Synthesis, characterization and catalytic properties of chiral BINOL functionalized mesoporous silicas for enantioselective Morita-Baylis-Hillman reaction

Several Chiral BINOL functionalized mesoporous silicas were prepared by post grafting of organosilane derivatives of (S)-BINOL (1,1'-bi-2-naphthol) on SBA-15 and characterized by C-13 CP/MAS NMR, FT-IR, UV-visible absorption spectra, elemental analysis, powder XRD, nitrogen adsorption-desorption isotherms and TEM techniques. Their catalytic properties were demonstrated in enantioselective Morita-Baylis-Hillman reaction of 3-phenylpropanal and cyclohexenone.

Adsorption of 4,4 '-thiobisbenzenethiol on silver surfaces: surface-enhanced Raman scattering study

Adsorption of 4,4'-thiobisbenzenethiol (4,4'-TBBT) on a colloidal silver surface and a roughened silver electrode surface was investigated by means of surface-enhanced Raman scattering (SERS) for the first time, which indicates that 4,4'-TBBT is chemisorbed on the colloidal silver surface as dithiolates by losing two H-atoms of the S-H bond, while as monothiolates on the roughened silver electrode. The different orientations of the molecules on both silver surfaces indicate the different adsorption behaviors of 4,4'-TBBT in the two systems.

Facile Synthesis and Optical Property of Porous Tin Oxide and Europium-Doped Tin Oxide Nanorods through Thermal Decomposition of the Organotin

Porous SnO2 and SnO2-Eu3+ nanorods have been facilely prepared using triphenyltin hydroxide microrods as precursors. The porous structure of SnO2 nanorods, which was aggregated by small SnO2 nanocrystallites, has been confirmed by TEM images and nitrogen adsorption-desorption isotherms. The optical property of the porous SnO2-Eu3+ nanorods was investigated by UV-vis absorption and photoluminescence spectra.

Synthesis of N-Methylimidazolium Functionalized Strongly Basic Anion Exchange Resins for Adsorption of Cr(VI)

N-Methylimidazolium functionalized strongly basic anion exchange resins in the Cl- form (RCI) and SO46- form (R2SO4) were synthesized and employed for adsorption of Cr(VI) from aqueous solution. FT-IR and elementary analysis proved the structures of anion exchange resins and the content of functional groups. The gel-type strongly basic anion exchange resins had high thermal stability according to TGA and good chemical stability under the experimental conditions. The adsorption behaviors of Cr(VI) on RCI and R2SO4 were studied using the batch technique. It was shown that adsorption equilibrium was reached rapidly within 60 min. The adsorption data for RCI and R2SO4 were consistent with the Langmuir isotherm equation.

Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+. The experimental data have been analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results showed that the biosorption equilibrium was well described by both the Langmuir and Redlich-Peterson isotherms.

Novel hybrid periodic mesoporous organosilica material grafting with Tb complex: Synthesis, characterization and photoluminescence property

A novel periodic mesoporous organosilica (PMO) material was synthesized through one-step co-condensation of 1,2-bis(triethoxysilyl)ethane (BTESE) and benzoic acid-functionalized organosilane (BA-Si) using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent under basic conditions. The materials were fully characterized by FTIR, XRD, N-2 adsorption-desorption isotherms and FESEM. FTIR spectra proved that BA-Si was successfully incorporated into the PMO materials (PMOs) via benzyl group as a linker. XRD and N-2 adsorption-desorption isotherms revealed the characteristic mesoporous structure with highly uniform pore size distributions. FESEM confirmed that the morphology of the PMOs was significantly dependent cri the molar ratio of two organosilica precursors.

Surface modification of poly(dimethylsiloxane) microchips using a double-chained cationic surfactant for efficiently resolving fluorescent dye adsorption

This paper described a double-chained cationic surfactant, didodecyldimethylammonium bromide (DDAB). for dynamic surface modification of poly(dimethylsiloxane) (PDMS) microchips to reduce the fluorescent dyes adsorption onto the microchannel. When DDAB with a high concentration was present as the dynamic modification reagent in the running and sample buffer, it not only reversed the direction of electroosmotic flow, but also efficiently suppressed fluorescent dyes pyronine Y (PY) or rhodamine 8 (RB) adsorption onto the chip surface. In addition, vesicles formed by DDAB in the buffer with higher surface charge density and electrophoretic mobility could provide wider migration window and potential for the separation of compounds with similar hydrophobicity. Factors affecting modification, such as pH and concentrations of the buffer, DDAB concentration in the buffer were investigated. Compared with commonly used single-chained cetyltrimethylammonium bromide, DDAB provided a better modification performance.

