Pore structure and adsorption properties of carbonized material prepared from waste paper

We have already reported the adsorptivity and pore structure of activated carbon made from waste newspaper in order to use the waste paper for purposes other than paper-making stock. However, manufacturing the activated carbon may not necessarily be an advantageous method based on environmental concerns and the effective use of the resource because the reaction during the activating process is endothermic and the amount of carbon consumed is significant. Here, we examine the pore structure and adsorption properties of waste newspaper used as an adsorbent in the form of a carbonized material. Waste newspaper was carbonized for 2 h in the temperature range 400°–1000°C. The specific surface area of the carbonized material obtained, 418 m²/g, was highest for the sample carbonized at 800°C, which was equal to or greater than that of commercially available charcoal. Moreover, the iodine adsorption number of 581 mg/g was the highest and the rate of adsorption was the fastest for the sample carbonized at 800°C. However, the humidity control capability was highest for the material carbonized at 600°–700°C. It has been determined that it is advantageous to carbonize waste paper at 800°C in order to use the carbonized material as an adsorbent, while carbonization at 600°–700°C is more advantageous for use as a humidity control material. Received: June 23, 2000 / Accepted: January 17, 2001     

Porous structure of activated carbon prepared from waste newspaper

In an earlier report, we presented a method for preparing activated carbon from waste newspaper as a way to recycle used paper for a purpose other than producing raw material for paper-making. In this article, we consider the porous structure of the activated carbon that affects its adsorption properties for various substances. The specific surface area of activated carbon prepared from waste newspaper was 838 m²/g, the micropore volume was 0.368 ml/g, and the mesopore volume was 0.138 ml/g, which is about the same as commercially available activated carbon. The activated carbon prepared from waste newspaper usually has a high content of ash, which makes little contribution to the adsorption properties. In particular, as compared with reagent-activated carbon, the quantities of mesopores with a pore radius of 3–25 nm and macropores with a pore radius of 25–250 nm were 8 and 14 times larger, respectively. Activated carbon prepared from waste newspaper has a well-developed porous structure, particularly in the mesopore and macropore ranges. Received: July 12, 1999 / Accepted: March 8, 2000     

Improved enzymatic hydrolysis of waste paper by ozone pretreatment

Waste paper samples made from newsprint, copier paper, and magazine paper, as well as samples of kraft pulp and thermomechanical pulp, were pretreated with ozone to improve enzymatic hydrolysis. The ozone treatment of pulps of newsprint and of magazine paper increased the specific surface areas and total pore volumes while decreasing the lignin content so that these values became similar to those of thermomechanical pulps. These morphological and chemical changes in the pulps resulted in the increased access of cellulase to the pulp fiber surface and increased enzymatic hydrolysis. For copier paper, in which the lignin content was very low, additives on the pulp fiber surface were oxidized and removed by ozone treatment and extraction, and this allowed improved enzymatic hydrolysis. In contrast, surface areas and total pore volumes of kraft pulp and bleached kraft pulp were decreased by the ozone treatment, resulting in morphological changes in the pulps that decreased enzymatic hydrolysis.     

西瓜皮基碳气凝胶的制备及其吸附性能

以西瓜皮为碳源,通过水热处理结合冷冻干燥法制备了碳气凝胶。采用FTIR、拉曼光谱、XPS和SEM等技术对碳气凝胶的表面基团、形貌和结构进行了表征。考察了碳气凝胶对罗丹明B和孔雀石绿模拟染料废水的吸附性能。表征结果显示,碳气凝胶呈现典型的三维无序网状多孔结构,其表面存在大量的羟基、羰基、羧基等官能团。实验结果表明,在罗丹明B或孔雀石绿初始质量浓度为10 mg/L、碳气凝胶加入量为0.5 g/L、吸附温度为常温、初始废水p H为染料废水自然酸碱度、吸附时间为1 h的条件下,碳气凝胶对孔雀石绿的去除率为92.7%,对罗丹明B的去除率为67.2%;循环使用4次到6次,罗丹明B和孔雀石绿的去除率略有降低。     

Effect of ZnCl<Subscript>2</Subscript> impregnation ratio on pore structure of activated carbons prepared from cattle manure compost: application of N<Subscript>2</Subscript> adsorption-desorption isotherms

