Activation mechanisms on potassium hydroxide enhanced microstructures development of coke powder

Coke powder is expected to be an excellent raw material to produce activated carbon because of its high carbon content. Potassium hydroxide(KOH), as an effective activation agent, was reported to be effective in activating coke powder. However, the microstructures development in the coke powder and its mechanisms when KOH was applied were still unclear. In this study, effects of KOH on the microstructure activation of coke powder were investigated using the surface area and pore structure analyzer, scanning electron microscope(SEM) and thermogravimetry-differential scanning calorimetry-mass spectrometry(TG-DSC-MS), etc. Results revealed that the addition KOH at its lower ratio(mass ratios of KOH and coke powder in a range of 0.5 and 1) decreased the specific surface area and average lateral sizes, but sharply increased of the specific surface area to 132 m^2·g^-1 and 355 m^2·g^-1 and decreased of the space size of aromatic crystallites upon the further increase of the KOH addition amounts(ratios of KOH and coke powder in a range of 3 and 7), generating a number of new micropores and mesopores. The mechanisms study implied surface reactions between KOH and aliphatic hydrocarbon side chain and other carbon functional groups of the coke powder to destruct aromatic crystallites in one dimension and broaden pores at lower KOH addition. In the activation process, KOH was decomposed to be more active components, which can be rapidly destruct the aromatic layers in spatial scope to form developed porous carbon structures within coke powder at higher KOH addition.

Catalysis of Active Carbon Supporting Transition Metal Oxides for Pyrotechnical Reagent with Potassium Perchlorate

In order to improve the pyrotechnical reagent with potassium perchlorate,composite catalyst of active carbon supporting transition metal oxides （TMO）,Fe2O3 and CuO,were prepared and added into pyrotechnical reagent with potassium perchlorate.Accelerating rate calorimeter （ARC） was used to study the catalysis of pyrotechnical reagent which is consisted of potassium perchlorate and composite catalyst.Composite catalyst of both Fe2O3 and CuO supported by active carbon can catalyze pyrotechnical reagent with potassium perchlorate.Furthermore,it can lower the apparent activation energy and accelerate the reaction with a smaller quantity than that with Fe2O3 and CuO.The maximal reaction rate of pyrotechnical reagent with potassium perchlorate mixed with Fe2O3/active carbon and CuO/active carbon is 8.31 min-1 and 9.13 min-1,which is 1.74 times and 1.91 times of pyrotechnical reagent mixed with no catalyst;time to maximal rate was 18.99 min and 1.96 min respectively,which is lower than pyrotechnical reagent mixed with no catalyst by 86.46% and 98.67% ;the apparent activation energy is 368.10 kJ·mol-1 and 325.29 kJ·mol-1,which is lower than pyrotechnical reagent mixed with no catalyst by 31.89% and 39.81% respectively.

Potassium-decorated active carbon supported Co-Mo-based catalyst for water-gas shift reaction

The effect of potassium-decoration was studied on the activity of water-gas shift （WGS） reaction over the Co-Mo-based catalysts supported on active carbon （AC）, which was prepared by incipient wetness co-impregnation method. The decoration of potassium on active carbon in advance enhances the activities of the CoMo-K/AC catalysts for WGS reaction. Highest activity （about 92% conversion） was obtained at 250 ？ C for the catalyst with an optimum K 2 O/AC weight ratio in the range from 0.12 to 0.15. The catalysts were characterized by TPR and EPR, and the results show that activated carbon decorated with potassium makes Co-Mo species highly dispersed, and thus easily reduced and sulfurized. XRD results show that an appropriate content of potassium-decoration on active carbon supports may favors the formation of highly dispersed Co 9 S 8 -type structures which are situated on the edge or a site in contact with MoS 2 , K-Mo-O-S, Mo-S-K phase. Those active species are responsible for the high activity of CoMo-K/AC catalysts.

Phenol Removal from Water with Potassium Permanganate Modified Granular Activated Carbon

In order to improve adsorption capacity of granular activated carbon (GAC), potassium permanganate was used to react with GAC to change the surface properties and improve the adsorption capacity of GAC. By batch experiments, improvement of adsorption capacity of potassium permanganate modified GAC (GACM) was studied. The influence of adsorption time, temperature, ratio of phenol with GAC/GACM, initial concentration of phenol and pH on adsorption efficiency of GACM was studied. The results showed that modified by potassium permanganate, the adsorption capacity of GAC improved to a higher level. The removal efficiency of phenol increased to about 20%.

