聚磷硫酸铁复合絮凝剂中铁的形态分布研究

基于磷酸根(PO43-)对聚合硫酸铁的强增聚作用,在聚合硫酸铁(PFS)中引入PO43-,研制出一种新型复合絮凝剂聚磷硫酸铁(PPFS).研究内容包括:聚磷硫酸铁的制备,用Ferron法研究PPFS中铁形态分布、用紫外可见光谱分析法研究PPFS中铁形态分布、用红外光谱分析法研究PPFS中铁形态分布.研究结果表明:紫外可...     

红外光谱法及单晶X衍射法研究Fe(Ⅲ)水解形态分布

采用Fe-Ferron逐时络合比色法研究了聚铁絮凝剂中不同pH值的Fe(a),Fe(b),Fe(c)的稳定性。结果表明,Fe(b)不稳定,10～15 d后全部转化为Fe(c),Fe(c)的含量经10～15 d后趋于稳定,Fe(a)的含量10 d后也趋于稳定。采用常温长时间结晶法从Fe(Ⅲ)-SO2-₄水溶液中制备出了单晶,并用红外光谱法及单晶X射线衍射法研究了所得单晶的结构。研究显示,从低pH值(pH 0.5左右)的Fe(Ⅲ)溶液中所得单晶中没有Fe—OH—Fe基团、Fe—OH基团、Fe的二聚羟基络合基团,仅为Fe(Ⅲ)离子形态的单晶,以氨水为碱化剂时其单晶化学式为Fe(H₂O)₆ (SO₄)₂NH₄·6H₂O。采用常温长时间结晶法,随水分的不断蒸发,不同初始pH值及不同碱化剂的Fe(Ⅲ)溶液一般都在pH 0.5左右结晶,还由于铁盐水解形态不稳定等原因引起。在低pH值下难以得到Fe(Ⅲ)的羟基络合物或聚合体单晶。实验研究显示,在絮凝剂水解形态研究中,红外光谱法、单晶X射线衍射法均有良好的应用前景。     

新型固体聚硅硫酸铁混凝剂的制备及结构表征

聚硅酸基混凝剂是重要的水处理剂之一,在混凝过程中扮演重要的作用,但易于产生自聚反应、形成硅胶、失去稳定性。因此,制备稳定的聚硅酸基混凝剂受到广泛关注。为获得一种稳定的聚硅酸基混凝剂,提出一种新型稳定的固体硅酸基混凝剂(PSPF)的制备方法。采用红外光谱与扫描电镜表征PSPF的结构与形貌;Ferron逐时络合比色分光光度法分析PSPF中Fe的形态;通过微污染源水的处理评估PSPF的混凝性能。以硫酸亚铁、硅酸钠、磷酸二氢钾、碳酸钠等为原料,确定硅铁摩尔比(n_Si/n_Fe)、磷铁摩尔比(n_P/n_Fe)与碱化度(n_OH/n_Fe)对PSPF的制备影响。结果显示在60 ℃水浴30 min条件下,PSPF最优合成条件为：n_Si/n_Fe为1∶4,n_P/n_Fe为1∶6与n_OH/n_Fe为1∶10。表征分析显示,PSPF是一种高分子聚合物,含有的新基团键(例如,Si—O—Si与Fe—O—Si),其有助于增大PSPF分子量与分子链与增强PSPF的混凝性能;PSPF形貌团簇,呈网状结构,有助于吸附架桥和网捕卷扫;Si含量增加提高了PSPF中Fe(b)和Fe(c)的含量,增强了PSPF的聚合度与固化效果。PSPF的混凝性能受PSPF投加量与水环境pH影响显著;在pH为6与投加量为8 mg·L-1时,残余浊度和UV254去除率分别可达0.33 NTU与58.6%。实验研究显示,混凝剂多因素(Si,Fe与P)调控对增强固体聚硅酸基混凝剂的固化效果、稳定性以及混凝性能具有良好的效果。     

