负载工艺对ACF担载二氧化钛光催化性能的影响

采用分散液中添加环氧树脂黏结剂并进行热处理的方法,制备出活性炭纤维(ACF)担载二氧化钛光催化材料。并对光催化材料的表面形貌和孔结构进行表征,评价复合光催化材料对亚甲基蓝溶液的光催化降解性能。重点探讨了负载方式、负载时间以及光催化剂的添加量等方面对光催化活性的影响。研究表明,当采用浸渍方式、负载时间控制在15 min左右、光催化剂添加量达11 g/L时,ACF/TiO2光催化复合材料中光催化剂负载量最佳,在15%左右,对亚甲基蓝(初始浓度为50 mg/L)的降解效果最好,在2 h内可以达到90%。     

Inhibition of PCDD/F by adding sulphur compounds to the feed of a hazardous waste incinerator

Sulphur compounds, including (NH₄)₂SO₄ and pyrite, were tested as suppressants in a hazardous waste incineration facility. The test results suggested that adding sulphur compounds only slightly reduced PCDD/F stack emissions; this restricted effect was attributed to the release of fly ash in large amounts during the sulphur adding experiments, i.e., it was due to a malfunctioning of the baghouse filter. Nevertheless, for the combined flow of flue gas + fly ash a reduction of more than 50% was achieved for the total PCDD/F concentrations and the total toxic concentrations, and an even higher inhibition capability was observed for PCDD. Also, a simulation of the thermodynamic equilibrium conditions by sulphur dioxide was conducted in the domain of experimental interest. Deactivation of catalysts, which promote PCDD/F formation, was found to be the dominant inhibition mechanism in low temperature PCDD/F formation. SO₂ could also inhibit the formation of molecular Cl₂ via the Deacon reaction, but that was not the main reason for inhibition.     

Reactive oxygen species metabolism during the cadmium hyperaccumulation of a new hyperaccumulator Sedum alfredii （Crassulaceae）

Sedum alfredii Hance, a newly discovered hyperaccumulator, could serve as a good material for phytoremediation Cd polluted sites. Malondialdehyde (MDA), reactive oxygen species (ROS) and antioxidases (catalase (CAT); superoxide dismutase (SOD); peroxidase (POD)) in the leaf were determined when S. alfredii was treated for 15 d with various CdCl2 concentrations ranging from 0 to 800 μmol/L. The results showed that the production rate of 2′,7′-dichlorofluorescein (DCF), which is an indicator of ROS level, reached up to the maximum at 400 μmol/L CdCl2 and then declined with the increase of CdCl2 concentration, while MDA accumulation tended to increase. CAT activity was significantly inhibited at all tested CdCl2 concentrations and SOD activity was sharply suppressed at 800 μmol/L CdCl2. However, the enhancement of POD activity was observed when CdCl2 concentration was higher than 400 μmol/L. In addition, its activity increased when treated with 600 μmol/L CdCl2 for more than 5 d. When sodium benzoate, a free radical scavenger, was added, S. alfredii was a little more sensitive to Cd toxicity than that exposed to Cd alone, and the Cd accumulation tended to decline with the increase of sodium benzoate concentration. It came to the conclusions that POD played an important role during Cd hyperaccumulation, and the accumulation of ROS induced by Cd treatment might be involved in Cd hyperaccumulation.     

Drinking water production by ultrafiltration of Songhuajiang River with PAC adsorption

In recent years, membrane ultrafiltration （UF） of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To evaluate the performance of ultrafiltration membranes for treatment of surface water in North China, a 48-m^2 low pressure hollow fiber membrane ultrafiltration pilot plant was constructed. Ultrafiltration was operated in cross-flow and with powdered activated carbon （PAC） adsorption. Turbidity was almost completely removed to less than 0.2 NTU （below Chinese standard 1 NTU）. It was found that PAC addition enhanced organic matter removal. The combined process of PAC/UF allowed to 41% removal of CODMn, 46% removal of DOC and 57% decrease in UV254 absorbance. The elimination of particles, from average 12000/ml in the raw water to approximately 15/ml in the permeated, was observed. When PAC concentration was below 30 mg/L, backwashing could recovery the membrane flux with backwash interval/backwashing duration of 1/30.     

Hydrothermal decomposition of pentachlorophenol in subcritical and supercritical water with sodium hydroxide addition

Hydrothermal decomposition of pentachlorophenol （PCP, C6HC150）, as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide （NaOH） addition. The experiments were conducted at a temperature range of 30（0-420℃ and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.25 to 1.39 mmol/L, and the NaOH concentrations were varied from 2.5 to 25 times of the concentrations of PCP. The result of this study showed that PCP conversion in supercritical water was highly dependent on the reaction temperature, residence time, and NaOH concentration. PCP conversion in subcritical water is, however, only dependent on reaction temperature. NaOH concentration and residence times were found to have little effect on PCP conversion in subcritical condition. It was found that NaOH concentration affected the dechlorinations of PCP in the supercritical water. The intermediates detected were proposed to be tetrachlorophenol and trichlorophenol, respectively.     

