改良剂对土壤重金属（Cd、Pb）的固定以及对烤烟生长影响

为了从源头减少烟草重金属对人类健康的潜在危害,通过盆栽试验,研究不同改良剂(凹凸棒土、活性炭、有机肥)对植烟土壤重金属(Cd、Pb)的原位固定以及其对烤烟重金属(Cd、Pb)吸收量和生长的影响.分析数据表明:与对照相比,改良剂使得土壤中二乙烯三胺五乙酸(DTPA)提取态Cd与Pb含量有着不同程度的减少,同时,改良剂抑制了烤烟对Cd和Pb的吸收,降低了叶片中Cd、Pb的含量;同时,烤烟南根向叶中转移Cd的能力大于Pb;土壤中DTPA提取态Cd与Pb的含量与烟叶中Cd、Pb的含量呈正相关,表明烟叶中Cd、Pb含量的降低是由于土壤中重会属的有效性下降所致;改良剂处理的土壤上烟叶叶绿素仪测定(SPAD)值与对照相比呈上升趋势,植株根系、高度、叶面积以及叶干重的增加,表现为改良剂降低了重金属对烤烟的毒害,促进了烤烟的生长.此外,随着改良剂剂量的增加,表现出的正面效益越明显.简而言之,3种改良剂增加了烟叶产量并且提高了健康质量.     

Modeling trade-off between PAH toxicity reduction and negative effects of sorbent amendments to contaminated sediments

Adding activated carbon (AC) to contaminated sediment has been suggested as an effective method for sediment remediation. AC binds chemicals such as polycyclic aromatic hydrocarbons (PAHs), thus reducing the toxicity of the sediment. Negative effects of AC on benthic organisms have also been reported. Here, we present a conceptual model to quantify the trade-off, in terms of biomass changes, between the advantageous PAH toxicity reduction and the negative effects of AC on populations of benthic species. The model describes population growth, incorporates concentration-effect relationships for PAHs in the pore water and for AC, and uses an equilibrium sorption model to estimate PAH pore water concentrations as a function of AC dosage. We calibrated the model using bioassay data and analyzed it by calculating isoclines of zero population growth for two species. For the sediment evaluated here, the results show that AC may safely protect the benthic habitat against considerable sediment PAH concentrations as long as the AC dosage remains below 4%.     

Field-scale reduction of PCB bioavailability with activated carbon amendment to river sediments

Remediation of contaminated sediments remains a technological challenge because traditional approaches do not always achieve risk reduction goals for human health and ecosystem protection and can even be destructive for natural resources. Recent work has shown that uptake of persistent organic pollutants such as polychlorinated biphenyls (PCBs) in the food web is strongly influenced by the nature of contaminant binding, especially to black carbon surfaces in sediments. We demonstrate for the first time in a contaminated river that application of activated carbon to sediments in the field reduces biouptake of PCBs in benthic organisms. After treatment with activated carbon applied at a dose similar to the native organic carbon of sediment, bioaccumulation in freshwater oligochaete worms was reduced compared to preamendment conditions by 69 to 99%, and concentrations of PCBs in water at equilibrium with the sediment were reduced by greater than 93% at all treatment sites for up to three years of monitoring. By comparing measured reductions in bioaccumulation of tetra- and penta-chlorinated PCB congeners resulting from field application of activated carbon to a laboratory study where PCBs were preloaded onto activated carbon, it is evident that equilibrium sorption had not been achieved in the field. Although other remedies may be appropriate for some highly contaminated sites, we show through this pilot study that PCB exposure from moderately contaminated river sediments may be managed effectively through activated carbon amendment in sediments.     

PCB bioavailability control in Lumbriculus variegatus through different modes of activated carbon addition to sediments

PCB bioavailability to a freshwater oligochaete (Lumbriculus variegatus) was studied using sediments from a PCB-impacted river that was treated with different modes of granular activated carbon (GAC) addition. For sedimenttreated with 2.6% GAC and mixed for 2 min prior to L. variegatus addition, the reduction in total PCB biouptake was 70% for 75-300 microm size carbon, and 92% for the 45-180 microm size carbon. For the case where the GAC was placed as a thin layer on top of the sediments without mixing, the reduction in total PCB uptake was 70%. PCB biouptake kinetics study using treated and untreated sediment showed that the maximum PCB uptake in tissue was achieved at 28 days and decreased after that time. Although the absolute uptake of PCB changed over time, the percent reduction in total PCB uptake upon GAC amendment remained constant after the first few days. Our results indicated that PCB bioavailability was reduced upon the addition and little or no mixing of GAC into sediments. PCB aqueous equilibrium concentration and desorption rates were greatly reduced after GAC amendment, indicating reductions in the two primary mechanisms of PCB bioavailability in sediments: chemical activity and chemical accessibility.     

