Studies on the structure of activated carbon fibers activated by phosphoric acid

By solid‐state ¹³C‐ and ³¹P‐NMR, XPS, and FTIR, the chemical structure of activated carbon fiber–P (ACF‐P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen‐containing groups were greatly reduced at high activation temperatures. Different from the ACF‐W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF‐P. The original ACF‐P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF‐P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF‐P activated at lower temperature possessed a large amount of oxygen‐containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of ³¹P‐NMR, P_2p‐XPS, and FTIR at 1620 cm^?1 shifted with the increase of activated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2253–2261, 2003     

Adsorption of VOC on modified activated carbon fiber

The surface chemistry of activated carbon fiber (ACF) was modified by CuSO₄. The static adsorption capacities of modified ACF for different volatile organic compounds (VOCs) were determined. The result indicates that ACF modified by CuSO₄ could get higher adsorption capacities for the vapors of benzene, toluene, methanol and ethanol than the untreated ACF. The increasing extent of the adsorption capacity of modified VACFs is different for various VOCs. The dynamic adsorption behavior of acetone vapor on modified ACF was also studied. The result confirms that the surface modification of ACF with CuSO₄ can enhance the affinity between ACF and acetone, which makes it possible to extract acetone of very low concentration from polluted air.     

活性碳纤维吸附水溶液中的二价铅离子

对活性碳纤维(ACF)吸附水溶液中的二价铅离子进行研究。分别运用静态和动态方法来考察ACF吸附Pb^2 的性能，测定了吸附等温线，探讨了吸附时间、DH值等因素对吸附的影响，并进行了ACF的再生实验。结果表明，ACF对水中二价铅离子的吸附特性良好，且吸附剂易于再生，可作为去除水中离子态重金属的优良吸附剂。     

活性炭纤维对钯的吸附性能研究

活性炭纤维是一种新型高效吸附材料,具有比表面积大,微孔发达,孔径分布窄,吸附速度快,吸附能力强等特点.通过活性炭纤维对钯溶液的吸附实验,探讨了静态条件以及动态条件下,溶液的初始浓度,系统的温度,活性炭纤维的质量,吸附时间,不同流速等条件对活性炭纤维吸附性能的影响.研究表明:活性炭纤维对钯有较强的吸附性能,最高吸附率可达...     

活性炭纤维对Cu2+的吸附性能研究

活性炭纤维(ACF)作为一种新型活性炭吸附材料已引起了化学家们的极大关注。孔结构分析表明:活性炭纤维的孔径分布窄,孔径比较均匀。本文以活性炭纤维作为去除水中重金属离子Cu2+的吸附剂,吸附实验表明,活性炭纤维对Cu2+的最大吸附量为148.50mg.g-1,吸附平衡时间短,当接触时间为50min时,即可达到吸附平衡,吸附过程符合Langmuir和Freundlich模型。动态吸附结果表明,活性炭纤维对Cu2+的吸附量随着流速的增加而降低。     

活性炭纤维吸附法脱除废水中对氯苯酚及吸附剂的再生

采用活性炭纤维 (ACF)处理对氯苯酚 (PCP)模拟废水 ,通过静态和动态吸附研究 ,测定了吸附等温平衡线、动态突破曲线 ,并研究了ACF对PCP的吸附速率。结果表明 ,ACF对PCP的吸附容量较大 ,吸附平衡关系服从Langmuir型吸附等温线 ;吸附速率快 ;吸附达饱和的ACF用NaOH溶液再生 ,解吸速率很快 ,再生后吸附容量基本不变     

Adsorption backup following light-emitting diode-irradiated photocatalytic unit for control of low-degraded toxic gaseous compounds

