Pramoch Rangsunvigit

Ethylbenzene Removal by Froth Flotation Under Conditions of Middle‐Phase Microemulsion Formation I: Interfacial Tension, Foamability, and Foam Stability

Abstract The objective of this study was to investigate the relationship of the froth flotation performance in removal of emulsified ethylbenzene in water with microemulsion formation and with foam formation characteristics. The surfactant used was dihexyl sulfosuccinate (Aerosol MA or AMA) which can form microemulsions with ethylbenzene. The systems studied were designed to form Winsor Type III microemulsions with ethylbenzene, which generally correspond to ultra‐low interfacial tensions between oil and water phases. By varying the surfactant concentration, NaCl concentration, and oil‐to‐water ratio, it was found that the lowest interfacial tension was obtained at 1 wt% AMA and 3 wt% NaCl, while the interfacial tension was not substantially influenced by the oil‐to‐water ratio. The highest oil removal was achieved in froth flotation with 0.3 wt% AMA and 3 wt% NaCl. No separation was experienced when the NaCl concentration exceeded 4 wt% due to the poor foamability of the froth formed under these conditions. Therefore, these results demonstrate that both interfacial tension and foam characteristics influence the efficiency of oil removal in the froth flotation process.

Preparation and photocatalytic activity of titania particulate film with silica as binder

SummariesA thin film of titania (TiO2) with silica (SiO2) as binder was prepared by sintering titania particles dispersed in cyclohexanone with added alkoxysilane (TEOS) and held on a glass substrate. TEOS was partially hydrolysed with hydrochloric acid at pH 4.0 before use to give a uniform titania thin film. X-ray diffraction and IR absorption measurements on the product revealed the formation of a titaniasilica composite thin film. Evaluation by the pencil hardness test of the mechanical strength showed that the composite film had a strength remarkably higher than that of a titania film with no silica binder. Although the addition of a silica binder was found to decrease the photocatalytic activity of the titania film, removal of silica by treatment with NaOH from the surface layer of the composite film gave a high photocatalytic activity to the film.RésuméUn film mince de dioxyde de titane (TiO2) avec silice (SiO2) comme liant a été préparé par frittage de particules de dioxyde de titane dispersées dans de la cyclohexanone avec l’addition de l’alkoxysilane (TEOS) et tenu sur un substrat de verre Le TEOS a été partiellement hydrolysé par le moyen d’acide chlorhydrique à pH 4.0, avant usage, pour donner un mince film uniforme de dioxyde de titane. Des mesures du produit par diffraction rayon x et par absorption IR ont révélé la formation d’un film mince d’un composite de dioxyde de titane-silice. Une évaluation par un essai de dureté crayon de la robustesse méchanique a montré que le film composite avait une robustesse qui était remarquablement plus élevée que celle d’un film de dioxyde de titane sans liant de silice. Bienque l’on a trouvé que l’addition d’un liant de silice a diminué l’activité photocatalytique du film de dioxyde de titane, l’enlèvement de la silice de la couche surfacique du film composite, par le moyen de NaOH, a donné au film une importante activité photocatalytique.ZusammenfassungEin dünner Film aus Titandioxid (TiO2) mit einem Silikat (SiO2) als Bindemittel wurde hergestellt durch das Sintern von Titandioxidpartikeln, die in Cyclohexanon und Alkoxysilan (TEOS) dispergiert waren und auf einem Glassubstrat gehalten wurden. Das Alkoxysilan wurde vor Verwendung mit Salzsäure bei pH4.0 teilweise hydrolysiert, damit wir einen durchgängigen dünnen Film aus Titandioxid erhielten. Die Messung von Röntgen-Diffraktion und IR Absorption zeigten, dab sich in dem Film ein Komposit aus Titandioxid und Silikat gebildet hat. Wir testeten die Härte und mechanische Stärke des Filmes durch den Bleistifttest und fanden dab der Film eine deutlich grössere Stärke hatte als ein Titandioxidfilm ohne das Silikatbindemittel. Während die Hinzufügung des Bindemittels die fotokatalytische Wirkungsweise des Titandioxidfilmes herabsetzte, lies sich dieses durch die Behandlung der Oberflächenschicht mit NaOH rückgängig machen.