Activated carbons were prepared from cattle manure compost (CMC) by ZnCl₂ activation with various ZnCl₂/CMC mass ratios. Based on the N₂ adsorption-desorption isotherms, mathematical models including the Dubinin-Radushkevich (DR) equation, the α_s plot, and the Horvath-Kawazoe method were used to analyze the pore structural characteristics of the prepared activated carbons. It was found that for carbons possessing both micro-and mesopores, the DR method provided a more accurate estimation than the α_s method for the extent of microporosity. The effect of the ZnCl₂ impregnation ratio on the pore structure was discussed using the DR method. The results revealed that pore evolution involved three distinct regions with increases in the amount of impregnated ZnCl₂: raising the ZnCl₂/CMC mass ratio from 0.00 to 0.50 resulted in a 19-fold increase in micropore volume (V_me ^D) but caused no change in the mesopore volume (V_me ^D); increasing the ZnCl₂/CMC mass ratio from 0.50 to 1.00 led to an increment in V_mi ^D of about 50% and in V_me ^D of 170%; while raising the ratio from 1.50 to 2.50 caused a slight decrease in V_mi ^D but a 200% increment in the value of V_me ^D.     

Catalytic degradation of PP with an Fe/activated carbon catalyst

We investigated the function of Fe and activated carbon (AC) as a catalyst by comparing Fe/AC with Fe/SiO₂ or AC, and also the effect of H₂ as a reaction gas on the product distribution in the catalytic degradation of polypropylene. Supported Fe promotes H₂ consumption to decompose solid residues, and AC support degrades heavy oil to produce light oil. As a result, using Fe/AC as a catalyst gives the maximum yield of the liquid product. For the reaction conditions, with a high reaction temperature or a long reaction time, the product distribution is more influenced by the thermal degradation than by the catalytic degradation. For the amount of Fe to load, 5wt% is the optimum condition in our reaction system. We demonstrated the mechanism of the degradation of polyolefins with hydrogen-capping catalysts.     

活性炭吸附黏胶纤维生产废气中的CS2

分别采用静态吸附和柱穿透吸附研究了活性炭对黏胶纤维生产废气中CS₂的吸附性能,考察了温度、水蒸气含量和预吸附H₂S时间对活性炭吸附CS₂效果的影响。实验结果表明：活性炭静态吸附CS₂的吸附等温线可用D-R方程很好地拟合,吸附温度升高,活性炭对CS₂的吸附量降低;Y-N方程能很好地拟合CS₂在活性炭上的柱吸附穿透过程,吸附温度升高,CS₂在活性炭上的吸附穿透时间缩短;进气水蒸气含量增大,吸附穿透时间缩短;预吸附H₂S时间延长,活性炭对CS₂的吸附穿透时间缩短;脱附温度升高,CS₂脱附率和脱附速率均加快。     

ACF床动态吸附及脱附性能试验研究

利用活性炭纤维(ACF)床在热态下进行动态吸附及脱附性能试验,研究了W/Q、水蒸汽含量对ACF吸附性能的影响,并利用ACF的选择性吸附性能,采用分段吸附,以达到同时高效吸附SO2和NOx.对ACF床进行了水洗脱附与负吸热空气法脱附试验.     

轻烃类VOCs在活性炭上的动态吸附行为

采用BET,XRD,FTIR技术对两类椰壳活性炭进行了表征,考察了空速和吸附温度对正戊烷和正己烷动态吸附穿透容量(DPC)及穿透时间的影响,并对正戊烷和正己烷的二元竞争吸附过程进行了研究。结果表明:两类活性炭材料的组成和官能团结构相似,具有大量微孔的片状活性炭(FAC)有利于轻烃类VOCs的吸附;采用FAC吸附正己烷时,DPC对空速和温度变化不敏感;二元竞争吸附过程中,开始阶段正戊烷和正己烷同时被吸附,随后已被吸附的正戊烷被强吸附质正己烷部分置换,直至正己烷吸附饱和,与一元吸附相比,正己烷的DPC和饱和吸附容量略有增加,正戊烷的DPC和饱和吸附容量大幅降低。     

Evaluation of the adsorption behavior of mixed perfluoroalkyl and polyfluoroalkyl substances onto granular activated carbon and styrene-divinylbenzene resins

