Preparation of activated carbon for mercury capture from chicken waste and coal

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.

The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury.     

Speciation of volatile mercury species present in digester and deposit gases

Volatile mercury compounds have been speciated in gases evolved from fermentation of sewage sludge as well as municipal waste. The species were trapped by sequential sampling, using a noble‐metal trap in series with an activated‐carbon trap. Thermally desorbed Hg⁰ and (CH₃)₂Hg were separated by GC at 70 °C and detected by cold vapour atomic fluorescence spectroscopy after thermal reduction. The amounts of mercury detected in the sewage gas correspond to concentrations in the range 50–110 ng m⁻³ for both species whereas the deposit gases were found to contain only elemental mercury. Monomethylmercury species could not be positively identified in any of the gas samples. Copyright © 1999 John Wiley & Sons, Ltd.     

Adsorbents from Waste materials

The possibility of using pyrolyzed wastes produced in already working incineration plants, as adsorbents for waste water treatment, was studied. Showing very poor adsorption properties, they were improved by steam activation technique used in the conventional activated carbon manufacturing. It is concluded that various organic waste materials can be converted to carbonaceous final products with a character similar to activated carbon. Their adsorption properties and pore size distribution are determined by the structure of the starting material. Although most of these samples have a low specific surface area, their pore volume is not negligible in the meso-and micropore range. Adsorption tests with model waste waters confirmed that adsorption properties are strongly influenced by the character of the suface. The adsorption capacity of these samples can be utilized for the treatment of strongly polluted industrial waste waters. Considering that the raw material ‘needed’ to manufacture these adsorbent is produced permanently and the adsorbents do not have to be regenerated, it might be worthwhile using these kinds of adsorbents in the primary treatment of industrial waste waters.     

硫化氢对活性炭脱除单质汞的影响

H₂S是煤气中的含硫成分,活性炭能否催化氧化煤气中的H₂S形成活性硫,以促进H₂S和Hg⁰的协同脱除是值得研究的。 本文首先通过程序升温脱附和热力学分析了低温情况下H₂S对活性炭脱除Hg⁰的影响。 在较低吸附温度130 ℃下,H₂S不仅不能作为硫源,还使活性炭对Hg⁰的吸附显著减弱,这主要是由于H₂S对活性炭表面的吸附氧的消耗以及H₂S对含氧官能团的氧的取代反应造成的。 在此基础上,进一步研究了高温下H₂S对活性炭的影响,高温也不能使活性炭有效渗入单质硫。 所以无论低温还是高温情况下,利用H₂S作为硫源使Hg⁰以HgS的形式脱除并不是活性炭脱汞的可行手段。 本文揭示了较宽的温度范围内H₂S对单纯的活性炭脱除Hg⁰的影响机理,能为用于煤气脱汞的活性炭的设计以及作为负载时机理研究提供支持作用。     

煤焦油沥青基纤维状活性炭的吸附性能

煤焦油沥青基炭纤维（ＣＰＣＦ）价格低廉含炭量高、易于活化,是制备纤维状活性炭（ＣＰＡＣＦ）的优良原料。本文讨论了ＣＰＣＦ的抗拉强度和活化条件对ＣＰＡＣＦ比表面积的影响。并同石油系沥青基炭纤维（ＰＰＣＦ）进行了比较。考察了不同比表面积的ＣＰＡＣＦ、ＰＰＡＣＦ和商品用颗粒活性炭（ＡＣ）对０．１ｍｏｌ／Ｌ碘溶液、０．００５ｍｏｌ／Ｌ亚早兰溶液和２９３Ｋ下三氯甲烷饱和蒸汽的吸附性能,及以上三样品在２９３Ｋ     

环境样品的热解-溶液吸收预处理及其汞同位素组成的测定

利用多道接收电感耦合等离子体质谱仪(MC-ICP-MS)可实现汞同位素的高精度测定,但对样品预处理的要求很高。目前,液态、固态、气态环境样品的预处理方式不一,存在一定的系统误差。该研究旨在尽可能统一各状态样品的预处理步骤。先将各样品中的不同形态汞富集转化为固体可吸附态,令其吸附在固态载体上,包括:采用金柱富集气体样品中的气态单质汞;以吹扫-金柱捕集法富集液体样品中的溶解气态汞和总汞;用膜过滤法收集大气中的颗粒态汞。最后以管式炉热解定量固态样品,采用高氧化效率的酸性高锰酸钾混合溶液吸收热解产生的Hg~0并氧化为Hg~(2+),保存于溶液中供MC-ICP-MS测定。优化了气体流速、吸收液体积及高锰酸钾浓度等参数,考察了方法空白、回收率及精密度等指标,并将建立的方法应用于大气气态单质汞、大气颗粒态汞、溶解气态汞、雨水总汞和土壤总汞等样品中汞同位素的分析。     

