Synthesis of iron composites on nano-pore substrates: Identification and its application to removal of cyanide

Two types of nano-pore substrates, waste-reclaimed (WR) and soil mineral (SM) with the relatively low density, were modified by the reaction with irons (i.e. Fe(II):Fe(III) = 1:2) and the applicability of the modified substrates (i.e. Fe-WR and Fe-SM) on cyanide removal was investigated. Modification (i.e. Fe immobilization on substrate) decreased the BET surface area and PZC of the original substrates while it increased the pore diameter and the cation exchange capacity (CEC) of them. XRD analysis identified that maghemite (γ-Fe₂O₃) and iron silicate composite ((Mg, Fe)SiO₃) existed on Fe-WR, while clinoferrosilite (FeSiO₃) was identified on Fe-SM. Cyanide adsorption showed that WR adsorbed cyanide more favorably than SM. The adsorption ability of both original substrates was enhanced by the modification, which increased the negative charges of the surfaces. Without the pH adjustment, cyanide was removed as much as 97% by the only application of Fe-WR, but the undesirable transfer to hydrogen cyanide was possible because the pH was dropped to around 7.5. With a constant pH of 12, only 54% of cyanide was adsorbed on Fe-WR. On the other hand, the pH was kept as 12 without adjustment in Fe-WR/H₂O₂ system and cyanide was effectively removed by not only adsorption but also the catalytic oxidation. The observed first-order rate constant (k_obs) for cyanide removal were 0.49 (±0.081) h⁻¹. Moreover, the more cyanate production with the modified substrates indicated the iron composites, especially maghemite, on substrates had the catalytic property to increase the reactivity of H₂O₂.     

潜流式人工湿地基质堵塞问题对策研究

基质堵塞是人工湿地长期稳定运行最关键的问题.针对滇池湖滨福保人工湿地运行后潜流湿地基质严重堵塞的问题,分析造成基质堵塞的原因,从工艺路线、碎石床结构、填料径粒和布水方式等方面对原有人工湿地进行分析研究,找出堵塞原因,提出技术改造方案,并经过工程模型实验进行验证,在此基础上确定"预处理-潜流湿地(垂直流)-调节池-潜流湿...     

原子荧光光谱法测定底泥中的总砷

采用硫酸-硝酸-高氯酸混合试剂热消解氢化物发生原子荧光法,测定底泥中的总砷。方法的检出限为0．016mg／kg,相对标准偏差为0．2％,加标回收率在92．8％-108％之间。此方法操作简便、灵敏度高、快捷、便于推广,适用于底泥中的总砷测定。     

电网干扰与应用系统电源的可靠性设计

电源是应用系统的重要组成部分,与所有电路相连,电源不可靠的影响是全局性的。系统的抗干扰性能是系统可靠性的重要指标,在分析了干扰因素及电网的异常的基础上,论述了交流供电的电源抗干扰措施和可靠性设计要点,其方法具有工程应用价值。     

工业废渣芦苇末的农用资源化技术

对造纸工业产生的机废渣芦苇末用农业载基质的技术的可行性进行了试验研究,结果表明,用芦苇末进行生物发酵处理后,加入适量的常规基质原料,可以作为平菇培养基质和园艺植物无土载培基质,与常规的棉籽壳培养平菇及草岩混合基质载培蔬菜相比,不但产量提高,成本降低,净产值增加,而且生态环境效显著。     

环境固体样品中多种甾体激素的同步检测方法及条件优化

采用超声辅助萃取-吸附剂净化-液相色谱-串联质谱同步检测环境固体样品中22种甾体激素,比较筛选了超声辅助萃取的有机溶剂和净化萃取液的吸附剂。结果表明,使用甲醇/乙腈/乙腈对固体样品中的甾体激素分别进行3次超声辅助萃取效果最佳,在0~150 mg/mL投加量范围内,N-丙基乙二胺粉末能有效减少浓缩萃取液中有机质的干扰并获得最高回收率,石墨碳粉末的有机质去除效果最好,但同时也造成目标物的显著损失,而硅胶粉末对有机质的去除效果不明显,因此选用N-丙基乙二胺粉末为萃取液的净化吸附剂,推荐使用量为150~400 mg/mL,在此优化条件下,22种甾体激素的标准曲线线性良好,方法检出限为0.025~0.696 μg/kg,加标回收率达到63.5%以上,且操作简便、耗时短,适用于各种复杂环境固体样品的检测分析。     

气相分子吸收光谱法测定水中氨氮干扰因素的研究

气相分子吸收光谱法测定成分复杂氨氮实际样品时,干扰因素造成测定结果不准确,而现有的标准方法和文献对干扰物质的研究不全面,制约了仪器的应用。该文系统地开展干扰因素的研究,提出干扰因素的消除方法,用加标回收率验证消除的有效性。结果表明,亚硫酸盐、硫化物等还原性物质对测定产生负干扰;石油烃、N,N-二甲基甲酰胺(DMF)等挥发性有机物、有机胺类以及亚硝酸盐对测定产生正干扰。根据不同干扰类型,通过加入适量酸性重铬酸钾溶液、在酸性条件下加热煮沸、预蒸馏等方法可消除干扰,消除干扰后加标回收率为84%~120%。生活污水、石化企业废水等6种典型水样消除干扰后,气相分子吸收光谱法和纳氏试剂分光光度法测定氨氮有较好的可比性,干扰消除方式有效。