Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid

The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II).     

磷酸法活化煤焦油渣制备活性炭研究

研究了以陕西煤焦油渣作为原料,用磷酸作为活化剂,在400～1000℃的条件下经一步炭活化法制备活性炭。研究了炭活化温度、时间、料剂比对煤焦油渣制备活性炭吸附性能及孔结构的影响。实验结果表明炭活化温度、炭活化时间主要影响活性炭产品的得率,高温和长时间会导致更多的碳损失;活性炭的吸附性能及孔结构主要受炭活化温度和料剂比影响。最佳活化工艺条件为850℃、3h、1∶3。通过其活性炭表面孔径分布及表面官能团含量变化表征,用磷酸浸泡煤焦油渣制备活性炭有利于大、中孔结构的产生,其最佳活化条件下孔径分布约在20～100nm。     

氯化锌活化法制备木质活性炭研究

采用氯化锌活化法在不同操作条件下制备木质活性炭产品,通过实验测定相应的活性炭得率及活性炭的碘值、亚甲基蓝吸附值和苯酚吸附值.分析研究了氯化锌活化法制备活性炭工艺过程中各种操作参数如浸渍比、活化时间和活化温度对活性炭的得率、活性炭碘值、亚甲基蓝吸附值和苯酚吸附值的影响.实验结果表明,浸渍比是氯化锌活化法制备活性炭的最重要的影响因素.综合考虑活性炭的得率和吸附性能受活化操作参数的影响规律,探讨了氯化锌活化法制备木质活性炭的最优操作参数.在实验范围内,选择氯化锌活化法制备木质活性炭的浸渍比100%,活化温度500℃左右和活化时间60～90min比较适宜.     

Synthesis of amorphous carbon fiber from a new organosilicon precursor

Synthesis of amorphous carbon fiber with atomic scale dispersed silicon was investigated. An organosilicon precursor (MSP), which was developed as heat resistant plastics in recent years, was used as a precursor. Temperature control during the melt-spinning was important in order to tailor precursor fibers having thin diameters. For the fiber curing, -ray irradiation previous to pyrolysis in an O₂ atmosphere was available. The effect of irradiation on the MSP fiber was investigated with mass change, FT-IR and SEM observation after pyrolysis. During the irradiation, oxygen was introduced in the fiber in proportion to the total dose, but the irradiation curing formed microscopic defects on the fiber surfaces at the same time which limited the resultant fiber strength.     

催化活化法制备高丁烷工作容量颗粒活性炭

在已报道的高丁烷工作容量(BWC)颗粒活性炭(GAC)的制备研究中,其制备周期比较长。在传统的磷酸法颗粒活性炭的制备过程中,采用了塑化阶段加入浓硫酸来促进杉木屑组织中生物高聚物的酸催化解聚并低分子化。研究结果表明浓硫酸添加量为6%时,GAC的BWC由未添加浓硫酸时的11.9 g/100mL增加到14.4g/100mL,提高了近21%;中孔孔容由0.508cm3/g增加到0.939cm3/g,提高了85%;BET比表面积由1902m2/g增加到2325m2/g,提高了22%;总孔容由1.029cm3/g增加到1.685cm3/g,提高了近64%;微孔容积由0.521cm3/g增加到0.746cm3/g,提高了43%。而且,其制备周期也从先前的20~70h缩短至5h以内。     

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid.     

Unburnt carbon from coal fly ashes as a precursor of activated carbon for nitric oxide removal

The aim of this work is to evaluate the characteristics of an activated carbon obtained from unburnt carbon in coal fly ashes to be used in the removal of NO. Carbon-rich fraction was obtained by mechanical sieving of fly ashes. The mineral matter was removed by conventional HCl and HF demineralization procedure. Activation was carried out with steam at 900 degrees C in order to develop porosity onto the sample. Characterization of samples was performed by several techniques with a main objective: to follow the mineral matter content, composition and distribution on the samples in order to better understand how to remove it from unburnt carbon in fly ashes. To study the use of this unburnt carbon as a precursor for the preparation of activated carbons for gas cleaning, the NO removal by ammonia using activated carbon as a catalyst at low temperature was performed. Results show a good performance of activated carbon in this reaction that is in relationship with BET surface area.     