Although several visible light-emitting diode (LED)-irradiated photocatalysts exhibited low photocatalytic decomposition efficiencies for toxic gaseous pollutants, activated carbon fiber (ACF) has rarely been used as a backup adsorption device for photocatalytic systems. Accordingly, this study accessed the applicability of a supplemental ACF following a visible LED-irradiated S-TiO₂ unit for the control of low-degraded benzene and toluene. The characteristics of the S-TiO₂ and ACF were determined using an XRD, a UV-Vis-NIR, and an FTIR spectrophotometer. For an LED/S-TiO₂ system, low degradation efficiencies regarding benzene and toluene (close to zero-7.2% and 7.1–64.4%, respectively) were found. In contrast, the mean degradation efficiencies of both compounds obtained from the photocatalytic-ACF hybrid system were all close to 100%. In addition, no peaks were observed in the gas chromatogram of air samples taken at the outlet of the hybrid system, whereas several trace peaks were observed in the standalone photocatalytic reactor results. The breakthrough of the ACF occurred at approximately 14 and 28 hours for benzene and toluene, respectively, and saturation occurred at approximately 28 and 42 hours, respectively. Consequently, this study newly found that the supplemental activated carbon fiber following a visible LED-irradiated S-TiO₂ unit could be applied effectively for the control of low-degraded toxic benzene and toluene.     

Removal of formaldehyde at low concentration using various activated carbon fibers

Adsorption of low concentration formaldehyde on pitch‐based, rayon‐based, and PAN‐based activated carbon fibers (ACFs) and an unactivated PAN‐based carbon fiber (PAN‐CF) was investigated by a dynamic method. The pore structure and surface chemistry of these samples were characterized by liquid nitrogen adsorption, elemental analysis, and X‐ray photoelectron spectroscopy. Results revealed that the pore structure, especially surface chemical composition, greatly influence the formaldehyde adsorption. PAN‐based ACFs showed the highest formaldehyde adsorption capacity because there are more abundant nitrogen‐containing groups, especially pyrrolic, pyridonic, pyridinic, and quaternary on the surface. The breakthrough time and formaldehyde adsorption capacity of one kind of PAN‐ACF were 361 min and 0.478 mmol/g, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Removal of volatile organic compound by activated carbon fiber

Experiments were carried out to study adsorption/desorption of volatile organic compound (VOC) on the activated carbon fiber (ACF) under dynamic conditions. The primary objective was to experimentally demonstrate the suitability of ACF in effectively adsorbing VOCs from inert gaseous stream under varying operating conditions, and compare its performance vis-à-vis that of the other commercially available adsorbents, such as granular activated carbon (GAC), silica gel, and zeolites. The adsorption experiments were carried out in a fixed tubular packed bed reactor under various operating conditions including temperature (35-100 °C), gas concentration (2000-10,000 ppm), gas flow rate (0.2-1.0 slpm) and weight of the adsorbent (2-10 g). A mathematical model was developed to predict the VOC breakthrough characteristics on ACF. The model incorporated the effects of the gas-particle film mass transfer resistance, adsorbent pore diffusion and the adsorption/desorption rates within the pore. The experimental data and the corresponding model simulated results were compared and found to be in good agreement. The ACF repeatedly showed a good regeneration capability following desorption by DC electrical heating.     

聚丙烯腈基活性碳纤维吸附CO2的性能

以国产聚丙烯腈(PAN)基碳纤维为原料,采用KOH为活化剂制备PAN基活性碳纤维。测定了不同ACF样品的CO2吸附量,并通过氮气吸附、碘吸附以及红外光谱对所得活性碳纤维的比表面积、孔结构及表面官能团进行表征。研究了活化温度、活化时间和表面改性对活性碳纤维CO2吸附量的影响。结果表明,活化温度是影响活性碳纤维CO2吸附量的主要因素。当活化温度为850℃时,所得活性碳纤维BET比表面积为1235m2/g,微孔比表面积为745 m2/g,在吸附温度为273 K、吸附相对压力P/P0为1时,CO2的吸附量达到87.29 mL/g。     

Influence of Water Vapor on the Adsorption of VOCs on Lignin‐Based Activated Carbons