Roles of sulfuric acid in elemental mercury removal by activated carbon and sulfur-impregnated activated carbon

This work addresses the discrepancy in the literature regarding the effects of sulfuric acid (H(2)SO(4)) on elemental Hg uptake by activated carbon (AC). H(2)SO(4) in AC substantially increased Hg uptake by absorption particularly in the presence of oxygen. Hg uptake increased with acid amount and temperature exceeding 500 mg-Hg/g-AC after 3 days at 200 °C with AC treated with 20% H(2)SO(4). In the absence of other strong oxidizers, oxygen was able to oxidize Hg. Upon oxidation, Hg was more readily soluble in the acid, greatly enhancing its uptake by acid-treated AC. Without O(2), S(VI) in H(2)SO(4) was able to oxidize Hg, thus making it soluble in H(2)SO(4). Consequently, the presence of a bulk H(2)SO(4) phase within AC pores resulted in an orders of magnitude increase in Hg uptake capacity. However, the bulk H(2)SO(4) phase lowered the AC pore volume and could block the access to the active surface sites and potentially hinder Hg uptake kinetics. AC treated with SO(2) at 700 °C exhibited a much faster rate of Hg uptake attributed to sulfur functional groups enhancing adsorption kinetics. SO(2)-treated carbon maintained its fast uptake kinetics even after impregnation by 20% H(2)SO(4).     

活性碳纤维电热再生研究

用自制电热再生装置对吸附甲苯的活性碳纤维进行电热再生试验,通过二次通用旋转组合设计试验方案,以甲苯脱附率和脱附质量两个指标考察了脱附温度、载气流量和碳纤维层厚度对活性碳纤维电热再生效果的影响,得出了局部最佳组合方案:当脱附温度为170℃、载气流量为1 2∞mⅣmin、碳纤维层厚度为16 mm时,甲苯脱附率平均值为92....     

活性炭和活性碳纤维在防化服中的应用与发展

叙述防化服的发展历程和分类,活性炭和活性碳纤维作为吸附材料的防化服的更新和防护机理,以及国内外活性炭和活性碳纤维在防化服中应用的进展。     

活性炭复合滤嘴对卷烟中薄荷醇转移行为的影响

  目的  筛选薄荷型卷烟的滤嘴材料。  方法  比较了接装纯醋纤滤嘴和活性炭醋纤滤嘴的薄荷型卷烟,检测其在存放和抽吸过程中烟丝、滤嘴和烟气部分中薄荷醇含量。  结果  1）存放过程中,活性炭复合滤嘴吸附烟丝薄荷醇的能力大于纯醋纤滤嘴,稳定期约为1.3倍;2）抽吸过程中,纯醋纤滤嘴样品薄荷醇向主流烟气的转移能力大于活性炭复合滤嘴样品,存放前转移率为1.9倍,中间平缓期转移率在1.2-1.7倍之间,但随着存放时间变化的幅度较大,转移率最大极差为3.7倍,稳定性较活性炭复合滤嘴差。  结论  对薄荷型卷烟滤嘴材料的选择和改进有指导意义。      

麦芽糖的粉末活性炭脱色研究

研究了六种不同的粉末活性炭对麦芽糖液的脱色效果,结果表明,粉末活性炭F的脱色效果较好,且对麦芽糖液中的色素吸附符合Freundlich方程。采用Plackett—Burman设计法,筛选出麦芽糖活性炭脱色的主要影响因素是活性炭用量,且最佳活性炭用量是麦芽糖液干物质质量的2．0％。     

Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion

We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures.     

活性炭纤维电热再生新方法

为了降低活性炭纤维(ACF)的使用成本,促进其推广应用,提出了一种新的再生方法。以甲醛为吸附质,采用动态吸附法和电热脱附,研究了ACF的吸附及电热再生性能,着重分析了电热再生的影响因素。实验结果表明:ACF对甲醛的饱和吸附量达299.5 mg/g;脱附时间为5 min,再生效率达91.3%;且ACF损耗很小。本方法再生时间短,效率高,吸附剂损失少,操作简便,是一种较为理想的再生方法。