Adsorption onto Activated Carbon Fiber Cloth and Electrothermal Desorption of Volatile Organic Compound(VOCs):A Specific Review

A general research program, focusing on activated carbon fiber cloths （ACFC） and felt for environmental protection was performed. The objectives were multiple： （i） a better understanding of the adsorption mecha- nisms of these kinds of materials; （ii） the specification and optimization of new processes using these adsorbents; （iii） the modeling of the adsorption of organic pollutants using both the usual and original approaches; （iv） applications of ACFC in industrial processes. The general question was： how can activated carbon fiber cloths and felts be used in air treatment processes for the protection of environment. In order to provide an answer, different approaches were adopted. The materials （ACFC） were characterized in terms of macro structure and internal porosity. Specific studies were performed to get the air flow pattern through the fabrics. Head loss data were generated and modeled as a fi.mction of air velocity. The performances of ACF to remove volatile organic compounds （VOCs） were approached with the adsorption isotherms and breakthrough curves in various operating conditions. Regenera- tion by Joule effect shows a homogenous heating of adsorber modules with rolled or pleated layers. Examples of industrial developments were presented showing an interesting technology for the removal of VOCs, such as dichloromethane, benzene, isopropyl alcohol and toluene, alone or in a complex mixture.

Adsorption and Desorption of Gold on the Magnetic Activated Carbon

Adsorption and desorption of gold on the magnetic activated carbon (MAC) were investigated The adsorption rate of gold is higher than that of conventional coconut carbon in cyanide leach solution The loading gold can be easily desorbed as coconut carbon. Crushed fine magnetic carbon can be selected by a magnetic separator, It is suggested that the MAC can be used in carbon-in-pulp (CIP)process for increasing the recovery rate of gold

NO adsorption and temperature programmed desorption on K_2CO_3 modified activated carbons

Fuel cell stacks as the automotive power source can be severely poisoned by a trace amount of NOx in atmosphere,which makes it necessary to provide clean air for fuel cell vehicles.In this work,activating commercial activated carbons with K2CO3 for the large enhancement of NO capture was studied.K2CO3 modified activated carbons(K2CO3 ACs)were prepared by impregnating activate carbons in K2CO3 solution under ultrasound treatment,followed by temperature programmed baking at 800 oC.The dynamic NO flow tests on K2CO3 ACs at room temperature indicated that NO adsorption capacity reached the maximum(96 mg/g)when K2CO3 loading was 19.5 wt%,which corresponded to a specific surface area of 1196.1 m2/g and total pore volume of 0.70 cm3/g.The ten-fold enhancement of NO adsorption on K2CO3 ACs compared to the unimpregnated activated carbon was mainly attributed to the formation of potassium nitrite,which was confirmed by FTIR and temperature programmed desorption measurements.Regeneration tests of NO adsorption on the optimum sample revealed that 76%of the NO adsorption capacity could be remained after the fourth cycle.

Behaviors and kinetics of toluene adsorption-desorption on activated carbons with varying pore structure

This work was undertaken to investigate the behaviors and kinetics of toluene adsorption and desorption on activated carbons with varying pore structure. Five kinds of activated carbon from different raw materials were selected. Adsorption isotherms and breakthrough curves for toluene were measured. Langmuir and Freundlich equations were fitted to the equilibrium data, and the Freundlich equation was more suitable for simulating toluene adsorption. The process consisted of monolayer, multilayer and partial active site adsorption types. The effect of the pore structure of the activated carbons on toluene adsorption capacity was investigated. The quasi-first-order model was more suitable for describing the process than the quasi-second-order model. The adsorption data was also modeled by the internal particle diffusion model and it was found that the adsorption process could be divided into three stages. In the external surface adsorption process, the rate depended on the specific surface area. During the particle diffusion stage, pore structure and volume were the main factors affecting adsorption rate. In the final equilibrium stage, the rate was determined by the ratio of meso-and macro-pores to total pore volume. The rate over the whole adsorption process was dominated by the toluene concentration. The desorption behavior of toluene on activated carbons was investigated,and the process was divided into heat and mass transfer parts corresponding to emission and diffusion mechanisms, respectively. Physical adsorption played the main role during the adsorption process.

