Adsorption of acid dye onto activated carbons prepared from agricultural waste bagasse by ZnCl2 activation

A series of activated carbons were prepared from agricultural waste sugarcane bagasse by chemical activation with zinc chloride (ZnCl2) as an activating agent at 500 degrees C and 0.5 h soaking time. The Langmuir surface area and total pore volume were used to estimate the average pore diameter of the carbon products. The values of the surface area and pore volume increased linearly with increase in the impregnation ratio (IR) up to 100 wt%. The adsorption capacities of the derived adsorbents for Acid Orange 10 were measured at 20 degrees C and 40 degrees C to gain further insights into the acidic surface oxides of the adsorbent from the results of Fourier transform infrared (FTIR) spectroscopy analysis and pH measurement. Adsorption isotherms of the acid dye on adsorbents prepared were determined and correlated with common isotherm equations. It was found that the Langmuir model appears to fit the isotherm data better than the Freundlich model. The physical properties of these adsorbents were consistent with the parameters obtained from the isotherm equations.     

The removal of uranium (VI) from aqueous solutions onto activated carbon developed from grinded used tire

In this study, activated carbon was prepared from waste tire by KOH chemical activation. The pore properties including the BET surface area, pore volume, pore size distribution, and average pore diameter were characterized. BET surface area of the activated carbon was determined as 558 m²/g. The adsorption of uranium ions from the aqueous solution using this activated carbon has been investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied by a batch method. The optimum pH for adsorption was found to be 3. The removal efficiency has also been determined for the adsorption system as a function of initial concentration. The experimental results were fitted to Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherm models. A comparison of best-fitting was performed using the coefficient of correlation and the Langmuir isotherm was found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of uranium ions onto waste tire activated carbon was 158.73 mg/g. The thermodynamic equilibrium constant and the Gibbs free energy were determined and results indicated the spontaneous nature of the adsorption process. Kinetics data were best described by pseudo-second-order model.     

天然超细针状羽绒粒子对染料的吸附性能

采用超细粉体加工设备制备了天然超细针状羽绒粒子,考察其对模拟染料废水溶液中酸性大红3R、直接耐酸大红4BS、还原大红R的吸附性能,探讨了pH、吸附剂用量等因素对染料吸附的影响。实验结果表明,超细羽绒粒子是一种针状介孔吸附材料,具有连续的孔径分布和发达的孔结构。染料溶液pH为3.0,超细羽绒粒子用量5 g/L时吸附效果最好。对吸附数据进行Langmuir、Freundlich、Tempkin以及D-R吸附模型线性拟合,得出超细羽绒粒子对3种染料的吸附规律最符合Langmuir等温吸附方程,其理论最大吸附容量分别为137.55、108.11和87.72 mg/g。对吸附能计算发现,超细羽绒粒子对酸性大红3R、直接耐酸大红4BS以及还原大红R的吸附是化学吸附过程。研究表明,超细羽绒粒子是一种最具有应用潜力的吸附印染废水中有毒有机染料的高效吸附剂。     

Roles of physical and chemical properties of activated carbon in the adsorption of lead ions

Elucidation of the roles of chemical and physical properties of activated carbons is an important basis for the systematic development of adsorbents with optimal properties specific for certain applications. Such an understanding has challenged most researchers and this has been attributed with the difficulty in decoupling the effect of chemical and physical properties that characterize activated carbons. This study proposed empirical modeling in resolving the effects of individual carbon properties in lead adsorption. A model based on lead adsorption and carbon properties including total surface area, mean pore size and heteroatom concentrations has been shown to adequately describe the lead adsorption onto activated carbons prepared from bagasse. To support this investigation a series of activated carbons were prepared from bagasse by physical and by chemical activation techniques. The surface chemical properties of the carbons were inferred from carbon pH and heteroatom concentrations. The physical characterizations of the carbons included total surface area by the BET technique and mean pore size measured using the Horvath-Kawazoe equation. Adsorption tests were conducted using a low concentration of lead (5 ppm) and the solution pH was maintained at 1.0 to maintain lead speciation to the un-complexed Pb(2+) ion. The adequacy of the proposed empirical models was statistically assessed. This form of analysis was shown to provide valuable information in tailor making adsorbents and selecting appropriate adsorbents for lead adsorption.     

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.     