Because of the remarkable chemical structure of perfluoroalkyl and polyfluoroalkyl substances (PFAS), as well as the complex conditions of water, selecting an appropriate adsorbent for treating PFAS is critical. Adsorption needs to be environmentally friendly, low cost, and consider the types of adsorbents that work well in mixed PFAS solutions. In the present study, we used mixed PFAS to estimate the PFAS activity. This research aimed to evaluate and compare the efficacy of the adsorption of PFAS from water using different adsorbents: granular activated carbon (GAC), IRA 910 (strong anion resin), and DOWEX MB-50 (mixed exchange resin). Batch adsorption isotherms and kinetic studies were performed for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS). Freundlich models consistently described the kinetic behavior with a high correlation coefficient (R² > 0.98). PFAS adsorption capacities on GAC and IRA910 were dependent on the chain length (PFOS > PFOA > PFHxS). The adsorption capacity of DOWEX MB-50 decreased because of the sulfonate effects (PFOS > PFHxS > PFOA). The rate constants (k₂) that represented the adsorption of PFAS on different adsorbents observed within 96 h were accurately determined by the pseudo-second-order (PSO) model. GAC achieved followed the relationship k₂(PFOS) > k₂(PFOA) > k₂(PFHxS). Furthermore, k₂ of IRA910 decreased in the order of k₂(PFOA) > k₂(PFOS) > k₂(PFHxS), implying that IRA910 promoted hydrophobicity more significantly on the adsorption of PFCAs than perfluoroalkane (-alkyl) sulfonic acids. The kinetics of DOWEX MB-50 revealed k₂(PFHxS) > k₂(PFOS) > k₂(PFOA) because gel-type resins like DOWEX MB-50 are more suitable for shorter-chain PFAS. Further investigation is needed to determine the effect of organic matter under natural conditions and evaluate adsorptive selection caused by operational complexities.     

活性炭吸附缓冲非稳态VOCs研究进展

活性炭类吸附剂可以有效地缓冲挥发性有机物(VOCs)的浓度负荷波动。综述了活性炭对非稳态VOCs吸附缓冲的作用原理及类型,从吸附剂、吸附质、进气性质和设备及操作条件等方面讨论了影响吸附缓冲性能的因素,并对今后该领域的研究方向提出了展望。指出:应当进一步研究吸附剂和吸附质的交互作用、波动负荷的影响以及VOCs在活性炭中的迁移扩散现象;同时,通过深层次的实验测试和模型模拟为反应器的设计和操作参数的估算提供指导。     

Utilization of turkey manure as granular activated carbon: physical, chemical and adsorptive properties

The high availability of large quantities of turkey manure generated from turkey production makes it an attractive feedstock for carbon production. Pelletized samples of turkey litter and cake were converted to granular activated carbons (GACs) by steam activation. Water flow rate and activation time were changed to produce a range of activation conditions. The GACs were characterized for select physical (yield, surface area, bulk density, attrition), chemical (pH, surface charge) and adsorptive properties (copper ion uptake). Carbon physical and adsorptive properties were dependent on activation time and quantity of steam used as activant. Yields varied from 23% to 37%, surface area varied from 248 to 472 m(2)/g and copper ion adsorption varied from 0.72 to 1.86 mmol Cu(2+)/g carbon. Copper ion adsorption greatly exceeded the values for two commercial GACs. GACs from turkey litter and cake show considerable potential to remove metal ions from water.     

城市污泥制备水中重金属吸附剂及其吸附特性研究

本实验利用城市污水厂的脱水污泥,通过化学活化法制备活性炭.研究活化温度、活化时间、固液比和活化剂浓度等因素对制备污泥活性炭的影响,确定氯化锌法制备污泥活性炭的最佳工艺为活化温度550 ℃、活化时间30 min、固液比1∶2、氯化剂浓度45％.将制备的污泥活性炭吸附Cu2＋,Cr6＋,Cd2＋3种重金属离子模拟废水,研究pH值、吸附时间、污泥投加量、温度等因素对吸附过程的影响.实验结果表明,剩余污泥对Cu2＋,Cr6＋,Cd2＋3种重金属离子都具有良好的吸附效果,在优化条件下,3种重金属离子去除率分别达到94％,76％,81％,吸附能力大小顺序为Cu2＋＞Cd2＋＞＋Cr6＋.     

Direct and indirect generation of waste in the Spanish paper industry

The paper industry has a relatively high degree of reliance on suppliers when compared to other industries. Exploring the role of the paper industry in terms of consumption of intermediate inputs from other industries may help to understand how the production of paper does not only generate waste by itself but also affects the amount of waste generated by other industries. The product Life Cycle Assessment (LCA) is a useful analytical tool to examine and assess environmental impacts over the entire life cycle of a product “from cradle to grave” but it is costly and time intensive. In contrast, Economic Input Output Life Cycle Assessment Models (IO-LCA) that combine LCA with Input–Output analysis (IO) are more accurate and less expensive, as they employ publicly available data. This paper represents one of the first Spanish studies aimed at estimating the waste generated in the production of paper by applying IO-LCA. One of the major benefits is the derivation of the contribution of direct and indirect suppliers to the paper industry. The results obtained show that there was no direct relationship between the impact on output and the impact on waste generation exerted by the paper industry. The major contributors to waste generation were the mining industry and the forestry industry.     

