高比表面积活性炭研制进展

高比表面积活性炭具有发达的内部孔隙结构和超强的吸附性能,它作为一种新型材料在许多高效吸附功能材料领域有广阔的应用前景,如化工、制药、食品和环境保护等领域。本文综述了活性炭的制备方法和国内外活性炭的研制状况,展望了活性炭发展趋势,并就目前的两大研究热点高比表面积活性炭在双电层电容器和溶剂回收两大领域的应用进行了着重探讨。     

超高比表面积活性炭的制备与表征

以无患子残渣为原料,KOH与K2CO3作为活化剂,采用微波炭化和活化两步法制备超高比表面积活性炭,通过正交实验优化活性炭的制备工艺,探讨了碱炭比、活化温度和活化时间对活性炭吸附亚甲基蓝吸附值的影响。利用N2吸脱附实验、XRD、FT-IR等实验技术,对制备的活性炭结构与性能进行了表征。结果表明,在碱炭质量比为4∶1、活化温度800℃、活化时间30 min的条件下,所制备的活性炭对亚甲基蓝吸附值为595 mg/g,BET比表面积为3 479 m2/g,吸附累积总孔容达1.8262 cm3/g,平均孔径为2.0997 nm。     

Fabrication of hydrophobic regenerated activated carbon with high specific surface area

Activated carbon (AC) has been widely used in the prevention and control of air and water pollution due to its excellent adsorption ability. However, the adsorption capacity of AC for targeting organic compounds is reduced because of the competitive adsorption of water molecules. The current study proposes hydrophobic modification and regeneration of waste AC as a solution to these issues. Using waste AC as raw material, SiO₂ particles were introduced to increase its surface roughness and micropores of AC. Nonpolar alkyl chain groups were grafted on the surface of AC to improve its hydrophobic performance, and high-temperature regeneration was used to increase its specific surface area. The experimental results showed that the water contact angle of AC increased from 30° (hydrophilic) to 142° (hydrophobic) after modification, and it maintained an angle of 139° even after high-temperature regeneration. The specific surface area of hydrophobic AC increased from 290 to 1075 m² g^?1 and the equilibrium adsorption capacity of hydrophobic AC for methylene blue is 425.4 mg g^?1 after regeneration. AC-adsorbed methylene blue also has excellent hydrophobicity (145°) and high specific surface area (1250 m² g^?1) after being modified and regenerated by the same methods. After being exposed to air for 600 days, the modified AC still has good hydrophobicity (125°). This indicates that our method of hydrophobic modification combined with regeneration has great significance to the recovery and utilization of waste AC.

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KOH活化法高比表面积竹质活性炭的制备与表征

以竹屑为原料,研究了KOH活化法高比表面积活性炭的制备工艺.分别考察了浸渍比、活化温度、活化时间等工艺参数对产品吸附性能的影响,并提出了可能的活化机理.在所研究的实验条件下,最佳的制备工艺是浸渍比1.0,活化温度800℃,活化时间2h.所得到的活性炭产品的比表面积和孔容可达2996m2/g和1.64cm3/g.该产品附加值高,在吸附领域特别是在双电层电容器的电极材料领域有广阔的应用前景.     

高比表面积聚苯乙烯基球状活性炭的制备研究

以聚苯乙烯基大孔吸附树脂球为炭前驱体,经空气预氧化、炭化和活化制备了高比表面积球状活性炭.系统考察了不同氧化和活化条件对氧化球和活化球的物理性能的影响.结果表明:升温速率、氧化温度和氧化时间分别为0.25℃/min、300℃和3h时所得到的氧化球的CCl4吸附值最高,可达970mg/g.此外,当活化温度和活化时间分别为850℃和4h时,球状活性炭的CCl4吸附值最高,为2700mg/g,相应的比表面积为1759m2/g.     

微波加热碳酸钾法制备烟杆基高比表面积活性炭

以烟杆炭化料为原料,采用微波加热碳酸钾活化法制备了高比表面积活性炭.研究了微波加热时间和碱炭比对活性炭的得率和吸附性能的影响,得到了优化工艺条件,所得活性炭产品的碘吸附值为1834mg/g,亚甲基兰吸附值为517.5mg/g,得率为16.65%.产品的吸附性能超过了双电层电容器专用活性炭(LY/T 1617-2004)标准的要求,同常规加热相比,活化时间缩短了78.26% .同时测定了该活性炭的氮吸附等温线,通过非定域化密度函数理论表征了活性炭的孔结构.该高比表面积活性炭的比表面积为2557m2/g,总孔体积为1.6470ml/g.     

