Adsorption of congo red on mesoporous activated carbon prepared by CO2 physical activation

This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide.Central composite design was applied to conduct the experiments at different levels by altering three operating parameters.Activation temperature(766-934℃),CO2 flow rate(0.8-2.8 L·min^-1)and activation time(5-55 min)were the variables examined in this study.The effect of parameters on the specific surface area,total pore volume and burn-out rate of activated carbon was studied,and the influential parameters of methylene blue adsorption value were identified employing analysis of variance.The optimum conditions for maximum methylene blue adsorption value were:activation temperature=900℃,activation time=29.05 min and CO2 flow rate=1.8 L·min(-1).The activated carbon produced under optimum conditions was characterized by BET,FTIR and SEM.The adsorption behavior on congo red was studied.The effect of parameters on the adsorbent dosage,temperature,PH and initial congo red concentration was investigated.The adsorption properties of the activated carbon were investigated by kinetics.The equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%,234 mg·g^-1,respectively when initial congo red concentration is 200 mg·L^-1 under adsorbent dosage(0.8 g·L^-1),temperature(30℃),PH7.

Preparation of mesoporous activated carbons from coal liquefaction residue for methane decomposition

Mesoporous activated carbons were prepared from direct coal liquefaction residue （CLR） by KOH activation method, and the experiments were carried out to investigate the effects of KOH/CLR ratio, solvent for mixing the CLR and KOH, and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition （CMD）. The results showed that optimal KOH/CLR ratio of 2 ： 1; solvent with higher solubility to KOH or the CLR, and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD. The resultant mesoporous carbons show higher and more stable activity than microporous carbons. Additionally, the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.

Conversion of Malaysian low-rank coal to mesoporous activated carbon:Structure characterization and adsorption properties

Malaysian Selantik low-rank coal(SC)was used as a precursor to prepare a form of mesoporous activated carbon(SC-AC)with greater surface area(SA)via a microwave induced KOH-activation method.The characteristics of the SC and SC-AC were evaluated by the iodine number,ash content,bulk density,and moisture content The structure and surface characterization was carried out using pore structure analysis(BET),scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDX),X-ray diffraction(XRD),Fourier Transform Infrared(FTIR),elemental analysis(CHNS),thermogravimetric analysis(TGA),and determination of the point of zero charge(pH(PZC)).These results signify a mesoporous structure of SC-AC with an increase of ca.1160 times(BET SA=1094.3 m^2·g^-1)as compared with raw SC without activation(BET SA=1.23 m^2·g^-1).The adsorptive properties of the SC-AC with methylene blue(MB)was carried out at variable adsorbent dose(0.2-1.6 g·L^-1),solution pH(2-12),initial MB concentrations(25-400 mg·L^-1),and contact time(0-290 min)using batch mode operation.The kinetic profiles follow pseudo-second order kinetics and the equilibrium uptake of MB conforms to the Langmuir model with a maximum monolayer adsorption capacity of 491.7 mg g^-1 at 303 K.Thermodynamic functions revealed a spontaneous endothermic adsorption process.The mechanism of adsorption included mainly electrostatic attractions,hydrogen bonding interaction,andπ-πstacking interaction.This work shows that Malaysian Selantik low-rank coal is a promising precursor for the production of low-cost and efficient mesoporous activated carbon with substantive surface area.

Preparation of Activated Carbons from Mongolian Lignite and Sub-Bituminous Coal by a Physical Method

Preparation of activated carbons by a physical activation technique is performed using the methods of coal pyrolysis and gasification at different temperatures. As increasing pyrolysis temperature from 520°C to 700°C, the yield of activated carbons from the Khuut (KH) sub-bituminous coal is lowered, and amount of micropores increases gradually;however there is no development of mesopores by the KH coal pyrolysis. When the KH coal has a small loss during its physical activation due to difficulty and inactivity of its macrostructure decomposition, the smaller porosity is developed in the resulting carbons. The Aduunchuluun (AD) lignite is activated by pyrolysis and gasification at the highest temperature of 700°C in the present study. It is identified that the gasification of AD lignite develops well a porous structure with the highest surface area of 522 m2/g which is three times larger than that (155 m2/g) of the activated carbon produced by pyrolysis of the same lignite. The IR and SEM analysis confirm a significant difference in chemical and structural changes between the AD, KH raw coals and corresponding carbon samples in the physical activation processes.