聚合硫酸铁絮凝剂的絮凝形态光谱研究

利用紫外-可见光谱研究了聚合硫酸铁絮凝剂的絮凝形态及其性能。研究内容包括：不同pH的聚合硫酸铁絮凝剂溶液的吸收光谱,吸收光谱中有关吸收峰对应的聚合硫酸铁絮凝剂微观形态、反应机理以及絮凝除浊、除色效果比较。研究发现：当pH值在1.0～2.5之间时,在200～1 100 nm范围内随着pH升高所有峰的吸收值均增加;当pH大于2.5时, 随着pH上升,峰的吸收值并不继续增加,有些吸收波段光谱吸收值反而下降, 甚至明显下降; 在pH值为2.0时,絮凝效果最好;在pH值为1.5～2.0之间和2.0～2.3之间也有较好的絮凝效果。在200～400 nm处, 不同pH的聚合硫酸铁絮凝剂的光谱曲线变化与絮凝效果有一定的对应关系。研究结果对于聚铁类絮凝剂的优势絮凝形态的分析和鉴定有潜在应用前景,有利于为聚铁高分子絮凝剂形态分析和鉴定提供一些简便易行的方法。     

聚(N-异丙基丙烯酰胺)模板法制备二氧化硅中空微球

以在50 oC水溶液中析出的聚(N-异丙基丙烯酰胺) (PNI-PAM)聚集体作为软模板,使正硅酸乙酯吸附在PNIPAM聚集体表面进行水解缩合,原位生成二氧化硅包裹PNIPAM的核壳结构微球;进一步冷却至室温使PNIPAM溶解在水中除去内核,从而成功合成出SiO₂中空微球．实验表明,只有在足够的PNIPAM和正硅酸乙酯含量以及正硅酸乙酯水解时间下,才能形成稳定的SiO₂中空微球．用TEM、SEM和FTIR对合成的SiO₂中空微球进行了表征,结果表明,微球尺寸为150 nm左右,并且由于PNIPAM上酰胺基团和正硅酸乙酯水解出来的硅醇间具有静电相互作用,使得SiO₂壳层上依然有PNIPAM残留.     

含稀土铕(Ⅲ)配位聚合物的研究Ⅰ.铕(Ⅲ)-噻吩甲酰三氟丙酮-聚(苯乙烯-丙烯酸)的结构表征

研究了铕 (Ⅲ )和噻吩甲酰三氟丙酮 (HTTA)形成的有机配合物与聚 (苯乙烯 丙烯酸 )PSAA在不同pH值时发生配位反应得到配位聚合物NaEu(Ⅲ ) TTA PSAA的 3种样品 (a) ,(b) ,(c)。红外光谱、紫外光谱、X光电子能谱的测试表明了Eu3 分别与PSAA ,TTA- 发生配位。元素分析和电导率测定结果证明了配位组成和结构在不同的 pH条件下发生变化。结果表明 ,配合物试样 (a) ,(b) ,(c)中Eu3 的含量分别为11 89% ,12 5 5 % ,13 4 1%。     

硅(磷)中心自由基与2-丁烯二酸二乙酯的加合反应机理

用ESR方法研究了硅(磷)中心自由基与2-丁烯二酸二乙酯的加合反应机理.具有顺式构型的马来酸二乙酯(DEM)与硅(磷)中心自由基反应,生成自由基加合物。DEM的聚合反应受到抑制。具有反式构型的富马酸二乙酯(DEF)易发生聚合反应,DEF与硅(磷)中心自由基的加合反应受到抑制.DEF与DEM在反应性能上的差异,主要来自DEF有较大的空间位阻效应.     

掺Pyridine-1有机改性硅凝胶制备及其性质

用正硅酸乙酯（ＴＥＯＳ）和甲基三甲氧基硅烷（ＭＴＭＳ）为共先驱体，采用溶胶－凝胶工艺制备了掺Ｐｙｒｉｄｉｎｅ－１的有机改性硅凝胶。用差热分析（ＤＴＡ）和ＦＴＩＲ研究了凝胶的热稳定性和结构。测定了凝胶的吸收光谱和荧光光谱。     

