Near—infrared SERS Study of the Adsorption of a PMMA Dip—coated onto Silver Mirror Substrate

The interface between a-PMMA thin film and silver mirror substrate was investigated using surface-enhanced Raman scattering (SERS). It is found that the molecular chain axis of a-PMMA tends to parallel the substrate in the interface. When the sample is annealed at different temperatures, some interesting changes appear in the SERS spectra. The spectra differences and their transition are due to the surface geometry change of the ester group.     

A Study on Adsorption of Electrogenerated Cystine Precipitate onto An Electrode using Electrochemical Quartz Crystal Impedance System

Insiluquartzcrystalimpedance(QCI)measurementduringelectrochemicalperturbationshasfoundwideapplicationsininvestigatingmetalandpolymerdepositionetc'-',asitprovidesmultidimensionalinsitupiezoelectricinformation.QCIanalysishasbeenbasedontheButterworth-VanDyke(BVD)equivalentelectricalcircuitcomposedofamotionalarmandastaticarminparallel.Themotionalarmcontainsthreeequivalentcircuitelementsinseries,namely,themotionalresistanceRI,themotionalinductanceL,andthemotionalcapacitanceC,,whilethestaticar…     

The Negative Solvatochromism of Reichardt‘s Dye B30 – A Complementary Study

The UV/Vis spectra of a hypothetical negative solvatochromic dye in a solvent are theoretically calculated assuming the classical damped harmonic oscillator model and the Lorentz-Lorenz relation. For the simulations, the oscillator strength of the solvent was varied, while for the solute all oscillator parameters were kept constant. As a result, a simple change of the oscillator strength of the solute can explain the redshift and intensity increase of the UV/Vis band of the solute. Simulated results are compared with measured UV/Vis spectroscopic data of 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl) phenolate B30 (Reichardt‘s dye) Significant correlations of the absorption energy (1/λ_max) with the molar absorption coefficient ϵ as function of solvent polarity are demonstrated for several derivatives of B30 . The approach presented is only applicable to negative solvatochromism. Therefore, while the approach is vital to fully understand solvatochromism, it needs to be complemented by other approaches, e. g., to describe the changes of the chemical interactions based on the nature of the solvent, to explain all its various aspects.     

A DFT Study of Thiophene Adsorption on the Rh（111） Surfaces

Thiophene adsorption on the Rh(111) surfaces has been investigated by density functional theory.The results show that the adsorption at the hollow and bridge sites is the most stable.The molecular plane of the thiophene ring is distorted,the C=C bond is stretched to 1.448  and the C-C bond is shortened to 1.390.The C-H bonds tilt 22～42oaway from the surface.The calculated adsorption geometries are in reasonable agreement with population analysis and density of states.The thiophene molecule obtains 0.74 electrons,reflecting the interaction between the lone pair of sulfur and the d-orbitals of metal.The reaction paths and transition states for desulfurization of the molecule have been investigated.The bridge adsorption structure of thiophene leads to a thiol via an activated reaction with an energetic barrier of 0.30 eV.This second step is slightly difficult,and dissociation into a C4H4 fragment and a sulfur atom is possible,with an energetic barrier of 0.40 eV.     

A Study of Water Interaction with γ-Al2O3Surface by Adsorption Calorimetry

The steps at 70, 62, and 56 kJ/mol were specified on the dependences of differential heats of adsorption on the values of adsorption aon the hydroxylated -Al₂O₃surface resulted from the interaction of adsorbed water molecules with the surface-coordinated water molecules, acid and basic hydroxyl groups, respectively; effective charges qwere estimated for the protons of coordinated water molecules and acid and basic OH groups. The hydration numbers were calculated in the region of monolayer coverage for the three aforementioned adsorption sites. The texture changes discovered in -Al₂O₃particles were attributed to the interlamellar swelling of the secondary sorbent packets formed from its primary particles.     

