Synthesis and adsorption properties of chitosan-crown ether resins

1　INTRODUCTIONTheeffectiveremovalorrecoveryoftoxicmetalsstillremainsamajortopicofpresentresearch .In creasedawarenessofthetoxicityofmetalshaspromptedtheimplementationofstrictregulationsforitsdisposal,causingtraditionaltreatmentprocessessuchaschemicalprecipitationtoundergochanges .Modernmetal removaltechnologiessuchasionex change ,reverseosmosis ,andmembranesystemsthatproduceeffluentsofbetterqualitymakeitpossibletorecoverandreusemetals[1,2 ] .Chitosan ,whichiseasilyderivedfromchitinbyN de…     

Adsorption Capacity of Kaolinite for Copper （Ⅱ） under Magnetic Field

The adsorption of Cu^2 on kaolinite under magnetic field was studied at 25℃.The magnetic effects were investigated by designing the variation of exposure time, rnagnetie flux density and the method of magnetic exposure. The results from these study show that the magnetic treatment significaatly enhance the fraction of adsorption of Cu^2 ,the adsorption of Cu^2 by kaolinite increases with the increase of pH value from 2 to 6. Both the magnetic exposure time and the magnetic flux density promote the fruetion of adsorption Cu^2 on kaolinite.     

铁铜微电解处理Cu2+-EDTA溶液及其机理研究

电镀废水中常含有EDTA等络合剂,部分重金属呈现络合态,这给重金属的去除带来了极大的挑战.微电解法处理络合废水破络效果好,成本低廉.为此,采用铁铜微电解法处理EDTA络合铜溶液,通过微电解过程的金属离子变化及沉淀物红外光谱分析可知,在微电解过程中主要变化为铁屑溶解、Fe2+和Fe3+质量浓度升高、Cu~(2+)质量浓度降低,并伴随EDTA质量浓度略微下降和Fe(OH)3沉淀生成;采用MINTEQ软件模拟Cu~(2+)、Fe2+和Fe3+与EDTA的络合形态分布,发现加入Fe3+能使EDTA与Cu~(2+)解络,Fe3+与Cu~(2+)摩尔比越大,p H越低,解络效果越好;在碱性条件下加入Fe2+能使EDTA与铜解络.Fe2+与Cu~(2+)摩尔比越大,p H越高,解络效果越好.结合实验和模拟结果可以明确Fe3+在酸性条件下的解络作用和铁屑对游离态Cu~(2+)的还原作用是微电解去除Cu~(2+)-EDTA的主要原因.     

A Modified Co-precipitation Method to Prepare Cu/ZnO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalyst and Its Application in Low Temperature Water-gas Shift (LT-WGS) Reaction

A modified co-precipitation method for the production of Cu/ZnO/Al₂O₃ complex was studied. The modification was that part of Al was introduced by adding Al³⁺ into Cu²⁺/Zn²⁺ solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N₂ adsorption, H₂-N₂O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al³⁺ can be doped in aurichalcite lattice, and the maximum doping amount of Al³⁺ was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al₂O₃ sample produced by the modified method, in which co-precipitated Al³⁺ was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area (26.1 m²/g) obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al₂O₃, which was decomposed from pseudo-boehmite in the calcination step.     

