Preparation of activated carbon from sawdust by zinc chloride activation

A series of activated carbons were prepared from sawdust by zinc chloride activation in different operation conditions. The effects of operation parameters such as impregnation ratio, activation temperature and time on the adsorption properties of activated carbons were measured and analyzed in order to optimize these operation conditions. The experimental results show that under the experimental circumstances studied, both the yield and the adsorption for iodine and methylene blue of activated carbon can reach a relatively higher value in the chemical activation process with the impregnation ratio of 100% ZnCl₂/sawdust in the activation temperature of 500 °C carbonized for 60–90 minutes which are the optimum activation conditions in making wood activated carbon. The most important operation parameter in chemical activation with zinc chloride was found to be the impregnation ratio.     

苯基键合高比表面积活性炭的制备及其对挥发性有机化合物的吸附性能研究

以核桃壳为原料,经过碳化、KOH活化, 制备了高比表面积活性炭,通过三甲基氧基苯基硅烷对活性炭表面进行改性,制得苯基键合高比表面积活性炭吸附材料.通过氮气吸附法测定了苯基键合活性炭的比表面积及孔径分布;采用红外光谱、X射线光电子能谱、X射线粉末衍射技术对苯基键合活性炭的有机官能团、表面元素的化学环境及晶体结构进行了表征.将该吸附材料制成采样管,吸附空气中的挥发性有机物,二硫化碳解吸后使用气相色谱进行分析.考察了苯基键合活性炭对乙醇、丙酮、正己烷、乙酸乙酯、四氢呋喃、1,2-二氯乙烷和苯共7种挥发性有机化合物(VOCs)的吸附性能,饱和吸附量在129~216 mg/g之间;在0.05~ 2.50 mg/mL范围内,7种组分的峰高与浓度呈良好的线性关系,检出限在0.92~3.60 mg/m3之间.     

Treatment of colored effluent of the textile industry in Bangladesh using zinc chloride treated indigenous activated carbons

The adsorption of colored compounds from the textile dyeing effluents of Bangladesh on granulated activated carbons produced from indigenous vegetable sources by chemical activation with zinc chloride was studied. The most important parameters in chemical activation were found be the chemical ratio of ZnCl₂ to feed (3:1), carbonization temperature (450-465 °C) and activation time (80 min). The adsorbances at 511 nm (red effluent) and 615 nm (blue effluent) were used for color estimation. It is established that at optimum temperature (50 °C), time of contact (30-40 min) and adsorbent loading (2 g l⁻¹), activated carbons developed from Segun saw-dust and water hyacinth showed substantial capability to remove coloring materials from the effluents. It is observed that adsorption of reactive dyes by all sorts of activated carbons is higher than disperse dyes. It is explained that activated carbon, because of its acidic nature, can better adsorb reactive dye particles containing large number of nitrogen sites and -SO₃Na group in their structure. The use of carbons would be economical, as saw-dust and water hyacinth are waste products and abundant in Bangladesh.     

Investigating parameters on the preparation of mesoporous activated carbons by the combination of chemical and physical activations using the Taguchi method

Mesoporous activated carbons were prepared from coconut shell by the combination of chemical and physical activation methods. Zinc chloride and CO₂ were used as chemical and physical agents, respectively. Optimum parameters were obtained from investigating the effect of various factors at different levels on the methane storage of wet activated carbons using the Taguchi experimental design method. Soaking time, carbonization temperature, and carbonization time were found as effective parameters in the methane storage. Finally, after achieving optimum levels for each factors based on the enhancement of methane storage, a confirmation experiment was conducted. Methane uptakes of the activated carbons were measured at temperature of 2?^°C up to the pressure of 80 bar and it turned out that the maximum amount of methane storage (241?V/V) had a good agreement with the predicted result from the Taguchi method.     

Preparation and Characterization of Antibacterial Polyacrylonitrile-based Activated Carbon Fiber Supporting Nano-ZnO

Polyacrylonitrile(PAN)-based activated carbon fiber(PACF) supporting nano-ZnO(PACF /nano-ZnO) was prepared by spin, pretreatment, carbonization, and KOH chemical activation at an activation temperature of 950 ℃ for 40 min. Nano-ZnO content, distribution and antibacterial properties of the PACF/nano-ZnO were studied. The pore structure and surface properties of the PACF/nano-ZnO were studied by Brunauer-Emmett-Teller(BET), N₂/77 K isothermal adsorption. The specific surface area increased markedly after the activation process and it was several hundred times greater than that before the process. The PACF/nano-ZnO shows a strong adsorption for Staphylococcus aureus(S. aureus) and Escherichia coli(E. coli) and antibacterial activity against them. As an experimental result, antibacterial properties of PACF/nano-ZnO increased with increasing the concentration of nano-ZnO particles, which suggests it is a promising antibacterial material.     