Kinetic Study of Radical Polymerization VIII. A Comprehensive Study of Solution Copolymerization of Vinyl Acetate and Methyl Acrylate by 1H‐NMR Spectroscopy

Radical copolymerization reaction of vinyl acetate (VA) and methyl acrylate (MA) was performed in a solution of benzene‐d₆ using benzoyl peroxide (BPO) as the initiator at 60°C. Kinetic studies of this copolymerization reaction were investigated by on‐line ¹H‐NMR spectroscopy. Individual monomer conversions vs. reaction time, which was followed by this technique, were used to calculate the overall monomer conversion, as well as the monomer mixture and the copolymer compositions as a function of time. Monomer reactivity ratios were calculated by various linear and nonlinear terminal models and also by simplified penultimate model with r _2(VA)=0 at low and medium/high conversions. Overall rate coefficient of copolymerization was calculated from the overall monomer conversion vs. time data and k _p  . k _t ^?0.5 was then estimated. It was observed that k _p  . k _t ^?0.5 increases with increasing the mole fraction of MA in the initial feed, indicating the increase in the polymerization rate with increasing MA concentration in the initial monomer mixture. The effect of mole fraction of MA in the initial monomer mixture on the drifts in the monomer mixture and copolymer compositions with reaction progress was also evaluated experimentally and theoretically.     

Effect of pH on the Rheology of A1-Mg M iteed Meta1 Hydroxide——Montmorillonite Aqueous Suspension

The effects of the pHs of Mtsuspension(pH_Mt),AMH sol(pH_A)and mixedsuspension(pH_mix)on the rheology of mixed su sp en sion w ere studied.The mixed suspension consisted of the alum in ium magnesium mixed metal hydroxide(AM H) colloidal prt icles which possessed permanent positive charges and the Na-montmorillon ite(M t)particles which po ssessed permanent nega tive charges.The results showed that the pHs did not affect the Bingham yield poin t(YP)of the mixed suspen sionsin the various pHs(i.e.,pH_Mt,pH_A and pH_mix)range of 8—10 almost. When the pH values were above 10 the YPs increased ma rked ly w ith increa sing pH_Mt and pH_mix,but decreased sharply with increasing pH_A.The mechanisms of the effect of pH on the rheology of mixed suspensions were also investigated.     

A Density Functional Theory Study on the Adsorption of CN on Ni（Ⅲ） Surface

The interaction of cyanide (CN) with different sites on Ni(111) surface is studied by using density functional theory (DPT). Ni19 cluster is used to simulate the surface. The present calculations show that the end-on bonded (through C atom) configuration is much more preferable than the side-on bonded CN or other configurations on the same adsorption site. For all adsorption modes, adsorption energies at the top, bridge, and three-fold sites on Ni(111) are comparable, with the bridge site of the end-on bonded CN (through C atom) more favorable than other adsorption sites. CN vibrational frequencies are red-shifted at all cases, except that the end-on CN bonded(through C atom) on the top site is blue-shifted. The bonding of CN on the Ni(111) surface is largely ionic.     

A Density Functional Theory Study on the Adsorption of CN on Ni(111) Surface

1 INTRODUCTION Cyanide, CN, is an important free-radical mole-cule of one carbon chemistry, organic chemistry, free-radical chemistry and cosmochemistry. And the im-portant industrial processes, such as the Andrussovreaction, depend on the reactivity of CN bond[1]. Thechemistry of cyanide is also important in the surfacechemistry of a number of C- and N-containing sys-tems[1, . During the past decade, the adsorption of 2]CN and CN-containing molecules on transition metalsurfa…     

A Periodic Density Functional Study on Adsorption Properties of Methoxy on Au（111） Surface

1INTRODUCTION Methoxy(CH3O)has been identified as the first intermediate in the decomposition of methanol on extensive list of clean transition metal surfaces,such as Ni(100)[1],Cu(100)[2,3],Cu(111)[4],Ag(111)[5],Au(110)[6],Pd(111)[7]and Ru(0001)[8].The electronic structure of the metal is a determining factor in OH bond scission.In fact,group IB clean surfaces have shown very low activity towards this reaction,al-though there are reports on low amounts of methoxy formed on clean Cu(…     

Deactivation Mechanism for COS Hydrolysis over TGH Catalyst——FT-IR Study of the Adsorption Behavior of COS,O_2 and H_2S

The adsorptions of COS, H2S and O2 were investigated over the TGH catalyst in this paper. It was found that the numbers of basic centers and basic intensities were reduced over the deactivated TGH catalyst. The PT-IR results of COS+H2S+O2 co-adsorption on the TGH catalyst show that the main causes of catalyst deactivation is the formation of element sulfur and trace sulfate.     