Preparation and modification of activated carbon for benzene adsorption by steam activation in the presence of KOH

A series of activated carbons from Taixi anthracite were prepared by steam activation in the presence of KOH and then they were modified by different methods. The regulation of porosity and the modification of surface chemistry were carried out with the aim to improve the benzene adsorption capacity of activated carbon. The influences of KOH and activation process parameters including activation temperature, activation time and steam flow rate on porosity of activated carbon were evaluated, and the effect of modification methods on surface chemistry was investigated. Also, the relationship between benzene adsorption capacity and porosity and surface chemistry was analyzed. Results show that activation temperature is the dominant factor in the activation process; the introduction of KOH into the raw material can enhance the reactivity of char in activation process, meanwhile it shows a negative effect on the porosity development, especially on the mesopore development. Results of FTIR analysis indicate that anthracite-based activated carbon with condensed aromatics and chemically inert oxygen does not present the nature to be surface modified. Besides, benzene adsorption capacity has an approximate linear relationship with surface area and in our preparation, benzene adsorption capacity and surface area of activated carbon are up to 1210 m 2 /g and 423 mg/g, respectively.

Preparation of Solid Waste-Based Activated Carbon and Its Adsorption Mechanism for Toluene

Regenerated activated carbon(RAC)samples were prepared by carbon activation using waste activated carbon from solid waste resources as the carbon source precursor coupled with adding alkaline additives,and then were further modified by potassium ferrate to finally prepare high-performance carbon for VOCs adsorption.At the same time,the samples before and after modification were systematically studied through characterization techniques such as SEM,Raman spectrometry,FT-IR,XPS,and dynamic/static adsorption.The results showed that the specific surface area and pore volume of the RAC after modification by the strong oxidant potassium ferrate increased by 1.4 times;the degree of defects was enhanced and the content of oxygen-containing functional groups on the surface increased significantly.Among them,the sample modified with potassium ferrate for 24 h had the best dynamic toluene adsorption performance(375.5 mg/g),and the dynamic adsorption capacity was twice that of the original sample(192.8 mg/g).The static adsorption test found that the maximum adsorption capacity of RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h was 796 mg/g,which indicated that the potassium ferrate modification treatment could significantly increase the VOCs adsorption performance of RAC.In addition,through consecutive toluene adsorption-desorption cycle tests,it was found that the RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h sample still retained 91%of adsorption activity after the fifth regeneration cycle.This indicates that RAC-6%K_(2)FeO_(4)+H_(2)SO_(4)-24h has good cycle stability and great application value for the efficient purification of industrial waste VOCs gas.

Preparation and Characterization of Activated Carbon Based on Wood (<i>Acacia auriculeaformis</i>, Côte d’Ivoire)

The objective of this work is to prepare one of the best activated carbon (CA) based on wood (Acacia auriculeaformis). The chemical activation method was used for varying the chemical agent namely phosphoric acid H3PO4 (CAA), sodium hydroxide NaOH (CAB), and sodium chloride NaCl (CAS). The physico-chemical analysis of the three activated carbons indicated that, under the conditions of preparation, the activated carbons possess activation efficiencies lower than 50% (41.81% for CAA, 26.25% for CAB and 48.87% for CAS), low ash content (CAA: 5.00%, CAB: 14.90 and CAS: 6.60%) and iodine values ranging from 190.35 mg/g to 380.71 mg/g, suggesting that the good quality of the prepared activated carbon. The surface functional groups using Boehm test and the zero point charge (pHZPC) methods confirmed the acidic, basic and neutral character for CAA, CAB and CAS respectively (CAA: pHZPC = 4.8, CAB: pHZPC = 8.2, CAS: pHZPC = 6.8). The surface specific areas were determined through the liquid phase adsorption of acetic acid and methylene blue using the Langmuir method and BET analysis. Also, the porosity was determined. The BET surface areas of CAA, CAB and CAS were respectively 561.60 m2/g, 265.00 m2/g and 395.40 m2/g. The influence of chemical activation agent on pores formation was confirmed by scanning electron microscopic (SEM) analysis. CAA was selected as the best activated carbon because of its good surface area and good pore volume compared to those found in the literature. Therefore, its application as an adsorbent for effluents treatment could be explored. In addition, the best activating agent for coal from Acacia auriculeaformis was found to be phosphoric acid.

