Effect of substrate on the phase transformation of TiO2 in pearlescent pigment

The TiO₂/substrate pearlescent pigments were prepared by the hydrolysis of TiOCl₂ on the substrate followed by a calcinations process. The natural mica (muscovite), synthetic mica (fluorophlogopite) and -alumina flake were selected as the substrates for pearlescent pigments. The effect of substrate on the anatase to rutile (A–R) phase transformation of TiO₂ was studied. The A–R phase transformation of TiO₂ during the preparation of pearlescent pigments and their proportion in the TiO₂ layer have been analyzed by XRD measurements. The phase compositions of TiO₂ layer in each pearlescent pigment are quite different depending on the substrates. The TiO₂ layer deposited on -alumina has higher rutile fraction than those on the natural and synthetic mica. The XPS analysis showed that the cations originally present in the substrates diffused into the TiO₂ layer. The TiO₂ layer deposited on -alumina contains Al, while those on the natural and synthetic mica substrates contain Si and K in addition to Al. The metal cations diffusing from the substrate into TiO₂ layer might retard the A–R phase transformation of TiO₂. The suppressing effect on the A–R transformation of TiO₂ by mixed cations seems to be much stronger than that of single cation, resulting in relatively higher rutile fraction in the case of TiO₂ layer deposited on -alumina.     

Correction to: Comparative study on anti-oxidative and anti-inflammatory properties of hydroponic ginseng and soil-cultured ginseng

Food Science and Biotechnology - The original version of this article unfortunately contained a mistake. The presentation of the row “Total (μg/g)” in Table 2 was incorrect.     

A study on removal efficiency of phenol and humic acid using spherical activated carbon doped by TiO<Subscript>2</Subscript>

This study aimed to find a way to remove organic pollutants, phenol and humic acid in aqueous solutions using TiO₂ spherical activated carbon (Ti-SPAC). The Ti-SPAC was manufactured by resin ion-exchange and a heating process. This method was very effective not only in creating TiO₂ on the surface of the supports evenly, but also in making activated carbon that has highly-developed micro pores. To estimate whether Ti-SPAC has the proper features as a photocatalyst and adsorbent, it was examined in detail by X-ray patterns, SEM image, EDXS, BET, EPMA. The results proved that Ti-SPAC is a very useful material for treating wastewater by photocatalysis and absorption.     

Space charge in polyethylene/ionomer blends

Measurements of thermally stimulated currents were made on ionomer/polyethylene blends. The objective of this work was to study space charge formation in these materials. Two ionomers were compared; both ionomers contained methacrylic acid, neutralized by zinc in one and by sodium in the other. A large current peak centered near 60°C was observed in all blends and associated with the motion of space charges injected into the blends during poling. All blends accumulated large negative space charge concentrations. The approach to the equilibrium space charge distribution (negative and spatially uniform in all blends) is much more rapid in the blends containing the sodium ionomer than in the blends containing the zinc ionomer     

Charge distributions in PC/SAN/PCL polymer blends

The formation of space charge in polycarbonate (PC)/poly (styrene-co-acrylonitrile) (SAN) blends containing poly (ϵ-caprolactone) (PCL) as a compatibilizer for improving the miscibility, has been studied by measuring spatial charge distributions. It is found that the miscibility of PC/SAN blends is improved as the PCL content increases. The amount of charge accumulated in the blends decreases when the PCL content increases to 15% by weight and then increases when the PCL content is >15% wt. The decrease of charge at the PCL content <15% wt was attributed to the combined effects of changes in conductivities and the molecular interactions at the domain interfaces. The increase of charge at the PCL content >15% wt was attributed to the trapping of charge at the amorphous and crystalline phases of PC and PCL     

Synthesis of new pH-sensitive polyurethane gels using polyethylene glycol modified urethane acrylate and urethane acrylate anionomer

New type of amphiphilic pH-sensitive polyurethane networks, derived from the mixture of polyethylene glycol-modified urethane acrylates (PMUA) and urethane acrylate anionomer (UAA), were prepared and their swelling behaviors were evaluated. Three kinds of polymerization methods were employed in the synthesis of polyurethane networks. Polyurethane networks prepared by a process similar to that of soap-free emulsion polymerization (UAHG) showed the highest swelling ratio and pH-sensitivity. Additionally, four kinds of UAHG gels were prepared at different composition of UAA. As the composition ratio of UAA to PMUA increased, swelling of UAHG gels in alkali pH buffer solution and their pH-sensitivity greatly increased. Additionally, swelling of UAHG gels changed reversibly with the change of pH. Received: 18 November 1996/Revised: 10 January 1997/Accepted: 14 January 1997     

Effects of filter additives on cake filtration performance

Effects of various additives, such as diatomaceous earth, inorganic adsorbent, and polymeric flocculant, on cake filtration performance were evaluated. By performing the standard vacuum filtration experiments under a constant pressure condition, we quantified their ability to reduce cake compressibility and to remove fine particulate matters. From the flux decline curves obtained, we used modified Ruth equation to determine the cake compressibility index. The filtrate clarity was quantified by measuring its turbidity spectrophotometrically. Diatomaceous earth filter aid was very effective in reducing the compressibility thereby improving filtrate flux. Calcium phosphate adsorbent was more effective in clarity improvement than in flux enhancement, whereas an anionic flocculant was effective in both aspects. When these additives were used together, the expected additive, synergic effect was not realized. However, about 3.5 times higher initial flux and 6-fold improved clarity were obtained as compared to the control experiment. Experimentally obtained flux decline curves were perfectly fitted into one of the Hermia’s blocking filtration law equations. Also, it was experimentally observed that the compressibility reduction improved filtrate clarity in a linear fashion. This type of approach is useful to quantitatively determine each additive’s characteristics and thus to maximize the performance of cake filtration operations.