Preparation of porous carbon directly from hydrothermal carbonization of fructose and phloroglucinol for adsorption of tetracycline

Hydrothermal carbonization of biomass is a promising method to prepare carbonaceous materials. Generally, post physical or chemical activation is necessary to increase surface area and porosity of the carbon. Herein, porous carbonaceous material (FPC) with large surface area (481.7 m²/g) and pore volume (0.73 cm³/g) was prepared directly from hydrothermal carbonization of fructose and phloroglucinol in hydroalcoholic mixture. Structure characteristics of the FPC and its adsorption capacity for a representative antibiotic tetracycline in aqueous solution were investigated. This work provides a green and efficient method to fabricate porous carbonaceous adsorbent that has great potential applications in chemical and environmental fields.     

Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels

The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)相似文献   

微波辐射法制备活性炭的应用研究进展

对微波辐射技术在活性炭的活化、表面改性及再生过程中的研究进展进行了概述。微波功率是影响活性炭的活化、改性、再生及其吸附性能和产率的主要因素之一。众多实验结果表明微波辐射技术是制备活性炭材料和提高活性炭吸附性能的有效途径。     

Adsorption of Cu(II) ions from aqueous solution by hazelnut husk activated carbon prepared with potassium acetate

Hazelnut husk (HH), an agricultural waste, was converted to carbonaceous material by chemical activation using potassium acetate. The produced activated carbon (KAHHAC) was characterized by FTIR, SEM, N₂ adsorption–desorption experiments, CHN elemental analysis, and determination of moisture, ash, and point of zero charge. KAHHAC was used for the batch adsorption of Cu(II) ions from aqueous solutions. Optimum pH and contact time were found to be 5.0 and 240 minutes, respectively. The adsorption equilibrium data were described well by the Langmuir equation providing 105.3?mg?g^?1 Cu(II) adsorption capacity. The pseudo-second-order model successfully described the kinetic of Cu(II) adsorption by KAHHAC. The adsorbed Cu(II) onto KAHHAC was completely desorbed by 0.5?M nitric acid. In conclusion, HH activated carbon (AC) produced by the potassium acetate activation method is a very useful and efficient sorbent material for the removal of Cu(II) from aqueous solution.     

Preparation and characterization of activated carbon from <Emphasis Type="Italic">Amygdalus Scoparia</Emphasis> shell by chemical activation and its application for removal of lead from aqueous solutions

Two series of activated carbon have been prepared by chemical activation of Amygdalus Scoparia shell with phosphoric acid or zinc chloride for the removal of Pb(II) ions from aqueous solutions. Several methods were employed to characterize the active carbon produced. The surface area was calculated using the standard Brunauer-Emmet-Teller method. The microstructures of the resultant activated carbon were observed by scanning electron microscopy. The chemical composition of the surface resultant activated carbon was determined by Fourier transform infrared spectroscopy. In the batch tests, the effect of pH, initial concentration, and contact time on the adsorption were studied. The data were fitted with Langmuir and Freundlich equations to describe the equilibrium isotherms. The maximum adsorption capacity of Pb(II) on the resultant activated carbon was 36.63 mg g⁻¹ with H₃PO₄ and 28.74 mg g⁻¹ with ZnCl₂. To regenerate the spent adsorbents, desorption experiments were performed using 0.25 mol L⁻¹ HCl. Here we propose that the activated carbon produced from Amygdalus Scoparia shell is an alternative low-cost adsorbent for Pb(II) adsorption.     

Physicochemical and thermal studies of viscose rayon borate fiber and its carbon fiber

Nonhalogen compounds have been studied for improvements in the flameproofing property and toxicity of flame retardants. Borate compounds have properties of multifunctional smoke suppressants, flame retardants, and afterglow suppressants. In this study, borate was coupled onto the surface of viscose rayon felt. Coupling and carbonization were confirmed by attenuated total reflectance Fourier transform infrared (ATR FTIR). The initial carbonization temperature was certified with ATR FTIR, elemental analysis of carbon, and thermogravimetric analysis. In the carbonization step, all chemical groups of the surface of the viscose rayon felt degraded to the various gases. Moreover, the weight percentage of the carbon element increased with increasing carbonization temperature. Initial rapid thermal degradation temperatures of viscose rayon prepared at various temperatures increased with the increasing reaction temperature. The activation energy was calculated with the Freeman and Carroll method. The activation energy of borate‐coupled viscose rayon decreased much more than before coupling. However, the activation energy increased with the increasing carbonization temperature in the carbonization step. Viscose rayon borates showed higher limiting oxygen index (LOI) values and volumetric resistance rate values than viscose rayon phosphates. In this article, the relationship between the activation energy and LOI is studied. The synthesized viscose rayon borate is found to be highly effective as a flame retardant and electrically resistant. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3875–3883, 2001     

