The Absorption Spectrum of the Ferrocyanide Ion in Aqueous Solution

Environmental effects on the absorption spectrum of the ferrocyanide ion in solution are used to detect the existence of a C.T.T.S. band overlaid by two intraionic transitions. pH effects on the spectrum are correlated with the known ionic equilibria.     

Radiolysis of Fremy's Salt in the Presence of Some Hydrated Electron Scavengers in Alkaline Aqueous Solution

Fremy's salt, ON(SO₃)₂^2?, was irradiated with γ-rays in deaerated alkaline aqueous solutions in the presence of NO₃^?, N₂O. In the presence of N₂O an increase of the G(-ON(SO₃)₂^2? = G from 6.1 to about 6.7 was observed within a limited range of concentration, while with NO₃^? the change is gradual. This is consistent with NO₂ and OH produced, respectively, in the reaction of e_aq^? with Fremy's salt, taking place in one-electron-equivalent processes, and with the assumption that pairs of radicals may originate from water molecules.     

Scavenging Kinetics in the Photochemistry of Some Ions in Aqueous Solution

Geminate recombination has been previously suggested in the photochemistry of several ions in solution, namely, the halides, phenolate ferrocyanide and thiocyanate. It is demonstrated that in the concentration range studied, the observed dependence of the quantum yield on scavenger concentrations is due to homogeneous competition between the scavenger and a product or rational intermediates, rather than to cage scavenging competing with geminate recombination.     

The Charge Transfer Photochemistry of Coordination Complexes in Aqueous Solution

Irradiation of charge transfer absorption bands of coordination complexes can result in net oxidation reduction or ligand exchange reactions. The photoredox processes generally involve the formation of reactive radicals in the primary photochemical act. The identification of these primary radicals is essential to the specification of the primary photochemical act since radical reactions with substrate, other radicals, etc. can make the net products and yields appear vastly different from the nature of the primary act. For example, in a few documented cases, the metal ion fragment formed in a photoredox process has characteristics of a radical and can couple with ligand radicals giving rise to a net photochemical process which appears to be ligand exchange rather than photoredox. A variety of radicals, organic as well as inorganic, can be generated and studied in aqueous solution. Some information has also been obtained concerning the nature of the photochemical precursors to the radicals formed in photoredox processes.     

Electron Beam Grafted Polymer Adsorbent for Removal of Heavy Metal Ion from Aqueous Solution

Abstract

An electron beam grafted adsorbent was synthesized by post irradiation grafting of acrylonitrile (AN) on to a non‐woven thermally bonded polypropylene (PP) sheet using 2 MeV electron beam accelerator. The grafted poly(acrylonitrile) chains were chemically modified to convert a nitrile group to an amidoxime (AMO) group, a chelating group responsible for metal ion uptake from an aqueous solution. The effect of various experimental variables viz. dose, dose rate, temperature, and solvent composition on the grafting extent was investigated. PP grafted with the amidoxime group (AMO‐g‐PP) was tested for its suitability as an adsorbent for removal of heavy metal ions such as Co²⁺, Ni²⁺, Mn²⁺, and Cd²⁺ from aqueous solution. Langmuir and Freundlich adsorption models were used to investigate the type of adsorption of these ions. The adsorption capacities of the adsorbent for the metal ions were found to follow the order Cd²⁺>Co²⁺>Ni²⁺>Mn²⁺. The kinetics of adsorption of these ions indicated that the rate of adsorption of Cd²⁺ was faster than that of other ions studied.     

Aniline and Anilinium Ion Ozonation in Aqueous Solution

The ozonation of aniline and anilinium ion in aqueous solution is investigated by determining the product distributions at different degrees of ozonation. Results indicate that anilinium ion, although less reactive than aniline, still has a remarkable reactivity towards ozone. The high anilinium ion reactivity and the observed product distributions are explained by assuming a radical mechanism for anilinium ion ozonation, whereas the behavior of aniline appears to be regulated mainly by the electrophilic ozonolysis mechanism.     

Low-Temperature Formation of Fluorapatite in Aqueous Solution

The low-temperature formation of Fluorapatite by the reaction of particulate calcium phosphate precursors in aqueous solution was investigated: Variations in the aqueous phase were measured and these corelated with the consumption of reations and the formation of apatitic phases. The variations in solution pH and fluoide are in accord with a mechanism by which CaF₂ precipitates relatively early in the reaction. After this, minimal fluoride is consumed until the formation of an apatitic phase reaches substantial for hydroxl and the pH increase. The extent of aptite formation exhibits a storong dependence on the concetration of the NaF solution in which reation is occuring. Analysis of reaction is saturated CaF₂ solution indicates that apatite formation precedes the uptake of fluoride from solution. For reaction in dilute suspension, a low concentration of NaF retards apatite formation whereas a higher one accelerates it. Alternatively, when reaction is carried outa low liquid-to-solids rario, apatite formation is accelerated in NaF solution regardless of concetration.     

