Materials Science Forum Vol. 998

Abstract: The objective of this research was to study the methyl ester purity and pressure drop when the reactants flowed through the 3D-printed continuous static mixer reactor. The various types of 3D-printed mixing elements: KSM, LSM, SMX-3, SMX-4, SMX-5, SMV-3, SMV-4, and SMV-5 were inserted into the tube to blend the refined palm oil (RPO) and potassium methoxide (CH₃KO) during the transesterification process. Therefore, the comparison of various types and plug flow (PF) reactors in continuous methyl ester production was carried out to assessed the purity of methyl ester with the condition was 23.81 vol.% methanol and 11.8 wt.% KOH at 50°C temperature. The results showed that the pressure drop had increased when a flow rate of water was increased. The pressure drop in the continuous reactor increased to 29.9% of SMV-5, 19.9% of SMV-4, 12.0% of SMV-3, 7.0% of SMX-5, 7.0% of SMX-4, 7.0% of SMX-3, 3.6% of LSM and 0.9% of KSM when compared with the empty tube cases. According to biodiesel production, the purity of methyl ester decreased by 93.63% of SMV-5, 92.49% of SMV-4, 91.63% of SMV-3, 51.68% of SMX-5, 47.47% of LSM, 46.17% of SMX-4, 45.31% of SMX-3, 42.36% of KSM, and 12.28% of PF, respectively, when compared to the highest purities achieved with PF reactor. Thus, a 662% improvement in ester purity was obtained by using the SMV-5 reactor instead of the PF reactor within 360 mm.

Abstract: The continuous methyl ester production process was studied using a hydrosonic reactor to determine the relationship between the rotor speed and the purity of methyl ester with TLC/FID technique. The hydrosonic reactor consisted of three main parts: a rotor, a stator, and a motor. The key part is a 3D-printed rotor; the dimensions were 60 mm in outer diameter, 50 mm in length. The rotating 3D-printed rotor was driven and axially rotated inside the stator by shaft, and 400 kW electric motor was used to blend the mixtures. The dimensions of stator were 70 mm inner diameter and 70 mm length, and 5 mm thickness. The gap distance between the rotor and stator was fixed at 10 mm. The hole on the surface of rotor was circular shape (80 holes of 6 mm diameter) and designed radically throughout the axis. The ratio of diameter to depth of the circular hole was 1.0. In the preliminary experiment, the location and dimension of holes were fixed, and 3D-printed rotor speed was varied at 1000, 2000 and 4000 rpm under the condition of 23 vol.% methanol, 10 g KOH/L and 37 L/hr RPO flow rate at 60°C. The results showed that methyl ester purification reached 93.920 wt.%, 95.325 wt.%, 96.700 wt.%, and 97.333 wt.% at 1000, 2000, 3000, and 4000 rpm of rotor speed. Therefore, over 90 wt.% of methyl esters can be produced from RPO by using rotor-stator type of hydrodynamic cavitation.

Abstract: The object of this study is to intensify the liquid-liquid extraction. Experiments were carried out inside a Rotating Packed Bed (RPB) operating at centrifugal force varying between 100g and 1000g. The system chosen for experimentation was removal of hexavalent chromium from aqueous solution using aliquat-336 as an extractant. The effect of centrifugal force on overall volumetric mass transfer coefficient () was investigated. Mass transfer characteristics of RPB were observed with the variation in rotational speed (300-1100rpm), aqueous phase (0.4-1.2 L/min) and organic phase (0.05-0.15 L/min) flow rate, feed (25-200 mg/L) and extractant (0.5-1.25 vol%) concentration. Significantly higher value of (~20-25 times) was achieved in RPB than that achieved in comparison with conventional packed bed extractor wherein flow is dictated by terrestrial gravity. In other words, same separation efficiency can be obtained within a much smaller rotating extractor.

Abstract: Platinum and iridium are known to belong to a family of partly miscible metals. On the other hand, these metals are high demanded as active components of the catalysts for a variety of industrially important processes. In the present work, a series of bimetallic Pt-Ir catalysts supported on alumina were prepared using a “single source precursor” concept. The ratio of metals in the alloy was varied from 1:3 to 3:1. The thermal stability and catalytic activity in CO oxidation of the samples were studied in a prompt thermal aging regime. Monometallic Pt/γ-Al₂O₃ and Ir/γ-Al₂O₃ samples were used as references. All the studied catalysts were characterized by UV-vis spectroscopy in initial state and after the aging treatment. It was found that the bimetallic nanoparticles being subjected to the high temperature aging at 600 and 800 °C undergo redistribution with further stabilization in a noticeably more active state. The observed increase in the catalytic activity is explained by an enrichment of the particles’ surface with platinum.

