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.

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.

Regeneration of Acid Orange 7 Exhausted Granular Activated Carbon Using Pulsed Discharge Plasmas

In this paper, a pulsed discharge plasma （PDP） system with a multi-needle-to-plate electrodes geometry was set up to investigate the regeneration of acid orange 7 （AO7） exhausted granular activated carbon （GAC）. Regeneration of GAC was studied under different conditions of peak pulse discharge voltage and water pH, as well as the modification effect of GAC by the pulse discharge process, to figure out the regeneration efficiency and the change of the GAC structure by the PDP treatment. The obtained results showed that there was an appropriate peak pulse voltage and an optimal initial pH value of the solution for GAC regeneration. Analyses of scanning electron microscope （SEM）, Boehm titration, Brunauer-Emmett-Teller （BET）, Horvath-Kawazoe （HK）, and X-ray Diffraction （XRD） showed that there were more mesopore and macropore in the regenerated GAC and the structure turned smoother with the increase of discharge voltage; the amount of acidic functional groups on the GAC surface increased while the amount of basic functional groups decreased after the regeneration process. From the result of the XRD analysis, there were no new substances produced on the GAC after PDP treatment.

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.

Combination of adsorption and biodegradation processes for textile effluent treatment using a granular activated carbon-biofilm configured packed column system

The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the deeolodzation of azo dye Acid Orange 7-containing wastewater.The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon(GAC)through attachment.The GAC-biofilm configured packed column system showed the ability to decolorize 10...

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.

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.

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 Citric Acid Concentration and Activation Temperature on the Synthesis of Carbon Nanotubes

A series of Ni-La-Mg catalyst samples were prepared by citric acid complex method, and carbon nanotubes were synthesized by catalytic decomposition of CH4 on these catalysts. The effects of the citric acid concentration and the activation temperature on catalytic activity were investigated by CO adsorption, TEM and XRD techniques. The experimental results showed that the particle size of the catalysts prepared through gel auto-combustion varied with the concentration of citric acid. Therefore carbon nanotubes with different diameters were obtained correspondingly. The effect of activation temperature on the activity of catalyst was negligible from 500 to 700 ℃, but it became pronounced at lower or higher temperatures.

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.

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。

颗粒活性炭活化过硫酸钠降解水中酸性橙

该文以偶氮染料酸性橙7(AO7)为目标污染物,研究颗粒活性炭(GAC)活化过硫酸钠(PS)降解水中AO7的效能和机理。通过研究GAC含量、PS浓度及p H对AO7降解的影响,发现当GAC为0.4 g/L、PS/AO7摩尔比=15∶1、150 min时,AO7的去除率可达到96.1%。在pH为3~9的条件下,AO7的去除均能达到较好的效果。猝灭实验结果表明,除了·OH、SO_(4)^(-),体系中的单线态氧及表面结合SO_(4)^(-)也参与了AO7的降解。XPS分析结果表明,C-O及π^(*)键可能作为活性位点参与PS活化产生活性物种对AO7进行降解。

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。

活性炭纤维布在精制磷酸脱色的应用

在湿法磷酸生产的42%~48%的磷酸提纯精制磷酸时,还需要对萃取出的75%磷酸进行脱色处理。一般采用活性炭颗粒、树脂、双氧水对磷酸进行脱色,活性纤维布在磷酸脱色中应用较少。活性炭纤维布是一种由含碳材料制成的、外观呈黑色、内部孔隙结构发达、比表面积大、吸附能力强的一类微晶质碳素材料。随着活性炭纤维布制造业发展,活性纤维布在磷酸脱色中应用具有很好的前景。

龙凤檀磷酸法活性炭的孔径分布与吸附性能的构效关系

以硬杂木龙凤檀的加工剩余物为原料,研究了磷酸活化法的活化温度、磷酸质量分数和浸渍比对龙凤檀活性炭吸附性能的影响,通过N_(2)吸附-脱附等温线对活性炭的结构进行分析,并根据吸附理论和DFT孔径分布图,拟合计算出活性炭有效孔道所占的孔容积与液相吸附性能(碘吸附值、亚甲基蓝吸附值和焦糖脱色率)的构效关系。研究结果表明:在磷酸质量分数60%、磷酸溶液与龙凤檀浸渍比3∶1(mL∶g)、活化温度500℃、活化时间120 min的条件下,磷酸活化法制备的龙凤檀活性炭具有最佳的吸附性能和优异的孔隙结构,碘吸附值为841 mg/g,亚甲基蓝吸附值为270 mg/g,焦糖脱色率为120%,比表面积为1516 m^(2)/g,总孔容为1.145 cm^(3)/g,均优于软杂木杉木制备得到的活性炭。应用密度泛函理论(DFT),计算出龙凤檀活性炭不同孔径区间对应的孔容积,经过理论分析和拟合计算,发现碘吸附值与孔径在1.0~2.7 nm之间的孔容积、亚甲基蓝吸附值与孔径在1.7~5.0 nm之间的孔容积、焦糖脱色率与孔径在2.7~6.3 nm之间的孔容积有着很好的线性关系(R2>0.95),表明活性炭的孔隙结构分布与其液相特征吸附性能之间具有很好的关联度。

磷酸活化文冠果果壳生物炭及其对亚甲基蓝的吸附性能

目的:探究文冠果相关产业废弃物处置方法。方法:以文冠果果壳为原料,磷酸为活化剂,在单因素试验基础上,采用Box-Behnken中心组合设计进行生物炭制备条件优化,并将最优制备条件下所得生物炭用于吸附水体中亚甲基蓝,通过考察吸附影响因素,确定磷酸活化制备的文冠果果壳生物炭对亚甲基蓝的吸附特性,并结合动力学分析探讨其吸附机理。结果:磷酸活化制备文冠果果壳生物炭的最优工艺条件为浸渍比(m果壳粉∶m磷酸溶液)1∶21,热解温度530℃,热解时间75 min。文冠果果壳生物炭吸附水体中亚甲基蓝最优条件为溶液初始pH 12.6,生物炭投加量1.0 g/L,亚甲基蓝初始质量浓度200 mg/L,吸附平衡时间120 min。文冠果果壳生物炭对水体中的亚甲基蓝吸附服从准二级反应动力学关系,吸附过程由液膜扩散控制、孔隙扩散控制和吸附解析平衡3个阶段组成。结论:磷酸活化可显著提升文冠果果壳生物炭比表面积和孔容,进而显著提升其对亚甲基蓝的吸附性能。

磷酸活化油茶壳制备高比表面积活性炭

以油茶壳为原料,磷酸为活化剂制备活性炭。以碘吸附值及产率为指标,探究加热温度、加热时间、浸渍比、浸渍时间、升温速率对油茶壳活性炭吸附性能的影响,并采用正交法优化活性炭制备条件,采用比表面积孔隙分析、FT-IR、XRD、SEM进行表征。结果表明:油茶壳活性炭较佳的制备工艺为加热温度400℃、加热时间140 min、浸渍比3∶1、浸渍时间6 h,此条件下制得的活性炭碘吸附值为1694 mg/g,比表面积1872 m^(2)/g,平均孔径1.36 nm,总孔容积为1.269 cm^(3)/g,微孔孔容占总孔容的56.26%,表面具有丰富的孔结构。