Photooxidation of the surfaces of polyphenylene oxide and polysulfone

Changes in the composition and structure of the surfaces of polyphenylene oxide (PPO) and polysulfone caused by UV photooxidation are followed using ESCA. The surface stoichiometry of PPO changes from C₈O₁ to C₈O_4.8 on photooxidation, the oxygen being added in the form of carbonyl and especially carboxyl groups. Surface photooxidation is rapid, the ESCA spectra showing substantial changes after a few minutes of irradiation, and no further changes being detected after 10 h of reaction. The surface photooxidation of polysulfone occurs in three stages. In the first 2 h rapid oxidation takes place at carbon atoms, the levels of C—O, carbonyl, and carboxyl groups increasing at comparable rates. This is followed by slower oxygen incorporation up to 15 h of reaction, during which time carbonyl and carboxyl levels increase and oxidation of the sulfone sulfur is observed. Some degradation occurs as groups containing carbon and oxygen are lost from the surface. Further oxidation then produces a decrease in the surface levels of C—O and carbonyl groups, and further degradation. The photooxidized surface has a stoichiometry of C₁₀O₆S, compared with C₂₇O₄S in the unreacted polymer.     

碘电极测定饮用水中的碘和碘离子

应用碘电极 ,采用亚砷酸钠为碘的还原剂进行前处理 ,选用磷酸二氢钠为总离子强度缓冲液 ,测定了总碘及碘离子含量。建立的方法对三碘树脂净水器净化后的水进行了测定 ,结果良好。当总碘和碘离子的浓度在 10 -7～ 10 -4范围内时 ,相关系数为 0 .9999,回收率大于 98.1%。由实验测定的电位选择系数可见 ,该法选择性好 ,检测下限低。     

Molecular engineering of semiconductor surfaces and devices

Grafting organic molecules onto solid surfaces can transfer molecular properties to the solid. We describe how modifications of semiconductor or metal surfaces by molecules with systematically varying properties can lead to corresponding trends in the (electronic) properties of the resulting hybrid (molecule + solid) materials and devices made with them. Examples include molecule-controlled diodes and sensors, where the electrons need not to go through the molecules (action at a distance), suggesting a new approach to molecule-based electronics.     

Ripple coarsening on ion beam-eroded surfaces

The temporal evolution of ripple pattern on Ge, Si, Al₂O₃, and SiO₂ by low-energy ion beam erosion with Xe ⁺ ions is studied. The experiments focus on the ripple dynamics in a fluence range from 1.1 × 10¹⁷ cm^-2 to 1.3 × 10¹⁹ cm^-2 at ion incidence angles of 65° and 75° and ion energies of 600 and 1,200 eV. At low fluences a short-wavelength ripple structure emerges on the surface that is superimposed and later on dominated by long wavelength structures for increasing fluences. The coarsening of short wavelength ripples depends on the material system and angle of incidence. These observations are associated with the influence of reflected primary ions and gradient-dependent sputtering. The investigations reveal that coarsening of the pattern is a universal behavior for all investigated materials, just at the earliest accessible stage of surface evolution.     

Cycloaddition chemistry of organic molecules with semiconductor surfaces

Recent investigations have shown that cycloaddition reactions, widely used in organic chemistry to form ring compounds, can also be applied to link organic molecules to the (001) surfaces of crystalline silicon, germanium, and diamond. While these surfaces are comprised of Si=Si, Ge=Ge, and C=C structural units that resemble the C=C bonds of organic alkenes, the rates and mechanisms of the surface reactions show some distinct differences from those of their organic counterparts This article reviews recent studies of [2 + 2], [4 + 2] Diels-Alder, and other cycloaddition reactions of organic molecules with semiconductor surfaces and summarizes the current understanding of the reaction pathways.     