氯氧化铋/氧化亚铜复合材料的制备及其可见光催化性能

通过水热法成功制备了BiOCl/Cu₂O 复合材料, 是一种良好的可见光响应的光催化剂。通过X 射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-vis) 和电化学阻抗谱(EIS) 等分析方法对BiOCl/Cu₂O 复合材料进行表征分析。以酸性橙(AO7) 为目标污染物进行光催化降解实验, 探究了BiOCl/Cu₂O 复合材料的光催化性能和降解机制。XRD 结果表明, 随着BiOCl 含量的增多, BiOCl 的衍射强度逐渐上升。SEM 结果表明, BiOCl 小纳米片附着在相对较大的八面体Cu₂O 表面形成复合结构。通过UV-vis 和EIS 分析结果可知, 复合材料的带隙相较于Cu₂O 略微增大但其阻抗明显变小。降解实验结果表明, 质量比为3 : 5 的BiOCl/Cu₂O 复合材料在90 min时的可见光催化降解率(56.8%) 明显高于Cu₂O 的降解率(26.3%), 其降解速率常数(0.009 3 min^-1) 是纯Cu₂O(0.003 3 min^-1) 的2.8 倍。自由基捕获实验表明BiOCl/Cu₂O 复合材料光催化过程中起主要作用的活性物种是超氧自由基(·O_{2^- )。6 次循环降解实验后光催化剂BiOCl/Cu2O(3 : 5) 对AO7 的降解率仍可达到48.3%。BiOCl 与Cu2O形成的异质结构在一定程度上降低了表面转移电阻, 加快了光催化过程中光生电子的转移速率, 提高了光生电子和空穴的分离率, 增强了光催化效果。}     

Cu2O/Cu2S 复合材料制备及可见光催化降解甲基橙的研究

通过水热法制备Cu₂O/Cu₂S 复合材料对甲基橙(MO) 进行光催化降解实验。在Cu₂O 中引入S 元素, 通过 改变Cu/S 投加摩尔比, 从而得到不同Cu/S 的复合材料。利用XRD、SEM、UV-vis、EIS 等手段对材料进行表征, 并 对MO 进行光催化降解实验。XRD 结果表明, 随着S 含量的增多, Cu₂S 的衍射强度逐渐上升, Cu₂O 的f111g 晶面 衍射强度逐渐降低。SEM 结果表明Cu₂S 能较好地包覆在Cu₂O 八面体的表面。通过UV-vis 和EIS 结果计算得知, 复合材料带隙为1.49 eV, 电荷转移电阻大幅降低。降解实验结果表明复合材料最佳Cu/S 投加摩尔比为15 : 1, 其在 100 min 时对MO (100 mL, 10 mg/L) 降解率达到91.4%, 明显高于纯Cu₂O 对于MO 的降解率(60.3%)。猝灭实验表 明了?OH 和 ?O₂ ^-在光催化过程中起到主要作用。     

Preparation and antimicrobial ability of natural proous antibacterial materials

The liquid ion exchange method, solid salt melt method and dry-wet circulation method were used to prepare natural porous antimicrobial materials with natural minerals, such as zeolite, spilite, palygorskite and montmorillonite, respectively. Atomic absorption spectrum and X-ray diffraction analysis were carried out to investigate the effects of Ag⁺, Cu²⁺ and Zn²⁺ on antimicrobial abilities of natural porous minerals, and the effect of preparation method on ion exchange capacity of antimicrobial material, respectively. The results show that for the ion exchange capacity, clay mineral is higher than fibrous mineral, i. e. both zeolite and montmorillonite are higher; the antimicrobial ability of material with Ag⁺ is the best; the exchange capacities of materials with Cu²⁺ or Zn²⁺ are all higher, but the antimicrobial ability of Cu²⁺ is better than that of Zn²⁺. Foundation item: Project (40072020) supported by the National Natural Science Foundation of China; project (2001AA322070) supported by the National High Technology Research and Development Program of China     

Effects of different conditions on Pb2+ adsorption from soil by irrigation of sewage in South China

Pb²⁺ adsorption onto a soil by irrigation of sewage in the Pearl River Delta of South China was examined as a function of the reaction time, solution pH, initial lead concentration, organic matter (humic acid) and competitive ions (Cu²⁺). The adsorption of Pb²⁺ onto the soil was investigated on batch equilibrium adsorption experiments. Results show that the Pb²⁺ adsorption on the soil is relatively rapid in the first 30 min and reaches equilibrium at 2 h, and the kinetics of the adsorption process on the soil is well characterized by the pseudo-second order reaction rate. Langmuir, Freundlich and Temkin isothermal models are fit for the adsorption of Pb²⁺ onto the soil, and the maximum amount of Pb²⁺ adsorption (Q _m) is 7.47 mg/g. The amount of Pb²⁺ adsorption increases with increasing the pH at the range of 1.2–4.5 and reaches a plateau at the range of 4.5–12. The presence of humic acid in soil decreases the adsorption of Pb²⁺ onto the soil at solution pH of 8 since the negatively charged humic acid with Pb²⁺ is difficult to be adsorbed on the negatively charged soil surface. The adsorption of Pb²⁺ onto the soil also decreases in the presence of Cu²⁺ due to the competition adsorption between Pb²⁺ and Cu²⁺.     