化学链燃烧过程中铁基烧结返矿载氧体反应活性及结构研究

使用流化床,以95%的甲烷作为还原性气氛,以烧结过程中烧结返矿作为载氧体,研究其在化学链燃烧过程中的反应活性以及烧结返矿在氧化还原循环中的结构特征。对烧结矿原料、还原后以及氧化再生的烧结矿进行形貌结构及物性表征。结果表明,在初始氧化循环过程中,烧结返矿的载氧能力和反应活性有显著的提高;前25个循环过程中,烧结返矿的比表面积显著增大,比表面积的增大是提高烧结返矿反应活性的主要原因之一。随着循环的进行,烧结返矿表面出现裂纹并逐渐加大。Raman检测结果显示,在还原过程中有新的铁晶型,纤铁矿(γ-Fe OOH)生成,而纤铁矿(γ-Fe OOH)的生成将降低烧结返矿的载氧能力。氧化循环过程中,采用甲烷作为还原性气体,并未发现有碳沉积现象的产生。     

Bioreduction of ionic mercury from wastewater in a fixed-bed bioreactor with activated carbon

Wide industrial use of mercury led to significant mercury pollution of the environment. It requires development of cleanup technologies which would allow treating large volumes of mercury contaminated water in a cost effective and environmentally friendly way. A novel bio-technology, developed from laboratory to industrial scale in Germany at HZI (former GBF), is based on enzymatic reduction of highly toxic Hg(II) to water-insoluble and relatively non-toxic Hg(0) using live mercury resistant bacteria immobilized on a porous carrier material in a fixed-bed bioreactor. Improvement of the original method was based on the use of activated carbon as a carrier for microorganisms and an adsorbent for mercury. Such integration of the process should increase the technology efficiency. In order to compare different carrier materials, activated carbon and pumice stones were used. The strain Pseudomonas putida was immobilized in bioreactors continuously fed with solutions of HgCl₂ enriched with nutrients. Simultaneously, experiments in two more reactors were run in the absence of microorganisms to investigate the influence of nutrients on the adsorption process. In the bioreactor with activated carbon, the outlet mercury concentration was approximately 50 % of that supplied with pumice. It may be concluded that the use of activated carbon in a fixed-bed bioreactor enables improvement of the technology by process integration. Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May 2007.     

Effect of Activated Carbon as a Support on Metal Dispersion and Activity of Ruthenium Catalyst for Ammonia Synthesis

IntroductionSince the beginning of the 2 0 th century,ammonia has been produced over the fused ironcatalyst known as Haber- Bosch process.Thecatalyst most widely used is Fe,promoted withK2 O and Al2 O3and other un- reducible oxides.Thefused iron catalyst has many advantages,such aslow unit price and long lifetime,worldwide about1 40 million tons of ammonia is manufactured peryear in the presence of Fe catalyst.But its lowactivity below40 0℃ makes it necessary to carryout the process at a …     

Application of Thermal Analysis to the Study of Some Waste Agricultural Products for the Preparation of Active Carbons

TG, DTG and DTA methods were used for the investigation of some waste agricultural products, such as grape seeds, walnut shells, plum and peach stones, which can serve as raw materials for the production of active carbons. It was demonstrated that thermo analytical methods are appropriate to study the thermal characteristics of the above wastes and the data obtained can be applied to the technological processes of active carbon preparation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of modified fly ash with hydrogen bromide on the adsorption efficiency of elemental mercury

Mercury is one of the most hazardous trace elements produced by coal-fired power plants. Mercury in the flue gas is predominately present as three different species: particulate mercury (Hg^p), oxidized mercury (Hg²⁺), and elemental mercury (Hg⁰). Of these three, elemental mercury is the most difficult to remove from flue gas streams due to its low reactivity and low solubility in water. With increasing production costs associated with activated carbon materials, and increasing restrictions on mercury emissions, the development of an alternative low cost absorbent to capture elemental mercury by using fly ash modified with bromide compounds is highly desirable. Modified fly ash is usually injected into the flue gas stream after the air pre-heater system of a coal-fired power plant to oxidize and subsequently absorb elemental mercury. Research on the quantity and method of modifying the bromide amended fly ash is needed to obtain the most efficient mercury capture rate. This study utilized the impregnation method to prepare three different fly ashes with hydrogen bromide (HBr). Adsorption capabilities of the modified fly ashes were then examined using a fixed bed reactor. Thermogravimetric (TG) analysis was employed to quantify the amount of hydrogen bromide in the modified fly ash, which was subsequently compared to the water extraction method using ion chromatography. TG-MS was also utilized to evaluate the release of HBr from the modified fly ash and elucidate the mechanism for mercury capture.     

