Iron-catalyzed oxidation of s(IV) species by oxygen in aqueous solution: Influence of pH on the redox cycling of iron

Redox cycling of Fe(II)/Fe(III) during the catalyzed aqueous S(IV) oxidation by dissolved oxygen in the presence of Fe(II) and/or Fe(III) at an initial pH_i of 4.4, often observed in atmospheric waters, was studied in detail. It has been found that the reaction rate is not considerably affected by the oxidation state of iron at the start of the reaction. An equilibrium between Fe(II) and Fe(III) was established a few minutes after the start of the reaction, regardless of the oxidation state of iron at the beginning of the experiment. The prevailing oxidation state of iron in a particular phase of the reaction depends on the concentration of S(IV) in the reaction solution. It has been found that the formation of polymerized hydroxo Fe(III) species is also included in the mechanism of the Fe-catalyzed oxidation of S(IV). The formation of these species was confirmed by the on-line measurement of Fe(II) and Fe_reac. The results also clearly demonstrate that the pH_i of the solution is a major factor, controlling the concentration of Fe(III) ions, the form of S(IV) species, and consequently the reaction rate of S(IV) oxidation by oxygen.     

紫外光催化氧化技术处理有机污染物的研究动态

主要介绍了北美先进的紫外光催化氧化技术对有机废水、废气的处理研究与应用，简要介绍三种类型光催化反应器的结构。该技术在国外处于研究阶段，预期应用前景很好，尤其适用于电力充沛地区有机废水、废气的处理，具有应用方便、处理效果好，投资费用低等特点。     

苦杏仁酸、苹果酸、乳酸对Cr(VI)还原作用的比较

不同温度和pH条件下,通过批式试验研究了苦杏仁酸、苹果酸、乳酸还原Cr(Ⅵ)的反应速率.结果表明,这3种α-OH酸还原Cr(Ⅵ)的能力表现为:苦杏仁酸＞苹果酸＞乳酸.苦杏仁酸对Cr(Ⅵ)的还原作用受pH变化的影响较大,而乳酸受温度变化的影响较大.同时研究了Mn(Ⅱ)对3种α-OH酸还原Cr(Ⅵ)反应速率的影响.结果表明,Mn(Ⅱ)对3种α-OH酸还原Cr(Ⅵ)均有催化作用,其中对苦杏仁酸表现更为明显.     

光、电催化氧化降解染料废水的研究

在光催化剂的参与下,光催化产生·OH、·O2-等自由基,电催化产生·OH、OH-等自由基,这些自由基是水系中存在的氧化能力最强的氧化剂.本实验将光、电协同催化应用于直接深兰L废水的处理上,研究了影响染料废水脱色(降解)的有关因素.表明了在电场作用下,光催化氧化的效果将得到加强,从而大大提高了染料废水的降解速率.     

Experimental and mechanism studies on seawater flue gas desulfurization

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｓｔａｌｌａｔｉｏｎｏｆｓｃｒｕｂｂｅｒｓｏｒｔｈｅｕｓｅｏｆｌｏｗｓｕｌｆｕｒ ｃｏｎｔａｉｎｉｎｇｃｏａｌａｒｅｔｗｏｏｐｔｉｏｎｓｕｓｅｄｂｙｐｏｗｅｒｐｌａｎｔｓｔｏｒｅｄｕｃｅＳＯ2 ｅｍｉｓｓｉｏｎｓ.ＴｈｅｍａｊｏｒｉｔｙｏｆｐｏｗｅｒｐｌａｎｔｓｃｏｎｔｒｏｌＳＯ2 ｅｍｉｓｓｉｏｎｓｕｓｉｎｇｌｉｍｅｂａｓｅｄｓｃｒｕｂｂｉｎｇ ,ａｌｔｈｏｕｇｈｔｈｉｓｄｅｓｕｌｆｕｒｉｚａｔｉｏｎｐｒｏｃｅｓｓｈａｓａｎｕｍｂｅｒｏｆａｄｖａｎｔａｇｅｓ,ｉｔａｌｓｏｈ…     

HNO_3催化氧化煤系硫铁矿生产聚铁工艺研究

提出一种以HNO3氧化煤系硫铁矿后产物FeSO4 、H2 SO4 以及补充的FeSO4 和H2 SO4 为原料 ,放出NO为催化剂 ,O2 为氧化剂 ,生产无机净水剂聚铁的生产方法 ,并讨论其工艺条件     

活性炭纤维在机动车尾气净化中的研究与应用展望

机动车尾气净化控制的一个难点在于冷启动阶段，此时由于温度较低，催化剂尚未完全起作用，导致排出的污染物浓度较高。阐述了活性炭纤维的基本特性，特别是其低温吸附与催化性能对NO和CO的转化作用，讨论了活性炭纤维作为机动车尾气净化材料所需的改性及方法，并展望了其应用前景。     

光催化降解亚甲基蓝的影响因素及动力学研究

进行了亚甲基蓝在硫化镉上的暗吸附反应,并作Langmuir拟合和Freundlich拟合计算其吸附速率常数。通过实验证明硫化镉光催化降解亚甲基蓝符合一级动力学反应。在低光强下,反应速率常数随着光强的增大而增大,两者之间存在显著的线性关系。改变光催化反应温度,计算表观活化能Ea为19.13kJ/mol,证明温度对反应影响较小。     

Gas-phase thermal explosions in catalytic direct oxidation of alkenes

The metal-based catalytic oxidation of alkenes to the corresponding epoxides is playing a significant role in the modern chemical industry. Nevertheless, these key processes are still lacking proper understanding with respect to the gas-phase runaway behaviour (thermal explosion) and to the hot spot formation on the catalytic surface, under the typical process conditions.This work aims to enlighten these aspects by considering either the catalytic or the gas-phase chemistry for the development of reactor operative diagrams, in order to define the best-operating conditions with respect to the selectivity, the productivity, and the process safety aspects.The proposed methodology has been applied to the oxidation of ethylene and propylene for the direct oxidation process by pure oxygen, considering a detailed kinetic model accounting for the homogeneous reactions, coupled with the heterogeneous catalytic mechanisms.Sensitivity and reaction path analyses were performed to individuate the ruling species and reactions determining the transition to runaway conditions.     

CuO和Cu(Ⅱ)催化臭氧氧化的研究

以乙二酸为实验对象,研究了CuO/Al_2O_3和Cu(II)对臭氧的催化作用实验结果表明,在低pH条件下,CuO/Al2O3有较强的催化臭氧氧化能力,可以将乙二酸的去除率提高约15%而在中性条件下,20g·l-1CuO/Al2O3的催化效果有限磷酸盐缓冲液可以强烈抑制臭氧氧化乙二酸以及CuO/Al2O3的催化作用与CuO/Al2O3相比,Cu(II)离子有更强的催化臭氧氧化乙二酸的能力