Effect of textural property of coconut shell-based activated carbon on desorption activation energy of benzothiophene

In this work,the effect of the textural property of activated carbons on desorption activation energy and adsorption capacity for benzothiophene(BT)was investigated.BET surface areas and the textural parameters of three kinds of the activated carbons,namely SY-6,SY-13 and SY-19,were measured with an ASAP 2010 instrument.The desorption activation energies of BT on the activated carbons were determined by temperature-programmed desorption(TPD).Static adsorption experiments were carried out to determine the isotherms of BT on the activated carbons.The influence of the textural property of the activated carbons on desorption activation energy and the adsorption capacity for BT was discussed.Results showed that the BET surface areas of the activated carbons,SY-6,SY-13 and SY-19 were 1106,1070 and 689 m2·g^(-1),respectively,and their average pore diameters were 1.96,2.58 and 2.16 nm,respectively.The TPD results indicated that the desorption activation energy of BT on the activated carbons,SY-6,SY-19 and SY-13 were 58.84,53.02 and 42.57 KJ/mol,respectively.The isotherms showed that the amount of BT adsorbed on the activated carbons followed the order of SY-6>SY-19>SY-13.The smaller the average pore diameter of the activated carbon,the stronger its adsorption for BT and the higher the activation energy required for BT desorption on its surface.The Freundlich adsorption isotherm model can be properly used to formulate the adsorption behavior of BT on the activated carbons.

Effect of Granular Activated Carbon on the Enhancement of Cometabolic Biodegradation of Phenol and 4-Chlorophenol

Enhancement of the cometabolic biotransformation of 4-chlorophenol（4-cp） and phenol were studied using chemically and thermally granular activated carbons（GACs）.It was found that both chemically activated and thermally activated GAC effectively adsorb phenol and 4-cp.More than 80% adsorped substrates were later desorpted,showing a reversible sorption behaviour in the GAC.For each activated carbon type,4-cp was preferentially adsorbed over phenol and the desorption efficiencies of both phenol and 4-cp were found to increase linearly with the initial mass of adsorbate in the adsorbent.The biodegradation of 500 mg/L phenol by Pseudomonas putida took 24 h while the biodegradation of 4-cp took 32 h.Inhibitions during the cometabolic biodegradation of 4-cp and phenol were alleviated by the addition of the GACs.The system with chemically-activated coconut type GAC had better system stability over thermally-activated peat type GAC.The results show that GAC can be regenerated by the cells enhancement of the cometabolic biotransformation of 4-cp and phenol can be accomplished using chemically-activated coconut type GAC.

Evaluation of alum-based water treatment residuals used to adsorb reactive phosphorus

Excess reactive phosphorus(PO4)in waterways can lead to eutrophication.A low-cost approach to reducing PO4 levels in surface water was evaluated using the alum-based water treatment residual(Al-WTR)or Al-WTR augmented with powdered activated carbon(PAC-WTR).Batch adsorption-desorption and continuous flow column experiments were performed to assess the specific adsorption capacities under various concentration and flow conditions.Both Al-WTR and PAC-WTR exhibited the ability to adsorb PO4.The overall,cumulative sorbed amount after a 28-d desorption step for Al-WTR was 33.93 mg/kg,significantly greater than the PAC-WTR value of 24.95 mg/kg(p<0.05).The continuous flow column experiments showed a theoretical PO4 uptake of 9.00 mg/g for Al-WTR and 7.14 mg/g for PAC-WTR over 720 h.When surface water was used,the Al-WTR and PAC-WTR columns removed 67.4%and 62.1%of the PO4,respectively.These results indicated that Al-WTR was more effective for in-field evaluation.

Pd在超级活性炭上的负载对其储氢性能的影响

负载金属Pd和PdO都有助于提高超高比表面积活性炭的吸氢性能,并能使其吸氢能力分别提高2倍～4倍和4倍～5倍左右.同时由于过渡金属在高温下容易发生团聚和迁移现象,负载在活性炭上的金属Pd的还原温度和还原时间应分别控制在125℃和2h.在0℃和27℃常压下,Pd/AC和PdO/AC(SBET为3886m2/g)对氢的饱和吸附量分别为:20mL/g、23mL/g和14mL/g、15.8mL/g,且它们的循环使用寿命良好.

