Palm kernel shell activated carbon (OPSA) produced by steam gasification at high temperatures generally results in high surface areas of 1146 to 1600 m² g^?1, attributed to the high volume of micropores (0.43 to 0.56 cm³ g^?1). The mesoporosity of naturally occurring activated carbons is observed to increase with decreasing particle size. Mechanical grinding was therefore performed to investigate its effect on the mesoporosity and microporosity of OPSA. RESULTS: Mechanical grinding had a strong effect on mesopore volume and average pore diameter, with an increase in mesopore volume from 47 to 66% as particle size decreases. Interestingly, no significant effect on the micropore fraction was observed in ground OPSA particles. CONCLUSIONS: The mechanically ground OPSA particles possessed dual adsorption capabilities due to the high microporosity and moderate mesoporosity contained in the structures. This results in interesting porosity behaviour of palm kernel shell activated carbons and the potential to provide materials of distinct sorption capacities with minimal treatment. Copyright © 2009 Society of Chemical Industry     

热改性活性炭吸附有机气体的性能

根据热重分析结果,确定了活性炭热改性的温度条件;采用Boehm滴定、傅式转换红外光谱仪（FTIR）、比表面积分析仪对活性炭表面物化性质进行了测试;以甲苯、丙酮、二氯乙烷、甲醇为吸附质,在283K下进行了固定床吸附实验,探讨了改性前后活性炭表面结构变化与吸附量之间的关系,同时计算了相应的动力学参数和吸附能。实验结果表明,热改性可以改善活性炭的孔径分布和改变表面官能团的分布,吸附量与有效孔容呈明显的线性关系;一阶动力学方程和二阶动力学方程均可描述四种吸附质在活性炭上的吸附过程;孔内扩散模型表明改性活性炭对有机气体的吸附速率均大于未改性活性炭;四种吸附质在活性炭上的吸附能均小于20kJ?mol-1,表明活性炭对四种有机气体以物理吸附为主。     

Adsorption of methylene chloride vapor on activated carbons

A laboratory investigation on the adsorption of hazardous methylene chloride (METH) vapor on the commercial activated carbons BPL and PCB, which were made from bituminous coal and coconut shell, respectively, was conducted at 283, 293, 303, and 313 K. The physical properties and surface functional groups of the two activated carbons were also measured and compared with each other. The experimental results indicate that the adsorption capacity of carbon PCB is slightly higher than that of carbon BPL. It was found that the Langmuir, Freundlich, and Dubinin–Radushkevich adsorption equations were well fitted by the measured adsorption data. The values of the parameters of the adsorption equations were determined for the two adsorbents. The physical properties (e.g. micropore volume) of the adsorbents are consistent with the parameters obtained from the adsorption results.     

The adsorption behavior of Cu(II), Pb(II), and Co(II) of ethylene vinyl acetate‐clinoptilolite nanocomposites

In this study, ethylene vinyl acetate (EVA) was mixed with clinoptilolite (C), a natural zeolite, to prepare EVA‐C nanocomposites. The films were characterized by SEM‐EDS, XRD, and FT‐IR, and heavy metal removal was studied using the batch technique. The effects of the initial pH value and concentration of solutions, contact time, and filler dosage on the adsorption capacity of the composites were investigated. To study the influence of pretreatment on the filler, clinoptilolite was activated using KCl, NaCl, and HCl. Adsorption results show that equilibrium was reached after 24 h, and that sorption reached its maximum at pH values between 5 and 7. The selectivity trend was observed to be Pb > Cu > Co, which was consistent for both single and mixed metal‐ion solutions. Pretreatment significantly increased adsorption capacity of the composite, but was dependent on the conditioning reagent. Nanocomposites filled with HCl‐activated particles demonstrated a high adsorption capacity of between 70 and 80% for all three metals, while KCl‐activated particles were the least efficient with a maximum adsorption capacity of 69% for Pb(II), 54% for Cu(II) and 48% for Co(II). The adsorption data were then fitted to both Langmuir and Freundlich isotherms over the entire concentration range, and the Langmuir isotherm showed a better fit of the experimental sorption data than the Freundlich isotherm. The results obtained show that this simple methodology which can be up‐scaled has great potential for the preparation of a wide variety of similar particle‐filled adsorbent nanocomposites in other environmental remediation applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dual solute adsorption of 2,4,6‐trichlorophenol and N‐[2‐(2,4,6‐trichlorophenoxy)propyl]amine on to activated carbon

The capacities of four activated carbon types to adsorb both 2,4,6‐trichlorophenol (TCP) and N‐[2‐(2,4,6‐trichlorophenoxy)propyl]amine (BTS40348), as single‐ and dual‐solutes, at pH 4, 7 and 9, were evaluated by use of the Freundlich isotherm model. Coal‐based activated carbon type F400 was found to most strongly adsorb both compounds, with adsorption optima at pH 4 and 9 for TCP and BTS40348, respectively. In dual‐solute isotherms, the adsorptive capacity for each solute was reduced with pH, dictating which solute was most strongly adsorbed. Compared with these batch isotherms, F400 adsorptive capacity was reduced in flow‐through column studies. Activated carbon bioregeneration was studied but the adsorptive capacity of the flow‐through column did not increase, indicating that biologically‐mediated desorption of solute did not occur. © 2001 Society of Chemical Industry     

