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951.
Xu Shengjun Lyu Ping Zheng Xiaoxu Yang Haijun Xia Bing Li Hui Zhang Hao Ma Shuanglong 《Environmental science and pollution research international》2022,29(38):56908-56927
Environmental Science and Pollution Research - Harmful algal blooms (HABs) are a worldwide problem with substantial adverse effects on the aquatic environment as well as human health, which have... 相似文献
952.
Hui-Fen Zhang Hao Qin Bao-Cai Li Yi Qin Huan-Hong Wang Bing Zhang 《Journal of the Air & Waste Management Association (1995)》2020,70(10):980-989
ABSTRACT Montan resin (MR) is a by-product produced during the refinement process of montan wax extracted from lignite and has no usage yet. Chemical modification is an effective method to change the material property for expanding or converting the application area of the material itself. Our previous study found that the high hydrophobicity of MR is the primary limiting factor for its utilization in agriculture. Based on this point, this study attempted to chemically modify MR using the oxidation of peracetic acid, resulting that the MR hydrophilicity was significantly improved, and a water-soluble product (WSP) was obtained. The optimized oxidation conditions of MR, including the reaction temperature (X1), reaction time (X2), weight ratio of oxidant and montan resin (X3), and oxidant concentration (X4), were determined using single-factor experiments and response surface analysis. The modification degree was evaluated using elemental and oil-water partition coefficient analyses, infrared (IR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS), revealing that the oil-water partition coefficient of the modified product decreased and that the number of chemical constituents with oxygen-containing functional groups clearly increased after modification. Furthermore, the WSP was tested its effects on germination and seedling growth of the wheat seed. Compared with the control group, the WSP showed a promoting effect on the growth and germination of wheat. The WSP concentrations of 600 mg·L?1 and 300 mg·L?1 had the most substantial effect on the root and seedling growth of wheat, respectively. Implications: Montan resin, a useless by-product produced from crude montan wax, was chemically modified via oxidation of peracetic acid. Its hydrophilicity was significantly improved, and a water-soluble product was obtained after the chemical modification. The optimized oxidation conditions of montan resin were determined using single-factor experiments and response surface analysis. The amount of chemical constituents with oxygen-containing functional groups increased in the modified products after modification, as determined by IR and GC-MS analysis, among other methods. The water-soluble modified product showed an obvious effect in promoting growth and germination of wheat at 600 mg·L-1 and 300 mg·L-1, respectively. 相似文献
953.
Liu W Zheng M Liu W Ma X Qian Y Zhang B 《Environmental science and pollution research international》2008,15(1):84-88
BACKGROUND AND AIMS: Polychlorinated diphenyl ethers (PCDEs), which are among the members of persistent organic pollutants, and PCDEs have been determined in a number of environmental samples. The main possible sources are the technical production of chlorinated phenols and all processes of incomplete combustion. PCDEs were observed in the fly ash from a municipal waste incinerator (MWI). It was speculated that the condensation of chlorophenols with chlorobenzenes occurred via PCDEs to form polychlorinated dibenzofurans (PCDFs). Nevertheless, PCDEs formation from condensation of chlorophenols with chlorobenzenes has not been confirmed by experimental observation. The objective of this paper is to investigate the formation mechanism of PCDEs from the condensation of chlorophenols with chlorobenzenes. The results are expected to be helpful in understanding the formation of PCDEs and in controlling and abating PCDEs emissions from MWI. METHODS: The pyrolysis of pentachlorophenol (PCP) and/or polychlorobenzenes (PCBz) was carried out in a sealed glass tube. The reaction products were extracted and purified with K2CO3 solution. The samples were concentrated and then cleaned up on an alumina column. GC/MS was used for identification and quantification of reaction products. RESULTS AND DISCUSSION: The results showed that the pyrolysis of hexachlorobenzene (HCB) at 340 degrees C for 6 h led to the formation of decachlorodiphenyl ether (DCDE) (2.41 microg/mg) and octachlorodibenzo-p-dioxins (OCDD) (0.24 micropg/mg), while the pyrolysis of PCP yielded DCDE (13.08 microg/mg) and OCDD (180.13 microg/mg). In addition, the amount of DCDE formation from the pyrolysis of the mixture of PCP and HCB was 4.65 times higher than the total amount of DCDE formation from the pyrolysis of HCB and PCP, respectively. This indicated that PCP and HCB were prone to condensation and formation of DCDE. DCDE was the main congener of PCDEs from condensation of PCP with HCB at 340, 400 and 450 degrees C. A small amount of nonachlorodiphenyl ether (NCDE) was formed by dechlorination reaction at 450 degrees C. The condensation of PCP with 1,2,4,5-tetrachlorobenzene (Cl4Bz) formed 2,2',3,4,4',5,5',6-octachlorodiphenyl ether (OCDE). Small amounts of heptachlorodiphenyl ether (HpCDE) and hexachlorodiphenyl ether (HxCDE) were detected at 450 degrees C. Meanwhile, polychlorinated dibenzo-p-dioxins (PCDDs) and PCDFs were detected from the condensation of PCP and PCBz. CONCLUSIONS: Experimental studies clarified the behavior of the formation of PCDEs from condensation of polychlorophenols and PCBz. The condensation of polychlorophenols with PCBz formed PCDEs through elimination of HCl between polychlorophenols and PCBz molecules. Another pathway of PCDEs formation was elimination of H2O between two polychlorophenol molecules. In addition, dechlorination processes had caused the specific homologous pattern of PCDEs under higher temperatures. 相似文献
954.