添加剂对厨余垃圾堆肥氮素转化与氮素损失的影响

采用静态好氧工艺,就不同添加剂对厨余垃圾堆肥氨挥发与氮素损失影响方面进行比较试验。试验设4个处理:A0,对照;A1,添加30 mL.kg-1(以干基计,下同)高温保氮菌剂;A2,添加1 mol.kg-1化学保氮剂;A3,同时添加30 mL.kg-1高温保氮菌剂和1 mol.kg-1化学保氮剂。堆肥结束时,与对照相比,A1、A2和A3处理堆肥全氮含量分别提高8.4%、38.4%和43.1%,有机氮含量分别提高9.9%、64.3%和68.8%,氨氮含量分别降低11.3%、86.5%和86.5%,厨余氨氮释放率分别降低13.4%、84.0%和86.5%,堆肥氮损失率分别下降17.5%、61.5%和67.2%。加入添加剂均可减少厨余垃圾堆肥氨挥发,降低堆肥氮损失。单独添加时,化学保氮剂较高温保氮菌剂作用大;但就3种处理比较而言,菌剂与化学药剂联合添加效果最好。     

改进的整合加和模型INFCIM及其应用于混合物毒性预测

目前,准确预测混合物毒性仍然面临着挑战, 为改进现有整合加和模型INFCIM,将该模型中“浓度=浓度+效应”形式修改为更加科学合理的“浓度=浓度+浓度”形式.利用分子电性距离矢量(MEDV)表征混合物组分的分子结构,以模糊数学中的隶属函数表征混合物组分的相似性和相异性,从而构建新的整合加和模型.利用6组六元混合物(共72个样本)验证模型的预测能力,结果表明,改进的模型能够准确预测无相互作用混合物毒性.在改进的模型中,利用多组混合物作为校正集,克服了INFCIM模型仅使用少量混合物数据作为校正集的缺点,使之更加可靠和具有代表性.     

吡啶类离子液体对青海弧菌Q67的混合毒性评估

合污染物产生的累积与毒性相互作用具有潜在的环境与健康风险。以6种吡啶类离子液体(IL)：丁基溴化吡啶([Bpy]Br)、己基溴化吡啶([Hpy]Br)、辛基溴化吡啶([Opy]Br)、丁基氯化吡啶([Bpy]Cl)、己基氯化吡啶([Opy]Cl)和辛基氯化吡啶([Opy]Cl)为混合物组分,应用直接均分射线法(EquRay)和均匀设计射线法(UD-Ray)分别设计4组二元IL混合物和2组三元混合物,每组混合物包括5条具有不同浓度配比的混合物射线。应用微板毒性分析法测定6种IL及其30条混合物射线对青海弧菌Q67的发光抑制毒性,以浓度加和(CA)为加和参考模型分析混合物毒性相互作用。结果表明,Logit函数能有效地拟合6种吡啶IL及其30条混合物射线的浓度-效应数据。若以半数效应浓度的负对数(pEC₅₀)为毒性指标,6个吡啶IL对Q67的毒性与烷基链上碳原子数目正相关,且每增加2个碳原子,其毒性约增加1。IL的阴离子(Br^-或Cl^-)对毒性没有影响。除己基氯化吡啶([Hpy]Cl)和辛基氯化吡啶([Opy]Cl)的二元混合物呈现明显拮抗作用外,其他二元及三元混合物都为加和作用。     

重金属与有机磷农药二元混合物对卤虫联合毒性的评价及预测

重金属和有机磷农药污染物在水域环境中普遍存在。以卤虫(Artemiasalina)为受试生物,采用固定浓度比法,研究了重金属Zn、Cd与辛硫磷和敌百虫2种农药以毒性单位比为4∶1、3∶2、1∶1、2∶3和1∶4构成的二元混合体系对卤虫的联合毒性,采用等效线图解法判定毒物间的相互作用类型。同时,基于单一化合物的浓度-效应曲线,运用浓度加和(CA)和独立作用(IA)2种模型对不同配比二元混合物的联合毒性进行预测。结果表明,Zn-Cd混合物联合毒性随Zn比例的增加而增强。低Zn比例的混合物(1∶4、2∶3)表现为拮抗效应,中、高Zn比例的混合物(1∶1、3∶2和4∶1)为加和效应。5种不同配比的有机磷农药混合物均表现为加和效应。金属-农药混合物则均为拮抗作用。模型预测结果表明,CA能够较好地预测辛硫磷与敌百虫二元混合物的联合毒性,而IA则更适用于对金属-农药混合物联合毒性的预测。以上结果表明,混合体系中各组分的比例是影响联合毒性的因素之一,毒性评估时应该充分考虑其影响。CA及IA模型同样适用于评估和预测包含相同或完全独立作用机制组分的混合物对非单细胞生物体(如卤虫)的联合毒性。     

氮素添加对樟树林红壤微生物的影响

为了研究氮素添加对红壤微生物的影响,以湖南植物园樟树红壤林地为研究区,设定了氮素添加的3个水平,即对照N0:0 g·m-2、低氮N1:5 g·m-2和高氮N2:15 g·m-2,利用平板计数法,氯仿熏蒸法和BIOLOG微平板技术,分析了氮素添加1个月和13个月后红壤微生物数量、生物量C、N以及群落功能多样性的响应变化.结果表明,氮素添加1个月后土壤细菌数量显著增加,13个月后显著减少,真菌和放线菌数量变化不明显;氮素添加1个月后,微生物量C、N均随氮素的增加而增加,氮素添加13个月后土壤微生物量C与1个月相比显著增加,土壤微生物量N却有降低的趋势,但差异不显著;土壤微生物的碳源利用率因施氮处理而发生分异.Shannon、Simpson和McIntosh指数的结果显示AWCD在氮素添加不同水平和不同时期有一定的差异,但差异并不显著.