The production of active carbon from corn cobs by chemical activation

Corn cobs obtained as waste from the corn industry, were analyzed by a TG-DTA unit in an atmosphere of flowing nitrogen. The carbonaceous products so formed were then produced on a preparative scale and activated chemically using potassium hydroxide. This resulted in the formation of a carbon with a very high surface area. The active carbon produced was then examined using thermal analysis in the temperature jump mode on a thermogravimetry unit. From this data the kinetics of degradation of the active carbon was determined using zero order rate kinetics. The pore structure of the active material was also examined using SEM. TheE _a for activated corn cobs was found to be 106 kJ mol_–1.     

Characteristics of activated carbon prepared from pistachio-nut shell by zinc chloride activation under nitrogen and vacuum conditions

Activated carbons with well-developed pore structures were prepared from pistachio-nut shells by chemical activation using zinc chloride under both nitrogen atmosphere and vacuum conditions. The effects of preparation parameters on the carbon pore structure were studied in order to optimize these parameters. It was found that under vacuum conditions, the characteristics of the activated carbons produced are better than those under nitrogen atmosphere. The impregnation ratio, the activation temperature, and the activation hold time are the important parameters that influence the characteristics of the activated carbons. The optimum experimental conditions for preparing predominantly microporous activated carbons with high pore surface area and micropore volume are an impregnation ratio of 0.75, an activation temperature of 400 degrees C, and a hold time of 1 h. Under these conditions, the BET surface areas of the carbons activated under nitrogen atmosphere and vacuum conditions were 1635.37 and 1647.16 m2/g, respectively. However, at a ZnCl2 impregnation ratio of 1.5, a furnace temperature of 500 degrees C, and a hold time of 2 h, the predominantly mesoporous activated carbon prepared under vacuum condition had a BET surface area of 2527 m2/g. Fourier transform infrared spectra were used to detect changes in the surface functional groups of the samples during the different preparation stages.     

Activated carbon pellets from eucalyptus char and tar TG studies

Char and tar derived from pyrolysis of Uruguayan Eucalyptus wood has been evaluated as raw materials for the preparation of high mechanical resistance activated carbon pellets. Thermogravimetric analysis was used as the main technique for studying tar and char pyrolysis in N2 and CO₂ atmospheres, and to determine the best conditions for CO₂ activation of the carbon pellets. Results indicated that activated carbon pellets with high surface area and good mechanical resistance were obtained by CO₂ gasification at 1098 K. Pellets properties can be explained as due to the independent contribution of each component.     

基于不同前驱体制备的硬碳负极材料的储锂性能

以聚丙烯腈、石油沥青和花生壳为前驱体,在1200℃下碳化制备三种不同的硬碳材料.通过扫描电子显微、X射线衍射、氮气吸附/脱附测试和拉曼光谱等方法探究不同前驱体所制备的硬碳材料的表面形貌和物相结构.通过恒流充放电测试考察了这三种硬碳负极材料的电化学性能.结果表明,花生壳基硬碳的初始放电比容量最高,但首圈库仑效率最低,石油...     

Analysis of the microporous structure of the low-cost activated carbon fibres obtained from flax and jute cloth

The paper presents the results of research devoted to obtaining the low-cost activated carbon fibres from waste flax and jute cloth by carbonisation in inert atmosphere and activation with air as well as to the analysis of the microporous structure of materials obtained on the basis of the nitrogen, argon and benzene adsorption isotherms, using among others, the unique LBET method with implemented of the new models of the multilayer adsorption on the heterogeneous surfaces of the carbonaceous adsorbents. As part of the research conducted, imaging of the surface of the low-cost activated carbon fibres obtained has also been done using scanning electron microscopy.     

