海枣核CO2活化和磷酸活化制备活性炭及其结构、吸附性能（英文）

由于具有很大的吸附容量,多孔炭材料是优良的吸附剂。笔者试图比较海枣核分别经CO2活化和磷酸活化所制活性炭的结构和吸附性能。活化过程和工艺条件对炭的物理化学性质影响较大,根据文献报道的结果选取了优化的工艺参数。基于氮气吸附等温线、SEM、FT-IR等分析结果,评估了活性炭的结构特征,吸附性能则由亚甲蓝吸附值表示。CO2活化得到了微孔活性炭,产率为44%、BET比表面积是666 m2·g-1;磷酸活化得到了产率为14.8%的中孔活性炭,BET比表面积为725 m2·g-1。CO2活化活性炭的平均孔径是1.51 nm,磷酸活化活性炭的则为2.91 nm。活性炭的亚甲蓝吸附等温线分别用Langmuir等温线和Freundlich等温线进行了验证,在优化工艺条件下制备的CO2活化炭和磷酸活化炭的亚甲蓝w单分子吸附容量分别为110 mg·g-1和345 mg·g-1。然而,磷酸活化产生的亚甲蓝吸附值最高达455 mg·g-1。     

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%。     

Preparation of activated carbons from coffee husks utilizing FeCl3 and ZnCl2 as activating agents

Ferric chloride was used as a new activating agent, to obtain activated carbons (AC) from agro industrial waste (coffee husks). This material was compared with two samples from the same raw material: one of them activated by using the classical activating agent, zinc chloride, and the other, activated with a mixture of the two mentioned activating agents in the same mass proportion. The carbonaceous materials obtained after the activation process showed high specific surface areas (BET), with values higher than 900 m(2)g(-1). It is interesting to observe that the activation with FeCl(3) produces smaller pores compared to the activation with ZnCl(2). An important fact to emphasize in the use of FeCl(3) as activating agent is the activation temperature at 280 degrees C, which is clearly below to the temperature commonly employed for chemical or physical activation, as described in the bibliography. All the studied materials showed different behaviors in the adsorption of methylene blue dye and phenol from aqueous solutions.     

Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation

Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.     

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.     

中药渣制备活性炭及其工艺优化

以中药渣为原料,采用真空化学活化法制备活性炭,并以活性炭的亚甲基蓝和碘吸附值为优化指标,选用Doehlert设计安排实验,在合适的范围内,对影响ZnCl2活化法最重要的两个因素活化温度和浸渍比进行了优化。结果表明,在实验条件范围内,对于所有的响应,活化温度的影响均大于浸渍比,且两者对活性炭产率的影响都不大。得到的最优条件为活化温度474℃,浸渍比1.225,在此条件下制得活性炭的亚甲基蓝值和碘值分别为316 mg.g-1和994 mg.g-1,与理论模型计算值非常接近。和普通商品活性炭相比,用该实验方法所制活性炭具有更好的实际吸附效果。     

Carbons prepared from Spartina alterniflora and its anaerobically digested residue by H3PO4 activation: characterization and adsorption of cadmium from aqueous solutions

Two series of activated carbons were prepared from Spartina alterniflora and from its anaerobically digested residue by H(3)PO(4) activation at various process conditions, and used as adsorbents for the removal of cadmium (II) in aqueous solutions. The surface areas and pore volumes of carbons were derived from adsorption isotherms (N(2) at 77K). The surface chemistry of carbons was investigated by infrared spectroscopy. Comparison study indicated that physicochemical properties of the activated carbons were strongly dependent not only on activation conditions but also on biopolymer contents of precursors. Several isotherm models were investigated and the adsorption isotherm data were best represented by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 47.85 mg/g at 25 °C. The results showed that the activated carbon produced from S. alterniflora could be employed as a promising adsorbent for removing cadmium (II) from aqueous solutions.     

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。     

Hydrolysis of tetracalcium phosphate in H3PO4 and KH2PO4

The activity product of tetracalcium phosphate (TTCP, Ca₄(PO₄)₂O), was determined at 37°C, and the hydrolysis of TTCP was investigated in 0.01–0.1 mol l^–1 H₃PO₄ and KH₂PO₄ solutions by means of calcium and phosphorus analyses, X-ray diffraction and infrared analysis. The activity product, defined as K _sp=(Ca²⁺)⁴ (PO ₄ ^3– )² (OH^–)², was 37.36 as pK _sp, which was smaller than that previously reported (42.4). TTCP easily hydrolysed to form calcium-deficient apatite (Ca-def OHAp, Ca_5–x (HPO₄) _x (PO₄)_3–x (OH)_1–x ), or dicalcium phosphate dihydrate (DCPD, CaHPO₄2H₂O), depending on the initial phosphate concentration. With 0.1 mol l^–1 H₃PO₄, TTCP hydrolysed to form DCPD within several minutes. In 0.025 mol l^–1 H₃PO₄ and 0.1 mol l^–1 KH₂PO₄, TTCP hydrolysed to form Ca-def OHAp through DCPD. In the latter solution, a small amount of octacalcium phosphate (OCP, Ca₈(H₂PO₄)₂(PO₄)₄5H₂O), was detected as an intermediate product. In 0.025 mol l^–1 KH₂PO₄, TTCP hydrolysed directly to form Ca-def OHAp. In 0.01 mol l^–1 H₃PO₄, hydrolysis of TTCP was not completed, although Ca-def OHAp was only a product. Thus the final product and the degree of hydrolysis depended on the pH and the overall Ca/P ratio in the reaction system. The rate of Ca-def OHAp formation seemed to be controlled by the dissolution rate of TTCP rather than the crystallization rate of the OHAp.     