Sb量子点掺杂钠硼硅玻璃的三阶光学非线性

采用溶胶-凝胶法以正硅酸乙酯、硼酸、金属钠为前驱体合成了含Sb量子点的钠硼硅玻璃。紫外-可见(UV-vis)吸收光谱分析表明量子点玻璃的表面等离子体共振吸收峰在566nm附近;利用飞秒激光钛宝石Z-扫描(Z-scan)技术在800nm波长处对玻璃样品的非线性光学性质进行研究,得到了该玻璃的非线性折射率γ,非线性吸收系数β和三阶非线性极化率χ(3)分别为8.59×10-17 m2/W、1.80×10-10 m/W、4.75×10-11 esu;X-射线粉末衍射(XRD)分析表明具有斜方六面体晶相结构的Sb量子点成功的掺入到玻璃基体中;通过透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)对量子点的尺寸大小和颗粒分布进行了表征,结果显示Sb量子点在玻璃中呈规则的球形,并且颗粒尺寸在19~25nm之间。     

聚合硫酸铁絮凝剂中痕量镉分光光度法测定研究

本文研究了分光光度法测定聚合硫酸铁絮凝剂中痕量镉的新方法并探讨了显色反应机理。本法是利用分光光度法测定聚合硫酸铁絮凝剂中痕量镉。显色剂为罗丹明B和碘化钾。表面活性剂为聚乙烯醇(PVA)。光度显色反应灵敏度高 ,其最大吸收波长为 60 7nm。表观摩尔吸光系数为 4 99× 1 0 5L·mol- 1 ·cm- 1 。桑德尔灵敏度为 2 2 5× 1 0 - 4 μgCd(Ⅱ )·cm- 2 。镉含量在 0～ 1 5 μg·2 5mL- 1 范围内服从比尔定律。回收率为 96%～ 1 0 5 %。方法操作简便 ,不需要萃取分离 ,可在水相中直接测定 ,故大大简化了操作手续。用本法测定了聚合硫酸铁絮凝剂中的痕量镉 ,得满意效果     

Silicon-29 NMR Study of Alkaline Aqueous and Alcoholic Tri-butylmethyl Ammonium (TBMA) Silicate Solutions

Silicon-29 NMR spectroscopy was used to characterize aqueous and alcoholic alkaline solutions of tri-butylmethyl ammonium (TBMA) silicates. The effect of TBMA cation on the equilibrium of silicate oligomers in aqueous alkaline silicate solutions was investigated using ²⁹Si NMR spectra. It was found that TBMA cation has a structure directing role and directs the silicate species to form minor amounts of silicate anion in the presence of high concentration of silicon. Silicon-29 NMR spectra of TBMA silicate solutions indicate that considerable changes occurred by changing the Si/TBMA ratio. The distribution of silicate species was affected by the presence of the alcohols, specifically methanol.     