Treatment of wastewater from acrylonitrile‐butadiene‐styrene (ABS) resin manufacturing by biological activated carbon (BAC)

Background: The wastewater originating from the production of acrylonitrile‐butadiene‐styrene (ABS) resin is a toxic and refractory industrial wastewater. The purpose of this work is to investigate the characteristics of adsorption and biodegradation of biological activated carbon (BAC) for ABS resin wastewater. Results: More than 80% of chemical oxygen demand (COD), total organic carbon (TOC) and organic nitrogen (Org‐N) was removed after the 100th run in BAC with the help of bioregeneration, and the treatment efficiency of BAC was higher than that of adsorption and biodegradation alone. The initial Org‐N was mainly transformed into NH₄⁺‐N, and the transform efficiency reached 65% after the 100th run. After bioregeneration, the COD and TOC removal efficiencies of BAC reactor reached 88.97% and 86.26%, respectively. The BAC had different bioregeneration efficiencies of 94.41, 64.82, 61.05 and 40.04% for 3, 3‐imminodipropiononitrile, 3, 3‐oxydipropiononitrile, α, α‐dimethyl‐benzylalcohol and acetophenone, respectively, which mainly resulted from the different polarity of the compounds. Conclusion: BAC could protect microorganisms from shock loadings of toxic, refractory and complicated ABS resin wastewater. The mechanism of the organic pollutants removal by BAC consisted of three phases including adsorption, bioregeneration and stability. © 2012 Society of Chemical Industry     

Adsorption of Hg(II) ions from aqueous chloride solutions using powdered activated carbons

Activated carbons were developed from Casurina equisetifolia leaves, by chemically treating with sulfuric acid (1:1) or zinc chloride (25%), at low (425 °C) and high (825 °C) temperatures. The resulting powdered activated carbons were applied for removing mercuric ions from aqueous solution at different agitation times and mercuric ion concentrations. The equilibrium data fitted well the Langmuir adsorption isotherm. The Langmuir adsorption capacities were 12.3 and 20.3 mg g⁻¹ for low temperature carbons and 43.9 and 38.5 mg g⁻¹ for high temperature carbons impregnated with H₂SO₄ and ZnCl₂, respectively. Studies of the effects of carbon dosage, NaCl concentrations and solution pH values were carried out for the more effective, high temperature carbons. Increasing NaCl concentration resulted in a significant decrease in the adsorption efficiency. Adsorption was high from solutions with low and neutral pH values and lower for solutions with alkaline pH values for the high temperature carbons.     

甲烷在成型前后活性炭上吸附的初步试验

通过对比试验,分析成型对活性炭储存甲烷特性的影响。首先,应用丙烯酸甲酯乳胶黏合剂对活性炭SAC-02成型,在温度区间268.15～338.15 K、压力范围0～15 MPa测试甲烷的吸附等温线;通过确定吸附量和等量吸附热,比较甲烷在成型前后活性炭上的吸附平衡。其次,测试储罐吸附床中心在室温、4个压力（6.5 MPa、5.5 MPa、4.5 MPa和3.5 MPa）下快速充放气过程的温度变化,分析成型对吸附过程热效应的影响。结果表明,成型活性炭的密度增大、比表面积减小、单位质量吸附剂上的甲烷吸附量减小;甲烷在成型前后活性炭上的等量吸附热均处于13～20.5kJ·mol^-1;成型活性炭吸附床中心温度在充放气过程中的变化幅度和变化速率均增大。比较试验结果时发现,选用黏合剂成型须综合考虑其对吸附床热导率、传质阻力及吸附剂微观结构的影响。     

活性炭配炭的吸附性能及其与孔结构的关系

采制11种典型水处理用商品活性炭样品,两两混合进行配炭,对配炭组分及配炭的碘值、亚甲蓝值、丹宁酸值和焦糖脱色率等吸附性能指标及孔结构特征进行了测试和表征。采用加权平均拟合、线性拟合及多项式拟合等方法,研究配炭吸附性能指标与配炭组分吸附性能指标间的量化关系,关联活性炭孔结构与吸附性能指标。结果表明：活性炭配炭的吸附性能指标可由配炭组分的吸附性能指标通过加权平均计算,相对误差<4%,且配炭的孔结构也具备加和性;活性炭碘值、亚甲蓝值、丹宁酸值和焦糖脱色率的大小分别取决于活性炭1.0~2.8nm、1.5~10nm、2.0~50nm和3.0~50nm孔隙的发达程度,与孔容积的线性相关系数介于0.91~0.94。