A Study of Synthesis, Immobilization and Catalytic Capability of Metalloporphyrin

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Adsorption kinetic,thermodynamic and desorption studies of phosphate onto hydrous niobium oxide prepared by reverse microemulsion method

A type of Nb₂O₅⋅3H₂O was synthesized and its phosphate removal potential was investigated in this study. The kinetic study, adsorption isotherm, pH effect, thermodynamic study and desorption were examined in batch experiments. The kinetic process was described by a pseudo-second-order rate model very well. The phosphate adsorption tended to increase with a decrease of pH. The adsorption data fitted well to the Langmuir model with which the maximum P adsorption capacity was estimated to be 18.36 mg-P g⁻¹. The peak appearing at 1050 cm⁻¹ in IR spectra after adsorption was attributed to the bending vibration of adsorbed phosphate. The positive values of both ΔH° and ΔS° suggest an endothermic reaction and increase in randomness at the solid-liquid interface during the adsorption. ΔG° values obtained were negative indicating a spontaneous adsorption process. A phosphate desorbability of approximately 68% was observed with water at pH 12, which indicated a relatively strong bonding between the adsorbed phosphate and the sorptive sites on the surface of the adsorbent. The immobilization of phosphate probably occurs by the mechanisms of ion exchange and physicochemical attraction. Due to its high adsorption capacity, this type of hydrous niobium oxide has the potential for application to control phosphorus pollution.     

Adsorption of Fe（CO）4 on the Sidewall of Boron Nitride Nanotubes： A Periodic DFT Study

The adsorption of Fe（CO）4 on various types of boron nitride nanotubes （BNNTs） areinvestigated by employing density functional theory. Our results indicate that Fe（CO）4 prefers to adsorb on the top of nitrogen atom via Fe atom, and the electronic property analysis indicates that the adsorption of Fe（CO）4 can reduce the band-gap of BNNTs.     

A Highly Ultrafine Core–Shell Ir–Cu Bimetallic Nanoparticles and Their Application in Catalytic Oxidation of Textile Dye,Congo Red,by Hexacyanoferrate(III) Ions: A Kinetic Approach

Kinetics and Catalysis - Bimetallic nanoparticles (BMNPs), a pioneer class of material research for catalysis, were intensively explored. We report a versatile catalyst, core–shell...     

A DFT Study of CO Adsorption on the Cu2O（111） Surface with Oxygen Vacancy

First-principles calculations based on density functional theory （DFr） and the generalized gradient approximation （GGA） have been used to study the adsorption of CO molecule on the Cu2O（111） oxygen-vacancy surface. Calculations indicate that the C-O bond is weakened upon adsorption compared with that over perfect surface. In addition, with the density increase of the defective sites, the adsorption energies of the defect-CO configuration increase whereas the C-O bond nearly remains constant.     

A Study of the Relative Importance of Lipophilic, π–π and Dipole–Dipole Interactions on Cyanopropyl, Phenyl and Alkyl LC Phases Bonded onto the Same Base Silica

Cyano (CN), butyl (C₄), phenyl and octadecyl (C₁₈) phases prepared from the same base silica gel were chromatographically characterized in order to assess the relative importance of lipophilic, π–π and dipole–dipole interactions in governing retention on these differing phases. Dipole interactions of analytes (possessing dipole moments and low lipophilicity) with CN phases were primarily responsible for the elution order. However, as the analytes’ lipophilicity increased, the lipophilic interaction predominated over the dipole interaction. In comparison, retention on the phenyl phase appeared to be complex, being controlled by a mixture of lipophilic, π–π and dipole–dipole interactions. Retention on the C₄ and C₁₈ phases was dictated by the analyte’s lipophilicity and its accessibility into the phase.     

A Study on the Preparation of Konjac Glucomannansilk Fibroin Composite Aerogels and Its Adsorption of Water Pollutant Cr(Ⅲ)

It is emergent to develop a green waste water adsorbent with high efficiency.Therefore,a type of low-cost,green and environmentally friendly konjac glucomannan(KGM)-silk fibroin(SF)composite aerogels were compounded via simple chemical grafting and vacuum freeze drying,and a study on its adsorption capacity was also conducted.The characterizations of FT-IR,SEM,XRD and DSC indicate that the modified aerogels show a porous network space structure and there is a strong hydrogen bond effect between the KGM and SF molecules,which improves the density,compressive strength and thermal stability of aerogel materials.The adsorption experiments show that KGM-SF aerogels can effectively adsorb the water pollutants Cr(Ⅲ)with a maximal adsorption capacity of 82 mg·g^-1.In addition,the adsorption isotherm and dynamic model analysis are used to elaborate the adsorption mechanism of KGM-SF aerogels and explain that the composite aerogels can be single molecule chemisorption.KGM-SF aerogels have potential adsorption capacity.