基于光谱分析的砷黄铁矿生物浸出过程中铁/砷/硫形态转化研究

基于同步辐射装置的As/S的K边及Fe的L边X射线吸收近边结构光谱(XANES)和X射线衍射(SR-XRD),结合扫描电镜(SEM)、傅里叶红外光谱(FTIR)、电感耦合等离子体发射光谱(ICP-AES)及各项浸出参数的测定,系统研究了(中度嗜热菌、嗜热硫化杆菌)浸出砷黄铁矿过程中铁、砷、硫的形态转化。结果表明,在生物作用下,砷黄铁矿的溶解速率明显高于化学浸出体系,伴随矿物溶解释放到溶液中的砷和铁在生物浸出体系中主要为As(Ⅴ)和Fe3+,而在无菌化学浸出体系则主要为As(Ⅲ)和Fe2+;细菌胞外多聚物(EPS)在细菌与硫化矿物的相互作用过程中起着至关重要的作用, FTIR的结果表明,生物浸出体系中吸附在矿物表面的吸附菌的EPS中蛋白质和多糖的含量均高于游离菌EPS;SEM的结果表明,砷黄铁矿表面在生物浸出过程中逐渐被腐蚀,且有浸出产物覆盖,而化学浸出10 d后,矿物表面依旧比较光滑;SR-XRD的结果表明,元素硫(S0)、黄钾铁矾和砷酸铁在生物浸出第4 d生成,并随时间延长逐渐累积,最终成为浸出渣中的主要成分。Fe的L边XANES结果表明,在细菌作用下矿物表面逐渐被Fe(Ⅲ)浸出产物覆盖;As的K边XANES结果表明,浸出渣中砷的价态包括As(-Ⅰ), As(Ⅲ)和As(Ⅴ),拟合结果表明,经过10 d的生物浸出,砷黄铁矿、雌黄(As2S3)和砷酸铁在矿渣中所占的比例分别为18.6%, 23.5%和57.9%,化学浸出10 d后,矿渣中除未溶解的砷黄铁矿外,仅有少量砷酸铁(6.2%)形成;S的K边XANES拟合结果表明,经过10 d的生物浸出,砷黄铁矿、 S0、硫代硫酸盐、施氏矿物和黄钾铁矾在矿渣中所占的比例分别为15.3%, 23.7%, 3.5%, 11.3%和46.2%,而在化学浸出10 d后的矿渣中,仅拟合到少量S0(7.8%)。基于上述结果可以得出,铁、砷、硫在砷黄铁矿生物作用下的形态转化过程分别为:Fe(Ⅱ)-Fe(Ⅲ), As(-Ⅰ)-As(Ⅲ)-As(Ⅴ), S-→S0→S2O■→SO■。结合溶液中的浸出参数发现,随着S0、黄钾铁矾、砷酸铁和雌黄的大量累积,砷黄铁矿的生物浸出严重受阻。硫代硫酸盐的生成表明砷黄铁矿的溶解途径与黄铁矿相似。     

不同因素影响下Fe(Ⅲ)水解中和法制备FeOOH矿相的光谱分析

羟基氧化铁(FeOOH)作为重金属等污染物的吸附材料倍受关注,但不同因素作用下形成的FeOOH产物矿相、结构性质的差异及其对环境功能的影响,却少有报道。采用X射线衍射仪,红外光谱仪,扫描电子显微镜和激光粒度分析仪,系统考察了Fe(Ⅲ)溶液水解中和形成FeOOH时,不同作用因素如铁盐种类、pH和温度等对产物矿相的影响。结果表明,pH 8条件下,Fe(Ⅲ)溶液水解产物均为二线水铁矿(Fe₅HO₈·4H₂O);随着pH升高,Fe₅HO₈·4H₂O会向α-FeOOH相转化。Cl-和NO-₃离子的存在分别有利于β-FeOOH和α-FeOOH的形成;SO2-₄会阻碍Fe₅HO₈·4H₂O向α-FeOOH相转化;Fe2+存在时,会促进Fe₅HO₈·4H₂O向α-FeOOH相转化。加热陈化,可促进Fe₅HO₈·4H₂O转化为α-FeOOH,且利于良好结晶α-FeOOH的形成。但pH≤5,富含Cl-的Fe(Ⅲ)溶液加热水解利于β-FeOOH的生成。不同因素影响下形成的FeOOH,在矿相、表面基团、颗粒形貌和粒径大小上存在一定的差异。     

Assessment of sulfur and iron speciation in a soil aggregate by combined S and Fe micro‐XANES: microspatial patterns and relationships

To test whether synchrotron‐based spectromicroscopy can be used to identify spatial patterns of sulfur (S) and iron (Fe) speciation as well as relationships between the speciation of S and Fe in soil colloids or aggregates at the micrometre and sub‐micrometre level, an anoxically prepared dissected soil aggregate (size ～1 mm³) was analyzed by µ‐XANES at the K‐edges of S (2472 eV) and Fe (7112 eV). The experiment included (i) elemental mapping at the S K‐edge (S, Si, Al) and the Fe K‐edge (Fe, Si), (ii) acquisition of 300 µm × 300 µm images of the region of interest with X‐ray energies of 2474 eV (addressing reduced organic and inorganic S), 2483 eV (total S), 7121 eV (divalent Fe) and 7200 eV (total Fe), as well as (iii) acquisition of S and Fe µ‐XANES spectra at two different positions, where image analysis suggested the dominance of reduced and oxidized S and Fe, respectively. Image analysis revealed a heterogeneous distribution of total Si, S and Fe as well as of different S and Fe species in the aggregate. Microregions which were either enriched in reduced or in oxidized S and Fe could be identified. A microregion with a large contribution of oxidized S (sulfate, sulfonate) to total S contained exclusively Fe(III) oxyhydroxides (probably ferrihydrite) as S‐bearing phase, whereas another microregion with a large contribution of reduced organic S (thiol, organic disulfide) to total S contained a small amount of Fe(II)‐bearing silicate in addition to the dominating Fe(III) oxyhydroxides. Our results show that combined S and Fe µ‐XANES is a powerful tool for studying microscale spatial patterns of S and Fe speciation as well as microscale relationships between the speciation of S and Fe in soil aggregates.     