Autohydrolysis treatment of bamboo and potassium oxalate(K_(2)C_(2)O_(4))activation of bamboo product for CO_(2) capture utilization

Typically,the hydroxide agents,such as sodium hydroxide and potassium hydroxide,which have corrosive properties,are used in the carbon activation process.In this study,potassium oxalate(K_(2)C_(2)O_(4)),a less toxic and non-corrosive activating reagent,was used to synthesize activated carbon from the solid residue after autohydrolysis treatment.The effect of the autohydrolysis treatment and the ratio of the K_(2)C_(2)O_(4)/solid residue are presented in this study.Moreover,the comparison between the activated carbon from bamboo and biochar from the solid residue are also reported.The resulting activated carbon from the solid residue exhibited a high surface area of up to 1432 m^(2)·g^(-1) and a total pore volume of up to 0.88 cm^(3)·g^(-1).The autohydrolysis treatment enhanced the microporosity properties compared to those without pretreatment of the activated carbon.The microporosity of the activated carbon from the solid residue was dominated by the pore width at 0.7 nm,which is excellent for CO_(2) storage.At 25℃ and 1.013×10^(5) Pa,the CO_(2) captured reached up to 4.1 mmol·g^(-1).On the other hand,the ratio between K_(2)C_(2)O_(4) and the solid residue has not played a critical role in determining the porosity properties.The ratio of the K_(2)C_(2)O_(4)/solid residue of 2 could help the carbon material reach a highly microporous textural property that produces a high carbon capture capacity.Our finding proved the benefit of using the solid residue from the autohydrolysis treatment as a precursor material and offering a more friendly and sustainable activation carbon process.

功能化 MgFe-LDH吸附环丙沙星的研究

该文采用水热法将镁铁层状双金属氢氧化物(MgFe-LDH)负载到活性炭纤维(ACF)上,制得MgFe-LDH/ACF(MFLA),并将ACF和MFLA作为吸附剂用于考察溶液初始pH、吸附时间、反应温度等对环丙沙星(CIP)吸附效果的影响。结果表明,MgFe-LDH已被固定在ACF上,且在Mg^(2+)和Fe^(3+)摩尔比为3∶1时制备的最佳MFLA(3-MFLA)晶型更完整。当CIP的初始浓度为20 mg/L时,ACF和3-MFLA分别在360、60 min时达到吸附平衡,其吸附量分别为3.00 mg/g和19.31 mg/g。拟二级动力学模型和Langmuir等温线模型均可准确地描述ACF和3-MFLA对CIP的吸附行为。CIP主要通过静电引力、氢键、离子交换、π-π相互作用和金属-碳π相互作用被3-MFLA吸附。此外,抗干扰实验、循环再生实验及固定床动态吸附实验结果均表明3-MFLA具有较高的实际应用潜力。

碳化硼陶瓷材料试样分解方法探讨

碳化硼陶瓷材料被应用于航空航天、核工业和工程陶瓷等方面。鉴于化学成分检测结果的准确性与分解方法不可分割,有合理高效的分解方法才能得出真实的化学成分含量。本文对碳化硼陶瓷材料的分解方法进行对比,以碳酸钙为熔剂在高温下对碳化硼进行分解。结果表明,碳酸钙熔样方法测得的碳化硼结果更稳定,熔样方式更简单。

酸处理对KF/AC催化合成洁净高效灭火剂CF_(3)I的影响

为了探究催化剂制备过程中不同酸处理对催化性能的影响,降低三氟碘甲烷(CF_(3)I)生产成本以推进其作为灭火剂在民航领域的应用,采用无机酸(HNO_(3)、HCl、H_(2)SO_(4))和有机酸(CH_(3)COOH、CF_(3)COOH、C_(6)H_(8)O_(7))分别对活性炭(AC,activated carbon)进行预处理,以处理后的AC作为载体制备一系列KF/AC催化剂,研究其在相同工况下催化合成的性能(以CF_(3)I收率计)。结果表明:除柠檬酸(C_(6)H_(8)O_(7))外,无机酸和有机酸处理均会使AC微孔孔容增加;不同酸处理均会增加AC表面羧基和催化剂碱性位点数量;K元素在微孔中的负载量对催化剂的性能起关键作用;有机酸处理可使微孔负载量达到未处理催化剂的3倍以上,效果明显优于无机酸处理;三氟乙酸(CF_(3)COOH)处理对催化性能提升最明显。

