STUDIES ON THE DYNAMIC COMPETITIVE ADSORPTION OF ORGANIC VAPORS ON THE ACTIVATED CARBON FIBERS ACTIVATED WITH PHOSPHORIC ACID

The dynamic competitive adsorption behaviors of different binary organic vapor mixtures on ACF-Ps under different operation conditions were investigated by gas chromatography in this paper. The studied mixtures included benzene/toluene, toluene/xylene, benzene/isopropylbenzene, ethyl acetate/toluene and benzene/ethyl acetate. Experimental results show that various ACF-Ps, as with ACF-W, can remove both vapors in binary vapor mixtures with over 99% of removal efficiency before the breakthrough point of the more weakly adsorbed vapor. In dynamic competitive adsorption, the more weakly adsorbed vapor not only penetrates early, but also will be displaced and desorbed consequently by stronger adsorbate and therefore produces a rolling up in the breakthrough curve. The ACF-Ps prepared at different temperatures have somewhat different adsorption selectivity. The feed concentration ratio of vapors, the length/diameter ratio and the thick of bed have effect on competitive adsorption. The competitive adsorption ability of a vapor is mainly related to its boiling point. Usually, the higher the boiling point, the stronger the vapor adsorbed on ACF-P.

Preparation of activated carbon from sunflower straw through H_(3)PO_(4) activation and its application for acid fuchsin dye adsorption

With the development circular economy, the use of agricultural waste to prepare biomass materials to remove pollutants has become a research hotspot. In this study, sunflower straw activated carbon (SSAC) was prepared by the one-step activation method, with sunflower straw (SS) used as the raw material and H3PO4 used as the activator. Four types of SSAC were prepared with impregnation ratios (weight of SS to weight of H3PO4) of 1:1, 1:2, 1:3, and 1:5, corresponding to SSAC1, SSAC2, SSAC3, and SSAC4, respectively. The adsorption process of acid fuchsin (AF) in water using the four types of SSAC was studied. The results showed that the impregnation ratio significantly affected the structure of the materials. The increase in the impregnation ratio increased the specific surface area and pore volume of SSAC and improved the adsorption capacity of AF. However, an impregnation ratio that was too large led to a decrease in specific surface area. SSAC3, with an impregnation ratio of 1:3, had the largest specific surface area (1 794.01 m2/g), and SSAC4, with an impregnation ratio of 1:5, exhibited the smallest microporosity (0.052 7 cm3/g) and the largest pore volume (2.549 cm3/g). The adsorption kinetics of AF using the four types of SSAC agreed with the quasi-second-order adsorption kinetic model. The Langmuir isotherm model was suitable to describe SSAC3 and SSAC4, and the Freundlich isotherm model was appropriate to describe SSAC1 and SSAC2. The result of thermodynamics showed that the adsorption process was spontaneous and endothermic. At 303 K, SSAC4 showed a removal rate of 97.73% for 200-mg/L AF with a maximum adsorption capacity of 2 763.36 mg/g, the highest among the four types of SSAC. This study showed that SAAC prepared by the H3PO4-based one-step activation method is a green and efficient carbon material and has significant application potential for the treatment of dye-containing wastewater.

Phosphoric Acid-assisted Pretreatment Strategy for the Rational Synthesis of Lignin-derived Hierarchical Porous Carbon Toward High-performance Supercapacitors

In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials derived from lignin. The introduction of H3PO4, cross-linked with lignin sources generated phosphate(and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char(IC)with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators,thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area(SSA) of 1345.1 m^2/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g(in a threeelectrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.

Catalytic activity of phosphorus and steam modified HZSM-5 and the theoretical selection of phosphorus grafting model

The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction （XRD） results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption （TPD） of ammonia. The oxidation state of phosphorus shown by XPS is ＋5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.

Preparation and Characterization of Activated Carbons from Asparagus Palm (Laccosperma robustum) Bark by Chemical Activation with H3PO4 and KOH

The present work deals with the preparation and characterization of activated carbons from the bark of the asparagus palm (Laccosperma robustum) by chemical activation with phosphoric acid and potassium hydroxide. The process was optimized on the basis of the analysis of the iodine number, methylene blue number and activated carbons yield as a function of the preparation parameters (concentration of the activating agents and the pyrolysis temperature). It emerges that the pyrolysis temperature and the concentration of activating agents influence the activated carbons preparation process. Their values were 500°C and 20% respectively for activated carbon with H3PO4 (ACP) and 700°C and 1.5% for activated carbon with KOH (ACK). The iodine numbers obtained were 850.26 mg/g for ACP and 865.49 mg/g for ACK. The methylene blue numbers obtained were 149.35 mg/g for ACP and 149.25 mg/g for ACK. The activated carbons yields obtained were 25% for ACP and 5.9% for ACK. The activated carbons prepared under optimal conditions have shown the pH of zero-point charge (pHzpc) of 4.4 and 7.0 for ACP for ACK respectively. The determination of the surface functions revealed that ACP had a strong acidic character while ACK had neutral character. The Fourier transformed infrared spectroscopy also showed the presence of different functional groups on the surface of the precursor and activated carbons.