复合膜电极对溶液中碘离子电化学离子分离性能

在多孔碳纤维毡基体上通过化学沉积法制备了具有电活性的聚吡咯复合膜电极,在两电极体系下对溶液中的碘离子进行电化学离子吸附分离操作,其中氧化状态下具有阴离子交换功能的聚吡咯复合膜电极作阳极。考察了不同操作电压、溶液pH值对膜电极分离性能的影响,并在混合溶液中考察了膜电极对碘离子选择性。结果表明,电压的适当升高与溶液pH值的降低有利于提高膜电极对碘离子的吸附速率和容量增高。复合膜电极表现出对碘离子优良的选择性吸附特性和可多次重复使用性。     

复合膜电极对溶液中碘离子电化学离子分离性能

在多孔碳纤维毡基体上通过化学沉积法制备了具有电活性的聚吡咯复合膜电极,在两电极体系下对溶液中的碘离子进行电化学离子吸附分离操作,其中氧化状态下具有阴离子交换功能的聚吡咯复合膜电极作阳极。考察了不同操作电压、溶液pH值对膜电极分离性能的影响,并在混合溶液中考察了膜电极对碘离子选择性。结果表明,电压的适当升高与溶液pH值的降低有利于提高膜电极对碘离子的吸附速率和容量增高。复合膜电极表现出对碘离子优良的选择性吸附特性和可多次重复使用性。     

Properties of semiconductor—molten salt electrolyte interface: review of the semiconductor—ammoniate of sodium iodide junctions

The influence of the supporting electrolyte on the charge transfer mechanism at the semi-conductor/electrolyte interface is often primordial in the utilization of semiconducting electrodes in solar energy conversion. This work specifies the behaviour of a range of S.C. (SiSe, (III, V) and (II, VI) compounds) in a “non-aqueous” protonic solvent: the liquid ammoniate of sodium iodide (LASI). In each case, the flat band potential was unambiguously determined and the influence of solvated protons, NH⁺₄ and water was studied.     

Arginine self-assembled monolayers against copper corrosion and synergistic effect of iodide ion

Self-assembled monolayers (SAMs) of arginine (Arg) were formed on copper surface. The corrosion protection properties of the Arg SAMs were examined by electrochemical impedance spectroscopy and polarization techniques in 0.5 M HCl solution. The results show that Arg SAMs have limited protection effect. The protective efficiency increased with an increase of self-assembly time and reached maximum protection at 6 h. When iodide ion was added to the Arg-containing solution, the ability of the corrosion inhibition of the mixed SAMs improved significantly. The corrosion protection mechanism of Arg SAMs is discussed based on AM1 quantum-chemical calculations.     

电导检测离子色谱法测定水和废水中碘化物

建立了一种电导检测一离子色谱法测定水和废水中碘化物的方法,并对色谱条件进行优化。采用IonPacASl9型阴离子分离柱,以40mmol·L-KOH为淋洗液,流速1．0mL·min-1,抑制型电导检测碘化物。碘化物的检出限为0．001mg·L-1,线性范围广,相关性好（r〉0．999）,相对标准偏差为0．3％-2．0％,加标回收率为91．3％～94．4％。该方法操作简单快捷,分离效果好,灵敏度高,适用于水和废水中碘化物的测定。     

吸附法去除电解用氯化钠中微量碘离子

在离子膜法制碱过程中,盐水中的碘离子会在电解过程中被氧化成碘酸根或高碘酸根,与盐水中的钠离子、钡离子、钙离子、镁离子等形成碘酸盐沉淀或高碘酸盐沉淀,造成膜堵塞、膜使用寿命缩短、电解电流效率降低、电压升高等问题。本文采用溶胶凝胶法制备了有机胺类碘离子吸附剂,研究了动态吸附氯化钠中微量碘离子的去除性能和吸附柱循环再生性能,结果表明：吸附柱可将盐水中碘离子含量降至0.2mg/L以下,碘离子与氢离子物质的量比为1∶2、料液流速为6.4mL/（g·min）、碘离子含量为10mg/L时,采用0.01mol/L的Na₂CO₃洗脱再生循环5次,吸附剂处理盐水体积约在3.0～3.6L/g之间。同时,考察了盐水中共存离子对除碘性能的影响,结果表明：盐水中共存离子Br^-、SO₄^2-、Mg²⁺、Fe²⁺会使吸附柱可处理盐水体积降低,为保证吸附柱除碘效率,盐水除碘步骤应在精制除钙镁、除铁之后。     

Photooxidation of some phenols in aerated acetonitrile using tetra-tert-butylphthalocyaninatozinc(II) as a sensitizer

Photooxidation of phenol and its some derivatives was performed in aerated acetonitrile in irradiation with visible light using tetra-tert-butylphthalocyaninatozinc(II) as a sensitizer. Decomposition of the substrates was accelerated by the addition of aqueous sodium hydroxide. The reaction proceeded via the pathway with singlet oxygen. As decomposed products of the phenols, p-benzoquinone and chlorohydroquinone were confirmed.     