Adsorption of Carbon Dioxide on Activated Carbon

The adsorption of CO2 on a raw activated carbon A and three modified activated carbon samples B, C, and D at temperatures ranging from 303 to 333 K and the thermodynamics of adsorption have been investigated using a vacuum adsorption apparatus in order to obtain more information about the effect of CO2 on removal of organic sulfur-containing compounds in industrial gases. The active ingredients impregnated in the carbon samples show significant influence on the adsorption for CO2 and its volumes adsorbed on modified carbon samples B, C, and D are all larger than that on the raw carbon sample A. On the other hand, the physical parameters such as surface area, pore volume, and micropore volume of carbon samples show no influence on the adsorbed amount of CO2. The Dubinin-Radushkevich (D-R) equation was the best model for fitting the adsorption data on carbon samples A and B, while the Preundlich equation was the best fit for the adsorption on carbon samples C and D. The isosteric heats of adsorption on carbon samples A, B, C, and D derived from the adsorption isotherms using the Clapeyron equation decreased slightly increasing surface loading. The heat of adsorption lay between 10.5 and 28.4 kJ/mol, with the carbon sample D having the highest value at all surface coverages that were studied. The observed entropy change associated with the adsorption for the carbon samples A, B, and C (above the surface coverage of 7 ml/g) was lower than the theoretical value for mobile adsorption. However, it was higher than the theoretical value for mobile adsorption but lower than the theoretical value for localized adsorption for carbon sample D.     

Preparation of Corn Stalk-Walnut Shell Mix-based Activated Carbon and Its Adsorption of Malachite Green

The mix-based activated carbon derived from corn stalk and walnut shell was prepared by chemical activation method using phosphoric acid as the activator. The optimized conditions for preparation were obtained by the orthogonal experiment, the characterizations of the activated carbon were performed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy(FTIR), Boehm's titration method and nitrogen adsorption. For the prepared mix-based activated carbon, the highest iodine number, methylene blue number and BET surface area are 720.5 mg/g, 195.0 mg/g and 1187 m²/g, respectively, and the pores are mainly mesopores. The mix-based activated carbon shows the higher adsorption capacity for malachite green than the raw materials, the activated carbons prepared only from corn stalk or walnut shell and the commercial activated carbon. The kinetics and thermodynamics of the adsorption can be satisfactorily described by the pseudo-second-order kinetic model and the Langmuir isotherm model, separately.     

Impregnated active carbons to control atmospheric emissions. 2. Influence of the raw material on the porous texture

The preparation of impregnated active carbons was optimized, in order to use them as catalysts for the deep oxidation of volatile organic compounds on atmospheric emissions. When impregnation is performed on the raw material or after activation, the influence of raw material on the texture and on the catalyst dispersion is already well studied. This paper aims to analyze the influence of raw material when the impregnation step is performed after the carbonization of different carbon precursors, as yet knowledge is very scarce. Olive stones, pinewood sawdust, nut shells, and almond shells were used as raw materials. In order to evaluate the influence of impregnation methodology of CoO, Co(3)O(4), and CrO(3) on the catalyst dispersion in the porous carbon texture, the impregnation step was made after activation and between carbonization and activation. On the first sequence, for all the raw materials, the impregnated oxides must be deposited on the internal surface, blocking part of the initial porous texture. When the impregnation step is conducted after carbonization, metal species act as catalysts during the activation step. The textures developed strongly depend either on the raw material or on the chemical state and distribution of the catalyst in the carbonized material. Olive stones and sawdust carbons stay with a microporous texture with very narrow pores where catalysts are not deposited. In nut shell and almond shell carbons, metal species are dispersed in the largest micropores and in a well-developed mesoporous texture.     

Target‐Specific Capture of Environmentally Relevant Gaseous Aldehydes and Carboxylic Acids with Functional Nanoparticles

Aldehyde and carboxylic acid volatile organic compounds (VOCs) present significant environmental concern due to their prevalence in the atmosphere. We developed biodegradable functional nanoparticles comprised of poly(d,l ‐lactic acid)‐poly(ethylene glycol)‐poly(ethyleneimine) (PDLLA‐PEG‐PEI) block co‐polymers that capture these VOCs by chemical reaction. Polymeric nanoparticles (NPs) preparation involved nanoprecipitation and surface functionalization with branched PEI. The PDLLA‐PEG‐PEI NPs were characterized by using TGA, IR, ¹H NMR, elemental analysis, and TEM. The materials feature 1°, 2°, and 3° amines on their surface, capable of capturing aldehydes and carboxylic acids from gaseous mixtures. Aldehydes were captured by a condensation reaction forming imines, whereas carboxylic acids were captured by acid/base reaction. These materials reacted selectively with target contaminants obviating off‐target binding when challenged by other VOCs with orthogonal reactivity. The NPs outperformed conventional activated carbon sorbents.