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861.
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研究了碳酰肼对钢铁厂烧结工序产生的二噁英的抑制效果。结果表明,添加了0.01%(质量分数,下同)、0.02%、0.05%、0.10%的碳酰肼之后,二噁英的排放质量浓度降为0.560、0.506、0.270、0.174ng-TEQ/m3,相对于基准值(0.821ng-TEQ/m3)大幅减少。碳酰肼对二噁英的从头合成以及前驱物生成都能起到一定的抑制效果。碳酰肼与Cu2+结合生成稳定的氮化物,削弱Cu2+的催化活性;与HCl反应,减少了生成二噁英的氯源;对FeCl3、CuCl2的催化活性也会产生影响。碳酰肼添加后,对多氯代二苯并呋喃(PCDFs)生成中高氯代二噁英的脱氯行为也有明显的抑制。 相似文献
864.
In this work, Bi4NbxTa(1−x)O8I photocatalysts have been synthesized by solid state reaction method and characterized by powder X-ray diffraction, scanning electron microscope and UV-Vis near infrared diffuse reflectance spectroscopy. The photocatalytic activity of these photocatalysts was evaluated by the degradation of methyl orange (MO) in aqueous solutions under visible light, UV light and solar irradiation. The effects of catalyst dosage, initial pH and MO concentration on the removal efficiency were studied, and the photocatalytic reaction kinetics of MO degradation as well. The results indicated that Bi4NbxTa(1−x)O8I exhibited high photocatalytic activity for the removal of MO in aqueous solutions. For example, the removal efficiency of MO by Bi4Nb0.1Ta0.9O8I was as high as 92% within 12 h visible light irradiation under the optimal conditions: initial MO concentration of 5-10 mg L−1, catalyst dosage of 6 g L−1 and natural pH (6-8), the MO molecules could be completely degradated by Bi4Nb0.1Ta0.9O8I within 40 min under UV light irradiation, and the photodegradation efficiency reaches to 60% after 7 h solar irradiation. Furthermore, the photocatalytic degradation of Bisphenol A (BPA) was also investigated under visible light irradiation. It is found that 99% BPA could be mineralized by Bi4Nb0.1Ta0.9O8I after 16 h visible light irradiation. Through HPLC/MS, BOD, TOC, UV-Vis measurements, we determined possible degradation products of MO and BPA. The results indicated that MO was degradated into products which are easier to be biodegradable and innocuous treated, and BPA could be mineralized completely. Furthermore, the possibility for the photosensitization effect in the degradation process of MO under visible light irradiation has been excluded. 相似文献
865.
Spatial trend and pollution assessment of total mercury and methylmercury pollution in the Pearl River Delta soil, South China 总被引:2,自引:0,他引:2
Total mercury (THg) and methylmercury (MeHg) were measured in large number of soil samples collected from areas with different types of land use, different depth in the Pearl River Delta (PRD) of South China. THg and MeHg concentrations ranged from 16.7 to 3320 ng g−1 and 0.01 to 1.34 ng g−1, respectively. THg levels are highest in the top 0-20 cm soil layer, and decrease from the surface to bottom layer soil. Spatial variation was observed with different types of land use. Urban parks had the highest concentrations and the other areas tended to decrease in the order of residential areas, industrial areas, vegetable fields, cereal fields, and woodlands. Temporal variation was also noted, and two relatively high THg contamination zones located in the northwestern part of the PRD have significantly expanded over the last two decades. Both THg and MeHg concentrations were correlated significantly with soil organic matter (OM), but not with soil pH. THg pollution status was evaluated using two assessment methods. 相似文献
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869.
可持续发展指标(体系)的分类及构建探讨 总被引:5,自引:0,他引:5
将国内外已有的可持续发展指标(体系)按学科特征归纳,分为应用经济学、生态学和统计学等3大类,分别评述其特征和不足,提出中国可持续发展指标的构建的进一步研讨,应充分开展实质性的跨学科研究,将经济发展指标的设置和选择作为重点,建立能解析可持续发展本质特征的长期性或阶段性批示指标,如生物多样性、人均维持基本生活的收入水平。 相似文献
870.