Research of Inclusion Complexation of 4,4'-Thiodiphenol Effected by β-Cyclodextrin in Aqueous Solutions and the Effect on Photodegradation

The inclusion behavior of 4,4′ -Thiodiphenol (TDP),a typical bisphenol and endocrine disruptor,reacts with β-cyclodextrin (β-CD) in aqueous solutions has been investigated by means of UV absorption spectrum and quantum-chemical calculation with Gaussian 98 software. The results show that the inclusion behavior of TDP is quite different in acidic solutions (pH 5.9) from that in alkaline solutions (pH 10.0). This behavior difference is attributed to the different formula structures in aqueous solutions at acidic and alkaline pH values that are demonstrated by quantumchemical modeling and calculation. TDP forms a 1∶1 β-CD inclusion complex in aqueous solutions. The equilibrium constant K was calculated to be 553.49 L/mol at pH 5.9 and 1 318.20 L/mol at pH 10.0 respectively for the inclusion complex reaction by using the modified Benesi-Heldbrand equation. After inclusion TDP's structure is changed especially at the inclusion part with the bond order becoming larger,which results in inhibitive photodegradation during direct photooxidation and H2O2 assisted photooxidation.     

Adsorption of Cd(II) from acidic aqueous solutions by tourmaline as a novel material

Batch experiments were conducted to investigate the behavior and mechanisms for the adsorption of Cd(Ⅱ) from aqueous solutions by tourmaline under acidic conditions. The results indicated that the adsorption of Cd(Ⅱ) significantly depend on the adsorption time, temperature, and the initial concentration of the metal ion. Furthermore, tourmaline had a very good adsorption capacity for Cd(Ⅱ) in acidic, neutral and alkaline aqueous solutions. This good adsorption capacity is attributed to the observation that tourmaline can automatically adjust the pH values of acidic (except pH 2.0 and 3.0), neutral or alkaline aqueous solutions to 6.4. Specifically, the removal capacity for Cd(Ⅱ) was higher at strongly acidic pH values (in contrast to industrial wastewater pH values) compared to that obtained for other types of adsorbents. Furthermore, the results obtained in this study showed good fits to the Langmuir and Freundlich adsorption isotherms. However, the Langmuir model fit better than the Freundlich model. The maximum uptake of Cd(Ⅱ) by tourmaline was 31.77, 33.11 and 40.16 mg/g at pH 4.0 at 15, 25 and 35°C, respectively. Therefore, tourmaline is an effective adsorbent for the removal of Cd(Ⅱ) from acidic aqueous solutions. In addition, the kinetics for the Cd(Ⅱ) adsorption by tourmaline closely followed the pseudo-second-order model. The thermodynamic parameters indicated that adsorption was feasible, spontaneous, and endothermic. Furthermore, the pH variation after adsorption, ζ-potential, metal ions desorbed and released, and FT-IR analysis indicated that the physisorption and chemisorption mechanisms of tourmaline for heavy metals. These mechanisms included water that was automatically polarized by tourmaline, the ion exchange process, and electropolar adsorption. Among the mechanisms, the automatic polarization of water caused by tourmaline is a unique adsorption mechanism for tourmaline.     

Formation of the Inclusion Complex of Orange II with β-Cyclodextrin and Its Photostability

Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange Ⅱ is 1∶1. The formation constant K=1.236×103 L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constant K=1.266×103 L/mol was determined by 1 H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange Ⅱ solutions containing β-CD and TiO2 was smaller by 51.9% than that of the Orange Ⅱ solutions only containing TiO2, while in the case of direct photolysis of Orange Ⅱ solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange Ⅱ under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis.     

Hemoglobin Biocatalyst Polymerization of Aniline by UV-vis Spectraphotometry

A biocatalytic route for the synthesis of a water soluble and conducting complex of polyaniline (PAN1)/sodium dodecylsulfate (SDS) is presented. Hemoglobin is used in SDS anion surfactant . The polymerization proceeded quickly to result in a homogeneous emeraldine-colored dispersion of PANI. Absorption spectra of PANI/SDS in the aqueous dispersions at various pH values confirms that the reversibility of dedoping and redoping process of PANI/SDS and shows that the transition from emeraldine salt to emeraldine base form occurred at about pH 10.0-11.0 in this anionic micellar system. PANI/SDS in the organic solutions dedoped initially and redoped after 24h.     