高锰酸钾复合盐和粉末活性炭去除原水中铊的试验研究

为应对未来可能发生的水源铊污染,开展除铊试验研究。结果表明,在水厂常规处理工艺的基础上,调节原水的pH到9.0,投加8.0 mg/L的高锰酸钾复合盐和50 mg/L粉末活性炭,可以把铊浓度从0.001 mg/L降低到0.00010 mg/L。处理后上清液中铝和锰的浓度也都没有超标。

A Computational Study on the Mechanism for the K_2CO_3-catalyzed Reaction of Carbon Dioxide and 1-Chlo-2-propanol

The microcosmic reaction mechanism of K2CO3-catalyzed 1-chlo-2-propanol and carbon dioxide has been investigated by density functional theory（DFT） at the GGA/PW91/DNP level.We optimize the geometric configurations of reactants,intermediates,transition states,and products.The energy analysis calculation approves the authenticity of intermediates and transition states.According to our calculations,four feasible reaction pathways are found.The main pathway of the reaction is ReA → IMA1 → TSA1 → IMA2 → IMA5 → TSA5 → P.Besides,we also in-vestigate the reaction mechanism of 1-chlo-2-propanol and carbon dioxide without K2CO3-catalyzation by the same theory and level.The computational results indicate that the activation barrier with K2CO3-catalyzed is smaller than the activation barrier without K2CO3-catalyzed.That is to say,K2CO3 can promote the reaction to give the product in a high yield,which is in agreement with the experimental results.

Calcinated Activated Carbon/MgFe-Layered Double Hydroxides for Enhanced Adsorption of Methyl Orange

Series of activated carbon(AC)modified MgFe-layered double hydroxides(LDH/ACs)were synthesized using ultrasonic-assisted co-precipitation method.Herein the mass ratio of Mg/Fe-LDH and AC was varied at 1.55,2.34,and 2.86,respectively.The calcinations of corresponding LDH/ACs were obtained at 723 K for 5 h and named as LDO-AC-1.55,LDO-AC-2.34 and LDO-AC-2.86,respectively.These products were characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET)measurements and scanning electron microscopy(SEM).LDO-ACs were applied for the removal of methyl orange(MO).The result showed that aggregation degree of MgFe-LDH decreased in the existence of AC.The pore sizes of LDO-AC-1.55,LDO-AC-2.34 and LDO-AC-2.86 markedly increased with the sharp decreasing of surface area.The values of the statured adsorption capacity of LDO-AC-1.55,LDO-AC-2.34 and LDO-AC-2.86 were obviously higher than those of MgFe-layered double hydroxides fabricated by traditional method(LDO0).The mechanism for the enhanced adsorption may be that the loose macrospore structure of LDO-AC-1.55,LDO-AC-2.34 and LDO-AC-2.86 abbreviates the diffusion resistance and bore repulsive force of MO molecular coupled with its space confinement effect in contrast with LDO0,which is favor for the free self-assembly of MO to form intercalation compound.MO-loaded LDO-AC-2.34 was regenerated by calcination and reused several times,still retaining its original adsorption capacity.

电位滴定法测定氯代碳酸乙烯酯中的总氯

建立电位滴定法测定氯代碳酸乙烯酯(CEC)中总氯含量的分析方法,用于指导工业生产。以乙醇为溶剂,增加CEC和水溶液的互溶性,通过在氢氧化钾溶液(200 g/L)中沸水浴加热5 min,使CEC样品中不同形态的含氯化合物全部碱解成氯化钾;以银电极为测量电极,饱和甘汞电极为参比电极,用硝酸银标准溶液滴定氯离子,测定总氯的质量分数。考察碱的类型、浓度、加入量和碱解时间的影响。样品加标回收率为99.75%~100.32%,相对标准偏差(RSD)小于0.5%(n=9)。方法操作简单,精密度和准确度符合要求,对产品质量控制和生产有重要意义。