Fabrication, characterization and evaluation of mesoporous activated carbons from agricultural waste： Jerusalem artichoke stalk as an example

This work explores the feasibility of Jerusalem artichoke stem （JAS）, an agricultural waste, as an alternative precursor for fabrication of mesoporous activated carbon （MAC） via conventional ZnC12 activation. The as-prepared JAS-MACs were characterized by thermogravimetric, nitrogen gas adsorption isotherm and high resolution scanning electron microscopy analysis. The interacting effects of chemical dosage, activation temperature and time on the mesoporosity, mesopore volume and carbon yield were investigated, and further optimized by response surface methodology （RSM）. The Brunauer-Emmett-Teller surface area, mesoporosity and mesopore volume of the JAS-MAC prepared under optimum condition were identified to be 1631 m^2·g ^-1, 90.16% and 1.11 cm3·g ^-1, respectively. Compared with commercial activated carbons, this carbon exhibited a comparable monolayer adsorption capacity of 374.5 mg .g 1 for Methylene Blue dye. The findings suggest that RSM could be an effective approach for optimizing the pore structure of fabricated activated carbons.

Pretreatment of Cylindrical Coconut Activated Carbon and Performance as Catalyst Support

Cylindrical coconut activated carbon（CCAC） support was graphitized at a high temperature（1900 ℃） in argon, then oxidized with an O2-N2-H2O mixture, and treated with nitric acid. Pretreatment of carbon support on its mechanical strength, physical structure, chemical composition and surface properties of cylindrical CCAC support was investigated by X-ray diffraction（XRD）, surface area analysis, scanning electron microscopy（SEM）, energy dis- persive spectroscopy（EDS）, thermogravimetric-differential thermogravimetric（TG-DTG） analysis and temperature programmed desorption-mass spectrometry（TPD-MS）, and the effect of CCAC support on the catalytic activities was also studied. The results show that the degree of graphitization, the purity（phosphorus, sulphur）, pore struc- ture（micropore, mesopore） and oxygen-containing functional groups（--COOH, --OH, --COOR） of carbon supports are obviously different, which have a great influence on the performance of Ru-based catalysts. After a series of pre- treatments, the surface physical and chemical properties of the commercial CCAC are modified and improved, and the activity of as-prepared Ru/AC catalyst is increased significantly.

PREPARATION OF MESOPOROUS CARBON BY CARBON DIOXIDE ACTIVATION WITH CATALYST

A mesoporous activated carbon (AC) can be successfully prepared by catalytic activation with carbon dioxide. For iron oxide as catalyst, there were two regions of mesopore size distribution, i.e. 2-5nm and 30-70nm. When copper oxide or magnesium oxide coexisted with iron oxide as composite catalyst, the content of pores with sizes of 2-5nm was decreased, while the pores with 30-70nm were increased significantly. For comparison, AC reactivated by carbon dioxide directly was also investigated. It was shown that the size of mesopores of the resulting AC concentrated in 2-5nm with less volume. The adsorption of Congo red was tested to evaluate the property of the result-ing AC. Furthermore, the factors affecting pore size distribution and the possibility of mesopore formation were discussed.

Natural Mesoporous Activated Carbon from Toxic Plant Stellera Chamaejasme Roots by Chemical Methods

Stellera chamaejasme,widely distributed on the Qinghai-Tibet Plateau,is a poisonous plant causing serious harm to grassland.Activated carbons have been prepared from the roots of Stellera chamaejasme via phosphoric acid and zinc chloride activation at500°C for 60 min with an impregnation ratio of 3:1.Yield(25.1%-27.6%),ash(4.5%-4.9%),methylene blue(195.0 mg/g-254.5 mg/g),iodine value(720.4 mg/g-810.5 mg/g),specific surface area(1023.3 m2/g-1216.7 m2/g),specific pore volume(2.13 cm3/g-2.26 cm3/g),mesopore volume(1.30 cm3/g-1.59 cm3/g)and average pore size(5.88nm-7.45 nm)of the products were determined.The results from both the zinc chloride and phosphoric acid activation processes showed that the activated carbons of S.chamaejasme roots exhibit a characterization of natural developed mesopores.

