低温等离子体改性活性炭纤维对不同极性苯系物的吸附

探究了不同改性时间下的活性炭纤维孔结构和表面化学性质的变化,并进一步研究了改性后的活性炭纤维对不同极性苯系物的吸附。通过BET比表面积、Boehm滴定分析、FTIR红外光谱对改性前后的活性炭纤维进行表征。结果表明,功率150 W,改性时间为30、60和90 min时,活性炭纤维烧失率随着改性时间延长而升高,分别达到16.5%、27.8%、45.5%。改性过程中,活性炭纤维比表面积和微孔孔容显著增加,有助于改善活性炭纤维吸附性能。在物理吸附和化学吸附作用下,改性活性炭纤维对邻二甲苯、间二甲苯和对二甲苯吸附性能有所提高,其中,改性90 min活性炭纤维对其吸附量分别增加了0.58、0.55和0.44 mg·mg-1。酸性含氧基团由原来的0.973 mmol·g-1增加到1.675 mmol·g-1,改性后酸性含氧官能团的增加使活性炭纤维表面极性增大,有利于对极性有机物邻、间二甲苯吸附量增加率的提高。     

污泥活性炭净水剂的制备及表征

以5种不同污水处理厂的污泥为原料,采用ZnCl2活化法(ZnCl2与污泥的投配质量比例为3∶5,活化24 h,炭化温度为550℃,炭化1 h)制备污泥活性炭。并对制得的污泥活性炭的比表面积、粒径分布、孔径分布、官能团及制备后浸出毒性等进行表征,初步判定来自不同污水厂、不同类型污泥化学改性后制得活性炭具有较好的吸附性能,从技术角度上看,作为废水的净水剂是可行的。     

响应面法优化甘蔗渣-污泥复合活性炭的制备工艺

为了提高污泥活性炭的吸附性能以提升其实际应用价值,提出在污泥中掺杂甘蔗渣制备复合活性炭,并采用Plackett-Burman联用响应面法对影响复合活性炭碘值的条件进行筛选优化。通过Plackett-Burman实验筛选出热解温度、热解时间和甘蔗渣与污泥干重比为主要影响因素,对这3个因素进行Box-Behnken实验,经响应面优化得到影响碘值的二次响应曲面模型,模型显示热解温度与热解时间、热解温度与干重比的交互作用显著,并确定了最佳制备条件:热解温度550℃、热解时间30 min和干重比50%,此时复合活性炭碘值为814 mg/g,优于未优化条件下制备的复合活性炭。通过比表面积、孔结构和碘值的测定以及元素和扫描电镜分析得出,甘蔗渣的掺杂提高了复合活性炭的比表面积、微孔体积、碘值及含碳量。研究结果表明,甘蔗渣掺杂和制备条件优化是提高污泥活性炭吸附性能的有效手段。     

不同预处理方法对活性炭纤维结构和吸附性能的影响

以商品活性炭纤维为原材料,采用水洗和HNO3、H_3PO_4和HF酸洗方法对其进行预处理。利用扫描电镜、比表面积测定仪及傅立叶红外光谱仪对其表面形貌和结构进行表征,并通过测定灰分含量、碘值和苯酚值考察其吸附性能。结果表明:预处理后活性炭纤维的形状和尺寸变得相对规整,表面酸性官能团数量增加,吸收谱峰变得尖锐,比表面积和总孔容增大。HF水浴去灰分效果最佳可达84.8%;H_3PO_4活化炭化的碘和苯酚吸附值最高,分别为1 925 mg/g和226 mg/g;而HNO3活化会造成表面刻蚀,碘和苯酚吸附值最低。确定H_3PO_4活化炭化为本实验最佳预处理方法。     

氧化、还原改性对活性炭吸附草甘膦的影响

研究了氧化、还原改性对活性炭吸附草甘膦的影响.以傅立叶红外光谱定性表面官能团变化,以扫描电镜观察表面形貌,以化学吸附分析仪测定后再通过测定样品的氮气吸附/脱附等温线计算比表面积和孔径.结果表明:(1)氧化改性使活性炭比表面积增大;还原改性使活性炭比表面积减小.还原阶段使先前氧化阶段中产生的孔道以及原有孔道均发生塌陷,导致还原改性活性炭比表面积减小.(2)在静态吸附的条件下,氧化改性和还原改性活性炭对草甘膦的吸附均为吸热反应.还原改性在活性炭表面产生的还原性官能团有利于活性炭对草甘膦的吸附,而氧化改性产生的氧化性官能团并不利于活性炭对草甘膦的吸附.(3)热力学参数的计算进一步表明,改性活性炭对草甘膦的吸附为吸热反应.     