Dissolution properties of calcined gangue

To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and Al ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of Al and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and Al appear to have synchro-dissolution behavior in alkaline solution, which means that Si and Al could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of Al is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.     

Effects of applied potential on the stress corrosion cracking behavior of 7003 aluminum alloy in acid and alkaline chloride solutions

Potentiodynamic polarization tests and slow strain rate test (SSRT) in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) in acid and alkaline chloride solutions under various applied potentials (E_a). The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution (AD) at open-circuit potential (OCP) and is highly susceptible to hydrogen embrittlement (HE) at high negative E_a in the solutions with pH levels of 4 and 11. The susceptibility increases with negative shift in the potential when E_a is less than -1000 mV vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when E_a is equal to -1000 mV vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.     

Corrosion-wear behavior of nanocrystalline Fe88Si12 alloy in acid and alkaline solutions

The corrosion-wear behavior of a nanocrystalline Fe₈₈Si₁₂ alloy disc coupled with a Si₃N₄ ball was investigated in acid (pH 3) and alkaline (pH 9) aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe₈₈Si₁₂ alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe₈₈Si₁₂ alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe₈₈Si₁₂ alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si₃N₄ ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe₈₈Si₁₂ alloy in the pH 9 aqueous solution.     

Preparation,Characterization and Antioxidant Activity of Inclusion Complex of Bakuchiol with Hydroxypropyl-β-cyclodextrin

Bakuchiol isolated from Psoralea corylifolia is a naturally occurring prenylated phenolic monoterpene with a variety of bioactivities. The aim of this study was to improve the water solubility and thermal stability of bakuchiol through complexing it with hydroxypropyl-β-cyclodextrin(HP-β-CD). The bakuchiol/HP-β-CD inclusion complex's behavior and characterization were investigated by ultraviolet-visible(UV-vis) spectroscopy, Fourier transform infrared spectroscopy(FT-IR), thermogravimetric analysis(TGA),X-ray diffraction(XRD),~1H nuclear magnetic resonance(NMR), and two-dimensional(2 D) NMR. The obtained results indicated the formation of 1∶1 inclusion complex for bakuchiol with HP-β-CD. Water solubility of bakuchiol was significantly improved by complexation with HP-β-CD as demonstrated by phase solubility studies. The encapsulation of bakuchiol was confirmed by UV-vis, FT-IR, and XRD. The thermal stability was effectively enhanced by TGA and derivative thermogravimetry(DTG) analysis. In vitro antioxidant activity showed that bakuchiol/HP-β-CD inclusion complex had a little higher antioxidant ability than free bakuchiol. Moreover, we got the possible inclusion mode for the bakuchiol/HP-β-CD inclusion complex through NMR analysis. These results suggest that the inclusion complex can be a potentially useful approach in the design of novel formulations of bakuchiol for medical applications.     

Molecular recognition study on a supramolecular system (Ⅷ) --The fluoroscopic study on inclusion complexation of adamantanol with cyclodextrin derivatives

The fluorescence spectral titrations have been performed in phosphate buffer solution (pH 7 2) at room temperature to give the stability constants for inclusion complexation of a series of chemically modified β cyclodextrins bearing aromatic groups with adamantanol. The molecular recognition mechanism is discussed from the viewpoint of the structural factors, electron effect of the substitutent groups and the size and chain length of the fluorophore. The results indicate that the complex stability of the cyclodextrin derivatives bearing a positively charged pyridinio moiety can be enhanced by the electrostatic interaction between the host cyclodextrins and the adamantanol guest and the microenvironment change plays a crucial role in the inclusion complexation.     

Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.     