活性炭孔隙结构在其甲苯吸附中的作用

选用4种商用活性炭(AC),利用氮气绝热吸附、扫描电子显微镜(SEM)和傅立叶变换红外光谱(FTIR)测试了活性炭的物化性质。以甲苯为吸附质,在温度为298.15 K下进行了静态和动态吸附实验,研究了活性炭孔结构对其吸附性能、吸附行为、表面覆盖率和吸附能的影响。结果表明:活性炭的比表面积和孔容是其吸附性能主要影响因素,孔径在0.8～2.4 nm之间的孔容和甲苯吸附量之间存在较好的线性关系,且线性斜率随甲苯浓度增加而变大。甲苯吸附行为符合Langmuir吸附等温模型和准一阶动力学方程式。活性炭孔结构是甲苯吸附速率的主要制约因素。在甲苯快速吸附阶段,微孔为吸附速率主要制约因素,在甲苯颗粒内扩散阶段,微孔和表面孔为吸附速率的主要制约因素,在吸附末尾阶段,中孔和大孔为吸附速率的主要制约因素。4种活性积炭对甲苯的吸附能随其比表面变大而变大。     

Analysis and comparison of inertinite-derived adsorbent with conventional adsorbents

To increase U.S. petroleum energy-independence, the University of Texas at Arlington (UT Arlington) has developed a coal liquefaction process that uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This paper reports on part of the environmental evaluation of the liquefaction process: the evaluation of the solid residual from liquefying the coal, called inertinite, as a potential adsorbent for air and water purification. Inertinite samples derived from Arkansas and Texas lignite coals were used as test samples. In the activated carbon creation process, inertinite samples were heated in a tube furnace (Lindberg, Type 55035, Arlington, UT) at temperatures ranging between 300 and 850 degrees C for time spans of 60, 90, and 120 min, using steam and carbon dioxide as oxidizing gases. Activated inertinite samples were then characterized by ultra-high-purity nitrogen adsorption isotherms at 77 K using a high-speed surface area and pore size analyzer (Quantachrome, Nova 2200e, Kingsville, TX). Surface area and total pore volume were determined using the Brunauer Emmet, and Teller method, for the inertinite samples, as well as for four commercially available activated carbons (gas-phase adsorbents Calgon Fluepac-B and BPL 4 x 6; liquid-phase adsorbents Filtrasorb 200 and Carbsorb 30). In addition, adsorption isotherms were developed for inertinite and the two commercially available gas-phase carbons, using methyl ethyl ketone (MEK) as an example compound. Adsorption capacity was measured gravimetrically with a symmetric vapor sorption analyzer (VTI, Inc., Model SGA-100, Kingsville, TX). Also, liquid-phase adsorption experiments were conducted using methyl orange as an example organic compound. The study showed that using inertinite from coal can be beneficially reused as an adsorbent for air or water pollution control, although its surface area and adsorption capacity are not as high as those for commercially available activated carbons. Implications: The United States currently imports two-thirds of its crude oil, leaving its transportation system especially vulnerable to disruptions in international crude supplies. UT Arlington has developed a liquefaction process that converts coal, abundant in the United States, to crude oil. This work demonstrated that the undissolvable solid coal residual from the liquefaction process, called inertinite, can be converted to an activated carbon adsorbent. Although its surface area and adsorption capacity are not as high as those for commercially available carbons, the inertinite source material would be available at no cost, and its beneficial reuse would avoid the need for disposal.     

污泥活性炭的表征及其对Cr（Ⅵ）的吸附特性

以城市污水处理厂污泥为原料,采用磷酸活化一微波热解法制备得到污泥活性炭,并将其用于吸附水溶液中的Cr（Ⅵ）。分别采用元素分析仪（VarioELcube）、比表面积孔径分布测定仪（ASAP2020）、扫描电镜（SEM）和傅里叶红外光谱（FT—IR）等仪器对原污泥及污泥活性炭的表面组成和结构进行表征,探讨污泥活性炭的孔隙结构参数和表面化学性能。通过静态吸附实验,考察了溶液初始pH,接触时间,初始Cr（Ⅵ）浓度对污泥活性炭吸附Cr（Ⅵ）效果的影响,并探讨了污泥活性炭去除Cr（Ⅵ）的机理。实验结果表明,pH越低吸附效果越好,吸附平衡时间为100h。不同温度下吸附过程均符合Langmuir等温吸附模型,30℃时最大吸附容量为27．55mg／g;吸附动力学过程符合准二级速率方程（R2〉0．99）;污泥活性炭对Cr（Ⅵ）的去除是一个吸附-还原耦合的过程。     

Adsorption Characteristics of Benzene on Biosolid Adsorbent and Commercial Activated Carbons

Abstract

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl₂) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl₂-immersed biosolids pyrolyzed at 500 °C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.     