双功能吸附剂的制备及其对水中毒死蜱的降解特性

对具有催化功能的负载Fe（Ⅲ）的活性炭进行了表征，与母体活性炭相比，其比表面积以及微孔体积均有所下降，酸性官能团的量有所增加；考察了普通浸渍法和超声浸渍法制备的双功能活性炭对毒死蜱的吸附和降解性能，结果表明，双功能活性炭对毒死蜱的吸附量有所降低，但对毒死蜱的降解能力增强，超声浸渍法所制备的活性炭对毒死蜱的降解能力要优于普通浸渍法所制备的活性炭。     

活性炭纤维催化臭氧化降解苯酚及其对炭表面性能的影响

研究了活性炭纤维(ACF)存在下苯酚的臭氧化降解,以及臭氧化过程对炭表面的影响.结果表明:ACF存在下的臭氧化能够显著提高苯酚的分解和矿化,ACF的用量为1 g时.反应10 min后苯酚和COD的去除率分别为96.8%和88.4%,而活性炭在同样条件下对苯酚和COD的去除率仅分别为68.0%和63.6%;臭氧化后的ACF表面含氧官能团、比表面积和总孔体积都发生了变化,内酯基减少,羧基、羟基和羰基增多,表面更亲水;比表面积增加且主要集中在微孔,而微孔体积的减少表明较小孔径的微孔数量显著增多,同时出现极少量中孔和大孔.     

污泥-秸秆基活性炭的制备及其对渗滤液COD的吸附

以市政污泥与玉米秸秆为原料,采用化学活化法热解制备污泥-秸秆基活性炭,研究其物化性质、热解动力学特性及对渗滤液中COD的吸附性能。考察吸附剂投加量、吸附时间和溶液p H对COD去除率的影响,并用吸附等温线对吸附数据进行了拟合。结果表明,秸秆比例越高,活性炭的吸附碘值和BET比表面积越大,最大可达663 mg/g和902 m2/g;活性炭表面呈不规则的多孔状;秸秆比例为45%的活性炭在最佳实验条件下对COD的吸附去除率为82%;活性炭对COD的吸附符合Langmuir和Freundlich等温模型。     

软锰矿-污泥活性炭的制备及其对废水中铅离子的吸附

以城市污水处理厂的剩余污泥为原料,掺杂一定量的软锰矿,采用氯化锌活化法制备一种软锰矿-污泥活性炭,并运用比表面积测定、电镜扫描、红外光谱分析及O2-TPO等表征手段对软锰矿-污泥活性炭及纯污泥活性炭进行了结构特性的比较分析,证明添加软锰矿将污泥活性炭的比表面积提高52.33%,是由于在制备过程中软锰矿催化了污泥中有机质的分解,同时也为新生炭提供了更多的骨架,促进了积炭反应的发生。软锰矿-污泥活性炭和纯污泥活性炭对废水中铅离子的吸附实验表明:当Pb2+初始浓度为40 mg/L、pH为5.0、活性炭用量为2 g/L、吸附时间为1 h时,软锰矿-污泥活性炭对废水中Pb2+的去除率可达88%,效果明显优于纯污泥活性炭。常温下软锰矿-污泥活性炭对Pb2+的吸附符合Lang-muir吸附等温式。     

污泥-烟煤基活性炭的制备及其对苯酚的吸附性能

以石化企业在污水处理过程中产生的干化剩余污泥为原料,大同烟煤作辅助添加料,采用化学活化法制备污泥-烟煤基活性炭,探讨了活化剂(ZnCl_2)用量、活化温度、活化时间等条件对所制备的活性炭性能的影响。以活性炭的碘吸附值为衡量指标,当污泥∶烟煤(质量比)=1∶1时获得制备污泥-烟煤活性炭的最佳工艺条件为:浸渍液为ZnCl_2∶原料(质量比)=2∶1,活化温度550℃,活化时间30 min,在该条件下制备的活性炭的碘吸附值为990 mg·g~(-1),比表面积为836m~2·g~(-1),产率为46.6%。同时,以苯酚为目标污染物,考察了所制备的污泥-烟煤基活性炭对苯酚的去除效果,结果表明:污泥-烟煤基活性炭投加量为2.0 g·L~(-1)时,4 h后达到吸附平衡,离子强度对吸附容量没有显著的影响,溶液pH在4~10范围内对苯酚有较好吸附,pH=6时苯酚吸附容量为138.9 mg·g~(-1)。与同类吸附剂相比,制备的污泥-烟煤基活性炭可高效吸附水溶液中的苯酚。     

Preparation of activated carbon using low temperature carbonisation and physical activation of high ash raw bagasse for acid dye adsorption