载铁活性炭的制备及对水中P(V)的吸附性能研究

通过直接蒸发法制备载铁活性炭,研究了载铁活性炭对水中P(V)的吸附等温线和吸附热动力学,并分析了pH值、P(V)初始浓度等因素对载铁活性炭吸附性能的影响.实验表明,载铁活性炭可以有效快速地吸附P(V),载铁活性炭对P(V)的去除效果随pH值的上升、P(V)初始浓度的增大而降低.吸附等温线符合Langmuir方程,最大吸附量为9.32 mg/g;准二级动力学能够很好地描述P(V)在载铁活性炭上的吸附行为,吸附速率常数在0.01 min.g/mg左右,且随着温度的升高逐渐增大.吸附P(V)的活化能Ea为10.89 kJ/mol,吸附行为是自发吸热的化学吸附过程.

文冠果子壳活性炭对Pb^(2+)的吸附及解吸

以废弃的文冠果子壳为原料,通过Zn;Cl2活化法制备活性炭。利用SEM-EDX技术,对文冠果子壳活性炭吸附前后元素组成进行分析。探讨吸附时间、吸附温度、p;H以及Pb^(2+)初始浓度对吸附的影响,考察时间、温度、稀硝酸浓度对解吸的影响,分析其吸附热力学性质和动力学特性,初步探讨吸附机理。研究结果表明:在吸附温度30℃,Pb^(2+)初始浓度0.003;2;mol/L,p;H;5.0,吸附40;min,吸附量最大可达656.54;mg/g;当稀HNO_3浓度0.06mol/L,温度60℃,解吸40;min,解吸率最大可达96.13%;活性炭对Pb^(2+)吸附等温线符合Langmuir模型,其吸附动力学过程以准二级动力学方程拟合效果最好;在303~323;K温度范围内,活性炭吸附Pb^(2+)的吉布斯自由能ΔGo<0、焓变ΔHo<0、熵变ΔSo<0,表明活性炭对Pb^(2+)吸附是一个自发的放热过程。

TPD数值模拟研究芴在活性炭上吸附的热力学

以吸附热力学为基础,建立了程序升温脱附数值模拟分析技术测定难挥发性有机物的热力学数据方法.通过程序升温脱附实验,测定了不同升温速率下芴从活性炭上脱附的速率曲线.运用所提出的方法,对芴在活性炭上的热力学参数进行了估算.结果表明实验程序升温脱附曲线与计算模拟流出曲线较为吻合,相对误差小于5%.本文建立的程序升温脱附理论模型能够较准确地描述芴在活性炭上的程序升温脱附过程.

珍贵橙色束丝放线菌发酵产安丝菌素P-3的分离纯化工艺优化

安丝菌素是从珍贵橙色束丝放线菌的发酵液中分离出来的苯安莎类抗生素,具有显著的抗肿瘤活性。常采用乙酸乙酯对发酵液进行分离萃取,然而其发酵液成分复杂,除菌丝体外还含有许多杂蛋白质及易溶于有机溶剂的色素,这对后续提取和精制有很大的影响,影响产品质量和回收率。本文通过对AP-3发酵液进行预处理,将AP-3发酵液调整pH至3后,用10g/L硅藻土辅助抽滤;收集滤液,添加20g/L活性炭于60℃吸附2h,然后用洗脱液乙酸乙酯对活性炭进行脱附处理,2h后达到动态洗脱平衡,对洗脱液采用中性氧化铝柱层析,以乙酸乙酯和石油醚作为洗脱剂进行梯度洗脱,最终获得AP-3纯度86.15%,经重结晶后得到AP-3纯品,经过HPLC检测AP-3纯度达95%。

基于PLC控制的车载移动式活性炭吸脱附系统

为了解决企业活性炭吸附饱和后无法循环使用的问题,上海建科环境技术有限公司研发了车载移动式活性炭吸脱附系统。为满足该系统控制需求,选用西门子200 SMART系列PLC为核心的控制器,设计了电气控制原理图以及系统软件,搭建了基于PLC的硬件控制平台。利用博途TIA V15平台编程和绘制了人机操作界面,画面直观和准确地反映了吸、脱附和催化燃烧系统运行的真实情况。西门子触摸屏使用和维护较为方便,适用于现场控制。实际运行表明该控制系统实现了对活性炭吸脱附和废气催化燃烧的监控,运行稳定,具有实际应用价值。

