含氮有机物对活性碳纤维还原吸附银的影响广州市科技计划基金

用H3PO4、ZnCl2等活化剂分别制备了两种化学活化的活性碳纤维(HPSACF和ZCSACF),并通过水蒸汽活化制备了水蒸气活化活性碳纤维(SACF).研究了它们对水溶液中Ag(NH3)2+的还原吸附性能,并与活性碳(AC)的还原吸附性能进行了比较.不同方法制备的活性碳纤维(ACF)对Ag(NH3)2+的还原吸附能力有显著的差异,以磷酸活化法制备的ACF的还原能力最强,而AC也有一定的还原吸附能力.含氮有机物的吸附对活性碳纤维或活性碳的还原吸附能力有很大的影响,一般而言,吸附至碳吸附剂上的对硝基苯酚和苯胺可促进AC、SACF和HPSACF的还原能力,且苯胺的促进作用大于硝基苯酚的促进作用.     

高含量银对活灰从硫脲溶液中吸附金的影响

研究表明高含量银离子的存在将大大降低活性炭从硫脲体系中吸附金的吸附速率和吸附容量。这主要是由于大量银离子阻碍了金在溶液中的扩散以及金在活性炭上吸附过程扣进行，同时少量银离子以大分子络合物的形成实战会并占据了较魇活笥炭表面所造成的。     

冶炼强度对高炉还原和热交换条件影响的分析

冶炼强度对高炉还原和热交换条件影响的分析阿．列．别林等在现有条件下，前苏联各钢铁厂高炉的冶炼强度基本上是不相同的，就是在容积相同的高炉上，这种差别也达３０％以上。目前尚无有效的方法对冶炼强度作有科学根据的选择。按以往的概念，鼓风可以加速高炉冶炼，也会...     

不同炭化材料和碳纤维对水中重金属Cu~(2+)的吸附研究

以花生壳、柑橘皮的不同炭化材料和碳纤维作为水中污染物的吸附剂,对重金属Cu2+进行了吸附研究。吸附试验结果表明:当改变水中p H时对吸附效果影响比较大,p H 5.5时吸附剂对水中Cu2+的吸附量最大;吸附时间在90 min后达到了吸附平衡状态;花生壳、柑橘皮吸附效果最好的加工炭化温度为250℃。     

羧甲基壳聚糖银的制备及对大鼠牙槽骨吸收的影响

经碱化、氯乙酸修饰和离子交换制备了羧甲基壳聚糖银(CMCT-Ag+),根据吸附前后溶液中金属离子浓度的变化计算吸附量,通过改变反应时间、取代度、温度和pH值测定了羧甲基壳聚糖(CMCT)对Ag+的吸附影响;另外,通过大鼠牙槽骨吸收模型分别检测了不同浓度的CMCT+-Ag+对大鼠牙槽骨吸收(ABL)的影响.结果表明:CMCT-Ag+收率为92.4%,取代度为0.98,Ag+含量为10.21%.CMCT-Ag+为粉红色粉末,不溶于水和乙醇,但溶于稀酸.络合反应时间对Ag+吸附量影响不大;而升温有利于吸附;Ag+吸附量随-COOH取代度的增加而增大;当溶液pH值达到5～7时,CMCT与Ag+络合程度趋于最大.表明环境因素影响CMCT-Ag+的络合,而控制实验条件可促进Ag+的络合.牙槽骨吸收实验结果证明,大于100.0 mg/kg的CMCT-Ag+具有较好的修复大鼠牙槽骨吸收的作用,这为进一步的临床应用奠定了实验基础.     

高含量银对活性炭从硫脲溶液中吸附金的影响

研究表明高含量银离子的存在将大大降低活性炭从硫脲体系中吸附金的吸附速率和吸附容量。这主要是由于大量银离子阻碍了金在溶液中的扩散以及金在活性炭上吸附过程的进行 ,同时少量银离子以大分子络合物的形式被吸附并占据了较大的活性炭表面所造成的。     

Adsorption of Perfluorinated Compounds onto Activated Carbon and Activated Sludge

The adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was investigated in the presence and absence of effluent organic matter (EfOM) at an environmentally relevant concentration range (0.1–500??μg/L). Adsorption of PFOS and PFOA to PAC fitted the Freundlich model well (r2>0.98), and adsorption capacity of PFOS (KF = 17.48) and PFOA (KF = 10.03) in the absence of EfOM was more than one order of magnitude higher than that in the presence of EfOM (KF = 0.66 for PFOS, KF = 0.20 for PFOA), indicating that EfOM greatly reduces the adsorption capacity of PAC. Moreover, EfOM was characterized by ultrafiltration, and fractions of nominal molecular weights were obtained to investigate their effect on the PFOS and PFOA adsorption. The fraction of <1??kDa had greater effect on adsorption than the fraction of >30??kDa, indicating that the similar molecular size of target compounds was the major contributor to adsorption competition. Additionally, biosorption of PFOS and PFOA to activated sludge fitted the linear isotherm (r2>0.9) within a concentration range of 50–400??μg/L. On the basis of our data, the estimated partition coefficient, Kd, was 729??L/kg for PFOS and 154??L/kg for PFOA, respectively, suggesting that PFOS and especially PFOA have a low tendency to partition onto sludge.     

银硫代硫酸盐在活性炭上的吸附机理

研究了银硫代硫酸盐在活性炭上的吸附行为。考察了硫代硫酸钠和亚硫酸钠浓度、温度和溶液pH对活性炭吸附银硫代硫酸盐的影响,采用了多种动力学模型拟合吸附过程,并通过XPS和FT-IR检测手段对其机理进行表征。结果表明：银硫代硫酸盐在活性炭上的吸附动力学符合准二级动力学模型,活性炭对银硫代硫酸盐的吸附等温线符合Freundlich模型。银在活性炭的吸附容量随着温度的升高而略有下降。在温度25℃、初始pH=8、初始银浓度500 mg/L、n(Na₂S₂O₃)/n(AgNO₃)=8(摩尔比)、n(Na₂S₂O₃)/n(Na₂SO₃)=5(摩尔比)、吸附时间5 h的最佳条件下,活性炭对银硫代硫酸盐络合物的饱和吸附容量最高可达18 mg/g。     

Modeling of Adsorption and Regeneration of Volatile Organic Compounds on Activated Carbon Fiber Cloth

A mathematical model is developed to predict continuous adsorption-regeneration cycling of volatile organic compounds (VOCs) on activated carbon fiber cloth (ACFC) at the indoor VOC concentration levels. The adsorption-regeneration model incorporates both the adsorption equilibrium and mass transfer fundamentals. It assumes local equilibrium between the gas-phase and the solid-phase, and axially dispersed-flow, film transfer, and intraparticle transport by surface and pore diffusion. Successful agreement between model simulations and experimental data was obtained and the kinetic properties of the adsorption/regeneration cycling on the ACFC were characterized. For the adsorption process, the film transfer is the dominant factor for mass transfer at low flow rates (45–184 L/min), and the intraparticle mass transfer rate controls over the gas-phase rate as the flow rates increase. The regeneration concentration profiles are most sensitive to the adsorption isotherms at the temperatures of interest, especially as desorption is initiated. The surface diffusivity also contributes to the shape of the regeneration profile: the tailing of desorption profile shifts up with the increase of surface diffusivity.     

Control of PAHs from Incineration by Activated Carbon Fibers

The aim of this research was to use activated carbon fibers (ACFs) to adsorb 16 polycyclic aromatic hydrocarbon (PAH) species from flue gas emissions during incineration. The operation conditions included the presence of three activated carbon fibers, the adsorption temperature (200, 300, and 340°C), and the weight of the ACFs. The removal efficiencies of the gaseous and solid-state PAHs were evaluated respectively. It was found that the BET surface area did not affect PAH removal when the BET surface area was enough for PAH removal and micropore volume was the determinant parameter for PAHs removal. The best adsorption temperature in this study was 300°C. The removal efficiency of PAHs was proportional to the weight of ACFs.     