Preparation and characterization of molybdenum carbides/carbon composites with high specific surface area

Molybdenum carbides/carbon composites (MCCs) with high specific surface area were prepared using the direct carbonization of a mixture of hydroxylpropyl cellulose, polyvinyl alcohol, K₂MoO₄ and K₂CO₃ at 900 °C in flowing Ar. X-ray diffraction pattern showed the formation of α-Mo₂C with small amount of Mo₃C₂ in carbon matrix. The particle size of carbides in MCCs varied from ca. 50 nm to 5 μm by changing the precursor ratio. The BET specific surface areas of the synthesized MCCs could be controlled from 400 to 1200 m²/g depending on the amount of K₂CO₃ added during the preparation by increasing the microporosity.     

超级电容器用活性炭的制备与电化学表征

以煤焦油沥青为前驱体,采用化学活化法制备了超级电容器用高比表面活性炭和活性炭电极.考察了活化温度对活性炭电极比电容量的影响,研究了活性炭材料的比表面积和孔结构与活性炭电极的充放电性能之间的关系,并对活性碳电极进行了电化学表征.结果表明,在500～700℃,随着活化温度的提高,活性炭电极的比电容量显著增大,当活化温度超过700℃时,活性炭电极材料的比电容量变化不明显.700℃活化温度下所制备的活性炭材料呈现明显的多孔结构,孔容为1.038cm3/g,比表面积为1959m2/g;所制成的活性炭电极比电容量为210F/g,等效内阻为0.9Ω/cm2,10mA/cm2充放电500次后保持90%以上电容量,交流阻抗谱在频率低于转化点时表现出纯粹的电容行为,循环伏安曲线显示出良好的可逆特性.     

微孔-介孔高比表面积佛手渣基活性炭的制备

在催化和吸附分离等领域,微孔-介孔结构活性炭有广阔的应用前景。以废弃的佛手渣为原料,运用氢氧化钾活化法制备微孔-介孔高比表面积活性炭。考察了炭化和活化等工艺条件对活性炭结构的影响。结果表明,较佳工艺条件下制备的活性炭碘值为1544mg·g-1,BET比表面积1676m2·g-1,微孔BET比表面积350m2·g-1,孔径集中分布在2～5nm之间。     

沥青活性炭的制备方法

由中温沥青制备活性炭的工艺流程，预处理过程存在热处理时间长、沥青破碎困难的问题，通过将沥青附载于玉米秸秆上，采用空气氧化法进行热处理，可以较好地解决上述问题。实验考察了热聚合法和空气氧化法两种热处理工艺对活性炭吸附性能的影响，发现空气氧化法效果优于热聚合法，其适宜的热处理条件为：温度400℃，时间2h。对活化工艺的研究结果表明：活化时碱炭比为5：1、炭料粒度100目、活化温度在800℃～900℃、活化时间在1h～1．5h，所制活性炭吸附性能高、且稳定。     

高比表面椰壳活性炭和纳米级Pd/C催化剂的制备与表征

以海南椰壳为原料,粉碎、过筛后,采用二步活化法制备活性炭.先500℃下碳化,然后以KOH为活化剂,炭碱质量比1∶2、1∶3、1∶4,炉温分别为700℃、800℃和900℃在氮气保护下活化.在炭碱比1∶4,活化温度800℃时,得到的活性炭比表面积高达3275m2/g.将得到的比表面积在1100～3200m2/g活性炭通过PdCl2超声浸渍法,水合肼还原制备纳米级钯炭催化剂,经SA、XRD、TEM等分析,得出比表面积越大,纳米钯粒子在活性炭上的分布越均匀,粒子颗粒越小.     

Preparation of high specific surface area hydroxyapatite for environmental applications

We report the preparation of hydroxyapatite in powdered form by aqueous reaction of calcium nitrate or hydroxide with phosphate ion at room temperature. With a slow maturation step of 48 h avoiding heat, the resulting products show large specific surface areas above 150 m²/g. The specific surface areas also depend on stirring speed with a maximum observed with gentle mixing. Ageing causes a decrease in specific surface area which tends to stabilize near 100 m²/g following a 1 year period. The hydroxyapatite may be spray dried and conserve interesting physical properties for environmental applications.     

高比表面积碳化钼/碳复合体的电化学性能研究

采用直接碳化法,羟丙基纤维素(HPC)、聚乙烯醇(PVA)、钼酸钾(K2MoO4)和碳酸钾(K2CO3)的混合物于900℃氢气氛围下碳化,制备了高比表面积碳化钼/碳复合体(MCCs).应用XRD、TG、SEM和电化学方法对其进行了表征和性能研究.XRD图谱表明,碳基上合成了α-Mo2C及微量Mo3C2.加入K2CO3增...     