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose(celluloseⅠ) can not be oxidized by TEMPO - NaOCl -NaBr system, one of TEMPO-mediated selective oxidantsystems, but regenerated cellulose(cellulose Ⅰ)can becompletely selectively oxidized. In the present work,natural cellulose pulp was treated with NaOH solution,which concentration is lower than 20 wt%. The alkalinecelluloses obtained were oxidized by TEMPO - NaOCl -NaBr system and the factors which influence the selectiveoxidation reaction rate have been investigated. Thestructure of the oxidized products has been characterizedby Fourier transform-infrared(FTIR), nuclear magenaticresonace(NMR) and wide angle X-ray diffraction(WAXD) methods, and their adsorption properties forCu2 and Cd2 in aqueous solutions have beenpreliminarily examined. The results show that after thealkaline treatment, the primary hydroxyl at C6 position ofnatural cellulose can be selectively oxidized to carboxylgroup in the reaction medium at pH 10.8, the oxidationrate becomes greater with the NaOH concentration andalkaline treatment time increasing. The alkaline treatmenthas a great effect on the crystal structure of naturalcellulose, but the crystal structure of alkaline cellulosekeeps almost unchanged after oxidation. The adsorptioncapacity is enhanced by introducing carboxyl groups intothe cellulose macromolecular chains.     

Electrosynthesis of poly（o-phenylenediamine） in ionic liquid and its properties

Ionic liquid 1-ethyl-3-methylimidazolium bromide (EMIMBr) and N-methylimidazolium tetrafluorobo-rate (HMIMBF4) have been used as solvent and electrolyte for the electropolymerization of o-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It was found that monomer was more easily oxidized in ionic liquid than acidic aqueous solution,and oxidative potential was reduced by 0.725 and 0.455 V,respectively. Electrode modified with poly(o-phenylenediamine) (PPD) has obvi-ous electrochemical activity in acid solution (pH 1-4). The apparent diffusion coefficient (Dapp) of PPD film is measured by chronocoulometry and chronoamperometry. The polymer structure is measured by UV and IR. IR spectrometry reveals that poly(o-phenylenediamine) has phenazine ring structure. The heat stability of polymer is observed from thermogravimetry.     

The synthesis and properties study of 6,13-diphenylpentacene

6,13-diphenylpentacene（DPP） was synthesized by 6,13-pentacenequinone and the Grignard reagent with the SnCl2/HCl as the reducing agent. It was detected by ^1H NMR, infrared spectra, X-ray diffraction （XRD）, UV-visible spectra and fluorescence spectra. Substitution with phenyl at the C-6 and C-13 positions of pentacene leads to phenomenal enhancement in solubility and a little enhancement in photooxidative stability. XRD results showed that the pattern of 6,13-diphenylpentacene was different from the patterns of pentacene and 6,13-pentacenequinone. UV-Visible spectra showed that the λmax of DPP in HCCl3 was 600 nm. The fluorescence spectra showed that DPP emitted purple （430 nm） and red （612 nm） when excited by UV, while only emitted red when excited by visible light. But it is still susceptible to photooxidation. The photooxidation product of DPP was also studied.     

Existence of multiple solutions for the laminar flow in a porous channel with suction at both slowly expanding and contracting walls

The asymptotic behavior of solutions of a similarity equation for the laminar flow in a porous channel with suction at both expanding and contracting walls has been obtained by using a singular perturbation method. However, in the matching process, this solution neglects exponentially small terms. To take into account these exponentially small terms, a method involving the inclusion of exponentially small terms in a perturbation series was used to find two of the solutions analytically. The series involving the exponentially small terms and expansion ratio predicts dual solutions. Furthermore, the result indicates that the expansion ratio has much important influence on the solutions.     