A solid silver iodide electrode as silver ion indicator in molten nitrates

Qualitative reasoning suggested the possibility of using silver iodide as indicator electrode for silver ions in molten media. The idea has been confirmed by employing a rotating disk electrode, in which the electroactive part was a AgI-tablet, for the determination of the diffusion coefficient of silver ions in molten potassium and sodium nitrates.     

mLLDPE薄膜的光氧化及热力学降解

茂金属线型低密度聚乙烯(mLLDPE)和传统线型低密度聚乙烯(LLDPE)薄膜经紫外灯照射不同时间后,用红外光谱和差示扫描量热法对薄膜跟踪测试。发现mLLDPE的羰基指数及不饱和碳碳双键的变化快于LLDPE;mLLDPE的氧化初始温度及熔融热焓的变化也明显低于LLDPE。     

Effect of surface nanocrystallization on corrosion and corrosion inhibition of low carbon steel: Synergistic effect of methionine and iodide ion

The corrosion properties of a nanocrystalline low carbon steel coating (SNCLCS) fabricated on a low carbon steel substrate by magnetron sputtering and the bulk steel (BLCS) were investigated in aerated 0.5 M H₂SO₄ solution by EIS and polarization techniques. The corrosion inhibiting effect of methionine and synergistic KI additives was also studied. The results show that both specimens underwent active corrosion with no transition to passivation in the potential range studied. Surface nanocrystallization was observed to increase the corrosion susceptibility of low carbon steel, leading to a decrease in interfacial impedance and an increase in the kinetics of the anodic reaction. Methionine inhibited the corrosion of both specimens with comparable inhibition efficiencies and iodide ions synergistically increased the inhibition efficiency. This synergistic effect was, however, more pronounced for BLCS. This has been discussed vis-à-vis the more positive surface charge on BLCS compared to SNCLCS.     

Synthesis and physicochemical studies of some new amphoteric ion exchangers

Some new amphoteric ion exchangers have been synthesized by condensing salicylic acid, p-hydroxybenzoic acid, sulfosalicylic acid, gallic acid, 3-hydroxy-2-naphthoic acid, β-resorcylic acid, and resacetophenone with epichlorohydrin employing ethylenediamine as a crosslinking agent. Some of the physicochemical properties, such as moisture content, true density, apparent density, void volume fraction, concentration of ionogenic groups, exchange capacity, rate of exchange, pH-titration curves, pK values, isoionic point, thermal stability, oxidation resistance, and swelling behavior in different solvents, have been investigated.     

Conductometric study of ion association in some polyelectrolytes

Conductances of sodium alginate, sodium carboxymethylcellulose and sodium carboxymethyl dextran solutions have been measured in the presence of sodium chloride. It has been found that the sum of the specific conductances of the components measured separately is always greater than the specific conductance of the mixture. The difference in specific conductance between the sum and the mixture, Δ, has been studied as a function of the polyelectrolyte concentration, concentration of sodium chloride and also temperature. An attempt has been made to interpret the results in terms of both electrostatic effects and the Donnan theory of membrane equilibrium. The latter approach does not seem satisfactory.     

Equilibrium,kinetic and isotherm of some metal ion biosorption

Trichoderma reesei was used as a biosorbent for the removal of Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ ions. The influence of factors such as pH, mass of biomass, contact time and temperature on biosorption efficiency was optimized. To calculate the isotherm parameters for the biosorption of Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ ions at optimized conditions, the experimental equilibrium data were fitted to Langmuir and Freundlich models. The calculated thermodynamic parameters, ΔG°, ΔH° and ΔS° showed that the biosorption of Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ ions onto T. reesei biomass was feasible, spontaneous and endothermic at the optimized conditions. The results of kinetic analysis showed that the biosorption of the selected metal ions onto T. reesei biomass obeys pseudo second order kinetics.