Abstract

Activated carbons with a wide range of burn‐off degrees obtained from Eucalyptus kraft lignin have been used to study the influence of the presence of water vapor on VOCs adsorption. The amount adsorbed and the rate of adsorption of both benzene and water vapor increase with activated carbon burn‐off as a consequence of an increase of micropore volume, broadening of micropore size distribution and increasing development of meso‐ and macroporosity. Similar results were found for MEK and methanol. Benzene is only partially desorbed at the adsorption temperature and an appreciable amount of it remains in the carbon, most likely in the narrow micropores. On the contrary, water vapor is completely desorbed at the adsorption temperature and its adsorption profile clearly exhibits two steps with different adsorption rates, associated to water molecules adsorbed on the active sites given rise to cluster formation and further migration and filling of the micropores. Adsorption with mixtures of VOC and water vapor has been carried out. The total amount adsorbed by the carbon, near the equilibrium point, is higher than in the case of the stream containing only the VOC. The adsorption rates for the mixtures streams are similar to that for the corresponding streams containing only the VOC in the case of carbons with a well developed porous structure. However, the presence of water vapor increases the rate of adsorption on the activated carbons with narrower microporosity. Saturation of the activated carbon with water vapor prior to the adsorption of a mixture containing benzene and water vapor has shown little effect on the amount of benzene adsorbed, suggesting that water and benzene molecules are adsorbed in different sites on the carbon surface.     

沥青基球状活性炭吸附性能的初步研究

通过对非极性有机物（苯）及极质有机构（氯仿）的动态吸附及对溶液中碘的吸附，初步研究了沥青基球状活性炭（ＰＳＡＣ）的吸附性能：作为对比研究了沥青基活性炭纤维（ＰＡＣＦ）和普通粒状活性炭（ＡＣ）与ＦＳＡＣ的吸附性能；结果表明，ＰＳＡＣ无论在气相还是液相吸附方面，其吸附性与ＰＡＣＦ相近，而明显优于ＡＣ。另外，亦从微观孔结构的角度初步探讨了造成它们吸附性能差异的原因。     

Surface Porosity of Lignin/PP Blend Carbon Fibers

Abstract

The surface porosities of carbon fibers derived from the polymer blend fibers of hardwood kraft lignin, HKL and polypropylene, PP, were discussed using thermal analyses, FTIR, and nitrogen adsorption. HKL/PP carbon fibers were prepared by two‐step thermal processing, thermostabilization, and carbonization. During the thermostabilization process, pores are created by oxidative degradation of the PP component. After thermostabilization some crystalline and highly oxidized PP components remained in the blend fiber. These residual PP components were subsequently pyrolyzed during carbonization, and effectively created a porous structure in the resulting carbon fibers. N₂ adsorption tests of the porous carbon fibers revealed the same type of adsorption/desorption isotherms as for activated carbon fiber. The internal surface area of the HKL/PP = 62.5/37.5 carbon fibers was calculated to be 499 m² g^?1. This value was lower than that for commercial activated carbon, 745 m² g^?1. However, these porous lignin‐based carbon fibers were not activated carbon fibers, which could be relatively easily done through steam activation. Thus, the HKL/PP blend carbon fibers appear to be promising precursors for activated carbon fibers.     

活性碳纤维对水中喹啉的吸附性能

采用活性碳纤维（activated carbon fiber,ACF）静态吸附模拟废水中的喹啉,考察了吸附时间、喹啉初始浓度、温度、pH值、有机物等对吸附速率与吸附行为的影响。结果表明,ACF对喹啉的吸附速率快,30 min内基本达到平衡,初始浓度较高时,最终吸附容量较大,达210 mg/g,低温和pH值小于7时,吸附效果较好,苯酚与喹啉产生竞争吸附,配水中的吸附行为能较好的符合Langmuir等温方程,吸附动力学符合准二级动力学模型,热力学参数ΔH0、ΔG0为负值,表明该吸附是一个自发的放热过程。本研究为环境功能材料ACF应用于工业化生产提供了理论依据,有必要在此基础上进行动态吸附实验以及实际焦化废水的吸附处理实验,同时ACF成本高及脱附再生等方面问题还有待进一步深入研究。     

Adsorption of trace polar methy-ethyl-ketone and non-polar benzene vapors on viscose rayon-based activated carbon fibers

The adsorption of polar methy-ethyl-ketone (MEK) and non-polar benzene vapors on viscose rayon-based activated carbon fiber (ACF) was investigated. The pore texture and surface composition of ACF were characterized by nitrogen adsorption at 77 K and X-ray photoelectron spectroscopy (XPS), respectively. Gas adsorption on the samples was measured by the gravimetric method and the Dubinin-Radushkevich (DR) equation was used to fit the experimental adsorption isotherms. The experimental results show that ACF with different pore texture and surface composition exhibited different adsorption and desorption behavior for polar and non-polar vapors. The effect of adsorbate polarity on the adsorption capacity at lower concentrations was more significant in the case of adsorbents with a smaller surface area. It was found that evacuation treatment greatly increased the adsorption rate.     