Preparation and characterization of waste ion-exchange resin-based activated carbon for CO<Subscript>2</Subscript> capture

Waste ion-exchange resin was utilized as precursor to produce activated carbon by KOH chemical activation, on which the effects of different activation temperatures, activation times and impregnation ratios were studied in this paper. The CO₂ adsorption of the produced activated carbon was tested by TGA at 30 °C and environment pressure. Furthermore, the effects of preparation parameters on CO₂ adsorption were investigated. Experimental results show that the produced activated carbons are microporous carbons, which are suitable for CO₂ adsorption. The CO₂ adsorption capacity increases firstly and then decreases with the increase of activation temperature, activation time and impregnation rate. The maximum adsorption capacity is 81.24 mg/g under the condition of 30 °C and pure CO₂. The results also suggest that waste ion-exchange resin-based activated carbons possess great potential as adsorbents for post-combustion CO₂ capture.     

STUDY ON THE FACTORS AFFECTING REDUCTION CAPACITIES OF ACTIVATED CARBON FIBERS

1. INTRODUCTION The discharge of effluent containing precious metal ions, which comes from electroplating, mining, smelting, and other industries, not only contaminate the environment where people live, but also cause the waste of natural resources. From…     

Adsorption of methane in activated carbons obtained from coconut shells using H3PO4 chemical activation

Activated carbon samples from coconut shells (Brazilian coconut species “Coco da Baía”) were prepared by chemical activation with phosphoric acid as the activating agent. Samples were characterized by nitrogen adsorption isotherms at 77 K. Some samples were randomly chosen in order to perform methane adsorption experiments under pressures between 1 and 60 bar at 303 K. A close relationship between surface area, micropore volume and methane adsorption capacity for carbons prepared from the same starting material was observed. The highest methane storage capacity in the tested samples was found to be 95 v/v at 303 K and 35 bar, which is comparable to results obtained for commercial samples indicated for this application. A moderate concentration of phosphoric acid (around 35%) seems to favor high surface areas, micropore volumes and, hence, gas storage capacity. The inclusion of an acid wash step before carbonization and the use of inert gas flow during carbonization also seem to enhance the development of porosity. This result suggests that activated carbons prepared from “Coco da Baía” by chemical activation with phosphoric acid have potential to be used as a storage media for natural gas.     

Fabrication and Characterization of Diatomite-supported Activated Carbon Functional Ceramic

Using porous diatomite ceramic as carrier and phenolic resin as carbon precursor, the activated carbon functional ceramic with the activated carbon fixed into porous ceramic was prepared by the impregnation load phenolic resin, carbonization and activation isolated air. The influences of impregnation, curing, carbonization, activation etc. on the material property were discussed. The iodine value, SEM, elemental analyzer, BET and spectrum analysis chart were used to characterize the microstructures and performance of material at different conditions. The results showed that the excellent comprehensive property of activated carbon functional ceramic was gained when it adsorbed phenolic resin in 4 h under vacuum condition at curing temperature of 150 ℃ for 0.5 h and carbonization temperature of 600 ℃ for 1.0 h, and then put into 25wt% KOH for 4.0 h at activation temperature of 700 ℃ for 1.5 h. The iodine value is 176.9 mg/g, the specific surface area can reach 86.3 m2/g and the yield of carbonization is 50.48%.     

Synthesis of activated carbon foams with high specific surface area using polyurethane elastomer templates for effective removal of methylene blue

Carbon foams have gained significant attention due to their tuneable properties that enable a wide range of applications including catalysis, energy storage and wastewater treatment. Novel synthesis pathways enable novel applications via yielding complex, hierarchical material structure. In this work, activated carbon foams (ACFs) were produced from waste polyurethane elastomer templates using different synthesis pathways, including a novel one-step method. Uniquely, the produced foams exhibited complex structure and contained carbon microspheres. The ACFs were synthesized by impregnating the elastomers in an acidified sucrose solution followed by direct activation using CO₂ at 1000 ℃. Different pyrolysis and activation conditions were investigated. The ACFs were characterized by a high specific surface area (S_BET) of 2172 m²/g and an enhanced pore volume of 1.08 cm³/g. Computer tomography and morphological studies revealed an inhomogeneous porous structure and the presence of numerous carbon spheres of varying sizes embedded in the porous network of the three-dimensional carbon foam. X-ray diffraction (XRD) and Raman spectroscopy indicated that the obtained carbon foam was amorphous and of turbostratic structure. Moreover, the activation process enhanced the surface of the carbon foam, making it more hydrophilic via altering pore size distribution and introducing oxygen functional groups. In equilibrium, the adsorption of methylene blue on ACF followed the Langmuir isotherm model with a maximum adsorption capacity of 592 mg/g. Based on these results, the produced ACFs have potential applications as adsorbents, catalyst support and electrode material in energy storage systems.     

