This work is an attempt to search for highly selective sensing materials for ethanol vapor. The electrical conductivity response of ZSM-5, Y, and mordenite zeolites towards ethanol vapor have been investigated for the effects of the framework, the charge balancing cation type, and the Si/Al ratio. All zeolites were characterized using XRD, FT-IR, SEM, TGA, BET, and NH 3 -TPD techniques. For the effect of the zeolite framework type, H + Y has a higher electrical conductivity sensitivity value than that of H + MOR because of a greater pore volume and available surface area. For the effect of the charge balancing cation, all NH 4 + ZSM-5 zeolites (Si/Al=23, 50, 80, 280) show negative responses, whereas the H + Y zeolites (Si/Al=30, 60, 80) and the H + MOR zeolites (Si/Al=30, 200) show positive responses. These differing behaviors can be traced to the electrostatic field at the cation sites in zeolite micropores, and their hydrophilic-hydrophobic character, which affect the adsorption properties of the zeolites. For the effect of Si/Al ratio, the electrical conductivity sensitivity towards the ethanol decreases with increasing Si/Al ratio or decreasing Al content, and there is a lesser degree of interaction between ethanol molecules and the active sites of the zeolites due to its higher hydrophobicity and the lower amount of cations. However, the H + Y (Si/Al=5.1) and the H + MOR (Si/Al=19) zeolites have lower conductivity sensitivity than those of H + Y (Si/Al=30) and H + MOR (Si/Al=30), respectively. The interactions between the C 2 H 5 OH molecules and the zeolites with respect to the electrical conductivity sensitivity were investigated and verified through infrared spectroscopy.

Eggshell is a rich source of CaCO3 with a high purity content of more than 96.35% w/w and a potential raw material for calcium hydroxyapatite preparation. Mesoporous and nano‐particulate calcium hydroxyapatite was prepared from duck eggshell from the chemical reaction with phosphoric acid followed by the calcinations at 800, 900, and 1000°C for 2 hours. The optimum condition to obtain the high purity calcium hydroxyapatite was by sintering calcium phosphate Ca3(PO4)2 at 1000°C for 2 hours. The average particle size, pore diameter, specific surface, and true density of the sample sintered at 1000°C for 2 hours were 101.93 ± 12.15 nm, 98.96 Å, 2.12 m2/g, and 3.02 g/cm3, respectively, appearing as a soft fine powder with a white color. The raw duck eggshell is a potential candidate as a bio‐ceramic material to prepare calcium hydroxyapatite suitable for use in various bio‐applications such as bone tissue engineering, drug and gene delivery, remineralizing agent in toothpaste, and bone void fillers for orthopedic and restoration.

Nafion is a currently used as a proton exchange membrane in vanadium redox flow batteries (VRBs). It is an excellent proton-conducting and fully hydrated membrane, but it is costly. In order to reduce the cost of the membrane used in VRBs and to reduce vanadium permeability across the membrane, sulfonated poly(ether ether ketone) (S-PEEK) and sulfonated poly(1,4-phenylene ether ether sulfone) (S-PPEES) membranes were fabricated and studied as a function of the sulfonation reaction time. The increase in the degree of sulfonation from 46 to 86% induced increases in the water uptake, ion exchange capacity, proton conductivity, and vanadium permeability. The vanadium permeability coefficients of S-PEEK and S-PPEES membranes are in the range of 0-24.95 Â 10 -7 cm 2 min -1 , which are significantly lower than that of Nafion 117, which is 30.84 Â 10 -7 cm 2 min -1 . The proton conductivity of S-PEEK in our study is nine times higher than sulfonated poly(arylene ether ketone) in a previous work and more suitable for using in VRBs.

No abstract

A new sulfonated poly(aromatic imide-co-aliphatic imide) (SPI) for the use as a polymer electrolyte membrane was successfully synthesized from 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylmethane-2,2'-disulfonic acid disodium salt (S-DDM), hexamethylenediamine, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride in a one-step reaction. S-DDM was prepared by the direct sulfonation of DDM monomer. The degree of sulfonation of the sulfonated copolyimide was varied by using various molar concentrations of S-DDM. The sulfonated copolyimide with the highest degree of sulfonation possessed the proton conductivity of 0.0032 S.cm -1 in a wet state. The highest methanol permeability of the sulfonated copolyimide was 2.75 × 10 -8 cm 2 .s -1 which is ~425 times lower than that of the Nafion 117. The highest membrane selectivity belonged to the membrane with 34% degree of sulfonation with the value of 1.65 × 10 6 s.S.cm -3 which is three orders of magnitude higher than the commercial Nafion 117.