Preparation and characterization of a chitosan-based low-pH-sensitive intelligent corrosion inhibitor

A chitosan (CS)-based low-pH-sensitive intelligent corrosion inhibitor was prepared by loading a pH-sensitive hydrogel with benzotriazole (BTA); the pH-sensitive hydrogel was synthetized by crosslinking CS with glutaraldehyde (GTA). Analysis by Fourier- transform infrared (FT–IR) spectroscopy showed that Schiff reactions occurred between amino and aldehyde groups. The swelling ability of the hydrogel was investigated using a mass method, and it was observed to swell more in an acidic environment than in an alkaline environment. The hydrogel’s loading capacity of BTA was approximately 0.377 g·g-1, and its release speed was faster in an acidic environment than in an alkaline environment because of its swelling behavior. The corrosion inhibition ability of the intelligent inhibitor was tested by immersion and electrochemical methods. The results showed that after 4 h of immersion, the polarization resistance (R4) value of copper with the intelligent inhibitor was approximately twice of that of copper with BTA, indicating that the intelligent inhibitor could effectively prevent copper from corroding.     

SEM in-situ investigation on fatigue cracking behavior of P/M Rene95 alloy with surface inclusions

The low-cycle fatigue behavior of powder metallurgy Rene95 alloy containing surface inclusions was investigated by in-situ observation with scanning electron microscopy (SEM). The process of fatigue crack initiation and early stage of propagation behavior indicates that fatigue crack mainly occurs at the interface between the inclusion and the matrix. The effect of inclusion on the fatigue crack initiation and the early stage of crack growth was very obvious. The fatigue crack growth path in the matrix is similar to the shape of inclusion made on the basis of fatigue fracture image analysis. The empiric relation between the surface and inside crack growth length, near a surface inclusion, can be expressed. Therefore, the fatigue crack growth rate or life of P/M Rene95 alloy including the inclusions can be evaluated on the basis of the measurable surface crack length parameter. In addition, the effect of two inclusions on the fatigue crack initiation behavior was investigated by the in-situ observation with SEM.     

Direct electroless nickel plating on silicon surface

Direct electroless nickel plating on n-Si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance, the effect of pH and temperature of the solutions on size of metal particles in deposits was examined, and also the element contents of deposits were analyzed by energy disperse spectroscopy (EDS). The results indicated that the size of metal particles increases with increasing temperature or decreasing pH. The possible mechanism of nickel deposition on n-Si(100) was discussed in terms of semiconductor electrochemistry, and the formation of nickel seed crystal on Si was mainly attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions.     

Synthesis,characterization, and property test of crystalline polyferric sulfate adsorbent used in treatment of contaminated water with a high As(Ⅲ) content

A crystalline polyferric sulfate(PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area(SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope(SEM) and transmission electron microscopy(TEM) images, X-ray diffraction(XRD) patterns, Fourier-transform infrared(FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10–100 mg/L under acidic, neutral, and alkaline conditions(pH 2.09–9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure(TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.     

Ab initio research on DNA base alkylation by theβ-position me-tabolite of methylethylnitrosamine

Ab initio calculation is carried out to study the different supposed mechanisms of DNA base alkylation by [β-sulphate-nitrosamines at RHF/6-31G(d) and MP2/6-31G(d) levels. Full geometric structure optimization is done for all reactants, intermediates, products and transition states. The activation energy and IRC are obtained. The results show that the anchimeric assistant effect promotes the alkylation of DNA base by β-sulphate-nitrosamines. Solvent calculation is carried out with Onsager model of SCRF method at the same level. The results indicate that the activation energy is decreased obviously in water.     

Enrichment of copper and recycling of cyanide from copper–cyanide waste by solvent extraction

The enrichment of copper from copper–cyanide wastewater by solvent extraction was investigated using a quaternary ammonium salt as an extractant. The influences of important parameters, e.g., organic-phase components, aqueous pH values, temperature, inorganic anion impurities, CN/Cu molar ratio, and stripping reagents, were examined systematically, and the optimal conditions were determined. The results indicated that copper was effectively concentrated from low-concentration solutions using Aliquat 336 and that the extraction efficiency increased linearly with increasing temperature. The aqueous pH value and concentrations of inorganic anion impurities only weakly affected the extraction process when varied in appropriate ranges. The CN/Cu molar ratio affected the extraction efficiency by changing the distribution of copper–cyanide complexes. The difference in gold leaching efficiency between using raffinate and fresh water was negligible.