Piezoelectric and dielectric properties of (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3–PVDF composites

(Li, Ta, Sb) modified sodium potassium niobate/poly(vinylidene fluoride) [(K_0.44Na_0.52Li_0.04)(Nb_0.86Ta_0.10Sb_0.04)O₃–PVDF] 0-3 composites were prepared by a cold press technique, and their piezoelectric and dielectric properties were characterized. All composites exhibited good dispersion of ceramic particles in the polymer matrix. The piezoelectric and dielectric constants were found to be enhanced as the concentration of sodium potassium niobate increases. Even though the process is simple, the composite prepared in this study showed better piezoelectric and dielectric properties than PZT–polymer composites. At room temperature, a (K_0.44Na_0.52Li_0.04)(Nb_0.86Ta_0.10Sb_0.04)O₃–PVDF (7:3) composite revealed a relative dielectric constant, ?_r = 166, piezoelectric constant, d₃₃ = 33 pC/N and coercive field, E_c = 5 kV/cm.     

Sugar recovery from rice straw by dilute acid pretreatment

Rice straw was pretreated with dilute sulfuric acid in order to decrease the amorphous portion and enhance enzyme accessibility. Dilute acid pretreatment process was optimized using a statistical method, and the relationships between each factor were investigated. Saccharification of pretreated rice straw was then performed, followed by fermentation of glucose, the hydrolysate of the saccharification process. The optimal dilute acid pretreatment process was as follows: temperature 110 °C, reaction time 14.02 min, and acid concentration 1.2%. Following dilute acid pretreatment, the solid weight was decreased by about 20% and 73.14% of the theoretical maximum content of xylose was solubilized. Glucose was recovered at a rate of about 90% at 24 h after rice straw was treated with dilute acid. Qualitative analysis such as SEM, XRD, and FT-IR were conducted after the pretreatment process, and the results supported the pretreatment process.     

Preparation and characterization of syndiotactic polystyrene/ethylene‐propylene copolymer blends

The reactive compatibilization of syndiotactic polystyrene (sPS)/oxazoline‐styrene copolymer (RPS)/maleic anhydride grafted ethylene‐propylene copolymer (EPR‐MA) blends is investigated in this study. First, the miscibility of sPS/RPS blends is examined by thermal analysis. The cold crystallization peak (T_cc) moved toward higher temperature with increased PRS, and, concerning enthalpy relaxation behaviors, only a single enthalpy relation peak was found in all aged samples. These results indicate that the sPS/RPS blend is miscible along the various compositions and RPS can be used in the reactive compatibilization of sPS/RPS/EPR‐MA blends. The reactive compatibilized sPS/RPS/EPR‐MA blends showed finer morphology than sPS/EPR‐MA physical blends and higher storage modulus (G') and complex viscosity (η*) when RPS contents were increased. Moreover, the impact strength of sPS/RPS/EPR‐MA increased significantly compared to sPS/EPR‐MA blend, and SEM micrographs after impact testing show that the sPS/RPS/EPR‐MA blend has better adhesion between the sPS matrix and the dispersed EPR‐MA phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2084–2091, 2002     

Pollutant destruction in a reverse-flow chromatographic reactor

A reverse-flow chromatographic reactor (RFCR) is a packed reactor in which the flow direction is reversed periodically and in which one of the reactants is strongly adsorbed on the catalyst. We study the performance of a RFCR used to destruct a pollutant A by a reaction with a reactant B, the emission level of which is subject to even stricter restrictions. Due to safety considerations, this reactant B is introduced in the center of the reactor. The RFCR operation enables a reduction of the regulated effluent products well below the minimum attainable under a steady-state operation of the same packed-bed reactor. Moreover, it can respond effectively to any perturbations in the pollutant feed rate and/or concentration. When the environmental regulations on the emission of B are stricter than those of A, it is often advantageous to feed slightly less B than the amount needed for complete conversion of A. We present a methodology for finding the operating conditions that lead to the minimal level of weighted emission of both A and B. A continuous feed of the reactant B is superior to operation in which the same amount of B is fed during each semi-cycle but in a non-continuous fashion.     

Separation of endocrine disruptors from aqueous solutions by pervaporation: Dioctylphthalate and butylated hydroxytoluene in mineral water

We examined the existence of endocrine disruptors in mineral water, ultrapure water, and tap water. GC/MS analysis revealed that dioctylphthalate (di‐n‐octylphthalate and di(2‐ethylhexyl)phthalate) in the water was found to be on the order of parts per billion. The dioctylphthalate concentration remained consistent for mineral water of the same brand, regardless of whether it was bottled in a PET bottle or a glass bottle. Therefore, the dioctylphthalate contamination in mineral water originated from the manufacturing line of the mineral water and not as a result of leaching from PET bottles. Butylated hydroxytoluene (BHT), an oxidization prevention agent in plastics, was detected at 2.05 ± 0.1 ppb in the mineral water bottled in glass bottles, but was not detected in the mineral water bottled in PET bottles. BHT contamination in the mineral water in the glass bottles is likely to have originated from the cap of the glass bottles, as the caps were sealed with polyethylene. We further investigated the feasibility of separating dioctylphthalate and BHT from the mineral water by pervaporation using hydrophobic polydimethylsiloxane membranes. We found that trace amounts (on the order of parts per billion) of organic chemicals such as dioctylphthalate and BHT in aqueous solutions can be removed and concentrated by the pervaporation using polydimethylsiloxane membranes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1737–1742, 2004     

Reverse Micellar Extraction of Lysozyme Using Two Dialkyl Sodium Phosphinates

The extraction of lysozyme was studied using di‐(2,4,4‐trimethylpentyl) sodium phosphinate, R₂POONa, and di‐(2,4,4‐trimethylpentyl) sodium dithiophosphinate, R₂PSSNa. For a R₂POONa reverse micellar system, all lysozyme was removed from the aqueous phase when the pH of the aqueous solution was set below the pI of the protein. The extraction of lysozyme into a R₂PSSNa reverse micellar system was independent of the pH of the aqueous phase. A solubilization limit of lysozyme exists in the R₂POONa reverse micellar phase. The lysozyme recovery was 70% from the R₂POONa reverse micellar phase, and less than 10% from the R₂PSSNa reverse micellar phase.     

Experimental study on the treatment of volatile organic compound vapors using a photoreactor equipped with photocatalyst‐coated fabrics

In this study, methods were developed to enlarge the scope of traditional applications of titanium dioxide (TiO₂) and to increase the value of felted fabric by allowing volatile organic compound (VOC) degradation as well as dust filtration in a photoreacting fabric filter. In the past, when a V–Ti mixed catalyst was used, the application of felted fabric as a support material for the catalyst was difficult because the active temperature of the catalyst ranged from 250 to 400°C. Thus, in this study catalyst‐coated felted fabric was manufactured at normal temperature conditions, and then fundamental de‐VOC performance tests were conducted under irradiation condition to develop a fabric filter having a de‐VOC function in addition to a dust‐filtration function. Toluene vapor was selected as a sample VOC because it poses health hazards, has been widely used as an organic solvent, and has been known as a compound that is difficult to dissociate. To manufacture and use a fabric filter that degrades VOC_S, and removes dust particles through using photocatalyst‐coated fabrics and light sources, optimum operating conditions were obtained by observing the degradation attributed to varying the toluene‐vapor flow rate, the initial toluene concentration, flue gas humidity, TiO₂ loading onto the surface of the fabric, and the intensity and wavelength of a near ultraviolet light lamp. To keep the flue gas humidity at a relatively constant level, a system to automatically control the humidity was constructed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3174–3179, 2004