Effect of corrosive solutions on C-S-H microstructure in portland cement paste with fly ash

By means of ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) combined with deconvolution technique, X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as energy dispersive X-ray system(EDX), the effect of 5 wt% corrosive solutions (viz. 5 wt% Na₂SO₄, MgSO₄, Na2SO4+NaCl and Na₂SO₄+NaCl+Na₂CO₃) on C-S-H microstructure in Portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO₄ solution, Mg²⁺ promotes the decalcification of C-S-H by SO ₄ ^2- ,increasing silicate tetrahedra polymerization and mean chain length (MCL) of C-S-H. However, the substituting degree of Al³⁺ for Si⁴⁺ (Al[4]/Si) in the paste does not change evidently. Effect of Na²SO⁴ solution on C-S-H is not significantly influenced by NaCl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO ₄ ^2- and CO ₃ ^2- attack, as well as the activation of fly ash by SO ₄ ^2- attack will increase the MCL and Al[4]/Si, which are both higher than that under Na₂SO₄ corrosion, MgSO₄ or Na₂SO₄ +NaCl coordination corrosion.     

Simultaneous electrogenerative leaching of chaicopyrite concentrate and MnO2

In order to enhance the electrogenerative leaching rate of chalcopyrite concentrate reasonably, the principle of generative process was applied to simultaneous leaching of chalcopyrite concentrate and MnO2. The results show that Cu^2＋ and Mn^2＋ in addition to electrical energy could be acquired in the simultaneous electrogenerative leaching process. The leaching cell has the open circuit potential of about 1.0 V and gains quantity of electricity of about 700 C. The optimum leaching rates of Cu^2＋ and Mn^2＋ are 23.10% and 22.1%, respectively after electrogenera- tive leaching for about 10 h under the present conditions.     

Characteristics of magnetic Fe3O4 nanoparticles encapsulated with human serum albumin

Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.     

Cu2+和Ni2+对水解-MBR工艺处理效能的影响特性

为降低电镀废水中重金属对生物处理系统的冲击,采用水解-膜生物反应器(MBR)组合工艺对电镀综合废水进行处理,以重金属离子Cu~(2+)、Ni~(2+)为代表,重点研究不同质量浓度的重金属冲击下对水解-MBR工艺处理电镀废水效能的影响,以及水中DOMs与微生物活性的变化情况.结果表明:在Cu~(2+)、Ni~(2+)质量浓度5~20 mg/L冲击下,水解-MBR组合工艺对COD和NH_4~+-N去除效率分别在75%和45%以上.硝化细菌抗重金属冲击能力较差,水解-MBR组合工艺对重金属Cu~(2+)、Ni~(2+)的耐受质量浓度可达20 mg/L,而单纯MBR工艺仅为10 mg/L.水解反应器可将污水中HPI大部分转化为HPO-A,改善难降解有机物可生化性,芳香族化合物的含量明显降低.随着重金属Cu~(2+)、Ni~(2+)质量浓度的升高,MBR反应器内活性污泥的SOUR值逐步下降,但水解-MBR工艺SOUR受重金属的抑制率均比单独MBR工艺低5%左右.由于水解使重金属毒性减弱,水解-MBR系统中微生物的活性较高,系统中EPS含量和出水质量浓度均显著低于单独MBR工艺,且可以有效减少膜表面胶体物质和溶解性有机物形成,降低污泥滤饼层的形成速度,有效减缓膜污染的速率.     