Activated carbons were prepared from bagasse through a low temperature (160 degrees C) chemical carbonisation treatment and gasification with carbon dioxide at 900 degrees C. The merit of low temperature chemical carbonisation in preparing chars for activation was assessed by comparing the physical and chemical properties of activated carbons developed by this technique to conventional methods involving the use of thermal and vacuum pyrolysis of bagasse. In addition, the adsorption properties (acid blue dye) of these bagasse activated carbons were also compared with a commercial activated carbon. The results suggest that despite the high ash content of the precursor, high surface areas (614-1433 m2 g(-1)) and microporous (median pore size from 0.45 to 1.2 nm) activated carbons can be generated through chemical carbonisation and gasification. The micropore area of the activated carbon developed from chars prepared by the low temperature chemical carbonisation provides favourable adsorption sites to acid blue dye (391 mg g(-1) of carbon). The alkalinity of the carbon surface and total surface area were shown to have complementary effects in promoting the adsorption of acid blue dye. Adsorption of the anionic coloured component of the acid dye was shown to be promoted in carbon exhibiting alkaline or positively charged surfaces. This study demonstrates that activated carbons with high acid dye adsorption capacities can be prepared from high ash bagasse based on low temperature chemical carbonisation and gasification.     

Physicochemical characteristics of carbonaceous adsorbent for dioxin-like polychlorinated biphenyl adsorption

It has been known that dioxin-like polychlorinated biphenyls (DL-PCBs) are present in almost all types of environments worldwide. Activated carbon treatment has been expected for the removal of DL-PCBs because it is a simple and low-cost removal technology. In the present study, the physicochemical properties of activated carbon were investigated to identify the characteristics of 16 different types of activated carbon on adsorption properties for DL-PCBs. To accomplish this, micropore volume, and pore diameter were calculated by t-plot analysis and the mesopore volume was analyzed by the Barrett-Joyner-Halenda (BJH) method. In addition, the Brunauer-Emmett-Teller (BET) surface area, pH, metal elements, and surface acid functional groups were analyzed. Then, adsorption experiments using DL-PCB in hexane solution were conducted, and the relationship between adsorption and physicochemical properties of activated carbon was investigated. The results showed that activated carbons having a surface area of 700-1200 m² g⁻¹ and micropores with diameters of about 0.7-0.8 nm exhibited high activity for the adsorption of PCBs. The results also clearly showed that the mesopore volume of activated carbon influenced the adsorption rate and the equilibrium adsorption.     

Adsorption of Cu2+ and methyl orange from aqueous solutions by activated carbons of corncob-derived char wastes

Corncob-derived char wastes (CCW) obtained from biomass conversion to syngas production through corncob steam gasification, which were often discarded, were utilized for preparation of activated carbon by calcination, and KOH and HNO₃ activation treatments, on the view of environment protection and waste recycling. Their adsorption performance in the removal of heavy metal ions and dye molecules from wastewater was evaluated by using Cu²⁺ and methyl orange (MO) as the model pollutant. The surface and structure characteristics of the CCW-based activated carbons (CACs) were investigated by N₂ adsorption, CO₂ adsorption, FT-IR, and He-TPD. The adsorption capacity varied with the activation methods of CACs and different initial solution concentrations, indicating that the adsorption behavior was influenced by not only the surface area and porosity but also the oxygen functional groups on the surface of the CACs. The equilibrium adsorption data were analyzed with the Langmuir, Freundlich, and Temkin isotherm models, and the adsorption kinetics was evaluated by the pseudo-first-order and pseudo-second-order models.     

Preparation of activated carbons from raw and biotreated agricultural residues for removal of volatile organic compounds

Activated carbons with diverse physical and chemical properties were produced from four agriculture residues, including raw barley husk, biotreated barley husk, rice husk, and pistachio shell. Results showed that with adequate steam activation (30-90 min, 50% H2O(g),/50% N2), activated carbons with surface areas between 360 and 950 m2 g(-1) were developed. Further increases in the activation time destroyed the pore structure of activated carbons, which resulted in a decrease in the surface area and pore volume. Biotreated agricultural residues were found to be suitable precursors for producing mesoporous activated carbons. The oxygen content of activated carbons increased with increasing activation time. Results from X-ray photoelectron spectroscopy examination further suggested that H2O molecules react with the carbon surface, enhancing the deconvoluted peak area of carbonyl and carboxyl groups. Equilibrium adsorption of toluene indicated that the adsorption capacities increased with an increase in the inlet toluene concentration and a decrease in temperature. The adsorption isotherms were successfully fitted with Freundlich, Langmuir, and Dubinin-Radushkevich equations. Activated carbons derived from agricultural residues appear to be more applicable to adsorb volatile organic compounds at a low concentration and high-temperature environment.     