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO4·2H2O), ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O)

Three crystalline ferric arsenate phases: (1) scorodite; FeAsO₄·2H₂O, (2) ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and (3) basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O) synthesized by hydrothermal precipitation (175–225 °C) from Fe(III)‐AsO₄³⁻–SO₄²⁻ solutions have been investigated via Raman and infrared spectroscopies. The spectroscopic nature of these high‐temperature Fe(III)‐ AsO₄³⁻–SO₄²⁻ phases has not been extensively studied despite their importance to the hydrometallurgical industrial processing of precious metal (Au and Cu) arsenic sulfidic ores. It was found that scorodite, FAsH and BFAS all gave rise to very distinct arsenate, sulfate and hydroxyl vibrations. In scorodite and FAsH, the distribution of the internal arsenate modes was found to be distinct, with the factor effect being more predominant in the crystal system. For the crystallographically unknown BFAS phase, vibrational spectroscopy was used to monitor the arsenate ↔ sulfate solid solution behavior that occurs in this phase where the molecular symmetry of arsenate and sulfate in the crystal structure is reduced from an ideal T_d to a distorted T_d or C₂/C_2v symmetry. With the new collected vibrational data of the pure phases, the use of attenuated total reflectance infrared (ATR‐IR) spectroscopy was finally extended to investigate the nature of the arsenate in an industrial residue generated by pressure oxidation of a gold ore, where it was found that the arsenate was present in the form of BFAS. Copyright © 2009 John Wiley & Sons, Ltd.     

Silicon-29 NMR Spectroscopy Study of the Effect of Tetraphenylammonium (TPA) as a Template on Distribution of Silicate Species on Alkaline Aqueous and Alcoholic Silicate Solutions

Silicon-29 nuclear magnetic resonance (NMR) spectroscopy is used to characterize aqueous and non-aqueous alkaline solutions of tetraphenylammonium (TPA) silicates. Effect of the TPA cation on the equilibrium of silicate oligomers in aqueous and non-aqueous alkaline silicate solutions is investigated using ²⁹Si NMR spectra. It was found that the TPA cation had a structural directing role, directing the silicate species to form minor amounts of high order silicate anion in the presence of a high concentration of silicon. ²⁹Si NMR spectra of TPA silicate solutions indicate that considerable changes occur by changing the Si/TPA ratio. Also the effect of different alcohols on the distribution of silicate species is investigated. The results obtained show that distribution of these species is affected by the presence of alcohols and that maximum variations in this distribution are observed in the presence of methanol.     

Evidence for the Fe(II)-Fe(III) Green Rust "Fougerite" Mineral Occurrence in a Hydromorphic Soil and Its Transformation with Depth

Mössbauer spectroscopy is used to characterize a Green Rust as a natural mineral for the first time. Samples are taken from a hydromorphic soil under the forest at Fougères (Brittany, France) during spring season. Spectra are compared with those of synthetic Green Rusts (GRs), i.e. hydroxy-chloride, -sulphate, -carbonate and display one ferric and one or two ferrous sites. Fe(II)/Fe(III) abundances ratio cannot be attributed definitely to one of those stoichiometric compounds. Therefore, the counter-anion species cannot be specified even though hyperfine parameters perfectly match values of synthetic samples. The Fe(II)/Fe(III) ratio obtained from the Mössbauer spectra decreases with sampling depth. The "fougerite" originates likely from the reduction of deeper Fe(III)-mineral species by anoxic waterlogging.