高比表面芦苇活性炭的制备及其对亚甲基蓝的吸附性能研究

以芦苇秸秆为原料,KOH为活化剂,通过单因素实验及正交实验优化芦苇活性炭的制备工艺,测定最优工艺下制备的活性炭对亚甲基蓝的吸附性能和吸附动力学,并进行红外光谱分析、BET比表面积结构分析。结果表明,最佳制备工艺为700℃、20%KOH质量分数、3 h时制备的芦苇活性炭。该活性炭理论最大吸附量为648.77 mg/g,Langmuir等温吸附曲线(R 2=0.9820)和二级动力学吸附曲线(R 2=0.9808)能够更好地描述吸附过程。红外光谱分析结果表明,所制备的活性炭中生成了酰胺基团。BET比表面积测定结果表明,最优工艺下制备的芦苇活性炭的比表面积为1183.40 m^(2)/g,总孔容为0.59 cm 3/g,平均孔径为2.00 nm。

花生壳制备活性炭及其应用研究

为解决农业废弃物花生壳利用价值过低导致浪费且污染环境的问题,以废弃花生壳为原料制备生物质活性炭并应用于染料废液吸附方面.以不同浓度的碳酸钾溶液为活化剂,在不同的炭化温度和炭化时间条件下制备活性炭材料,探讨其在不同条件下对染料废液龙胆紫溶液吸附性能,并获得制备花生壳基活性炭最佳的工艺条件.研究结果表明:当碳酸钾浓度为50%,炭化时间为100min,炭化温度为500℃时所制备的活性炭对染料废液龙胆紫吸附性能最优,去除率高于99%.该研究为利用花生壳制备生物质活性炭并应用于吸附方面提供了实验数据.

柔性活化碳纤维膜用于钾离子电池负极材料

钾离子电池是一种安全、可靠、低成本的新型电化学储能器件,但其负极存在容量小、动力学缓慢和循环稳定性差等问题。本工作利用静电纺丝技术结合空气活化方法制备了活性碳纤维柔性自支撑电极。活性碳纤维的三维多孔道网络结构有利于提高电极与电解液的浸润性和促进钾离子扩散。同时,氧和氮的共掺杂提供了额外的氧化还原位点,提高了储钾容量。作为钾离子电池负极材料,优化后的活性碳纤维在0.05 A·g^(-1)的电流密度下平均可逆容量达到363.7 mAh·g^(-1),且在1.0 A·g^(-1)的电流密度下经过2500次循环后容量保持率为88.5%。

水蒸气和KOH二次活化对活性炭孔隙结构的影响研究

以商业活性炭为原料,采用水蒸气和KOH为活化剂,在不同活化条件下制备二次活化样品。用DFT方程考察活性炭孔径的变化;用FT-IR技术对活性炭表面官能团进行分析表征;采用XRD技术测试活性炭中的乱层结构。结果表明:无论何种活化方式,延长活化时间和提高活化温度,均有利于制备高比表面积且孔径发达的活性炭;化学二次活化较物理活化更易制得高比表面积且孔径发达的活性炭,且两种活化方式制备的活性炭的孔结构存在明显的差异;在适宜的条件下,KOH二次活化制备的活性炭在孔径<4.00 nm的范围内孔结构发达,孔径在4.00 nm~8.00 nm出现明显的分布峰,且石墨化结构破坏严重。

半干旱区水钾互作对春玉米碳代谢及产量的影响

采用裂区试验设计,分别设置3个灌溉水平[灌溉定额50(W1)、150(W2)、250 mm(W3)]和3个钾素营养水平[不施钾(K0)、施K2O 80 kg·hm^(-2)(K1)和施K2O 120 kg·hm^(-2)(K3)],通过田间试验,探究不同灌溉、施钾水平对膜下滴灌春玉米碳代谢及产量的影响。结果表明:水钾互作能显著提高玉米产量,在同一灌溉水平下,玉米碳代谢关键酶活性整体表现为K1依次高于K2、K0,其中对核酮糖二磷酸羧化酶活性影响最大,K1较K2、K0分别提高8.96%和42.89%,在同一钾素营养水平下,玉米碳代谢关键酶活性表现为W3依次高于W2、W1;其中K1条件下,蔗糖磷酸合成酶提高最多,W3分别较W1、W2提高30.50%和2.89%。水钾互作对春玉米碳代谢关键酶活性表现出显著的交互作用。综合而言,玉米产量及碳代谢关键酶活性会随着灌溉水平升高而增强;在一定钾素水平内,碳代谢关键酶活性及产量会随着钾素营养水平增加而增加,但过高的钾素水平会抑制酶活性及产量的提高。在半干旱区玉米生产实践中灌溉150 mm、施钾80 kg·hm^(-2),可使春玉米的碳代谢强度显著增强,并且能获得较高产量。