Accelerated Adsorption with Activated Carbon Fiber

Abstract

The properties of a new type of polyamphoteric activated carbon fiber (ACF) were investigated theoretically and experimentally. Results are compared with those from granular activated carbon (GAC) and ion-exchange resin (IER) materials. The adsorption rate of ACF was found to be two orders of magnitude higher than that of the GAC and one order of magnitude higher than that of the IER.     

Reductions in cod and acute toxicity of wastewater generated from refined cotton production using activated carbon fibre (ACF)

Activated carbon fibre is investigated for adsorption of organic pollutants from wastewater generated from refined cotton production. UV–Vis spectroscopy and FTIR are used to evaluate the chemical changes. Results indicate that the main organic components of refined cotton production wastewater are guaiacyl (G‐) and hydroxyphenyl (H‐) lignin. It is found that 85% of COD can be removed at 40°C with ACF dosage of 90 g L^?1. The adsorption process is described by the Redlich–Peterson isotherm model. The kinetic data follows a pseudo‐second‐order equation. Over 99% of acute toxicity for Refined Cotton Production (RCP) wastewater has been reduced after adsorption using ACF. © 2012 Canadian Society for Chemical Engineering     

活性炭处理活性艳红X-3B染料废水的静态研究

采用活性炭纤维(ACF)、粒状活性炭(GAC)、椰壳活性炭(椰壳AC)分别处理活性艳红X-3B模拟染料废水。实验结果表明,在相同的活性炭用量下,吸附率顺序为:椰壳AC>ACF>GAC;温度10~50℃,吸附效率随温度升高而增大;溶液在弱酸性条件下,3种炭材料均有较好的吸附效果;随着染料溶液浓度的提高,脱色率是下降的;加热和微波均可使GAC和椰壳AC再生,而且再生后的吸附性能均基本可恢复到原来的100%,ACF经微波再生后,吸附量达原来的2.4倍。     

活性炭纤维表面结构及其吸附银机理研究

用Ｘ射线光电子能谱（ＸＰＳ）等分析方法对剑麻基碳化纤维、磷酸化学活化纤维及其热处理纤维吸附Ａｇ＋前后的表面结构进行了研究,结果表明：活性炭纤维的氧化还原吸附性能不与其比表面积成正比,而受表面官能团影响很大,且还原吸附的纳米银与纤维的界面间除相互的物理作用外,还有Ａｇ－Ｏ－Ｃ配位键合存在;纤维还原能力强,但负载的纳米银与载体纤维之间的相互作用力并不一定大,而活化作用使纤维表面的Ｏ物种利于Ａｇ的成核和成键,促进Ａｇ－Ｏ－Ｃ的形成,使负载上的纳米银较稳定。     

活性炭纤维吸附邻硝基苯胺水溶液的研究

采用活性炭纤维(ACF)处理邻硝基苯胺模拟废水,通过静态和动态吸附实验,研究了pH、盐含量、吸附时间对吸附效果的影响,测定了吸附等温线和动态穿透曲线,并进行了ACF再生实验。结果表明,在实验条件下,ACF对邻硝基苯胺的吸附速率很快,5 min去除率达96%,在pH4.4~10.4条件下吸附效果较好,盐的含量对吸附效果影响较小,吸附等温线能用Langmuir和Freundlich方程较好地拟合。溶液流速增大,穿透时间提前,吸附饱和的ACF用无水乙醇再生,重复5次,邻硝基苯胺的回收率均在95%以上,ACF的吸附效率无明显变化。