80TH APCA Annual Meeting & Exhibition June 21-26, 1987

To increase U.S. petroleum energy-independence, the University of Texas at Arlington (UT Arlington) has developed a coal liquefaction process that uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This paper reports on part of the environmental evaluation of the liquefaction process: the evaluation of the solid residual from liquefying the coal, called inertinite, as a potential adsorbent for air and water purification. Inertinite samples derived from Arkansas and Texas lignite coals were used as test samples.

In the activated carbon creation process, inertinite samples were heated in a tube furnace (Lindberg, Type 55035, Arlington, UT) at temperatures ranging between 300 and 850 °C for time spans of 60, 90, and 120 min, using steam and carbon dioxide as oxidizing gases. Activated inertinite samples were then characterized by ultra-high-purity nitrogen adsorption isotherms at 77 K using a high-speed surface area and pore size analyzer (Quantachrome, Nova 2200e, Kingsville, TX). Surface area and total pore volume were determined using the Brunauer, Emmet, and Teller method, for the inertinite samples, as well as for four commercially available activated carbons (gas-phase adsorbents Calgon Fluepac-B and BPL 4?×?6; liquid-phase adsorbents Filtrasorb 200 and Carbsorb 30). In addition, adsorption isotherms were developed for inertinite and the two commercially available gas-phase carbons, using methyl ethyl ketone (MEK) as an example compound. Adsorption capacity was measured gravimetrically with a symmetric vapor sorption analyzer (VTI, Inc., Model SGA-100, Kingsville, TX). Also, liquid-phase adsorption experiments were conducted using methyl orange as an example organic compound. The study showed that using inertinite from coal can be beneficially reused as an adsorbent for air or water pollution control, although its surface area and adsorption capacity are not as high as those for commercially available activated carbons.

Implications: The United States currently imports two-thirds of its crude oil, leaving its transportation system especially vulnerable to disruptions in international crude supplies. UT Arlington has developed a liquefaction process that converts coal, abundant in the United States, to crude oil. This work demonstrated that the undissolvable solid coal residual from the liquefaction process, called inertinite, can be converted to an activated carbon adsorbent. Although its surface area and adsorption capacity are not as high as those for commercially available carbons, the inertinite source material would be available at no cost, and its beneficial reuse would avoid the need for disposal.     

Adsorption of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-metylphenoxyacetic acid onto activated carbons derived from various lignocellulosic materials

Adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-metylphenoxyacetic acid (MCPA) from aqueous solution onto activated carbons derived from various lignocellulosic materials including willow, miscanthus, flax, and hemp shives was investigated. The adsorption kinetic data were analyzed using two kinetic models: the pseudo-first order and pseudo-second order equations. The adsorption kinetics of both herbicides was better represented by the pseudo-second order model. The adsorption isotherms of 2,4-D and MCPA on the activated carbons were analyzed using the Freundlich and Langmuir isotherm models. The equilibrium data followed the Langmuir isotherm. The effect of pH on the adsorption was also studied. The results showed that the activated carbons prepared from the lignocellulosic materials are efficient adsorbents for the removal of 2,4-D and MCPA from aqueous solutions.     

α-FeOOH对靛蓝胭脂红的吸附性能

采用水热法合成纳米针铁矿α-FeOOH,利用XRD、SEM对产物物相和形貌进行表征,研究了α-FeOOH对靛蓝胭脂红的吸附性能,并进行动力学和等温吸附模型分析。结果表明,α-FeOOH对靛蓝胭脂红具有良好的吸附性能,25℃时最大吸附量为40.31 mg·g-1。用Langmuir、Freundlich、D-R和Tempkind等4种等温吸附模型对实验数据进行拟合,Langmuir方程对实验数据拟合效果最好,D-R方程和Tempkin方程结果显示吸附是物理吸附。吸附过程符合准一级动力学方程,内扩散模型和Boyd模型结果显示膜扩散为吸附过程的主要速控步骤。     

Equilibrium and kinetics of adsorption of phosphate onto iron-doped activated carbon

Purpose

Two series of activated carbons modified by Fe (II) and Fe (III) (denoted as AC/N-Fe^II and AC/N-Fe^III), respectively, were used as adsorbents for the removal of phosphate in aqueous solutions.

Method

The synthesized adsorbent materials were investigated by different experimental analysis means. The adsorption of phosphate on activated carbons has been studied in kinetic and equilibrium conditions taking into account the adsorbate concentration, temperature, and solution pH as major influential factors.