Ethylbenzene Removal by Froth Flotation Under Conditions of Middle‐Phase Microemulsion Formation II: Effects of Air Flow Rate, Oil‐to‐Water Ratio, and Equilibration Time

Abstract Dihexyl sulfosuccinate (aerosol MA or AMA) was used to prepare microemulsion solutions in a study of the froth flotation process in batch mode to remove emulsified ethylbenzene from water. Oil removal, surfactant removal, and enrichment ratio were used to evaluate the performance of froth flotation. In this study, the effects of air flow rate, oil‐to‐water ratio, and equilibration time were investigated. A very high air flow rate was found to create more turbulence in the froth flotation column, resulting in low oil removal. As the oil‐to‐water ratio decreases, the enrichment ratio increases, whereas the oil removal slightly decreases. The froth flotation column with a feed solution in which the oil and water had been allowed to equilibrate was found to yield much higher ethylbenzene removal than that with a nonequilibrium feed solution. When the feed solution was agitated for 40 minutes to induce a state closer to equilibrium than with no mixing, the ethylbenzene removal was nearly as high as that with the equilibrium feed solution.

Effect of metal type and loading on hydrogen storage on NaAlH4

Although hydrogen has a great potential as clean energy, safe practical storage of hydrogen for applications such as fuel cells has been a major challenge. NaAlH4 is one of the metal hydrides, which are candidates for hydrogen storage in vehicles. However, the rather slow absorption/desorption kinetics is still a significant drawback. To alleviate this problem, purified NaAlH4 was ground with TiCl3, ZrCl4, or HfCl4. Desorption kinetics and capacities were observed under TPD-like operation. Absorption efficiency was determined by raising the temperature up to 125 8C. Of the three doped metals investigated for the positive effect on facilitating NaAlH4 decomposition, TiCl3 assists the best on the first reaction while ZrCl4 and HfCl4 do for the second one. Despite the kinetics enhancement directly involves with the ZrCl4 amount, there is a threshold of ZrCl4-content which affects. 6% ZrCl4 is considered as an appropriate amount to improve the hydrogen release because it simultaneously decreases the desorption temperature and gives the outstanding rate. In hydrogen desorption, ZrCl4 provides the most amount of released hydrogen, but for hydrogen absorption TiCl3-doped NaAlH4 possesses the highest capacity. It is believed that the metal size is one of the key factors resulting in such the behavior.

Phenol Hydroxylation with TS-1 in a Chromatographic Reactor

ABSTRACT Phenol hydroxylation with TS-1 was studied in a chromatographic reactor. TS-1 not only acts as the catalyst for the reaction but also the adsorbent for the separation. The reaction/separation was carried out at 60°C with water and 0.2wt% of aqueous H2O2 as the desorbent. Separation of hydroquinone (HQ) can be achieved in all cases. With water as the desorbent, separation of catechol (CT) depends on the phenol feed concentration, which has been confirmed from both reaction/separation in the chromatographic reactor and equilibrium competitive adsorption experiment. Some unknown by-products not commonly reported in batch experiments have been observed here. TS-1 can also be regenerated using just water. With the aqueous mixture of H2O2 as the desorbent, separation of HQ and CT is possible. Reactive separation schemes based on the simulated counter-current technology have been proposed according to the experimental results.

Surfactant‐Enhanced Carbon Regeneration in a Vapor‐Phase Application

Abstract Coal‐based granular activated carbon (GAC) is saturated with trichloroethylene (TCE) by passing air through a fix bed adsorber. In surfactant‐enhanced carbon regeneration, an aqueous solution of anionic surfactant, sodium dodecyl sulfate (SDS), is passed through the bed to induce desorption of TCE. More than 95% of the sorbed TCE was removed in the desorption operation with a 0.1 M SDS solution at a superficial flow rate of 1 cm/min. The desorption rate of TCE from pores of GAC is limited by pore diffusion and not significantly affected by either the concentration of SDS in the regenerant (when well above the critical micelle concentration) or its flow rate. From the breakthrough curve of a subsequent adsorption cycle without a flushing step following the desorption, only 7% of the virgin carbon effective adsorption capacity is observed for the regenerated carbon. With a water flushing step following the regeneration step, the effective adsorption capacity is significantly improved to about 15% of that of virgin carbon. Increased temperature of the flushing water also enhances the effective adsorption capacity of the regenerated GAC. Separate batch adsorption‐desorption isotherms of SDS on GAC support the enhanced desorption of SDS at elevated temperatures. The drastic reduction in the effective adsorption capacity of regenerated GAC results from the residual SDS remaining in the pores of GAC as confirmed by thermal gravimetric analysis. Both the regeneration and water flush steps are rate limited under conditionsused here.

Metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide by cytochrome P450 enzymes in human liver microsomes

The in vitro metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide was investigated using human liver microsomes and recombinant cytochrome P450 (P450 or CYP) enzymes for the first time. Both isomers of rose oxide were incubated with human liver microsomes, and the formation of the respective 9‐oxidized metabolite were determined using gas chromatography‐mass spectrometry (GC‐MS). Of 11 different recombinant human P450 enzymes used, CYP2B6 and CYP2C19 were the primary enzymes catalysing the metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide. CYP1A2 also efficiently oxidized (‐)‐cis‐rose oxide at the 9‐position but not (‐)‐trans‐rose oxide. α‐Naphthoflavone (a selective CYP1A2 inhibitor), thioTEPA (a CYP2B6 inhibitor) and anti‐CYP2B6 antibody inhibited (‐)‐cis‐rose oxide 9‐hydroxylation catalysed by human liver microsomes. On the other hand, the metabolism of (‐)‐trans‐rose oxide was suppressed by thioTEPA and anti‐CYP2B6 at a significant level in human liver microsomes. However, omeprazole (a CYP2C19 inhibitor) had no significant effects on the metabolism of both isomers of rose oxide. Using microsomal preparations from nine different human liver samples, (‐)‐9‐hydroxy‐cis‐ and (‐)‐9‐hydroxy‐trans‐rose oxide formations correlated with (S)‐mephenytoin N‐demethylase activity (CYP2B6 marker activity). These results suggest that CYP2B6 plays important roles in the metabolism of (‐)‐cis‐ and (‐)‐trans‐rose oxide in human liver microsomes. Copyright

Energy Storage of NiO/TiO2 Bilayer Films and its Effectiveness in the Degradation of Acid Orange 7

The concept of storing energy in TiO2 when it was illuminated with light and using the catalyst when there was no light was tested for the first time. Ni(OH)2 was incorporated into TiO2 for the energy storage purpose. Ni(OH)2 was subjected to three different temperatures (300 – 500°C) before the incorporation. NiO/TiO2 bilayer films were prepared with spin-coating method. The films were tested for its electrochemical and photoelectrochemical properties in 1 M NaOH. The NiO/TiO2 film prepared with Ni(OH)2 calcined at 300°C showed energy storage potential. The catalysts were then investigated for their catalytic activity in the photocatalytic degradation of acid orange 7 (AO7). The experiments were carried out in a batch reactor containing 500 ml of 20 ppm AO7 and 0.2 g NiO/TiO2 bilayer film. The reaction were carried out under UV illumination for 2 h before continuing without the illumination (dark condition) for another 2 h. NiO/TiO2 showed photcatalytic properties even without illumination implying that the energy stored during the illumination drove the photocatalytic reaction.

Phenol hydroxylation using Ti- and Sn-containing silicalitesElectronic supplementary information (ESI) available: XRD pattern of Ti?Sn?S-1s. See http://www.rsc.org/suppdata/cc/b3/b303455k/

New bimetallic framework and non-framework titanium and tin silicalite have been investigated for phenol hydroxylation with H2O2 in different solvents, and the optimized catalyst composition showed 26% higher initial rate than reference TS-1.

Roles of Sodium Dodecyl Sulfate on Tetrahydrofuran-Assisted Methane Hydrate Formation

Sodium dodecyl sulfate (SDS) markedly improved tetrahydrofuran (THF) - assisted methane hydrate formation. Firstly, methane hydrate formation with different THF amount, 1, 3, and 5.56 mol%, was studied. SDS with 1, 4, and 8 mM was then investigated for its roles on the methane hydrate formation with and without THF. The experiments were conducted in a quiescent condition in a fixed volume crystallizer at 8 MPa and 4°C. The results showed that almost all studied THF and SDS concentrations enhanced the methane hydrate formation kinetics and methane consumption compared to that without the promoters, except 1 mol% THF. Although, with 1 mol% THF, there were no hydrates formed for 48 hours, the addition of just 1 mM SDS surprisingly promoted the hydrate formation with a significant increased in the kinetics. This prompts the use of methane hydrate technology for natural gas storage application with minimal promoters.