Production and characterization of KOH-activated carbon derived from polychlorinated biphenyl residue generated by the sodium dispersion process

Polychlorinated biphenyl (PCB) residues from the sodium dispersion (SD) process were employed as the raw materials for the production of activated carbon using KOH activation. The pore properties, such as the specific surface area and pore size distribution, were characterized using the Barrett–Joyner–Halenda method and the Horvath–Kawazoe method based on the N₂ adsorption isotherm at 77 K. The activated carbon produced showed similar adsorption capacities and specific surface areas to the commercially available product. The effects of the activation conditions on the porosity of the activated carbon produced were studied. The most significant factor affecting the specific surface proved to be the activation temperature. The activated carbon produced from PCB residues from the high-temperature (423–443 K) SD process had a binary pore size distribution well developed in the 4 nm region and in the micropore region. The pore structure of the carbon produced from PCB residues from the low-temperature (333–393 K) SD process had a wide range of micropores and mesopores.     

Agricultural solid waste for the removal of organics: adsorption of phenol from water and wastewater by palm seed coat activated carbon

Adsorption studies for phenol removal from aqueous solution on activated palm seed coat carbon (PSCC) were carried out under varying experimental conditions of contact time, phenol concentration, adsorbent dose and pH. Adsorption equilibrium was reached within 3 h for phenolic concentrations 10-60 mg l(-1). Kinetics of adsorption obeyed a first order rate equation. The percent removal remained constant over the pH range 4-9 for a phenolic concentration of 25 mg (l-1). The equilibrium data could be described well by the Freundlich isotherm equation. The adsorption of phenol on PSCC follows the film diffusion process. A comparative study with a commercial activated carbon showed that PSCC is two times more effective than commercial activated carbon. The studies showed that the palm seed coat carbon can be used as an efficient adsorbent material for the removal of phenolics from water and wastewater.     

微波法稻壳制备活性炭研究

稻壳是稻米加工后产生的大宗农业废弃物,高效、高附加值利用稻壳,对促进循环经济发展具有重要意义。以稻壳为原料,氯化锌为活化剂,采用微波处理,制备出微细孔发达的商业级活性炭。微波法生物质制活性炭,加热时间短,能耗低,是具有商业前景的绿色化学工艺。     

饱和吸附2,4-二硝基甲苯后活性炭的电化学再生

以2,4-二硝基甲苯为吸附物,对吸附饱和的活性炭进行电化学再生,考察了再生时间、电流密度、体系pH、电解质NaCl质量浓度等对再生效果的影响。最佳的电化学再生工艺条件为电解质NaCl质量浓度15.0 g/L,电流密度20 mA/cm~2,体系pH为 5,再生时间2 h,在此条件下活性炭再生率可达102.57%。再生前后活性炭的微孔结构基本不变,微孔孔径分布于0.3～1.0 nm。再生后活性炭的比表面积增大,石墨化程度提高,表面含氧基团含量增加,总氧含量增加,碳含量有所下降。     

Preparation and performance of arsenate (V) adsorbents derived from concrete wastes

Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10–700 mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105 °C, the maximum removal capacity being 175 mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca₃(AsO₄)₂. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries.     

催化臭氧氧化—生物活性炭吸附组合工艺处理反渗透浓水

采用催化臭氧氧化—生物活性炭吸附组合工艺处理反渗透(RO)浓水,比较了4种催化剂催化臭氧氧化的性能,优化了初始RO浓水pH、臭氧氧化时间、生物活性炭柱空床停留时间(EBRT)等工艺条件。实验结果表明:以WP-01为催化剂催化臭氧氧化RO浓水时无需调节废水pH;臭氧氧化反应5 min时RO浓水的BOD5/COD达0.28,可生化性得到显著改善;WP-01催化剂重复使用30次其催化活性没有明显下降;生物活性炭吸附单元的EBRT控制在30 min左右,可确保出水COD稳定在50 mg/L以下,符合GB 18918—2002《城镇污水处理厂污染物排放标准》的一级A标准;催化臭氧单元处理每吨RO浓水的电费约为1.22元。