ELECTROCARBOXYLATION OF ORGANIC COMPOUNDS WITH CARBON DIOXIDE CATALYZED BY METALLOPORPHYRINS(Ⅲ)——EFFECTS OF AXIAL LIGANDS ON CATALYTIC ACTIVITY OF CoTPP

The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,peptide containing —SH and amino acid containing imidazolyl en- hance the catalytic activity.The effect of imidazole amounts on the catalytic activity of CoTPP is studied.

ELECTROCARBOXYLATION OF ORGANIC COMPOUNDS WITH CARBON DIOXIDE CATALYZED BY METALLOPORPHYRINS(Ⅱ)——ELECTROSYNTHESIS OF SOME ORGANIC COMPOUNDS WITH CO_2 CATALYZED BY CoTPP

The catalyzation of CoTPP for electrocarboxylation of alkyl halides, alkenes and ketones with CO_2 are studied. The electrocarboxylation of these organic compounds with CO_2 in the presenec of catalyst can occur at more positive potential than that of no catalyst. The products of electrocarboxylation were identified by UV, IR and GC-MS. The electrocarboxylation mechanisms of different organic compounds are discussed.

Microwave-assisted conversion of biomass wastes to pseudocapacitive mesoporous carbon for high-performance supercapacitor

Developing an efficient approach of transforming biomass waste to functional carbon-based electrode materials applied in supercapacitor offers an important and high value-added practical application due to the abundance and considerable low price of biomass wastes.Herein,a hierarchical carbon functionalized with electrochemical-active oxygen-containing groups was fabricated by microwave treatment from the biomass waste of camellia oleifera.The obtained mesoporous carbon(MAC)owns nanosheet morphology,rich mesoporosity,large surface area(1726 m2/g)and very high oxygenic functionalities(16.2 wt%)with pseudocapacitive activity.Prepared electrode of supercapacitor and tested in 2.0 M H2 SO4,the MAC exhibits an obvious pseudocapacitive activity and achieved a superior supercapacitive performance to that of directly activated carbon(DAC-800)including high specific capacitance(367 F/g vs.298 F/g)and better rate performance(66%vs.44%).The symmetrical supercapacitor based on MAC shows a high capacity of275 F/g,large energy density of 9.55 Wh/kg(at power density of 478 W/kg)and excellent cycling stability with 99%capacitance retention after 10000 continuous charge-discharge,endowing the obtained MAC a promising functional material for electrochemical energy storage.

Highly active and stable Co nanoparticles embedded in nitrogen-doped mesoporous carbon nanofibers for aqueous-phase levulinic acid hydrogenation

Developing a highly active and durable non-noble metal catalyst for aqueous-phase levulinic acid(LA)hydrogenation to g-valerolactone(GVL)is an appealing yet challenging task.Herein,we report well-dispersed Co nanoparticles(NPs)embedded in nitrogen-doped mesoporous carbon nanofibers as an efficient catalyst for aqueous-phase LA hydrogenation to GVL.The Co zeolitic imidazolate framework(ZIF-67)nanocrystals were anchored on the sodium dodecyl sulfate modified wipe fiber(WF-S),yielding one-dimensional(1-D)structured composite(ZIF-67/WF-S).Subsequently,Co NPs were uniformly embedded in nitrogen-doped mesoporous carbon nanofibers(Co^(R)NC/SMCNF)through a pyrolysis-reduction strategy using ZIF-67/WF-S as the precursor.Benefiting from introducing modified wipe fiber WF-S to enhance the dispersion of Co NPs,and Co^(0) with Co-N_xdual active sites,the resulting Co^(R)NC/SMCNF catalyst shows brilliant catalytic activity(206 h^(-1) turnover frequency).Additionally,the strong metal-support interactions greatly inhibited the Co NPs from aggregation and leaching from the mesoporous carbon nanofibers,and thus increasing the reusability of the Co^(R)NC/SMCNF catalyst(reusable nine times without notable activity loss).