Results

Maximum removals of phosphate are obtained in the pH range of 3.78?C6.84 for both adsorbents. Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Results suggest that the main phase formed in AC/N-Fe^II and AC/N-Fe^III is goethite and akaganeite, respectively; the presence of iron oxides significantly affected the surface area and the pore structure of the activated carbon.

Conclusions

Studies revealed that iron-doped activated carbons were effective in removing phosphate. AC/N-Fe^II has a higher phosphate removal capacity than AC/N-Fe^III, which could be attributed to its better intra-particle diffusion and higher binding energy. The activation energy for adsorption was calculated to be 22.23 and 10.89 kJ mol^?1 for AC/N-Fe^II and AC/N-Fe^III, respectively. The adsorption process was complex; both surface adsorption and intra-particle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.     

Removal of congo red from aqueous solution by bagasse fly ash and activated carbon: kinetic study and equilibrium isotherm analyses

Present investigation deals with the utilisation of bagasse fly ash (BFA) (generated as a waste material from bagasse fired boilers) and the use of activated carbons-commercial grade (ACC) and laboratory grade (ACL), as adsorbents for the removal of congo red (CR) from aqueous solutions. Batch studies were conducted to evaluate the adsorption capacity of BFA, ACC and ACL and the effects of initial pH (pH(0)), contact time and initial dye concentration on adsorption. The pH(0) of the dye solution strongly affected the chemistry of both the dye molecules and BFA in an aqueous solution. The effective pH(0) was 7.0 for adsorption on BFA. Kinetic studies showed that the adsorption of CR on all the adsorbents was a gradual process. Equilibrium reached in about 4h contact time. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2 g l(-1), respectively. CR uptake by the adsorbents followed pseudo-second-order kinetics. Equilibrium isotherms for the adsorption of CR on BFA, ACC and ACL were analysed by the Freundlich, Langmuir, Redlich-Peterson, and Temkin isotherm equations. Error analysis showed that the R-P isotherm best-fits the CR adsorption isotherm data on all adsorbents. The Freundlich isotherm also shows comparable fit. Thermodynamics showed that the adsorption of CR on BFA was most favourable in comparison to activated carbons.     

聚乙烯醇(PVA)改性膨胀石墨对亚甲基蓝废水的吸附

以天然鳞片石墨为原料,聚乙烯醇 (PVA) 为改性剂,采用浸渍法制备改性膨胀石墨 (M-EG), 对改性膨胀石墨 (M-EG) 的官能团结构组成、比表面积、孔径分布及孔隙度等进行了表征,研究了其对亚甲基蓝染料废水的吸附性能,并对其吸附动力学、等温吸附类型和吸附热力学进行了研究.结果表明,经PVA改性后,M-EG的比表面积、孔隙度均增大,表面极性降低;M-EG对亚甲基蓝染料的吸附符合二级动力学吸附模型,并符合Langmiur等温吸附模型和Freundlich等温吸附模型;该反应为吸热的自发反应.     

Investigation of the Treatability of the Primary Indoor Volatile Organic Compounds on Activated Carbon Fiber Cloths at Typical Indoor Concentrations

Abstract

Volatile organic compounds (VOCs) are a major concern for indoor air pollution because of the impacts on human health. In recent years, interest has increased in the development and design of activated carbon filters for removing VOCs from indoor air. Although extensive information is available on sources, concentrations, and types of indoor VOCs, there is little or no information on the performance of indoor air adsorption systems for removing low concentrations of primary VOCs. Filter designs need to consider various factors such as empty bed contact time, humidity effects, competitive adsorption, and feed concentration variations, whereas adsorption capacities of the indoor VOCs at the indoor concentration levels are important parameters for filter design. A preliminary assessment of the feasibility of using adsorption filters to remove low concentrations of primary VOCs can be performed. This work relates the information (including VOC classes in indoor air, the typical indoor concentrations, and the adsorption isotherms) with the design of a particular adsorbent/adsorbates system. As groundwork for filter design and development, this study selects the primary VOCs in indoor air of residences, schools, and offices in different geographical areas (North America, Europe, and Asia) on the basis of occurrence, concentrations, and health effects. Activated carbon fiber cloths (ACFCs) are chosen as the adsorbents of interest. It is demonstrated that the isotherm of a VOC (e.g., toluene on the ACFC) at typical indoor concentrations—parts per billion by volume (ppbv) level—is different than the isotherm at parts per million by volume (ppmv) levels reported in the publications. The isotherms at the typical indoor concentrations for the selected primary VOCs are estimated using the Dubinin–Radushkevitch equation. The maximum specific throughput for an indoor VOC removal system to remove benzene is calculated as a worst-case scenario. It is shown that VOC adsorption capacity is an important indicator of a filter’s lifetime and needs to be studied at the appropriate concentration range. Future work requires better understanding of the realistic VOC concentrations and isotherms in indoor environments to efficiently utilize adsorbents.     