Abstract: Commercial Ni-Cr and specially prepared Ni-Pd alloys were used as a catalyst’s precursor for the synthesis of the heteroatom-doped carbon nanofibers. In order to provide the intercalation of the doping heteroatom into the structure of the carbon product, the synthesis was performed in the one pot regime, when heteroatom-containing substance was subjected to decomposition simultaneously with carbon source compound. Chlorobenzene, 1-bromobutane, 1-iodobutane, and melamine were used as heteroatom-and carbon-containing sources in the experiments carried out in a closed reactor system. 1,2-dichloriethane, being a source of chlorine and carbon, was decomposed in a flow-through reactor system. Additionally, acetonitrile and carbon dioxide were admixed to 1,2-dichloriethane as nitrogen and oxygen sources. It was found that in all the cases, except for halogenated butanes, the amount of the intercalated heteroatom can reach 3-8 at.%. Both the substrate’s nature and the composition of the reaction mixture were found to affect the morphologic features of the carbon nanostructures produced.

Abstract: This paper explored the chemical, mechanical, and morphological characteristics ofpolycaprolactone and starch composite membranes by utilizing SEM, FTIR, W-CA, UTM, and biodegradability tests. Native Philippine arrowroot (Marantaarundinacea L.) starch was extracted for the study. Varying polymer concentrations along with 85% solvent NMP, the films were plasticized with PEG 4000 and prepared through solvent casting and NIPS. The films were found to be hydrophilic. Increased starch contentimproved porousnessand biodegradation rate, with 4.12%/day in 5 days for the highest starch-containing film, with the highest weight loss of 38.02% in 15 days for 20% starch-containing films. However, degradation decreased as time went by. Increasing amounts of starch also increased elongation at break, albeit reducing Young’s modulus and tensile strength of the films. Coupled with notable morphological and chemical interaction, arrowroot starch and PCL composite films can indeed be successfully fabricated, proving the potential of Marantaarundinacea L. in the field of bioplastic research.

Abstract: Nanocellulose (NC) has been successfully isolated from Oil Palm Empty Fruit Bunch (OPEFB) by using catalyst 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) through mediated oxidation process. For use as a reinforcing component in polymer bionanocomposites, NC has to be completely dried to avoid agglomeration in the non-polar solvent. In this research three types of approaches namely, oven drying (OD), freeze drying (FD) and solvent exchange (SE) were used to remove the water. Based on the dispersion stability results, the NC prepared from the OD technique gave longer stable suspension than that produced by FZ and SE. Besides, this method is also relatively simple and cost effective.

Abstract: Niobium is an important constituent of Zr-Nb alloys being used widely in the nuclear industries as fuel claddings and pressure tubes. In this article, MD based simulations are performed to obtain grain boundary (GB) energies in ∑3 symmetrical and asymmetrical tilt grain boundaries (ATGBs) along <110> tilt axis. Grain boundary energies are also obtained analytically by utilizing the equation establishing the relationship between inclination angle and grain boundary energy for ATGBs. It is observed that in both the cases the GB energies increase with the increase in inclination angle of the ATGBs. The increase in the GB energy follows the same trend with a little offset between the results obtained analytically and MD based simulations. The offset between both the results can be attributed to the limitations of the potentials employed for the simulations. MD based simulations thus provide an accurate method to calculate the GB energies.

Abstract: Thin films of vanadium oxide were synthesized by DC magnetron sputtering on a glass slide. Process parameters including temperature, argon and oxygen ratio (Ar:O₂) and base pressure were investigated. It was found that the control of sputtering base pressure is very important in realizing the pure VO₂ (M) thin films. These thin films have grown at low base pressure of 5x10^-6 mbar. The results of the valence electron analysis show the outstanding phase of VO₂ and a small amount of V₂O₅ and V₂O₃ phases. The hysteresis loop of electrical resistance property of the VO₂ thin films illustrated the quality of film, which is related to metal-insulator transition phase (MIT) at the transition temperature (T_c) of approximately 63°C. The sample was tested for its electrical properties by a four-probe setup with a temperature controller during heating and cooling cycles.

Abstract: Stable electronic configuration between the interface of an n-type oxide semiconductor core and a p-type polymer shell is necessary in order to guarantee a consistent functioning core-shell structure. This research aims to use silane-aniline to link between an n-type Titanium (IV) oxide (TiO₂) core and p-type polyaniline emeraldine salt (PANI-ES) shell. Core-shell structure was created by functionalizing TiO₂ powders with silane aniline molecules using simple soaking technique and then polymerizing the attached aniline molecules using an oxidative technique. Infrared spectroscopy reveals the presence of Si-O bonds signifying the presence of linkage between the inorganic core and polymeric shell. Polymerization of the attached aniline molecules may have led to coupling of aromatic rings to form long polymeric structures which caused widening and shifting of aromatic rings’ IR peak to lower wavenumber. In conclusion, silane-aniline was successfully utilized to connect the n-type TiO₂ core and p-type PANI-ES shell.