甘蔗渣基水合氧化铁对源水中单宁酸的吸附特征

利用甘蔗渣(BR)、甘蔗渣水合氧化铁(HFO-BR)和甘蔗渣水合氧化锆(HZO-BR)三种材料对源水中单宁酸进行吸附去除,探讨其吸附特征。试验结果表明:甘蔗渣水合氧化铁(HFO-BR)和甘蔗渣水合氧化锆(HZO-BR)具有较宽的pH适用范围,当吸附剂剂量为1.6g/L、反应时间为180min时,两种复合材料对50mg/L单宁酸的去除率分别为96.54%和97.89%,比甘蔗渣对单宁酸的去除率分别提高10.56%和11.91%。准二级动力学方程能较好的拟合三种材料对单宁酸的吸附动力学过程,揭示其吸附以离子交换吸附为主。Langmuir和Freundlich方程均能较好地拟合单宁酸等温吸附试验数据,表明三种材料对单宁酸的吸附既有单分子层吸附,又有多分子层吸附。     

Formation of Lithium Niobate from Peroxide Aqueous Solution

A novel aqueous chemical solution was developed as a precursor both for LiNbO₃ powder and thin film. In this method, hydrogen peroxide aqueous solution (H₂O₂) reacts with niobium and lithium alkoxide ethanol solution to form metal peroxide aqueous solution. From this solution, crystalline LiNbO₃ were synthesized at a temperature as low as 350°C. LiNbO₃ thin films with well-developed grains were fabricated by spin-coating on silicon and sapphire substrates. In comparison with the alkoxide solution method, this peroxide solution method provides significant advantages, such as low weight loss in the sintering process and easy handling.     

乙烯水合物在正丙醇溶液中的生成行为研究

研究了在正丙醇溶液中,压力和温度因素对乙烯水合物生成的影响。实验结果表明：压力的升高促进了水合物的生长,水合物生成速率随压力升高而加大;温度的降低促进了水合物的生长,水合物终止生成所需的时间减少,终止生成对应的压力降低。     

Efficient Removal of Hg(II) by Polymer-Supported Hydrated Metal Oxides from Aqueous Solution

Chelating PS-EDTA resins modified by metal (Fe, Al, and Zr) oxides were used as adsorbents to remove Hg(II) from aqueous solutions. The modified resins were characterized by BET, FTIR, and XPS. The amino, carboxylate, and the metal oxides on resins exhibited a synergistic effect for Hg(II) removal. It was observed that the modification of PS-EDTA resin not only increased the adsorption of Hg(II) but also accelerated the adsorption rate of Hg(II). The equilibrium data of Hg(II) were best described by the Freundlich isotherm, and the kinetics were found to follow the pseudo-second-order kinetic model. Also, thermodynamic parameters showed that Hg(II) adsorption was endothermic and spontaneous in nature. The increasing the concentration (0.1–2.0 g/L) of NaNO₃ in Hg(II) solution did not affect the adsorption of Hg(II). Moreover, the competitive adsorption indicated that the modified resins had higher selectivity towards Hg(II) over Cd(II), Pb(II), Zn(II), or Cu(II) in a binary system. All of the above results indicated that the modified resin was an efficient and reusable adsorbent for Hg(II) removal due to its simple preparation, high adsorption capacity, fast adsorption rate, ionic strength independence, high selectivity, and good reusability. These properties are of potential application in the fixed-bed continuous-flow column for Hg(II) removal from wastewaters.     

Products of Ozonolysis of Aromatic Compounds in Aqueous Solution Containing Nitrite Ion

Aqueous solutions of 4-chlorophenol, 2,4-dichlorophenol, methoxybenzene, 1-naphthol, and naphthalene at a concentration of 0.5-1 × 10^?4 M reacted with two equivalents of ozone at pH 7.25-10.65 to form various oxidation products. When the reactions were conducted in the presence of nitrite ion (0.5-1.0 × 10^?4 M), a nitration reaction occurred with three of the five aromatic compounds (4-chlorophenol, 2,4-dichlorophenol, and 1-naphthol). Aromatic compounds that undergo nitration under the conditions of the experiments have a higher reaction rate than that for the reaction of ozone and nitrite ion.     

近临界条件下乙烯水合物在甲醇水溶液中的生成行为研究

研究了近临界条件下乙烯水合物在甲醇水溶液中的生成行为,考察了温度、压力以及甲醇浓度对乙烯水合物生成行为的影响。实验结果表明在乙烯的近临界条件下,P-t曲线为一光滑的曲线,不易明确区分溶解阶段、成核阶段和生长阶段;随着初始压力的升高,水合物生成速率加快,且始末压差增大,水合物生成量增多;随着温度的降低,过冷度增大,促进水合物生长,压力下降速率增加,水合物生成量增多;甲醇水溶液浓度的增加,抑制了乙烯水合物的生成。     

Hydride Transfer: A Dominating Reaction of Ozone with Tertiary Butanol and Formate Ion in Aqueous Solution

This article provides evidences that hydride transfer is an important primary step in ozone reactions of formate and tertiary butanol in aqueous media. In both systems, one argument is the fact that the free hydroxyl radical yields are relative low ((40 ± 4)% and (7 ± 0.8)% for formate and tertiary butanol, respectively). Another hint is the high exergonicity of these reactions: ΔG = –249 kJ mol^?1 for formate/ozone system and ΔG = –114 kJ mol^?1 for hydride transfer followed by a methyl shift in the reaction between tertiary butanol and ozone. In addition, the main product of tertiary butanol ozonolysis is butan-2-one [(89 ± 3)%], a compound that is formed only via hydride transfer. For the reaction of ozone with formate an activation energy of (54.6 ± 1.2) kJ mol^?1 and a pre-exponential term of (2.5 ± 1.2) × 10¹¹ were determined (in the presence of tertiary butanol as ^?OH scavenger) whereas for tertiary butanol the two activation parameters were (68.7 ± 1.9) kJ mol^?1 and (2.0 ± 1.5) × 10⁹, respectively.     

