活性炭载体对TiO2/AC光催化降解苯酚影响研究

分别以典型煤基活性炭和椰壳活性炭为载体,采用溶胶-凝胶法制备了TiO2/AC复合光催化剂,采用低温氮气吸附、X射线衍射、扫描电镜等对其性能进行了表征,分析了活性炭载体对复合光催化剂性能的影响.结果表明:TiO2在椰壳活性炭载体上的负载率高于煤基活性炭,TiO2负载使椰壳活性炭的比表面积和微孔容明显减小,TiO2溶胶对微...     

Preparation of titanium dioxide/activated carbon composites using supercritical carbon dioxide

The penetration of titanium tetraisopropoxide (TTIP) dissolved in supercritical CO₂ into the nano-spaces of an activated carbon was studied for the preparation of a TiO₂-coated activated carbon. The conversion of TTIP to TiO₂ through thermal decomposition was confirmed by evolved gas analysis during heat treatment under a N₂ flow. Acetone was detected in the evolved gas, which suggested that some isopropoxide groups in TTIP reacted with the carbonyl groups on the activated carbon surface. This chemical reaction with carbon is expected to be advantageous for favorable attachment to the carbon surface. The crystallite size of anatase in the TiO₂/carbon composites was 4.1 nm, as estimated from the X-ray diffraction pattern, which almost corresponded to the graphene crystallite size; L_a (3.3-3.4 nm), as estimated from both the Raman spectrum and X-ray diffraction pattern. As the size of the crystallite prepared by bulk condensation of TTIP was more than 15 nm, these results confirmed that the anatase crystals were present in the carbon pores. Also, it was suggested that the crystal growth of TiO₂ was influenced by the carbon nano-spaces.     

银掺杂二氧化钛/活性炭复合材料的制备及其光催化性能研究

为提高二氧化钛/活性炭（AC）复合材料对可见光的利用率,基于溶胶-凝胶法制备了银掺杂的二氧化钛/活性炭复合光催化剂。利用一系列测试方法对光催化剂进行了表征,通过亚甲基蓝（MB）和Cr（Ⅵ）废水的降解效果研究了其光催化活性。结果表明,掺杂银的材料,吸附性能和可见光下的光催化性能均得到提升。在材料投加量为400 mg/L情况下,银-二氧化钛/AC复合光催化剂在30 min内对10 mg/L MB溶液的降解率达到98.55%,在60 min内对20 mg/L MB溶液、10 mg/L Cr（Ⅵ）溶液的降解率分别达到76.92%和53.90%;与未掺杂的材料相比,降解率分别提升了14%、47%、137%。这是由于Ag纳米颗粒可以有效地俘获价带电子,减少电子空穴的复合,从而提高了光催化效果。     

Functionalized activated carbon for the adsorptive removal of perchlorate from water solutions

Two types of activated carbon, namely, Filtrasorb 400 and Nuchar SA, were functionalized by quaternary ammonium salts (quats), as to enhance perchlorate adsorption. Results showed that the adsorption of quats on Nuchar SA increased with increase in chain length (hydrophobicity) of quats. Filtrasorb 400, however, had limited uptake of long-chain quats such as dodecyltrimethylammonium and hexadecyltrimethylammoium (HDTMA). Results indicated that perchlorate removal by the functionalized activated carbon was directly related to the chain length of the modifying quats. Perchlorate removal by functionalized activated carbon increased with increase in chain length of the modifying quats and became less pH-dependent. Modified Nuchar SA had higher overall perchlorate removal capacity than the modified Filtrasorb F400, but was more strongly affected by pH than Filtrasorb 400. Activated carbon treated with HDTMA exhibited the best perchlorate removal capacity among all quats studied. Results indicated that tailoring the activated carbon surface with HDTMA rendered the activated carbon surface positively charged, which resulted in substantial increase in perchlorate removal compared to unfunctionalized activated carbons.     