The adsorption of dopamine on gold and its interactions with iron(III) ions studied by microcantilevers

The adsorption of dopamine (DA) molecules on gold and their interactions with Fe3+ were studied by a microcantilever in a flow cell. The microcantilever bent toward the Au side with the adsorption of DA due to the change Of Surface stress induced by the intermolecular hydrogen bonds of DA or the charge transfer effect between adsorbates and the Substrate. The interaction process between DA adsorbates and Fe3+ was revealed by the deflection curves of microcantilever. As indicated by the appearance of a variation during the decline of curves, two steps were observed in the curve at relative high concentrations of Fe3+. In this case, Fe3+ reacted with DA molecules only in the outer layers and the complexes removed with solution. Then Fe3+ reacted further with DA molecules forming the surface complex in the first layer next to the gold. At this stage, the stability Of Surface complexes was time dependent, i.e., unstable initially and stable finally. This may be due to the surface complexes change from mono-dentate to bi-dentate complexes. In another case, i.e., at relative low concentration of Fe3+, only the first step was observed as indicated by the absence of a variation.

Chitosan(Chitin)/Cellulose Composite Biosorbents Prepared Using Ionic Liquid for Heavy Metal Ions Adsorption

Chitosan(chitin)/cellulose composites as biodegradable biosorbents were prepared under an environment-friendly preparation processes using ionic liquids. Infrared and X-ray photoelectron spectra indicated the stronger intermolecular hydrogen bond between chitosan and cellulose, and the hydroxyl and amine groups were believed to be the metal ion binding sites. Among the prepared biosorbents, freeze-dried composite had higher adsorption capacity and better stability. The capacity of adsorption was found to be Cu(II) (0.417 mmol/g) > Zn(II) (0.303 mmol/g) > Cr(VI) (0.251 mmol/g) > Ni(II) (0.225 mmol/g) > Ph(II) (0.127 mmol/g) at the same initial concentration 5 mmol L-1. In contrast to some other chitosan-type biosorbents, preparation and component of the biosorbent were obviously more environment friendly. Moreover, adsorption capacity of chitosan in the blending biosorbent could be fully shown.

Adsorption Behavior of Exogenous Thorium on Soil Contaminated by Rare Earth Industries

The adsorption behavior of exogenous thorium on soil was studied to evaluate the contaminated risk on soil. The adsorption capacity, equilibrium time, distribution coefficient and desorption ability were investigated by the experiments of static adsorption. The strong adsorption ability of exogenous thorium on soil samples was observed by high adsorption ratio (> 92%) and low desorption ratio (< 5%) in equilibrium, and the biggest distribution coefficient was over 10(4). The adsorption capacity and equilibrium time were related to soil properties. According to the results of adsorption, Freundlich equation (r >= 0.916 7) and Elovich equation (R-2 >= 0. 898 0) were primely fit for describing the thermodynamics and kinetics of the adsorption of exogenous thorium on soil samples, respectively, which indicated that the adsorption was belonged to the nonlinear adsorption, and was affected by the diffusion of thorium on soil surface and in mineral interbed. Sequential extraction procedure was employed to evaluate the bound fractions of exogenous thorium adsorbed on soil samples.

Investigations on the adsorption behavior of Neutral Red on mercaptoethane sulfonate protected gold nanoparticles

A detailed investigation on the adsorption behavior of Neutral Red (NR) molecules on mercaptoethane sulfonate-monolayer protected gold clusters (MES-MPCs) has been conducted by the spectroscopic method. It is found that cationic NR molecules are adsorbed on the negatively charged MPCs surfaces via electrostatic attractive forces. The absorption study shows that the optical properties of NR molecules are significantly influenced upon the adsorption. Based on the electrostatic adsorption nature and the excellent stability of MES-MPCs against the electrolytes, this association can be released by the addition of electrolyte salts, which can be monitored by both absorption and fluorescence spectroscopy. In addition, dication Ca2+ is found to be more effective in the release of NR than univalent Na+. Moreover, the MES-MPCs exert energy transfer quenching of NR fluorescence by both static and dynamic quenching. However, static quenching seems to be the dominating quenching mechanism. Furthermore, this energy transfer quenching exhibits strong dependence of Au core size, and 5.0 nm MPCs show stronger ability in quenching the NR fluorescence than that of 2.7 nm MPCs.