修饰改性棉秆介微多孔炭材料对甲醛气体的吸附性能研究

炭材料修饰改性是提高炭基材料吸附挥发性气体能力的重要手段。首先使用KOH对棉秆基炭材料刻蚀改性,再使用碳酸钠(Na_(2)CO_(3))和亚硫酸氢钠(NaHSO_(3))进行修饰改性,研究未改性棉秆炭材料(C)、KOH改性棉秆炭材料(C_(k))以及Na_(2)CO_(3)与NaHSO_(3)改性炭材料(C_(k-s))对甲醛性能的影响,采用正交试验方法优化了棉秆介微多孔炭材料的最佳制备工艺,通过比表面积测试、扫描电子显微镜和X射线能量色散谱仪对制备的材料进行了表征。结果表明:C、C_(k)和C_(k-s)平均孔径分别为2.51nm、2.15nm和1.93nm,三者均为介微多孔炭基材料,C_(k)和C_(k-s)对甲醛去除率分别高达84.0%和86.4%,相较于未改性C(甲醛去除率24.1%)均有极大提高;C_(k-s)平均孔径、比表面积和总孔容均小于C_(k),但对甲醛去除率略高于C_(k),说明Na_(2)CO_(3)和NaHSO_(3)对低比表面积炭材料进行修饰改性具有提高其吸附甲醛的能力。C_(k)和C_(k-s)的吸附过程分别符合准一级和准二级动力学模型,为单分子层吸附,理论最大吸附量分别达3.95mg/g和5.78mg/g。

高硫煤基多孔碳材料的可控制备及其用于锂硫电池

高性能、低成本的多孔碳材料是理想的锂硫电池硫宿主材料,但利用廉价的原料实现其规模化制备仍面临巨大挑战。以资源丰富的高硫煤为原料,采用氧化镁和氢氧化钾作为模板剂和活性剂,制备了煤基多孔碳材料,并研究了其作为锂硫电池硫宿主材料的构效关系。研究发现,煤基碳材料制备过程中,模板剂MgO作用下产生介孔(占比74%);活性剂KOH主要导致微孔(占72%)生成;MgO和KOH共同作用制备的碳材料PCMgO+KOH比表面积大(1616 m^(2)/g)、孔容高(1.02 m^(3)/g)、孔结构丰富(介孔54%、微孔46%)。电化学性能测试结果表明,S@PCMgO+KOH具有良好的倍率性能和优异的循环稳定性,在1 C充放电倍率循环500圈后容量仍能保留553.2 mAh/g,容量保持率达65.5%,每个循环的衰减率低至0.069%;在2 C下,循环500圈后容量为484.0 mAh/g,容量保持率为63%,每圈衰减率仅0.075%,具有良好的倍率性能和优异的循环稳定性。PCMgO+KOH优异的电化学性能主要来自其较小的欧姆电阻和电荷转移电阻、快速的多硫化物氧化还原反应动力学及对多硫化锂优异的束缚能力。本研究为价廉性高的锂硫电池硫宿主材料的制备提供了可选择的路线。

高性能锂离子电容器正极材料石墨烯-介孔炭复合物的制备及性能分析

【目的】设计同时具有高质量活性和高体积活性的锂离子电容器(lithium-ion capacitor,LIC)复合正极材料。【方法】借助扫描电子显微镜、透射电子显微镜、康塔全自动比表面和孔径分析仪、四探针测试仪,通过实验分析了颗粒之间的微观形貌、堆叠方式、接触模式和界面特性对复合电极的电导率、电学性质的影响规律。【结果】将介孔活性炭(mesoporous activated carbon,MC)与单分散石墨烯/单壁碳纳米管杂化物(graphene/single-walled carbon nanotube hybrid,GNH)混合,紧密压缩制成锂离子电容器正极材料。GNH均匀地包裹在MC颗粒表面,与MC面对面接触,增大接触面积;而且GNH在MC颗粒之间形成均匀的三维导电网络,提供了快速的电子传导。另外,GNH具有开放结构,会优先吸附电解液离子,与MC界面间存在浓度梯度;同时,GNH具有较高的导电性,与导电性较差的MC界面间存在接触电势差效应。两者共同促使GNH和MC界面之间形成快速的离子和电子双传输路径,促进离子在MC内部的扩散,从而避免了高电流密度下因离子扩散缓慢而造成的容量损失。【结论】添加5%GNH提高了倍率性能,并且在不牺牲堆积密度的前提下同时提高质量和体积能量密度。

