Experimental study on the inhibition of biological reduction of Fe(III)EDTA in NO_x absorption solution

INTRODUCTION Nitrogen oxides (NOx) are significant airborne contaminants resulting from fossil fuels combustion. The use of metal chelate additives for combined re- moval of NOx and SO2 in FGD (flue-gas desulfuriza- tion) systems was investigated by several groups (Harriott et al., 1993; Tsai et al., 1989; Shi et al., 1996a; 1997). Fe(II)EDTA (EDTA, ethylenediami- netetraacetate) as an additive for removing nitric oxide (NO) from flue gas had been extensively stud- ied, with the …     

Availability and toxicity of Fe(Ⅱ) and Fe(Ⅲ) in Caco-2 cells

The objective of the present study was to compare the toxicity and availability of Fe(Ⅱ) and Fe(Ⅲ) to Caco-2 cells.Cellular damage was studied by measuring cell proliferation and lactate dehydrogenase (LDH) release. The activities of two major antioxidative enzymes [superoxide dismutase (SOD) and glutathione peroxidase (GPx)] and differentiation marker (alkaline phosphatase) were determined after the cells were exposed to different levels of iron salts. The cellular iron concentration was investigated to evaluate iron bioavailability. The results show that iron uptake of the cells treated with Fe(Ⅱ) is significantly higher than that of the cells treated with Fe(Ⅲ) (P＜0.05). Fe(Ⅱ) at a concentration>1.5 mmol/L was found to be more effective in reducing cellular viability than Fe(Ⅲ). LDH release investigation suggests that Fe(Ⅱ) can reduce stability of the cell membrane. The activities of SOD and GPx of the cells treated with Fe(Ⅱ) were higher than those of the cells treated with Fe(Ⅲ), although both of them increased with raising iron supply levels. The results indicate that both Fe(Ⅱ) and Fe(Ⅲ) could reduce the cellular antioxidase gene expression at high levels.     

催化分光光度法测定痕量Fe(Ⅲ)

基于Fe(Ⅲ)对过硫酸钾与亮绿间的氧化还原反应的催化作用,建立了测定痕量Fe(Ⅲ)的催化分光光度新方法。线性范围为0.008～0.10μg/25ml,检出限为9.8ng/ml。用于矿样中Fe(Ⅲ)的测定,结果满意。     

The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3 ) dosage. The existence of a critical pH value determining the catalysis of Fe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.     

胶束增敏H点标准加入法测定水中Fe(Ⅱ)、Fe(Ⅲ)

pH2.8时,二甲酚橙-邻菲罗啉混合显色剂中加入乳化剂OP,采用H点标准加入法-分光光度法同时测定水中的Fe(Ⅱ)和Fe(Ⅲ)。在合适的波长条件下,Fe(Ⅱ)和Fe(Ⅲ)浓度比为1:15～10:1时均可以利用该方法同时准确测定,摩尔吸光系数ε=6.6×104L.moL-1.cm-1,对环境水样进行测定回收率为97.3%～101.9%,结果令人满意。     

甲基橙探针分光光度法测定Fe(Ⅲ)含量

在pH 3.50的酸性条件下,甲基橙(MEO)与Fe(Ⅲ)反应生成具有正、负吸收峰的橙红色离子缔合物,最大正吸收和最大负吸收波长分别位于525nm和415nm,Fe(Ⅲ)的质量浓度在0~2.23mg/L范围内遵从比尔定律,表观摩尔吸光系数分别为6.39×104 L/(mol·cm)(正吸收)和2.59×104 L/(mol·cm)(负吸收)。当用正、负吸收叠加测定时,灵敏度可提高到8.99×104 L/(mol·cm)。该方法用于奶粉中Fe(Ⅲ)含量的测定,相对标准偏差为1.5%~2.1%之间,加标回收率在98.9%~101%之间。     

Fe(Ⅲ)-EDTA/H_2O_2催化光降解苯酚模拟废水

研究UV254光照下,Fe(Ⅲ)-EDTA/H2O2对苯酚的催化光降解效能。首先考察反应时间、溶液初始pH值、Fe(Ⅲ)与EDTA的浓度比值对UV/Fe(Ⅲ)-EDTA催化光降解苯酚的影响,进而考察UV/Fe(Ⅲ)-EDTA/H2O2体系对苯酚的降解效能。结果表明:当溶液pH为7,Fe(Ⅲ)/EDTA浓度比值为1:1时,经过1h反应,UV/Fe(Ⅲ)-EDTA体系对苯酚的催化光降解效率达61.13%。在溶液初始pH为3⁷时,UV/Fe(Ⅲ)-EDTA对苯酚的降解率均可达60%以上。在中性条件下,UV/Fe(Ⅲ)-EDTA体系添加H2O2后可把苯酚的降解率从61.13%提高到91.30%。反应前后溶液的紫外扫描光谱表明光降解过程中苯酚的苯环共轭结构被破坏。最后对UV/Fe(Ⅲ)-EDTA/H2O2体系催化光降解机理进行了初步探讨。     

Fe( Ⅲ) - 改性ZSM- 5 催化剂酸性和积炭性能研究

本文用NH3 - TPD、吡啶- IR、GC 和微反色谱等技术考察了Fe ( Ⅲ) - ZSM- 5 催化剂在芳构化反应中的酸性、积炭行为以及催化性能的变化规律.结果表明, Fe ( Ⅲ) 修饰了沸石表面酸性, 减少了部分强B 酸中心, 加强了弱L 酸中心. 缓和了表面积炭和催化活性下降速率。并发现在反应初期, 强B 酸中心下降、积炭量的生成以及催化活性下降速度均较快.