Determination of the entropy change for electrode reaction and dilute enthalpy of some ions by thermo-eletrochemical technology

Based on thermo-electrochemical equation for an electrode reaction, the entropy change of it can be obtained by the thermo - electrochemical technology (TECT). The entropy changes of Fe (CN) ₆ ⁻³ /Fe (CN) ₆ ⁻⁴ , H⁺/H₂(P⁰), Cu⁺²/Cu and Zn⁺²/Zn electrode reaction systems and the dilute enthalpies of the H⁺, Cu²⁺ and Zn²⁺ ions under the ion concentrations studied have been determined by a specially designed thermo-electrochemical equipment. The enthalpy change and entropy change for the five systems at unlimitedly diluted concentrations agree well with the literature. Project supporterd by the National Natural Science Foundation of China Synopsis of the first author Fang Zheng, Ph. D. and professor, born in April 1944, majoring the metallurgical thermodynamics and thermoelectrochemistry, supervised and participated in three projects supported by the National Natural Science Fundation of China and some other projects. More than 70 academic papers have been published.     

Structure and Infrared Radiation Properties of Substituted Cordierites

Zn^2＋ - or Ti^4＋ -substituted cordierites with the nominal compositions of Mg1 .6 Zn0.4 Al4 Si5 O18 and Mg1.8 Ti0.2 Al4.4 Si4.6 O18 respectively, were prepared by a conventional solid state reaction method. The structure of the substituted eordierites was characterized by X- ray diffraction （ XRD ）, infrared （ 1R ） spectroscopy and 29 Si magic angle spinning （ MAS ） nuclear magnetic resonance （ NMR ）. The infoared radiation properties were investigated in the bands within 2.5-25μm. Compared with the na-substituted cordierite composition （ Mg2 Al4 Si5 O18 ）, Zn^2＋ - or Ti^4＋ -substituted cordierites show superior infrared properties. XRD and IR results confirm the formation of hexagonal a-eordierite as the main eo＇stal phase for the substituted cordierites. 29 Si MAS NMR result indicates that Zn^2＋ or Ti^4＋ Substitutions for partial Mg^2＋ of a-eordierite promoted the ordering of the distribution oral and Si atoms in T1 （ tetrahedra connecting six-raembered rings together with [ MgO6] octahedra ） and T2 （ tetraheda forming six-reentered rings） tetrahedral sites. This resulted in a lattice deformation and increased the anharmonicity of polarization vibration, which is responsible for the improvement of infrared radiation properties of the substituted eordierites.     

Mechanism and behaviors of Cr3+-doped TiO2

TiO₂ powder and TiO₂ thin film on the surface of glazed ceramic tile were prepared by sol-gel method. The influences of different doping Cr³⁺ concentration on the photocatalytic activity of TiO₂ were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO₂ powder and film. The results indicate that photocatalytic activity of doping Cr³⁺-TiO₂ thin film is higher than that of powder, and the interaction between Cr³⁺-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr³⁺-doped energy level in TiO₂ is 0.62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr³⁺ dopant energy level, the semiconductor energy level model of Cr³⁺ in TiO₂ powder and thin film were established, and the doping mechanisms of Cr³⁺-doped in TiO₂ powder and thin film were analyzed. Foundation item: Project (20466001) supported by the National Natural Science Foundation of China     

Influence of Polyepoxysuccinic Acid on Solid Phase Products in Portland Cement Pastes

The influence of polyepoxysuccinic acid(PESA) on the solid phase products in hydrated Portland cement pastes was investigated by isothermal calorimetry, X-ray diffraction(XRD), ²⁹Si and ²⁷Al nuclear magnetic resonance(NMR). The results indicated that PESA bonds Ca²⁺ ions in pore solution to prevent portlandite formation, and also combines with Ca²⁺ ions on the surface of silicate minerals to prolong the control time of phase boundary reaction process, leading to the retardation of silicate mineral hydration. Meanwhile, the interlayer Ca²⁺ ions in Jennite-like structure bridging PESA and C-S-H gels prevent silicate tetrahedron and aluminum tetrahedron from occupying the sites of bridging silicate tetrahedron, which causes the main existence of dimer in C-S-H structure, deceases the degree of Al³⁺ substituting for Si⁴⁺ and promotes the transformation from 4-coordination aluminum to 6-coordination aluminum. Furthermore, the -Ca⁺ chelating group from reacting PESA with Ca²⁺ ions combines easily with SO₄^2- ions, resulting in transformation from ettringite, AFm to TAH(Third aluminum hydrate). However, with the higher addition of PESA, it will bridge the excess PESA by Ca²⁺ ions to form a new chelate with ladder-shaped double chains structure, which not only reduces the amount of PESA bonding Ca²⁺ ions, but also decreases its solidifying capability for SO₄^2- ions, leading to the transformation from TAH to AFm or ettringite. Meanwhile, at later hydration, the inhibition effect of PESA on cement hydration is weakened, and the transformation degree from TAH to AFm is higher than that to AFt with the addition of PESA.     