木屑基介孔活性炭的制备及其对刚果红的高效吸附

以废弃生物质木屑作为原料,K_(2)C_(2)O_(4)为活化剂,鸡蛋壳为模板剂制备介孔活性炭。采用扫描电镜(SEM)、X射线光电子能谱仪(XPS)和N_(2)吸附-脱附等温线等方法对活性炭的结构进行表征,并考察了活性炭对刚果红(CR)染料的吸附性能。结果表明,当木屑与K_(2)C_(2)O_(4)的质量比为1∶1.5,添加与木屑等量的鸡蛋壳,活化温度为800℃、活化时间为2 h时,所制备的活性炭AC-1比表面积为2009 m^(2)/g,介孔率可达70.5%。AC-1对CR的最佳吸附容量高达862.1 mg/g。吸附过程是以化学吸附为主的单层复合吸附过程,符合准二级动力学模型和Langmuir等温模型。

Immobilized reactor for rapid destruction of recalcitrant organics and inorganics in tannery wastewater

The wastewater discharged from tanneries lack biodegradability due to the presence of recalcitrant compounds at significant concentration. The focal theme of the present investigation was to use chemo-autotrophic activated carbon oxidation(CAACO) reactor, an immobilized cell reactor using chemoautotrophs for the treatment of tannery wastewater. The treatment scheme comprised of anaerobic treatment, sand filtration, and CAACO reactor, which remove COD, BOD, TOC, VFA and sulphides respectively by 86%, 95%, 81%, 71% and 100%. Rice bran mesoporous activated carbon prepared indigenously and was used for immobilization of chemoautotrophs. The degradation of xenobiotic compounds by CAACO was confirmed through HPLC and FT-IR techniques.

铁催化活化制备沥青基球状活性炭中孔形成机理的研究

利用XPS、XRD、SEM和穆斯堡尔光谱 (MES)等手段分析了掺杂铁制得的中孔沥青基球状活性炭中铁的形态变化、中孔形貌等 ,并在此基础上提出了掺杂铁沥青基球状活性炭中孔的形成机理。

添加Fe_3O_4对煤基活性炭孔结构的影响

选用太西无烟煤为原料,以Fe3O4为添加剂制备出煤基活性炭,利用N2吸附等温线、碘值、亚甲基蓝值、X射线衍射分析仪(XRD)和扫描电子显微镜(SEM)对其进行表征。结果表明:添加质量分数6%的Fe3O4,煤基活性炭具有较大的比表面积,其值为993.5 m2/g,与未添加Fe3O4的活性炭比较,碘值提高了4%,亚甲基蓝值提高了42%;添加Fe3O4使活性炭的石墨微晶形成乱层结构,促进了微孔和中孔的发育;由于炭化过程中部分Fe3O4转化为α-Fe,因其在活化过程中起到催化作用,因此提高了活性炭中孔的数量。

用复合添加剂调变活性炭孔隙制备中孔活性炭

以宁夏某商品无烟煤活性炭为原料，以硝酸钾和助剂作为复合添加剂，选择不同的浸渍量及配比，进行再活化、酸洗、水洗，制备中孔发达的活性炭．通过测定活性炭的碘值、亚甲蓝吸附量及氮吸附、脱附等温线，研究了添加剂浸渍量及配比和活化工艺的改变对活性炭碘值、亚甲蓝值及孔结构的影响规律．结果表明：复合添加剂有助于提高碘值和亚甲兰值，但过高的烧失率却会使碘值下降；提高复合添加剂的量，有利于活性炭中孔和大孔的发展，使微孔率降至35％左右，而中孔率33％～35％；复合添加剂以1：1配比时，不仅使中孔率更大，而且在较低的烧失率下就可以获得较大的孔容（0．64～0．66mL／g）；选择2％，49／6和69／6的添加剂量，可以灵活调整活性炭微孔、中孔和大孔的比例，实现活性炭孔隙的定向调变．