Peanut Shell Activated Carbon： Characterization, Surface Modification and Adsorption of Pb^2＋ from Aqueous Solution

Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell （PAC） was used for the removal of Pb^2＋ from aqueous solution. The impacts of the Pb25 adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared （FTIR） spectroscopy, X-ray photoelectron spectroscopy （XPS）, Boehm titration. The textural properties （surface area, total pore volume） were evaluated from the nitrogen adsorption isotherm at 77 K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon （GAC） showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% （by mass）] modified PAC has larger adsorption capacity of Pb^2＋ from aqueous solution （as much as 35.5 mg·g^-1）. The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.

Effects of mechanical activation on the kinetics of terbium leaching from waste phosphors using hydrochloric acid

The effect of mechanical activation （MA） on the kinetics of terbium （Tb） leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy and reaction order, were determined using the shrinking-core model and the Arrhenius equation. Results obtained from experiments with different concentrations of HC1 and under different leaching temperatures were used for the determinations. The impacts of factors such as rotational speed, HC1 concen- tration and leaching temperature on the leaching rate of Tb were also discussed. The results showed that MA could dramatically increase the leaching rate of Tb from waste phosphors, and the apparent reaction rate （kap） of leaching was accelerated as well. For inactivated waste phosphors, the apparent activation energy （Eap） was 52.82±3.95 kJ/mol, indicating that the rate-controlling step of the leaching process was the chemical reaction. The Eap dropped to 25.96 ±3.90 kJ/mol and 10.96±2.79 k J/tool when the waste phosphors were mechanically activated at rotational speeds of 400 and 600 r/min, respectively; the leaching process transformed to a hybrid （chemical-reaction and diffusion） control process, and even a reagent-diffusion （through the product layer） control process. The apparent reaction order for Tb leaching from 400 r/min-activated waste phosphors was 2.49±0.11, and it decreased to 1. 16±0.17 when the rotational speed of 600 r/min was used. Kinetics results indicated that MA could make Tb leaching occur spontaneously, and thc activation intensity of waste phosphors was strengthened with higher rotational speed.

High-valued Utilization of China Fir Sawdust Extracted Essential Oil:Preparation of Granular Activated Carbons for n-Butane Adsorption

[Objective] The aim was to study on the high-valued utilization of China Fir sawdust extracted essential oil.[Method] In the field of fir essential oil extraction,the processed China fir sawdust was used to prepare low-valued products.The high-valued utilization of China fir sawdust extracted essential oil(CFSEEO),namely as a precursor to prepare granular activated carbons(GACs),was attempted.The materials were characterized by ultimate analysis,SEM and XRD.[Rusult] A butane working capacity(BWC)of 14.3 g/100 ml was obtained by using the GACs with apparent density of 0.25 g/ml.It was available to introduce the technology of extracting essential oil from the China fir sawdust(CFS)in the industrial production process of activated carbons with high BWC(12.0-16.5 g/100 ml)and high surface area(2 000-2 630 m2/g)using phosphoric acid based on previous studies of the authors.[Conclusion] The resulting carbon prepared with the raw materials containing lower moisture exhibited a better property on n-butane adsorption.

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.

海藻渣多孔炭的制备及其电化学性能研究

海藻渣作为海藻提取海藻酸钠的废弃物,来源广泛但是利用率不高。以海藻废渣为前驱体,提供炭源,以H_(3)PO_(4)为活化剂,采用一步炭化活化法制备海藻渣基多孔炭。当海藻渣与质量分数50%的H_(3)PO_(4)浸渍比为2∶1,活化温度450℃,活化时间120 min时,所制得的海藻渣基多孔炭材料孔隙结构最为丰富,其比表面积高达428.30 m^(2)/g,总孔体积为0.56 cm^(3)/g,微孔占比32.14%。对最优条件下制得的海藻渣基多孔炭电化学性能进行三电极体系测试,结果表明最大比电容为123.40 F/g,同时兼具良好倍率性能、低阻抗和循环稳定性。在此基础上,进一步组装了对称超级电容器,两电极体系的测试结果亦表现出良好的倍率性能与充放电可逆性,其中单个器件最大能量密度可达10.75 Wh/kg。可见,无论是三电极还是两电极体系,海藻渣基多孔炭材料的超级电容性能均具有较好的储能优势和实际应用潜能。

