Fabrication of multifunctional TiO2–fly ash/polyurethane nanocomposite membrane via electrospinning

In this study, we demonstrate the fabrication of multifunctional composite polyurethane (PU) membrane from a sol gel system containing TiO₂ and fly ash (FA) nanoparticles (NPs). The adsorptive property of FA and photocatalytic property of TiO₂ can introduce different functionalities on PU mat for water purification. Different types of PU nanofiber mats were prepared by varying the composition of NPs in blend solution. FE-SEM, TEM, TGA, XRD, UV–visible spectra, and water contact angle measurement confirmed the incorporation of FA and TiO₂ NPs on/into PU nanofibrous mat. The influence of NPs on PU membrane was evaluated from the adsorption of heavy metals (Hg, Pb), removal of dyes (methylene blue), antibacterial activity, and water flux. The improvement of all these activities is attributed to the adsorptive property of FA and photocatalytic/hydrophilic property of TiO₂ NPs. Therefore, as-synthesized composite membrane can be utilized as an economically friendly filter media for water purification.     

Calibration of Psychrometers at Spring Singapore

To assess the uniformity of the psychrometer coefficient of psychrometers commercially available in the market, results of calibrations of aspirated psychrometers and whirling (or sling) psychrometers performed by our laboratory at about 23°C and 55% rh over a period of six years are analyzed. It is found that although the psychrometer coefficient of a particular psychrometer can be quite consistent with long-term stability typically within the range of  ± 1% rh equivalent, there are larger variations (up to 4% rh equivalent) among different psychrometers even of the same type. The psychrometer coefficient variations in other temperature and humidity conditions are also studied through experiment using a randomly chosen aspirated psychrometer.     

Effects of blending alcohols with poultry fat methyl esters on cold flow properties

The low temperature operability, kinematic viscosity, and acid value of poultry fat methyl esters were improved with addition of ethanol, isopropanol, and butanol with increasing alcohol content. The flash point decreased and moisture content increased upon addition of alcohols to poultry fat methyl esters. The alcohol type did not result in a statistically significant difference in low temperature performance at similar blend ratios in poultry fat methyl esters. In addition, blends of ethanol in poultry fat methyl esters afforded the least viscous mixtures, whereas isopropanol and butanol blends were progressively more viscous, but still within specifications contained in ASTM D6751 and EN 14214. Blends of alcohols in poultry fat methyl esters resulted in failure of the flash point specifications found in ASTM D6751 and EN 14214. Flash points of butanol blends were superior to those of isopropanol and ethanol blends, with the 5 vol.% butanol blend exhibiting a flash point (57 °C) superior to that of No. 2 diesel fuel (52 °C). Blends of alcohols in poultry fat methyl esters resulted in an improvement in acid value with increasing content of alcohol. An increase in moisture content of biodiesel was observed with increasing alcohol content, with the effect being more pronounced in ethanol blends versus isopropanol and butanol blends. Finally, none of the alcohol–methyl ester samples exhibited a phase separation at sub-ambient temperatures.     

Measurement of diffusion and flow of gas through a porous solid

Experiments for measuring the flow or diffusion of a gas through a porous solid are described. The experiments allow calculation of an effective diffusion coefficient and the tortuosity factor for a porous sample of undefined pore characteristics.     

Interaction of gas bubbles with liquid lead

The interaction of bubbles of hydrogen and argon-oxygen mixtures with liquid lead has been investigated using an oxide solid electrolyte cell of the type where O denotes oxygen, of variable concentrations dissolved in molten lead. Oxygen concentration in molten lead has been varied through bubbling oxidising or reducing gases. The variation in concentration has been obtained by measuring continuously the cell e.m.f. by a recorder. The effects of bubble size and temperature on mass transfer coefficient of oxygen during oxygen dissolution and oxygen removal operations have been studied. The liquid phase mass transfer coefficient increases with decreasing bubble size and increasing temperature. The observed variations agree well with equations available in the literature for low temperature liquids.     

Relationship of Surface Area of pH-Dependent Suspensions and Water Retention

The equilibrium water retention, M_W/M_S, of suspensions having a pH-dependent surface charge (carbonate-containing aluminum hydroxide and fumed silica) appears to be due to water adsorbed by the surface as well as water retained in pores. The water retained in pores has a lower limit determined by the closest packing porosity. Maximal water retention occurred when the pH was equal to the point of zero charge and attractive particle interactions predominated. The contribution of pore water to M_W/M_S can be minimized by selecting a pH significantly different from the point of zero charge. The water retention properties of the suspension under these conditions are believed to be due to adsorption and the closest packing porosity. Preliminary results indicate that this M_W/M_S can be related to the surface area of the suspended solid.     

Particle Morphology of Amorphous Aluminum Hydroxycarbonate and Its Effect on Tablet Production

The particle morphology of amorphous aluminum hydroxycarbonate was studied by disaggregation induced by phosphate adsorption and direct observation by high resolution transmission electron microscopy. The primary particles are sheet-like and have equivalent diameters of 55A or less. The primary particles are believed to correspond to planar polymers comprised of six-membered rings of aluminum ions joined by double hydroxide bridges. Secondary particles form by attractive interaction of primary particles. The size of the primary particles affects the porosity of the secondary particles. The granulating and tableting properties of two spray dried amorphous aluminum hydroxycarbonates were shown to be related to the size of the primary particles and the porosity of the secondary particles.     

Surface charge characteristics of aluminum hydroxycarbonate as influenced by carbonate equilibrium

The isoelectric point of aluminum hydroxycarbonate suspension increases upon dilution with deionized water. The increase in the isoelectric point is directly related to the degree of dilution. Dilution with bicarbonate ion-containing solutions reduced the change in isoelectric point in comparison to dilution with deionized water. The change in isoelectric point was inversely related to the concentration of bicarbonate ion in the diluting solution. The increase in isoelectric point observed following dilution with deionized water was reversed by the addition of bicarbonate ion. The observations suggest that carbonate ions occupying potential determining sites in the primary particles are in equilibrium with carbonate/bicarbonate ions in solution. Formulation or processing factors which affect the equilibrium will affect the isoelectric point of aluminum hydroxycarbonate suspensions and will influence their physical properties.     

Removal of a dye from simulated wastewater by adsorption using treated parthenium biomass

In the present study adsorption of rhodamine-B from aqueous solution on formaldehyde treated parthenium biomass (WC) and phosphoric acid treated parthenium carbon (PWC) was studied. Aqueous solutions of various concentrations (50-500 mg/l) were shaken with certain amount of adsorbent to determine the adsorption capacity of rhodamine-B on WC and PWC. The effectiveness of formaldehyde treated parthenium biomass (WC) and phosphoric acid treated parthenium carbon (PWC) in adsorbing rhodamine-B from aqueous solution has been studied as a function of agitation time, adsorbent dose, initial dye concentration and pH. The adsorption capacities of the studied adsorbents were in the order PWC>WC. Initial pH had negligible effect on the adsorption capacity. Maximum dye was sequestered from the solution within 60min after the start of every experiment. After that, the concentration of rhodamine-B in the liquid-phase remained constant. The adsorption of rhodamine-B onto PWC and WC followed second-order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity Q(0) was 59.17 mg/g at initial pH 7.0 for the particle size 0.3-1.0mm for phosphoric acid treated parthenium carbon (PWC). The FT-IR spectra of the adsorbents were recorded to explore number and position of functional groups available for the binding of dye cation onto studied adsorbents. SEMs of the adsorbents were recorded to explore the morphology of the studied adsorbents.