KOH/NaOH活化法辣椒秸秆制备高表面积活性炭与表征

以废弃辣椒秸秆为原料,KOH/NaOH为活化剂,采用正交试验,研究了活化温度、时间、炭化温度及KOH/NaOH/C对吸附性能的影响,得出最佳工艺条件即活化温度为700℃、活化时间为80min、炭化温度为450℃、KOH/NaOH/C为3∶1∶1。此条件下制得的样品Langmuir比表面积高达3217.237m2/g,吸附平均孔径为3.590nm,皆高于单一KOH活化样品(SLangmuir=3159.200m2/g,D=2.672nm)。同时采用SEM和FT-IR对KOH/NaOH活化样品的表面形貌和官能团进行分析,并与单一KOH活化样品进行对照,发现它们的化学组成相似,并皆具有丰富和发达的孔隙结构,但KOH/NaOH活化样品出现更多的中孔和一定量的大孔。     

高比表面积蜂窝状活性炭对CO2的吸脱附行为

以比表面积为2621m2/g的超高比表面积活性炭为原料,酚醛树脂为粘结剂,制得比表面积为1887m2/g的蜂窝状活性炭,并考察了其对CO2的吸脱附性能.研究结果表明,在25℃/常压下,该蜂窝状活性炭对CO2的饱和吸附量为2.15mmol/g,对浓度为15％的CO2的平衡吸附量为0.96mmol/g;当采用抽真空脱附时,...     

Adsorption behaviors of some phenolic compounds onto high specific area activated carbon cloth

Adsorption of phenol, hydroquinone, m-cresol, p-cresol and p-nitrophenol from aqueous solutions onto high specific area activated carbon cloth has been studied. The effect of ionization on adsorption of these ionizable phenolic compounds was examined by studying the adsorption from acidic, basic and natural pH solutions. Kinetics of adsorption was followed by in situ UV spectroscopy over a period of 90 min. First-order rate law was found to be valid for the kinetics of adsorption processes and the rate constants were determined. The highest rate constants were obtained for the adsorption from solutions at the natural pH. The lowest rate constants were observed in basic solutions. The rate constants decreased in the order p-nitrophenol approximately m-cresol>p-cresol>hydroquinone approximately phenol. Adsorption isotherms were derived at 30 degrees C and the isotherm data were treated according to Langmuir, Freundlich and Tempkin isotherm equations. The goodness of fit of experimental data to these isotherm equations was tested and the parameters of equations were determined. The possible interactions of compounds with the carbon surface were discussed considering the charge of the surface and the possible ionization of compounds at acidic, basic and natural pH conditions.     

水热法制备高比表面积的多层笼状纳米氧化锌

采用水热法制备出具有高比表面积的多层笼状结构纳米ZnO.通过XRD、SEM、EDS、TG-DTA、N2吸附等方法对产物的结构、组成、及形貌进行了表征,初步探讨了葡萄糖与Zn2+投料比R对最终产物的形貌、比表面积、孔径及孔径分布的影响.由于该方法具有工艺简单、绿色环保,无需引入表面活性剂的优点,便于大规模生产.     

中间相沥青不熔化纤维自烧结制备高传导性炭材料研究

以中间相沥青为原料,通过带形截面喷丝板进行熔融纺丝,对所获中间相沥青纤维进行适度氧化处理,而后通过热压工艺将氧化中间相沥青纤维进行无黏结自烧结成型,并借助红外分析和扫描电镜等手段研究了不同最终氧化温度对带状沥青纤维的官能团变化与由其自烧结制备高导热炭材料的成型性及性能影响。结果表明:经260℃不熔化处理的中间相沥青纤维热压成型,能获得具有高密度、高抗弯强度和高传导性的新型炭材料,所制备材料的密度高达2.16 g/cm3,抗弯强度达到125.9MPa,电阻率和热导率分别达到0.56μΩm和830W/(m.K)。     

Sustainable porous hollow carbon spheres with high specific surface area derived from Kraft lignin

Hollow carbon spheres (HCSs) have attracted tremendous interest in recent years due to their intriguing structure-induced physicochemical properties and significant potential for numerous applications. However, the preparation of HCSs with precise structural control using a simple and scalable strategy remains challenging. In this work, hollow carbon particles having a well-defined spherical morphology were successfully produced using a green, economical, and facile spray drying method together with a carbonization process. Kraft lignin was employed as the carbon precursor in place of lignosulfonate with potassium hydroxide (KOH) as an activation agent. The high specific surface area (1536.5–2424.8 m² g^?1) with micro-mesoporous structure of HCSs can be easily tuned by controlling the mass ratio of KOH to carbon precursor. The KOH-to-lignin mass ratios were utilized below 1.5, lower than those in previous studies typically used higher than 3, which was in accordance with green chemistry principles. In addition, these HCSs have applications as electrode materials in supercapacitors for energy storage devices. With the great achievements and continuous efforts in this important field, these results suggest that our approach will open a new path for the development of advanced carbon materials and high value-added utilization of Kraft lignin as a promising material for potential applications.