黄血盐钠反应液过滤方式的改进及研究

对氰化钠法生产黄血盐钠过程中黄血盐钠反应液的几种不同过滤方式进行了对比研究,确定了在现阶段较先进的过滤方式,采用全自动板框压滤机压滤黄血盐钠反应液,改变了传统的重力过滤、真空过滤等过滤方式,并确定了黄血盐钠反应液的过滤步骤、条件。     

γ-AlOOH自水溶液中对Eu(Ⅲ)离子及其配合物的吸附

研究了γ AlOOH自水溶液中对Eu(Ⅲ )离子及其配合物的吸附。结果表明 :①吸附等温线符合Langmuir极限公式 ;②Eu(Ⅲ )离子吸附的表观活化能为 43 .43kJ·moI- 1 ;③吸附百分率随溶液pH值增大而增大 ,S形曲线在pH =4.0～ 6.5出现突跃 ;④Eu(Ⅲ )离子及其配合物的形态和表面基团电荷分布随溶液pH值变化而变化 ,γ AlOOH对配合物的吸附也随之而变 ;配体能抑制水解 ,pH >7仍然存在吸附作用 ;氨基乙酸和碳基水杨酸配合物的吸附曲线与Eu(Ⅲ )离子接近 ,而多元羟基酸配合物的吸附曲线与Eu(Ⅲ )离子有较大差异。     

Arsenic Removal from Aqueous Solution by Iron Oxide-Coated Biomass: Common Ion Effects and Thermodynamic Analysis

Abstract

A batch study showed that the presence of anions (sulfate, chloride, and nitrate) in solution did not affect the adsorption process of both As(V) and As(III) by iron oxide-coated A. niger biomass. It was found that the presence of Ca²⁺, Fe²⁺, and Mg²⁺ ions at a concentration of 200 mg/L in solution could increase the removal efficiency of As(V) by 86.5%, 95.4%, and 65.8%, respectively. Similarly, the presence of Ca²⁺, Fe²⁺, and Mg²⁺ ions at a concentration of 200 mg/L in solution could increase the removal efficiency of As(III) by 39.3%, 97%, and 8.4%, respectively. The batch adsorption-desorption study showed that the reactions between the arsenic species and the iron oxide-coated A. niger biomass were reversible. Desorption of As(V) and As(III) at neutral pH was approximately 15%. As(V) desorbed more than As(III) in acidic (pH 1.33) and alkaline (pH 12.56) solutions. At a pH of 1.33, 67% of the adsorbed As(V) desorbed, and the percentage of desorbed As(III) was only 47.1% in the same condition. At a solution pH of 12.56, 73.4% of the As(V), and 43.7% of As(III) desorbed. The thermodynamic study showed the spontaneous nature of the sorption of arsenic on IOCB. The high value of the heat of adsorption {ΔH ≈ ? 133 kJ/mol for As(V), and 88.9 k/mol for As(III)} indicated that the mechanism of arsenic sorption was chemisorption.     

硝酸银负载型阳离子交换树脂的制备及其对水溶液中溴离子的吸附研究

利用硝酸银溶液对D001大孔型磺酸基聚苯乙烯阳离子树脂进行浸渍处理,制备出硝酸银负载型阳离子交换树脂.将离子树脂作为载体,对水溶液中的溴离子进行吸附性能测试.通过改变吸附剂用量、吸附时间和吸附温度,探究不同吸附条件对吸附剂吸附水中溴离子性能的影响.结果表明:该吸附剂使用的优化条件为吸附剂添加量1 g、吸附时间40 min、吸附温度25℃.在该优化条件下,吸附剂对水中溴离子的吸附量为64.97 mg·g-1,吸附率可达99.96％.     

硝酸银负载型阳离子交换树脂的制备及其对水溶液中溴离子的吸附研究

利用硝酸银溶液对D001大孔型磺酸基聚苯乙烯阳离子树脂进行浸渍处理,制备出硝酸银负载型阳离子交换树脂.将离子树脂作为载体,对水溶液中的溴离子进行吸附性能测试.通过改变吸附剂用量、吸附时间和吸附温度,探究不同吸附条件对吸附剂吸附水中溴离子性能的影响.结果表明:该吸附剂使用的优化条件为吸附剂添加量1 g、吸附时间40 min、吸附温度25℃.在该优化条件下,吸附剂对水中溴离子的吸附量为64.97 mg·g-1,吸附率可达99.96％.