超声波强化活性炭颗粒吸附PFOA和PFOS

研究了20 kHz超声波强化活性炭颗粒吸附不同种类水溶液中全氟辛烷磺酸（PFOS）和全氟辛酸（PFOA）的动力学。结果表明：平衡吸附被证实符合BET多层等温吸附,最大单层吸附容量为qmPFOS>qmPFOA;在PFOS和PFOA初始浓度为50 mg/L时超声波辐照下活性炭颗粒吸附符合表观拟二级动力学关系,平衡吸附容量和起始吸附速率分别为qePFOS>qePFOA和 hPFOS> hPFOA;在去离子水（MQ）中的PFOS和PFOA 最大单层吸附平衡容量qm和平衡吸附容量qe及起始吸附速率h和吸附动力学常数K均大于预处理或未预处理后的垃圾渗滤地表水（Pre-GW和GW）中对PFOS和PFOA的平衡吸附量和吸附动力学常数;20 kHz超声波强化活性炭颗粒吸附PFOS和PFOA效果明显,其吸附动力学常数增强因子为7.7和4.4。     

Application of TiO2-mounted activated carbon to the removal of phenol from water

TiO₂-mounted activated carbon was prepared through hydrolytic precipitation of TiO₂ from teraisopropyl orthotitanate and following heat treatment at 650–900 °C for 1 h under a flow of nitrogen. The removal of phenol from its aqueous solution under UV irradiation was measured on TiO₂-mounted activated carbons thus prepared. Although BET surface area of TiO₂-mounted activated carbons decreased drastically in comparison with the original activated carbon, the efficiency of phenol removal under UV irradiation was high. The sample heated at 900 °C, which consisted mainly of rutile phase, showed the highest total removal of phenol. Efficiency of phenol degradation is reduced because of phenol adsorption on the catalyst.     

Thermal modeling of activated carbon based adsorptive natural gas storage system

A homogeneous, isotropic porous matrix of activated carbon inside a portable steel cylinder is considered as the adsorption bed for natural gas (NG) which is idealized as pure methane for the purpose of simulation. The heat and fluid flow inside the porous adsorption bed are modeled using a volume averaging technique and Darcy-Brinkman formulation. The effective thermal conductivity of the activated carbon-methane system is calculated as a function of uptake according to the Luikov model. Heat generation due to the exothermic process of adsorption is considered. The governing equations are solved using an implicit finite volume method for the given boundary conditions. Three different models of adsorption are considered, namely (i) a no-flow model, (ii) flow model with uniform adsorption and (iii) a flow model with local adsorption. For each of these models, transient temperature profiles in the adsorption bed during the charging process are obtained, and the corresponding mass adsorption potentials are calculated. Parametric studies are performed to investigate the effects of gas inlet temperature and rate of charging on the maximum bed temperature and the time required to fill the cylinder.     

Synergy effect on a suspended mixture of ceria and activated carbon for the photocatalytic degradation of phenol

Ceria, prepared by a precipitation method, was used as a new photocatalyst under UV light irradiation. The as-prepared sample was characterized by XRD and SEM. Results showed that the ceria was cubic fluorite structure and sized in nanometer range. The photocatalytic degradation of phenol was investigated in the presence of a suspended mixture of ceria and activated carbon. A synergy effect was observed with an enhancement of the apparent rate constant by a factor of 5.6 times. The apparent quantum yield of the ceria-AC system was also increased 2.9 times. The activated carbon with strong adsorption activity provided sites for the adsorption of phenol. Then, the adsorbed phenol would migrate continuously to the surface of ceria particles. Some phenol still remained adsorbing on the catalyst when no traces of phenol were detected in the solution. This adsorbed phenol could be degraded by maintaining UV-irradiation.     

Chemically activated carbon nanofibers for adsorptive removal of bisphenol-A:Batch adsorption and breakthrough curve study

Activated carbon nanofibers(ACNFs) with small diameter can significantly increase the accessibility of intra pores and accelerate adsorption of molecules from water.In this study,ACNFs were made by blending K₂CO₃ or ZnCl₂ as the activating agent into the polyacrylonitrile(PAN) in dimethylformamide solution for electrospinning prior to pyrolysis.Bisphenol-A(BPA),an endocrine disruption pollutant,is widely applied in the production of polycarbonate plastics and epo...     