磷酸法低灰分活性炭的制备研究

磷酸活化法是目前工业上生产生物质基活性炭的主要方法,但较高的灰分含量限制其在医药、食品等高端领域应用。基于此,以湿法磷酸为活化剂、废木屑为碳源,研究活化条件(温度、时间等)和洗涤条件(介质、酸浓度、温度等)对活性炭灰分及性能的影响,运用TG、FT-IR、XRD、SEM和TEM等表征方法分析活性炭的表面性质和微观结构。结果表明,难溶性磷酸盐是活性炭灰分产生的主要因素,通过控制活性炭制备和洗涤工艺可调控难溶性磷酸盐含量,从而调控活性炭灰分、碘值和亚甲蓝值。获得最佳工艺条件:活化温度为500℃、活化剂H_(3)PO_(4)质量分数为70%、酸屑质量比为2∶1、活化时间为60min及N_(2)气氛保护;洗涤液用量为100mL、洗涤介质为H_(3)PO_(4)、H_(3)PO_(4)质量分数为20%、洗涤温度为80℃及洗涤时间为60 min。最佳工艺条件下制备的活性炭灰分为1.07%、碘值为1241.4 mg/g、亚甲蓝值为285 mg/g、比表面积为2290 m^(2)/g,表明该技术制备的活性炭具有应用于食品、医药等高端行业领域的潜质。

磷酸三丁酯脱色活性炭热解再生研究

以磷酸三丁酯(TBP)脱色后的粉末废活性炭(WAC)为材料,利用高温热解的方法,以亚甲基蓝吸附量和碘值为评价指标,研究了再生温度、再生时间、再生次数对废活性炭再生效果的影响。实验结果表明,WAC的再生最优条件为500℃下再生90 min,再生4次仍能恢复其82%的亚甲基蓝吸附性能及67%的碘吸附性能。通过同步热分析仪(TG-DSC)测定活性炭的失重、吸热和放热情况;借助比表面积及孔径分析仪、傅里叶红外光谱仪(FT-IR)、扫描电子显微镜(SEM)等测试手段对再生前后的活性炭进行表征,从而验证其再生效果。对废活性炭的热解机理进行了综合分析,为湿法磷酸净化工艺流程中磷酸三丁酯脱色活性炭的热解再生提供了理论指导。

偏高岭土-磷酸基地聚物的力学性能及微观结构分析

为明确不同浓度磷酸溶液激发偏高岭土的最佳液固比(L/S)值,本文设置了4、5、6、7、8 mol·L^(-1)五组磷酸溶液以及0.6、0.7、0.8、0.9四种L/S值来制备偏高岭土-磷酸基地聚物(MPAG)。以MPAG的7和28 d抗压、抗折强度作为评价指标,探究上述预设变量对MPAG力学性能的影响,进一步研究每组浓度最佳L/S值试样经硫酸盐侵蚀后的抗压强度,并对MPAG物相组成和微观形貌进行表征及分析。结果表明:MPAG主要由无定形磷酸铝相组成;当磷酸溶液浓度为4~6 mol·L^(-1)时,L/S值为0.6时,制得的试样抗压强度更大,溶液浓度增大至7或8 mol·L^(-1)时,推荐L/S值为0.7;MPAG抗硫酸盐侵蚀能力佳,浸泡28 d后抗压强度保留率达84%~93%;任一L/S值下,使用6 mol·L^(-1)磷酸溶液制备的试样均取得该L/S值的最大抗折强度;当L/S值为0.6时,28 d最大抗折强度为6.80 MPa。本文研究结果可为MPAG的制备及应用提供参考。

柱状活性炭固体磷酸的制备及其催化性能的研究

为了降低酯化反应实验教学的安全隐患同时也为了增强学生的绿色环保意识,可采用固体酸替代强腐蚀性的浓硫酸来催化乙酸乙酯的合成。实验采用直接浸渍法和二次煅烧法制备了柱状活性炭固体磷酸,以磷酸负载量为评价指标优化了制备条件,利用二次煅烧后的柱状活性炭固体磷酸催化乙酸乙酯的合成并对其反应条件进行了优化。结果表明柱状活性炭固体磷酸的最佳制备条件为煅烧温度为260℃,活性炭的浸渍时间为25 h,煅烧时间为4 h。经SEM分析,二次煅烧后的柱状活性炭固体磷酸结构更加蓬松,更有利于酯化反应的进行。在最佳反应条件下,乙酸乙酯的产率能达到80.4%,重复使用3次后乙酸乙酯的产率依然可达41.7%。实验引导学生设计并制备了具有较高催化活性的固体磷酸催化剂,该过程不但可在学生心中牢牢树立安全第一、结果与环保并重的理念,也为酯化反应的绿色化改进提供有意义的借鉴。

Influences of additives on phosphoric acid treatment of titanium dioxide as a novel white pigment