一种VOCs处理装置应用问题和优化改造

挥发性有机物(VOCs)作为有毒有害物质,对空气质量造成了严重影响。其中活性炭吸附脱附及催化燃烧装置被广泛用于VOCs的控制排放,VOCs浓度较高时,存在无法稳定达标排放问题。通过对活性炭吸附脱附与催化燃烧原理及装置实际工况分析,对其进行了针对性的优化改造。改造后,非甲烷总烃平均排放浓度、平均排放速度分别达到7.61 mg/m^(3)和289.94 g/h,分别降低了76.70%和78.24%,完全满足VOCs排放标准。结果表明:通过优化改造,不仅提高了该装置对VOCs的处理效果,而且实现了VOCs稳定达标排放,达到了该区域空气质量控制的目的。

活性炭吸附脱附+催化燃烧工艺处理喷涂中的有机废气

针对常州某机械制造企业喷涂有机废气排放不达标问题,将传统的活性炭吸附工艺提升为“干式过滤+活性炭吸附脱附+催化燃烧工艺”,经监测,废气污染物非甲烷总烃排放浓度低于50 mg/m^(3),去除效率达80%~90%,废气污染物排放满足《大气污染物综合排放标准》(DB 32/4041—2021)相关要求。废气处理设施年运行费用大大降低,环保达标的同时取得一定的经济效益。

水性聚酯纺织浆料生产废气挥发治理技术优化与应用研究

研究了水性聚酯纺织浆料生产废气挥发治理技术优化与应用。通过试验对比不同工艺单元的处理效率,选择了水喷淋、干式过滤、活性炭吸脱附和催化燃烧装置等多种治理技术,并通过优化组合方案,达到了较好的治理效果。同时,本文也对治理技术的优缺点进行了分析和评价,为类似企业废气治理提供参考。

沸石分子筛和活性炭吸附/脱附甲苯性能对比

考察了甲苯在NaY型沸石分子筛(简写为NaY)、13X型沸石分子筛(简写为13X)、Hβ型沸石分子筛(简写为Hβ)、MCM-22型沸石分子筛(简写为MCM-22)和ZSM-5型沸石分子筛(简写为ZSM-5)上的吸附/脱附性能,同时与椰壳活性炭(AC)的吸附/脱附性能进行对比。结果表明,各吸附剂对甲苯的平衡吸附量大小依次为:AC>NaY>Hβ>13X>MCM-22>ZSM-5,甲苯从吸附剂表面脱附难易程度依次为:AC>NaY、13X>Hβ>MCM-22>ZSM-5;ZSM-5对甲苯的平衡吸附量和吸附强度都最小,这是由于甲苯无法进入ZSM-5的内部孔道造成的;在低甲苯质量浓度(<1000mg/m3)时,NaY平衡吸附量超过AC,因此NaY更适合应用在低浓度有机废气吸附治理中;Langmuir吸附方程比Freundlich吸附方程更符合沸石分子筛吸附甲苯的行为。

活性炭吸附法在挥发性有机物治理中的应用研究进展

挥发性有机化合物(VOCs)是一类重要的大气污染物,其所带来的环境污染问题已经引起全世界的关注。活性炭吸附法是治理VOCs污染的有效手段。本文从介绍VOCs治理技术出发,简述了活性炭吸附法在VOCs治理中的使用现状,概括了活性炭吸附法治理VOCs的工艺技术和存在问题,指出变温-变压吸附、变电吸附以其高效节能环保的优点,在VOCs治理中具有较好的发展前景。分析了活性炭表面化学性质、吸附质的物性、操作条件对活性炭吸附法治理VOCs的影响,为VOCs治理专用活性炭的改进和新产品的开发,提供了理论依据。在总结现有研究进展的基础上,预测了活性炭吸附法治理VOCs技术的发展趋势,提出对工艺的改进以及与其他VOCs废气处理技术的耦合使用,针对不同VOCs排放场所开发不同活性炭品种和VOCs回收装置将是以后研究的重要方向。

活性炭吸附法脱硫实验研究和工业性应用

研究了周期性水洗涤脱附对活性炭脱硫性能的影响。经过 4次吸附、脱附循环后 ,活性炭的动态吸附性能和脱附性能达到平衡。活性炭颗粒越小 ,床层穿透时间越长 ,脱硫效率越高。当进口SO2 质量分数为 3× 1 0 - 3时 ,活性炭脱硫效率达到96 %以上。工业性实验表明 ,采用水洗涤脱附 ,活性炭脱硫效率稳定。燃煤烟气工业性实验排放烟气SO2 质量分数小于 9×1 0 - 5,脱硫效率达到 93 %。