生物基质活性炭对挥发性有机物的吸附

以咖啡渣和柚子皮生物基质为原料用磷酸活化法制成活性炭,探讨了制备条件对活性炭制备的影响,并研究了其对正丁烷的吸附行为。磷酸活化过程中磷酸的用量为生物基质质量的1.5倍为宜,咖啡渣采用超声干燥法,柚子皮采用水热法制备。制备的活性炭对正丁烷均有较好的吸附能力,以柚子皮为原料、磷酸用量为原料质量两倍活化制成的活性炭吸附性能最佳,最大吸附量约为商用活性炭的2倍。吸附剂均能较好地与兰格缪尔曲线相拟合,计算了不同正丁烷覆盖度下的等量吸附热,其变化规律与吸附曲线变化规律相一致。     

溴化十六烷基吡啶改性沸石对水中甲基橙的吸附

采用溴化十六烷基吡啶(CPB)对天然沸石进行改性制备得到了CPB改性沸石,通过批量吸附实验考察了CPB改性沸石对水中阴离子染料甲基橙的去除作用。结果表明,天然沸石对水中甲基橙的吸附能力很差,而CPB改性沸石则可以有效吸附去除水中的甲基橙。CPB改性沸石对水中甲基橙的吸附能力随CPB负载量的增加而增加,CPB负载量最大的改性沸石对水中甲基橙的吸附能力最强。双分子层CPB改性沸石对水中甲基橙的去除率随吸附剂投加量的增加而增加,而CPB改性沸石对水中甲基橙的单位吸附量则随吸附剂投加量的增加而降低。双分子层CPB改性沸石对水中甲基橙的吸附平衡数据可以采用Langmuir等温吸附模型加以描述。根据Langmuir模型计算得到的CPB负载量为341 mmol/(kg沸石)的双分子层CPB改性沸石对水中甲基橙的最大吸附容量为63.7 mg/g(303 K和pH 7)。准二级动力学模型适合用于描述双分子层CPB改性沸石对水中甲基橙的吸附动力学过程。pH和反应温度对双分子层CPB改性沸石吸附水中甲基橙的影响较小。以上结果说明,双分子层CPB改性沸石适合作为一种吸附剂用于去除废水中的甲基橙。     

介孔铁锆复合氧化物的制备及其对Cr(VI)的吸附性能

以十六烷基三甲基溴化铵(CTAB)为模板剂,以铁(Fe)和锆(Zr)为原料,采用不同Fe/Zr摩尔比例,制备出Fe/Zr复合氧化物吸附剂,对吸附剂的比表面积、孔径分布、晶型结构和零点电位(pHzpc)进行了表征.筛选吸附容量最佳的Fe/Zr吸附剂,考察了吸附条件对其去除水中Cr(VI)效果的影响,探讨了吸附动力学和等温线规律.结果表明:最佳吸附剂的Fe/Zr摩尔比为5/1,具有典型的介孔材料结构特征;该吸附剂在pH为2~8范围内均有良好的除Cr(VI)效率;30 min内即可达到吸附平衡,最大吸附容量为60.90 mg/g.介孔Fe/Zr复合氧化物与现有除Cr(VI)吸附剂相比具有更高的吸附能力,是一种具有较好应用潜力的水处理除Cr(VI)吸附剂.     

TiO2@碳纳米管吸附去除盐酸四环素

采用静电组装法制备了TiO2@碳纳米管复合吸附剂,用以除去水中的盐酸四环素。通过FE-SEM、EDS和XRD进行表征,考察了pH、初始浓度和吸附剂用量对吸附过程的影响,研究了吸附动力学、等温模型和热力学,并对吸附剂的再生进行了评价。结果表明,复合吸附剂对盐酸四环素的最大饱和吸附量为52.33 mg/g;最佳吸附pH值为6,强酸不利于吸附;当初始浓度在15~60 mg/L范围内时,吸附量随着初始浓度的增大而增加;当吸附剂投加量为0.50 g/L时,吸附效率最高。吸附过程符合准二级动力学模型和Langmuir等温模型。热力学参数ΔG H >0,表明该吸附过程是自发、吸热过程。H2O2-TiO2光催化协同效应可有效完成吸附剂的再生。