Crystal structure studies of mixed system of NaH2PO4 and KH2PO4 with H3BO3

X-ray powder analysis of solid solution of NaH₂PO₄ and KH₂PO₄ with H₃BO₃ was carried out. Both the systems were observed to be tetragonal. The crystallographic data are reported.     

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.     

Effect of moisture on H(2)S adsorption by copper impregnated activated carbon

The aim of this study is to investigate the effect of moisture on adsorption efficiency of hydrogen sulfide (H(2)S) by impregnated activated carbon (IAC). Copper(II) nitrate was used as an impregnant. Two humidification conditions of IAC, pre-moistened and gas stream containing moisture, were studied. The experimental results revealed that the copper species onto the IAC was suggested to be Cu(OH)(2) that deposited on activated carbon during the impregnation process. The adsorption mechanism of H(2)S by copper impregnated IAC was proposed, involving physic-sorption and chemical reactions. Moreover, the H(2)S breakthrough capacity decreased with increasing the relative humidity of gas stream. The causes were attributed to three points as follow: the competition adsorption occurred between moisture and H(2)S; the copper(II) species reduced to copper(I) species leading to IAC deactivation; and the rate of chemical reaction restrained by moisture.     

活性炭动态吸附ICP-AES法测定粗铅中的金

该文建立活性炭动态吸附-电感耦合等离子发射光谱测定粗铅中金的方法。通过实验确定粗铅样品的取样方法,采用硝酸-王水溶样-活性炭动态吸附富集金,这一过程可实现共存干扰元素的分离;灼烧灰化,以王水溶解金定容。在选定的仪器工作条件下采用电感耦合等离子体发射光谱(ICP-AES)测定其中的金含量。结果表明,方法检出限为0.066μg/g,标准加入回收率为96.0%～104.0%,相对标准偏差(RSD)为1.03%～4.01%,具有良好的准确度和精密度,测定结果与火试金测定结果吻合。该方法高效、环保,结果可靠,适用于大批量粗铅样品的测定。     

Enhanced adsorption of phenol from water by ammonia-treated activated carbon

Influence of treatment with gaseous ammonia on adsorption properties toward phenol from water was examined for commercially available CWZ-series activated carbons. The treatment was carried out at elevated temperatures ranged from 400 degrees C to 800 degrees C for 2 h. In comparison with untreated material, activated carbons modified with ammonia demonstrated enhanced adsorption of phenol from water. The enhancement depended on the treatment temperature and porous structure of studied activated carbons. Fourier transform infrared spectroscopy (FTIR) measurements confirmed presence of N-containing species in ammonia-treated activated carbons. Optimal conditions of the modification with ammonia were determined. Influence of the N-containing groups and porous structure of activated carbons on adsorption of phenol is discussed.     

Equilibrium, kinetics and mechanism of malachite green adsorption on activated carbon prepared from bamboo by K(2)CO(3) activation and subsequent gasification with CO(2)

In this work, the adsorption of malachite green (MG) was studied on activated carbon prepared from bamboo by chemical activation with K(2)CO(3) and physical activation with CO(2) (BAC). Adsorption studies were conducted in the range of 25-300 mg/L initial MG concentration and at temperature of 30 degrees C. The experimental data were analyzed by the Freundlich isotherm, the Langmuir isotherm, and the multilayer adsorption isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 263.58 mg/g. The rates of adsorption were found to confirm to pseudo-second-order kinetics with good correlation and the overall rate of dye uptake was found to be controlled by pore diffusion throughout the entire adsorption period. The results indicate that the BAC could be used to effectively adsorb MG from aqueous solutions.     

Microwave-assisted preparation of Li3V2(PO4)3/C composite with high-rate capacity

A fast sol–gel assisted microwave heating approach has been developed for the synthesis of high-rate Li₃V₂(PO₄)₃/C cathode material. This approach can synthesize Li₃V₂(PO₄)₃/C particles with high purity and good crystallinity in 12 min at a low microwave power of 320 W. In the voltage range of 3.0–4.3 V, the obtained Li₃V₂(PO₄)₃/C delivers a reversible discharge capacity of 100 mAh g^?1 after 100 cycles at 20 °C, exhibiting excellent rate capability and cycling performance. The rate-recovery performance also suggests that the Li₃V₂(PO₄)₃/C material possesses excellent structure stability after high-rate cycles, presenting excellent application value in high-power lithium ion batteries.     

Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon

The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.