活性碳纤维的制备及其吸附性

耐熔性沥清基纤维经过碳化处理后,在一定温度下的CO₂气流中进行活化处理,得到的活性碳纤维具有良好的吸附性和再生性。     

Modeling Volatile Organic Compound Sorption in Activated Carbon. II: Multicomponent Equilibrium

A new approach is presented for modeling multicomponent volatile organic compound (VOC) sorption equilibrium in ultra- and supernanoporous activated carbons. The model uses “Dubinin–Astakhov thermal equation of equilibrium adsorption” (DA-TEEA) for single-component adsorption thermodynamics and “ideal/real adsorbed solution theories” (IAST/RAST) for the multicomponent mixing rules. Use of the Henry’s Law adsorption isotherm resolves the singularity of DA-TEEA at zero-coverage conditions. The introduced method predicts multicomponent adsorption equilibria of VOCs based on equilibrium data of only one similar component. Single and binary adsorption equilibria of acetone and benzene vapors in Kynol ACFC-5092-20 activated-carbon-fiber-cloth adsorbents are predicted with the presented models and compared with modeled and measured characterization data available in the literature. The Wilson model for nonideal binary solution mixtures is used to predict the activity coefficients needed in DA-TEEA/RAST. Modeled results are compared against measured characterization data. The selected Henry’s Law upper-bound pressure (HUBP) is found to be an important factor controlling the accuracy of the multicomponent equilibrium models. An optimum HUBP can generate highly accurate results from both DA-TEEA/IAST and DA-TEEA/RAST. The accuracy realized by applying this method to acetone–benzene mixtures is sufficient for engineering design and development purposes.     

Organic Vapor Recovery and Energy Efficiency during Electric Regeneration of an Activated Carbon Fiber Cloth Adsorber

An electrothermal-swing adsorption system was demonstrated on the bench scale for capture and recovery of organic vapors from air streams. Methyl propyl ketone (MPK), methyl ethyl ketone, n-hexane, acetone, and methylene chloride were removed and recovered at 200–1,020?ppmv in a 40.0 slpm air stream while using activated carbon fiber cloth (ACFC) adsorbent. Removal efficiencies were greater than 99.9%. Liquid recovery fractions increased with increasing relative pressure, ranging from 0.11 for methylene chloride (P/Psat = 2.1×10?3) to greater than 0.80 for MPK (P/Psat = 2.2×10?2). The electrical energy consumed during regeneration per mol of liquid organic compound recovered decreased with increasing relative pressure of the inlet gas stream, ranging from 4,698 kJ/mol for methylene chloride to 327 kJ/mol for MPK. Equilibrium ACFC adsorption capacity, throughput ratio, and length of unused bed were also evaluated. These results are encouraging for the development of a new technology to capture and readily recover a wide range of organic vapors from air streams.     

Thermal Behavior of Activated Carbon Cloths Heated by Joule Effect

Activated carbon cloths (ACC) are promising adsorbents for the treatment of air loaded with volatile organic compounds (VOC). Their characteristics and properties allow them particularly high adsorption capacities and useful handling. Moreover, the Joule effect regeneration of these media may be used as a regeneration process. These peculiarities make it possible to design and size ACC filters for a wide range of industrial applications: low VOC concentration and flow for indoor air quality as well as high concentration and flow in some industrial effluents. Hence, innovating reactors could be equipped with such an adsorption-desorption process which permit us to recover the condensed compounds. The heating of ACC by Joule effect (between 20 and 250°C) is generally highly homogeneous, and the spatial distribution of the temperatures is directly connected to the activation level distribution in the material. A characterization method and a modeling approach are proposed to describe the ACC thermal behavior and to compare and select the best media in term of regeneration process. This allows sizing of future industrial processes.     

Removal of Toluene Vapor with Dispersed Activated Carbon

This work considers the mechanisms of mass transfer in a process of dispersed sorbent injection. During experiments, an air supply was dosed with toluene vapor, at partial pressures between 4 and 15 Pa. Powdered activated carbon (PAC) was added to remove the toluene from the air, and the resulting mixture was passed through a 3-m-long, tubular, aluminum test section. Toluene concentrations were measured at seven axial locations within the test section. Comparing the measurements with mathematical models indicated the importance of adsorption kinetics. At reduced toluene inlet concentrations the PAC removed a slightly bigger fraction of toluene from the air stream. This fraction increased with PAC concentration. The effect on removal of varying the air temperature between 25 and 85°C was small. Alternative models incorporating either pore diffusion or surface diffusion were fitted to the results. The quality of the fits was fair only, but sufficient to show that the pore diffusivity that gave the best fit was far larger than would be expected from the Knudsen diffusivity in the pores. That is, surface diffusion was an important part of the intraparticle mass transfer.