Roles of physical and chemical properties of activated carbon in the adsorption of lead ions

Elucidation of the roles of chemical and physical properties of activated carbons is an important basis for the systematic development of adsorbents with optimal properties specific for certain applications. Such an understanding has challenged most researchers and this has been attributed with the difficulty in decoupling the effect of chemical and physical properties that characterize activated carbons. This study proposed empirical modeling in resolving the effects of individual carbon properties in lead adsorption. A model based on lead adsorption and carbon properties including total surface area, mean pore size and heteroatom concentrations has been shown to adequately describe the lead adsorption onto activated carbons prepared from bagasse. To support this investigation a series of activated carbons were prepared from bagasse by physical and by chemical activation techniques. The surface chemical properties of the carbons were inferred from carbon pH and heteroatom concentrations. The physical characterizations of the carbons included total surface area by the BET technique and mean pore size measured using the Horvath-Kawazoe equation. Adsorption tests were conducted using a low concentration of lead (5 ppm) and the solution pH was maintained at 1.0 to maintain lead speciation to the un-complexed Pb(2+) ion. The adequacy of the proposed empirical models was statistically assessed. This form of analysis was shown to provide valuable information in tailor making adsorbents and selecting appropriate adsorbents for lead adsorption.     

孔结构和表面化学性质对活性炭吸附性能的影响

测定了室温下3种活性炭(GAC-C、GAC-P和GAC-T)对CO2、CH4和N2的吸附性能,并对颗粒活性炭孔结构和表面化学性质进行了表征,探讨了孔结构和表面化学性质对活性炭吸附性能的影响。结果表明:由于吸附机理、孔结构、表面含氧官能团和分子极性的差异,CO2、CH4和N2在活性炭上的饱和吸附量和吸附常数的关系为CO2>CH4>N2;CH4和N2的饱和吸附量主要受活性炭微孔孔容的影响,N2和CO2饱和吸附量的差异分别是由0.572～2.0 nm的微孔和0.4～6 nm的孔引起的;CH4吸附常数主要受较大中孔和大孔影响,N2吸附常数与微孔密切相关,大孔对CO2的吸附常数影响最大。     

Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase

Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O₃) and in liquid phase using nitric acid (HNO₃). The activated carbon samples were characterized using N₂ adsorption–desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m²/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich–Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO₃), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems.     

Characterization of activated carbons prepared from sugarcane bagasse by ZnCl2 activation.

Activated carbons were prepared from the agricultural waste of sugarcane bagasse by the chemical activation with zinc chloride (ZnCl2) at the activation temperature of 500 degrees C with soaking time of 0.5 hour. The influence of activation parameters on the final carbon products was examined by varying the impregnation ratio (i.e., mass ratio of added ZnCl2 to bagasse) and bagasse size. The physical properties of carbon products were characterized by nitrogen adsorption/desorption isotherms (at 77 K) and helium displacement method. The surface area and pore volume of carbons were thus obtained by the BET equation and t-plot method. Also, the particle density and porosity of carbons were estimated by the total pore volume and true density. The increases of the values of surface area and pore volume are approximately proportional to the impregnation ratio. The microporous carbon product with the BET surface area of 905 m2/g and total pore volume of 0.44 cm3/g was obtained in the present study. Further, the adsorption isotherms of two acid dyes from aqueous solutions onto the carbon products were performed at 30 degrees C. The results show that the adsorption isotherms of acid dyes with high molecular weight or large molecular size on the microporous adsorbents of activated carbons are plateau forms, indicating multilayer adsorptions, which may be attributed to the steric hindrance of the adsorbate molecules.     

Ozonation of activated carbon and its effects on the adsorption of VOCs exemplified by methylethylketone and benzene

Ozonation can modify the surface property of an activated carbon such as specific surface area, pore volume, and functional group. Results indicate that ozonation can increase the specific surface area of an activated carbon from 783+/-51 to 851+/-25 m2/g due in part to increasing micropores (those below 15 A). However, there is no change in macropore and mesopore upon ozonation. The amount of oxygen functional group (OFG) increases from 197+/-4 to 240+/-4 microeq/g, mostly in hydroxyl and carboxyl groups upon ozone treatment. These oxygen-containing functional groups are stable in the temperature range 30-250 degrees C, but begin to decompose when temperature increases beyond 300 and 350 degrees C. When the temperature reaches 1200 degrees C, all OFGs virtually disappear. The effect of ozone treatment on the adsorption of volatile organic carbon (VOC) was exemplified by methylethylketone (MEK) and benzene. The adsorption density of MEK and benzene by ozone treated activated carbon (AC(O3)) are greater than that by the untreated (AC), with MEK being more adsorbable than benzene. Results of factorial analysis indicate that physical characteristics, namely, micropore, BET surface area, pore diameter (PD), micropore volume (MV) play an important role on benzene and MEK adsorption.