煤矿安全评价是现代绿色矿山建设的主要指标之一。为对煤矿安全进行有效的评价,综合分析影响煤矿安全的人员因素、地质因素、技术设备因素、环境因素等各项指标。应用广义线性理论和SAS统计分析方法,建立基于GLM模糊评价模型。通过计算各项指标对应等级的煤矿安全影响权重〖AKω- ij,结合模糊综合评价方法得出煤矿的安全生产状况,同时通过优势比分析各指标的敏感性因子,得出防范指标危险性的有效措施。研究表明:该模型依据标准整理数据,操作性强,较准确地得出煤矿安全的状况,为煤矿的安全评价和管理决策提供依据。 相似文献
955.
Research aimed at understanding the inhibition effect of CaO on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation form dioxins precursors, such as chlorophenols (CPs) and chlorobenzenes (CBs). The results indicated that a clear dioxin inhibition effect occurred both in open and sealed system when CaO was used. In the open system, PCDDs were the main congeners and the inhibition efficiency was all over 99% in the experiments. In the experiments with CaO, less than 0.1% of the initial PCP was detected in the absorption tube and only about 1% of the initial PCP was examined as calcium pentachlorophenate in the reaction tube. In the sealed system, the inhibition efficiency was over 90% at temperature range between 280 and 450 degrees C when PCP was used as model precursor. When HCB and 2,3,4,5-T4CP replaced PCP, significant inhibition effect was also observed. As CaO has the advantageous properties of non-toxicity and non-volatile nature, it is our hope that the result will contribute to the development of a new technique to cope with the problem of dioxin pollution in MWIs. 相似文献
956.
957.
958.
Bing Geng Yanfang Zhu Zhaohui Jin Tielong Li Haiyan Kang Shuaima Wang 《Frontiers of Environmental Science & Engineering》2007,1(3):357-361
Catalytic reduction of nitrate in groundwater by sodium formate over the catalyst was investigated. Pd-Cu/γ-Al2O3 catalyst was prepared by impregnation and characterized by brunauer-emmett-teller (BET), inductive coupled plasma (ICP), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). It was found that total nitrogen was effectively removed from the nitrate solution (100 mg/L) and the removal efficiency was 87%. The catalytic activity was affected by pH, catalyst amount used, concentration of sodium formate, and initial concentration of nitrate. As sodium formate was used as reductant, precise control in the initial pH was needed. Excessively high or low initial pH (7.0 or 3.0) reduced catalytic activity. At initial pH of 4.5, catalytic activity was enhanced by reducing the amount of catalyst, while concentrations of sodium formate increased with a considerable decrease in N2 selectivity. In which case, catalytic reduction followed the first order kinetics. 相似文献
959.
影响石油污染物挥发行为的因素 总被引:4,自引:0,他引:4
进行了4种不同石油制品在不同温度时的挥发试验,并对其挥发量与挥发时间的关系进行了模拟,试验结果表明,柴油和煤油的挥发量与挥发时间呈二次多项式关系,而90#汽油的挥发量与挥发时间呈对数关系,混合芳烃的挥发量与挥发时间呈线性关系。柴油经过不同程度的挥发后,其物理性质如粘度和比重发生了改变,其中柴油粘度随着挥发而增加,并且柴油的粘度与挥发质量分数有很好的正相关性,相关系数为0.988。 相似文献
960.