Catalytic ozonation of p-chlorobenzoic acid by activated carbon and nickel supported activated carbon prepared from petroleum coke

The aim of this research was to investigate catalytic activity of petroleum coke, activated carbon (AC) prepared from this material, Ni supported catalyst on activated carbon (Ni/AC) in the ozonation of aqueous phase p-chlorobenzoic acid (p-CBA). Activated carbon and Ni/AC catalyst were characterized by XRD and SEM. The presence of petroleum coke did not improve the degradation of p-CBA compared to ozonation alone, but it was advantageous for p-CBA mineralization (total organic carbon, TOC, reduction), indicating the generation of highly oxidant species (*OH) in the medium. The presence of either activated carbon or Ni/AC considerably improves TOC removal during p-CBA ozonation. Ni/AC catalyst shows the better catalytic activity and stability based on five repeated tests during p-CBA ozonation. During the ozonation (50 mg/h ozone flow rate) of a 10 mg/L p-CBA (pH 4.31), it can be more mineralized in the presence of Ni/AC catalyst (5.0 g/L), TOC removal rate is over 60% in 60 min, 43% using activated carbon as catalyst, only 30% with ozonation alone.     

ZnCl_2活化红枣核制备多微孔活性炭及表征

以红枣核为原料,采用ZnCl2活化法,研究了活化温度、活化时间以及浸渍比等工艺参数对活性炭结构性能与表面化学性能的影响。采用低温N2吸附-脱附以及元素分析对活性炭结构进行表征,采用Boehm滴定、pHZPG、FT-IR等手段对活性炭表面性能进行表征。研究结果表明,当浸渍比为0.8,活化温度为700℃,活化时间为60 min时,活性炭的微孔结构较发达,活性炭BET比表面积为1 031 m2/g,总孔体积为0.504 cm3/g,平均孔径为1.95 nm,零电荷点(p HZPG)为7.01,活性炭的收率为41.6%。     

低温活化制备纤维状活性炭复合材料

以玻璃纤维毡为基质，在玻璃纤维上涂布聚乙烯醇和氯化锌的混合物，得到多孔碳纤维前驱体。通过控制活化条件、改变活化剂浓度以及原料的配比，制备了一系列复合型纤维状多孔炭材料（GFAC），结果显示，活化温度、活化时间和ZnCl2的浓度强烈影响GFAC的比表面积、孔径分布和在玻璃毡上的碳层含量。在450℃的低温下制得的复合材料的比表面积达650m^2／g，中孔体积达65％．空气与ZnCl2共同活化，比在N2气氛中活化更能提高碳层的比表面积，可制得微孔比表面积达75％，比表面积达到400m^2／g的GFAC。GFAC样品具有较好的机械强度，其动态吸附速率接近ACF。     

以超临界和亚临界水活化掺金属化合物的酚醛树脂制备球形活性炭(英文)

以掺稀土金属化合物氯化铈的酚醛树脂为原料,采用超临界和亚临界水活化制备了具有较好中孔结构和机械强度的球形活性炭。通过77K氮气吸附对所制球形活性炭进行表征,并研究不同活化方法、活化条件对其孔隙结构的影响。结果表明:氯化铈具有催化作用,在超临界水环境下促进了孔结构的发展,优势中孔分布于4nm和7nm;而活化方法和活化压力对孔结构的影响较小。     

A new antacid drug from activated carbon modified with calcium carbonate

Activated carbons were previously modified with different sodium carbonate solutions and then, they were soaked in a calcium nitrate solution. This procedure allowed to precipitate calcium carbonate on the microporous carbons. Then, these solids were washed with abundant distillated water. These modified carbons were characterized by means of XRD, SEM, HRTEM and BET surface area measurements. XRD confirmed the presence of calcium carbonate species, while the surface area measurements indicated that microporous solids were partially blocked. SEM and HRTEM showed that precipitated calcium carbonate crystals were found on the surface of the activated carbon. These solids were tested as antacids in a synthetic gastric juice and they were able to neutralize it. A commercial compound formulated with calcium carbonate was used as a reference system.     