Thermochemical studies of the toxic action of heavy metal ions on<Emphasis Type="Italic">Escherichia coli</Emphasis> by microcalorimetry

By using an LKB2277, BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Escherichia coli growth at 37°C inhibited by four kinds of heavy metal ions are determined, and parameters such as growth rate constants, inhibitory ratio, half-inhibitory concentration etc. were obtained. The experimental results show that heavy metal ions can inhibit Escherichia coli growth obviously, but low concentration of Cu²⁺ has a promoting action. The half inhibitory concentrations of Zn²⁺, Cd²⁺, Hg²⁺ and Cu²⁺ are 28.3, 10.9, 3.19 and 69.6 μg. mL⁻¹, respectively. Judged from the rate constant, the half-inhibitory concentration and the molecular mass, the inhibitory sequence is Hg²⁺>Cd²⁺>Zn²⁺>Cu²⁺. This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest. Li Xi: Born in 1968 Funded by the National Natural Science Foundation of China (29973030 and 30170010)     

Combustion synthesis and luminescent properties of CaO: Eu<Superscript>3+</Superscript>, M<Superscript>+</Superscript> (M=Li,Na, K) phosphor

Li⁺, Na⁺, or K⁺ co-doped CaO: Eu³⁺ phosphors were prepared by the combustion synthesis method and characterized by X-ray diffraction (XRD), photoluminescence and photoluminescence excitation (PL-PLE) spectra. The experimental results show that, upon excitation with 250 nm xenon light, the emission spectrum of the CaO: Eu³⁺ consists of 4f-4f emission transitions from the ⁵ D ₀ excited level to the ⁷ F _J (J=1, 2, 3) levels with the mainly electric dipole transition ⁵ D ₀→⁷ F ₂ of Eu³⁺, indicating that the Eu³⁺ occupies a low symmetry. The charge-transfer band (CTB) shows somewhat red shift with the decreasing ionic radii of co-doped alkali metal ions. The PL and PLE intensities are significantly enhanced, especially the strongest intensity of luminescent is CaO: Eu³⁺, Li⁺ phosphor, when alkali metal ions are incorporated. The strongest peak of emission is slightly shifted from 614 to 593 nm, indicating that the Eu³⁺ ion locates in a symmetric position (O _h ) when alkali metal ions are incorporated.     

Cu2+对温州软粘土电阻率特性影响的试验研究

温州制革、电镀等轻工业发达,废水中Cu²⁺含量较高,多处地下水和土壤受到污染。选取典型温州软黏土,将土样重塑,加入不同浓度的Cu²⁺和适量水泥进行固化,通过测试不同土样电阻率来研究Cu²⁺对土体性能的影响。电阻率测试在改装的一维压缩固结试验中进行,压缩中部分土样电阻率变化不显著,但可量测到压缩过程中电阻率的变化规律。试验结果表明：电阻率可以很好地评估加入水泥之后土体性质的改变,在实际工程中可以用来反映土体的污染程度;土体在Cu²⁺含量和含水量很高时,不宜采用电阻率法评估土体污染压缩的过程。     

Competitive adsorption of heavy metal ions on peat

The uptake capacities, and the adsorption kinetics, of copper, Cu(Ⅱ), nickel, Ni(Ⅱ), and cadmium, Cd(Ⅱ), on peat have been studied under static conditions. The results show that the adsorption rates are rapid: equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacifies follow the order Cu2 ＞Ni2 ＞Cd2 in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu2 ＞ Ni2 ＞Cd2 in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.