Adsorption equilibrium of copper ion and phenol by powdered activated carbon, alginate bead and alginate-activated carbon bead

The adsorption equilibrium characteristics for single and binary components of copper ion and phenol onto powdered activated carbon, alginate bead and alginate-activated carbon (AAC) bead were studied. Adsorption equilibrium data of phenol and copper ion onto the adsorbents could be represented by Langmuir equation. The adsorption capacity of Cu²⁺ onto different adsorbents was in the following order: alginate bead > AAC bead > powdered activated carbon (PAC). On the other hand, that of phenol was: PAC > AAC bead > alginate bead. Multi-component equilibrium data were correlated by three different models. Among them the ideal adsorbed solution theory (IAST) gave the best fit to our data. And the adsorption amount of Cu²⁺ onto AAC bead was greater than that of phenol in the binary components.     

Influence of activated carbon upon titania on aqueous photocatalytic consecutive runs of phenol photodegradation

The photocatalytic degradation of phenol was performed at room temperature in aqueous suspended mixtures of TiO₂ and activated carbon (AC). The main objective of the present work was to verify the potential of TiO₂/AC system in the photocatalytic degradation of phenol and the principal intermediate products after performing three consecutive runs. The phenol disappearance follows a first-order kinetics. Therefore, the apparent first-order rate constant of phenol and total organic carbon photodegradations were selected to evaluate the photoefficiency of the system. From the present results it can be concluded that there is a synergistic effect between both solids which is determined by the numbers of photocatalytic runs. From a practical point of view, TiO₂/AC is able to photomineralize phenol and total organic carbon for three and two, respectively, consecutive runs more efficiently than TiO₂ alone.     

Parameter effect on photocatalytic degradation of phenol using TiO2-P25/activated carbon (AC)

P25 powder embedded and TiO₂ immobilized on activated carbon (TiO₂-P25/AC) was prepared by P25 powder modified sol-gel and dip-coated method. The photocatalysts were characterized by XRD, BET, SEM and their photocatalytic activities were evaluated through phenol degradation in a fluidized bed photoreactor. The addition of P25 in the photocatalysts could significantly enhance the photocatalytic activity, and the optimum loading of P25 was 3 g L^?1. The operating parameter results indicated that the optimum pH for phenol degradation was 5.2; the effect of air flow rate gave an optimal value of 2 L min^?1; the increasing of UV light intensity led to an increase of degradation efficiency due to more photons absorbed on the surface of the photocatalyst. The kinetics of the phenol degradation fitted well with the Langmuir-Hinshelwood kinetics model. Finally, the photocatalytic ability of TiO₂-P25/AC was reduced only 10% after five cycles for phenol degradation.     

Novel high performance magnetic activated carbon for phenol removal: equilibrium,kinetics and thermodynamics

A series of novel iron oxide based magnetic activated carbons (MAC) were fabricated through simple one-step method from Pomelo Peel using hydrochloric acid pickling water as chemical activation agent and iron oxide precursor. The characterizing results show that the MAC prepared through physiochemical activation at 973 K has a relative high surface area of 760 m²/g and can be fast separated from water under a moderate magnetic field. Batch adsorptions of phenol onto the MAC were investigated for its equilibrium, the kinetic modeling and thermodynamics. Equilibrium data were best described by Langmuir model, and the estimated maximum adsorption capacity of the MAC-973 was up to 1.1?×?10² mg/g at 298 K. Chemical reaction was found to be a rate-controlling parameter to this phenol-MAC batch adsorption system due to strong agreement with the pseudo-second-order kinetic model.     

投加粉末活性炭对超滤膜去除海水中有机物的影响

超滤膜的有机污染问题是膜法海水预处理技术在海水淡化工程应用面临的重要挑战,粉末活性炭吸附是目前常用的膜前预处理手段之一。本文对比分析了直接超滤和投加粉末活性炭后对海水中有机物的截留能力,利用三维荧光光谱分析了投加粉末活性炭对超滤膜截留有机物的影响机制,并考察了海水超滤过程中通量变化及膜污染情况。研究结果表明,投加粉末活性炭能够强化超滤膜对海水浊度和有机物的去除,当粉末活性炭投量为200mg/L时,整个系统对海水中DOC去除率从直接超滤时的55.1%提高到77.6%。利用粉末活性炭的吸附作用及其在超滤膜表面形成的疏松滤饼层能够显著提高超滤系统对海水中腐植酸类有机物的去除能力。与直接超滤相比,粉末活性炭-超滤系统对改善膜通量的作用有限,但粉末活性炭形成的滤饼层能够避免超滤膜与有机物直接接触,可显著减缓超滤膜的不可逆污染。     