Production of carbon fibres from a pyrolysed and graphitised liquid crystalline cellulose fibre precursor

Regenerated cellulose fibres, spun from a liquid crystalline precursor, were pyrolysed at temperatures in the range 400–2,500?°C. Raman spectroscopy and X-ray diffraction showed that the degree of graphitisation of the fibre increased with increasing temperature. Electron microscopy, however, suggested that the fibres have a skin–core structure. This observation was confirmed by micro-Raman analysis, whereupon the ratio of the intensities of the D and G bands shows that the skin consists of a graphitised structure, whereas the core consists of significantly less graphitised material. The contributions of the graphitised skin and the inner core to the potential mechanical properties of the fibres were also assessed by following the position of the 2D Raman band during tensile deformation of the fibre. The Raman band shift rate against strain was used to evaluate the fibre modulus, which suggested a modulus of ~140 GPa for the skin and 40?GPa for the core, respectively. If this incomplete graphitisation could be overcome, then there is potential to produce carbon fibres from these novel precursor materials.     

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.     

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.     

Improvement in electrochemical capacitance of activated carbon from scrap tires by nitric acid treatment

Activated carbon （AC） obtained from the industrial pyrolytic tire char is treated by concentrated nitric acid （AC-HNO3） and then used as the electrode material for supercapacitors. Surface properties and electrochemical capacitances of AC and AC- HNO3 are studied. It is found that the morphology and the porous texture for AC and AC- HNO3 have little difference, while the oxygen content increases and functional groups change after the acid treatment. Electrochemical results demonstrate that the AC-HNO3 electrode displays higher specific capacitance, better stability and cycling performance, and lower equivalent series resistance, indicating that AC obtained from the industrial pyrolytic tire char treated by concentrated nitric acid is applicable for supercapacitors.     

Removal of direct blue-86 from aqueous solution by new activated carbon developed from orange peel

The use of low-cost, easy obtained, high efficiency and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from orange peel for the removal of direct blue-86 (DB-86) (Direct Fast Turquoise Blue GL) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH and contact time were studied. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. Optimum pH value for dye adsorption was determined as approximately 2.0. Maximum dye was sequestered within 30min after the beginning for every experiment. The adsorption of direct blue-86 followed a pseudo-second-order rate equation and fit well Langmuir, Tempkin and Dubinin-Radushkevich (D-R) equations better than Freundlich and Redlich-Peterson equations. The maximum removal of direct blue-86 was obtained at pH 2 as 92% for adsorbent dose of 6gL(-1) and 100mgL(-1) initial dye concentration at room temperature. The maximum adsorption capacity obtained from Langmuir equation was 33.78mgg(-1). Furthermore, adsorption kinetics of DB-86 was studied and the rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2>0.99) with intraparticle diffusion as one of the rate determining steps. Activated carbon developed from orange peel can be attractive options for dye removal from diluted industrial effluents since test reaction made on simulated dyeing wastewater show better removal percentage of DB-86.     

Synthesis of nanocrystalline MoN from a new precursor by TPR method

Molybdenum nitride (MoN) nanoparticles with high BET surface area (S _BET = 351.0352 m²/g) have been successfully obtained from ammonium polymolybdate, (NH₄)₆Mo₇O₂₄. Differential thermal analysis (DTA), thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD) analysis were used to investigate the effect of water in the precursor. X-ray photoelectron spectroscopy (XPS) was used to determine the empirical formula of the product. Also, MoN nanorods with high aspect ratio have been prepared using Al₂O₃ template. XRD, transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) were used to characterize the structure of the nanorods.     

炭前驱体对活性炭孔结构和电化学性能的影响

分别以毛竹和石油焦为炭前驱体,采用KOH活化法制备超级电容器用高比表面积活性炭材料,考察了碱/炭比对不同炭前驱体所制得的活性炭的孔结构、吸附性能和电容性能的影响。结果表明,在相同的碱/炭比下,竹基活性炭孔径2nm的微孔较发达,而石油焦基活性炭孔径在2～50nm的中孔率较高。在适宜的工艺条件下,以毛竹为炭前驱体可制得比表面积为2610.7m2/g,比电容为206F/g的活性炭材料;以石油焦为炭前驱体可制得比表面积为2597.9m2/g,比电容为213F/g的活性炭材料。