Titanium dioxide is a photocatalytically active substance used as a white pigment for cosmetics.In sunlight,titanium dioxide catalyzes decomposition of a certain amount of sebum on the skin by ultraviolet radiation.Herein,a novel white pigment for use in cosmetics was developed from titanium dioxide and phosphoric acid at pH=4 with and without glycerin,sodium lactate,lactic acid,and urea.The chemical composition,powder properties,photocatalytic activity,color phase,and smoothness of the samples were studied.Addition of glycerin led to a decline in the intensity of the X-ray diffraction(XRD)peak of TiO_(2) relative to that of the other samples.The particle size of the materials prepared with and without additives was 0.3μm;however,extensive aggregation was observed in the obtained materials.The photocatalytic activity of TiO_(2) was inhibited by phosphoric acid treatment.The materials prepared with sodium lactate,lactic acid,and glycerin exhibited higher photocatalytic activity than that prepared without additives.The obtained materials showed a high reflectance in the range of visible light,and the L^(*)values in L^(*)a^(*)b^(*) color space were high(where L^(*)defines lightness,a^(*) denotes the red/green value,and b^(*) the yellow/blue value).These results indicate that the samples prepared in this work are suitable for use as white pigments.

Preparation and Characterisation of Corncob-Based Biosorbents in Côte d’Ivoire

This study focuses on the preparation of corncob-based biosorbents. The chemical impregnation method was used to vary the chemical agent namely phosphoric acid H3PO4 (BA) and sodium hydroxide NaOH (BB). The physicochemical analysis of the two biosorbents indicated that under the same preparation conditions, the bio-sorbents have after activation yields lower than 50% (24.37% for BB and 49.09% for BA). In addition, the biosorbents have iodine index values between 444.17 mg/g and 418.79 mg/g and specific surfaces related to the adsorption of methylene blue ranging from 18.54 m2/g to 19.70 m2/g. The study of surface functional groups by using the Boehm test and pH zero point charge (pHPZC) confirmed the acidic nature of BA and BB biosorbents with respective values pHPZC = 4.01 and pHPZC = 4.90. The Langmuir method and BET analysis determined the specific surface areas by liquid phase adsorption of methylene blue as well as the porosity. The BET surface areas of BA and BB obtained are 72.01 m2/g and 63.10 m2/g respectively. The influence of the chemical activating agent on the formation of pores was confirmed by electron microscopy (SEM) analysis. From this study, it is found that the best activating agent for corn cobs was found to be phosphoric acid because the BA biosorbent was revealed to be the most favourable due to its surface area and good pore volume which are high compared to sodium hydroxide NaOH. Moreover, their application as adsorbent for effluent treatment could be explored.

MoVO/P-AC催化剂组成调控及其在甘油气相高值化转化中的应用

甘油是重要的生物质平台化合物之一,其制取高附加值丙烯醛、丙烯醇等工艺开发有助减少石化资源的利用和碳排放。本文以磷酸处理的活性炭(AC)为载体,采用过量浸渍法制备MoVO/P-AC(Cat^(x),x=Mo∶V,n∶n)催化剂用于甘油气相脱水反应中,并采用BET、XRD、XPS、H_(2)-TPR和NH 3-TPD对催化剂物理化学性质进行表征。结果表明:Cat^(x)主要存在于高分散的MoO_(3)-V_(2)O_(5)和(VO)_(2)P_(2)O_(7)中,且与P-AC载体之间存在强相互作用,Cat^(x)表面仅存在弱酸和中强酸中心;Mo/V用量调控了Cat^(x)中活性组分间的协同作用、氧化还原能力和酸性强度。Cat^(x)对甘油催化转化性能(丙烯醛、丙烯醇和乙醛的收率)高低顺序为:Cat^(5.0)>Cat^(4.0)>Cat^(6.0)>Cat^(3.0)>Cat^(2.0)。310℃反应时,Cat^(5.0)上甘油的转化率达到85.9%,丙烯醛、丙烯醇的选择性分别为51.8%、10.5%,且展现出较好的再生性,为甘油制丙烯醛和丙烯醇高性能催化剂开发提供理论基础和依据。

改性玉米芯生物炭的制备及其在废水中的应用

生物炭具备独特的多孔结构和丰富的表官能团,为废水处理、土壤改良、农作物增收、环境修复等提供一类有效的技术材料。本文选取玉米芯为实验材料,采用高浓度磷酸浸泡活化制备玉米芯生物炭,用碘值确定生物炭的最佳制备工艺条件,最后通过扫描电镜(SEM)、X射线衍射(XRD)对最佳制备条件的生物炭进行性能表征分析,并将制备的生物炭去处理模拟废水中氨氮,结果表明:污水中投加改性后的生物炭对氨氮的去除具有良好的处理效果。