影响非甲烷总烃监测结果准确性的因素研究及控制

结合非甲烷总烃监测工作实际情况,对样品采集、保存与运输、分析测试与数据处理、采样容器清洗与保存等过程详细研究后发现,采样容器从样品中吸附吸收的难挥发性与高化学活性组分和其自身的本底干扰对监测结果准确性的影响最严重,且其中残留的污染物使用传统方法难以消除。为此,通过改进采样容器清洗方法、完善相关质控措施和制定采样容器合格清洗与分类管理的判断依据,以降低各影响因素对非甲烷总烃监测结果准确性的影响。     

RS和GIS技术在县级区域泥石流危险区划中的应用研究——以四川省泸定县为例

泥石流危险度评价是泥石流灾害预测预报和减灾防灾工作中的重要内容和决策基础。以泸定县为例,利用RS、GIS技术,以流域范围为评价单元,选取影响泥石流发育和形成的因子,采用数理统计方法和层次分析法得出各因子对泥石流的敏感系数和权重,最后建立县级区域泥石流危险度多因子综合评价模型,从而实现区域泥石流危险度评价。     

Disproportionate variations in denitrification and anaerobic ammonium oxidation across freshwater-oligohaline wetlands in Min River Estuary,Southeast China

Environmental Science and Pollution Research - Spatial and temporal variations in soil denitrification and anaerobic ammonium oxidation (anammox) across the freshwater-oligohaline wetlands in...     

Precise regulation of acid pretreatment for red mud SCR catalyst: Targeting on optimizing the acidity and reducibility

• The optimum SCR activity was realized by tuning the acid pretreatment. • Optimized catalysts showed NO_x conversion above 90%. • The NH₃ and NO adsorption capacity of Al-O₃-Fe is stronger than Fe-O₃-Fe. • The formation of almandine consumes Fe³⁺ and Al³⁺ and weakens their interaction. Red mud (RM), as an alkaline waste, was recently proved to be a promising substitute for the SCR catalyst. Dealkalization could improve the acidity and reducibility of red mud, which were critical for SCR reaction. However, the dealkalization effect depended on the reaction between acid solution and red mud. In this study, we realized the directional control of the chemical state of active sites through tuning the acid pretreatment (dealkalization) process. The pretreatment endpoint was controlled at pH values of 3–5 with diluted nitric acid. When the pH values of red mud were 3 and 5 (CRM-3 and CRM-5), activated catalysts showed NO_x conversion above 90% at 275°C–475°C. The high initial reaction rate, Ce³⁺/(Ce³⁺ + Ce⁴⁺) ratio, and surface acidity accounted for the excellent SCR performance of CRM-5 catalyst. Meanwhile, more Fe³⁺ on the CRM-3 surface improved the NH₃ adsorption. There was a strong interaction between Al and Fe in both CRM-5 and CRM-3 catalysts. DFT results showed that the adsorption capacity of the Al-O₃-Fe for NH₃ and NO is stronger than that of Fe-O₃-Fe, which enhanced the NO_x conversion of the catalyst. However, the almandine was formed in CRM-4, consumed part of Fe³⁺ and Al³⁺, and the interaction between Al and Fe was weakened. Also, deposited almandine on the catalyst surface covered the active sites, thus leading to lower NH₃-SCR activity.     

Recovery of precious metals from e-wastes through conventional and phytoremediation treatment methods: a review and prediction

Journal of Material Cycles and Waste Management - E-waste, also known as waste from electrical and electronic equipment, is a solid waste that accumulates quickly due to high demand driven by the...