Pilot production of activated carbon from cotton stalks using H3PO4

Cotton stalks, an agricultural waste, were chemically activated in a batch process using H₃PO₄ in a locally designed carbonizer at 420 °C in the absence of any purging gases. Mechanically cut short sticks were soaked in diluted H₃PO₄ for a short duration (Batch 1) and an extended period (Batch 2) prior to thermal treatment. The derived carbons contained both coarse and fine grains with acidic effect. Porosity was characterized by N₂ adsorption at −196 °C and the isotherms analyzed by the α-method to estimate total and microporous surface areas in addition to total and microporous volumes. The produced carbons exhibited well-developed porosity that was essentially microporous in composition. Several key performance parameters were altered considerably as a result of impregnation with H₃PO₄ and the extended chemical activation period (Batch 2). Most of the internal porosity of both carbons was accessible to adsorption of iodine, whereas the uptake of methylene blue dye was proportional to the average size of micropores which were larger for the batch with a longer acid soaking time. SEM and FTIR investigations revealed the presence of a developed honeycomb structure and different oxygen functionalities on surfaces of the activated products which are advantageous in liquid-phase applications. Preliminary laboratory-scale experiments with Pb(II) indicate that adsorption capacity of target heavy metals compares favorably with commercially available activated carbons. The raw material, pre-processing, and activation process prove feasible for the production of activated carbon on a large scale, thereby providing a sustainable strategy for treatment of toxic waste streams.     

The Analysis of Pore Development and Formation of Surface Functional Groups in Bamboo-Based Activated Carbon during CO2 Activation

Pore development and the formation of oxygen functional groups were studied for activated carbon prepared from bamboo (Bambusa bambos) using a two-step activation with CO₂, as functions of carbonization temperature and activation conditions (time and temperature). Results show that activated carbon produced from bamboo contains mostly micropores in the pore size range of 0.65 to 1.4 nm. All porous properties of activated carbons increased with the increase in the activation temperature over the range from 850 to 950 °C, but decreased in the temperature range of 950 to 1000 °C, due principally to the merging of neighboring pores. The increase in the activation time also increased the porous properties linearly from 60 to 90 min, which then dropped from 90 to 120 min. It was found that the carbonization temperature played an important role in determining the number and distribution of active sites for CO₂ gasification during the activation process. Empirical equations were proposed to conveniently predict all important porous properties of the prepared activated carbons in terms of carbonization temperature and activation conditions. Oxygen functional groups formed during the carbonization and activation steps of activated carbon synthesis and their contents were dependent on the preparation conditions employed. Using Boehm’s titration technique, only phenolic and carboxylic groups were detected for the acid functional groups in both the chars and activated carbons in varying amounts. Empirical correlations were also developed to estimate the total contents of the acid and basic groups in activated carbons in terms of the carbonization temperature, activation time and temperature.     

Effects of Burn-off and Activation Temperature on Preparation of Activated Carbon from Corn Cob Agrowaste by CO(2) and Steam

Previous studies have successfully demonstrated that corn cob is a suitable precursor for production of good activated carbon by chemical activation. However, respond to the need for cleaner production, this study focuses on the physical activation by gasifying agents such as CO(2) and steam. The activation temperatures under investigation are 1073 and 1173 K. Within the limit of 50 wt% burn-off, experimental results reveal that the BET surface area, pore volume, and average pore diameter of the resulting activated carbon generally increase with the extent of burn-off in both gasifying agents and at both temperatures. The higher activation temperature can overcome the drawbacks of a longer period of activation required to attain larger surface area and can offer higher potential to produce activated carbon of greater adsorption capacity from agriculture wastes such as corn cobs. Additionally, the BET surface areas of properly prepared activated carbons can satisfy commercial requirements, when compared with commercial activated carbon. The BET surface areas of the activated carbons after about 71 and 59 wt% burn-off of CO(2) and steam activations at 1173 K are 1705 and 1315 m(2)/g, respectively, indicating high adsorption capacities. Thus, it is feasible to produce high-quality microporous activated carbon from corn cob agrowaste using N(2) carbonization followed by physical activation with CO(2) or steam. Copyright 2000 Academic Press.     

Highly selective CO2 capture on N-doped carbon produced by chemical activation of polypyrrole functionalized graphene sheets

N-doped porous carbon produced via chemical activation of polypyrrole functionalized graphene sheets shows selective adsorption of CO(2) (4.3 mmol g(-1)) over N(2) (0.27 mmol g(-1)) at 298 K. The potential for large scale production and facile regeneration makes this material useful for industrial applications.