Improved phenol decomposition and simultaneous regeneration of granular activated carbon by the addition of a titanium dioxide catalyst under a dielectric barrier discharge plasma

A catalytic method using titanium dioxide (TiO₂) under a dielectric barrier discharge (DBD) plasma was studied to improve the decomposition of phenol adsorbed on granular activated carbon (GAC) and the simultaneous regeneration of the saturated GAC. The TiO₂–GAC hybrid was fabricated by an impregnation-desiccation method and characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherms and Boehm titration to investigate its adsorption and catalytic characteristics before and after the adsorption and DBD processes. The adsorption experiments showed that the GAC and TiO₂–GAC both followed pseudo-second-order kinetic models with adsorption isotherms that were well represented by the Langmuir model. TiO₂–GAC exhibited remarkable catalytic activity, increasing the phenol degradation by 19% and TOC removal by 8.7% relative to GAC in DBD treatment. TiO₂–GAC also exhibited better regeneration efficiency than GAC, and the reusability of the hybrid material was examined over four consecutive adsorption-regeneration cycles. The above results may be due to the enhanced generation of active species, such as hydroxyl radicals and hydrogen peroxide, on TiO₂–GAC relative to GAC during the discharge process, and the main intermediate products were analysed to explore the mechanisms involved in DBD plasma.     

二氧化钛光催化分解水制氢技术进展

简单介绍了二氧化钛光催化分解水制氢的基本原理。综述了加入牺牲剂、碳酸钠、贵金属负载化、金属离子掺杂、阴离子掺杂、染料光敏化、半导体复合以及离子注入等提高二氧化钛光催化制氢的方法,讨论了这几种改性技术的机理以及对提高二氧化钛在可见光下的制氢效率的作用。重点讨论了阴离子掺杂和离子注入技术的机理和研究进展,指出离子注入是目前扩展二氧化钛光响应的最为有效的技术。最后讨论了光催化分解水制氢的氢氧分离问题,并通过与其他制氢技术的对比分析,指出光催化制氢将是通往氢经济的非常有潜力的制氢技术。     

二氧化碳的高温吸附剂及其吸附过程

分析了CO2对全球气候变化的影响和减排的必要性,介绍了CO2的基本特性和主要分离方法;针对电厂烟道气流量大、温度高的特点,着重比较了用于CO2高温吸附的多种物理吸附剂和化学吸附剂的吸附性能,主要包括活性炭、沸石分子筛、金属氧化物、水滑石类混合物和锂盐化合物;重点讨论了用于高温烟道气中CO2吸附的新型吸附剂Li2ZrO3的吸附性能及影响因素,如CO2吸附速率、反应温度、ZrO2颗粒大小、改性化合物的种类和用量等;认为Li2ZrO3是从高温烟道气中吸附CO2的高效吸附剂;强调了吸附过程与分离过程的综合考虑是减排CO2未来的重点研究方向。     

活性炭负载纳米二氧化钛对水体中砷的去除

采用批处理吸附实验,研究了颗粒活性炭和粉末活性炭负载纳米二氧化钛对水体中砷的去除效果及其初步机理。X射线衍射表征两种活性炭负载纳米二氧化钛后饱和吸附As(Ⅴ)和As(Ⅲ)前后的晶体结构图谱表明,其对砷的吸附属于表面吸附。结果说明,活性炭负载纳米二氧化钛便于纳米材料的回收,是发挥纳米二氧化钛除砷效果的重要措施。     

Color removal from dye wastewaters by adsorption using powdered activated carbon: Mass transfer studies

Color removal from synthetic dye wastewater which typically emanates from the Taiwan textile industry has been studied using powdered activated carbon (PAC) as an adsorbent. The CIE colorimetric system has been used in the measurement of color for the treatment of disperse-red-60 dye wastewater. The effect of contact time, dye concentrations and PAC dosage on color and color removal has been investigated. A film-pore double resistance diffusion model for mass transfer has also been used in this study to determine the effective diffusivity, D_eff, for the adsorption of disperse-red-60 dye wastewater to PAC.     

Impregnated activated carbon for mercury removal

The problems of mercury removal from, in particular, industrial waste air are well known. This Paper discusses research and development of impregnated activated carbon, using various adsorbents, specifically for mercury removal. Sulphur impregnations are found to be most technically effective.