FTIR evaluation on the fuel stability of calophyllum inophyllum biodiesel: Influence of tert-butyl hydroquinone (TBHQ) antioxidant

Mohamed Shameer P.,Ramesh K. 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7

‘Storage oxidation stability’ is one of the most significant criteria for appraising the biodiesel quality. Poor oxidation stability is the chief technical blockage related with the commercialization of biodiesel. The present paper investigates the effects of Tert- butyl hydroquinone (TBHQ) antioxidant additive concentrations on the long-term storage stability, thermal stability and accelerated oxidation stability of Calophyllum inophyllum biodiesel. Fourier transform infra-red (FTIR) spectroscopy was used to characterize the biodiesel oxidation variability, following the regions of C-H and O-H bonds in FTIR spectrum for different concentrations of TBHQ. Addition of TBHQ at 1000 ppm concentration (B100A3) with pure biodiesel enhances the oxidation stability by 94.67 %, storage stability by 14.47 % and thermal stability by 69.55 %; whereas further concentration of antioxidant deteriorates the formation of hydrophobic and hydrophilic clusters between biodiesel/antioxidant compounds, which is characterized by FTIR spectrum data. It is concluded that the Calophyllum inophyllum biodiesel could be accumulated for an extensive period by dosing 1000 ppm of TBHQ antioxidant.

Stability of H2O2 as an Oxidizer for Cu CMP

Do-Won Lee,김태군,김상용,장의구,Nam-Hoon Kim 한국전기전자재료학회 2005 Transactions on Electrical and Electronic Material Vol.6 No.1

Chemical mechanical polishing is an essential process in the production of copper-based chips. On this work, the stability of hydrogen peroxide (H2O2) as an oxidizer of copper CMP slurry has been investigated. H2O2 is known as the most common oxidizer in copper CMP slurry. But H2O2 is so unstable that its stabilization is needed using as an oxidizer. As adding KOH as a pH buffering agent, stability of H2O2 decreased. However, H2O2 stability in slurry went up with putting in small amount of BTA as a film forming agent. There was no difference of H2O2 stability between pH buffering agents KOH and TMAH at similar pH value. Addition of H2O2 in slurry in advance of bead milling led to better stability than adding after bead milling. Adding phosphoric acid resulted in the higher stability. Using alumina C as an abrasive was good at stabilizing for H2O2.

고추씨유, 캡사이신 및 토코페롤의 첨가가 돈지와 대두유의 산화안정성에 미치는 영향

이치호,한규호,김아영,이슬기,홍고은,변장원,최강덕,양철영,Lee, Chi-Ho,Han, Kyu-Ho,Kim, Ah-Young,Lee, Seul-Ki,Hong, Go-Eun,Pyun, Chang-Won,Choi, Kang-Duk,Yang, Cheul-Young 한국축산식품학회 2008 한국축산식품학회지 Vol.28 No.5

This study was designed to compare the thermal oxidative stability of lard, soy bean oil, and hot pepper seed oil for 0-3 d at $100^{\circ}C$, and to evaluate the effect of capsaicin on thermal oxidative stability in lard and soy bean oil. As result, thermal oxidation stability was shown in the order hot pepper seed oil>soy bean oil>lard for 0-3 d at $100^{\circ}C$. In blended oils, hot pepper seed oil effectively inhibited lipid oxidation when mixed with lard than soy bean oil by showing the ratio of 30% pepper seed oil plus 70% lard and 60% pepper seed oil plus 40% soy bean oil inhibited lipid oxidation during storage periods. And to investigate the antioxidative effect of antioxidants such as capsaicin and alpha-tocopherol in hot pepper seed oil, 1,200 and 2,400 ppm capsaicin, or 0.3% alpha-tocopherol were added in soy bean oil and lard and stroed for 0-3 d at $100^{\circ}C$. Capsaicin inhibited lipid oxidation in lard but not in soy bean oil, however alpha-tocopherol exhibited a prooxidaton effect in soybean oil. Therefore, it suggests that the application of hot pepper seed oil or capsaicin in lard may be better for thermal oxidative stability.

Effect of 2,2-azobis (2-amidinopropane) dihydrochloride oxidized casein on the microstructure and microrheology properties of emulsions

Wang, Jianming,Tan, Yaoyao,Xu, Hui,Niu, Sisi,Yu, Jinghua 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.5

The impacts of protein oxidation on the droplet size and microrheology properties of casein emulsions with 20% oil content were investigated. The degree of protein oxidation was indicated by carbonyl concentration. The droplets in the emulsions of different-oxidation-degree casein had bimodal distribution, but their size altered due to oxidation. The effects of protein oxidation on the morphology, motion type, viscoelasticity, and stability of droplets were also investigated by microrheology analysis. The droplet motion was blocked by protein oxidation due to mean square displacement slope results. Solid-liquid balance values provided the liquid behavior dominating these emulsions. Oxidation of carbonyl concentration 16.72 raised the primary droplets, increased the elasticity, decreased the viscosity, and promoted the droplet motion rate, resulting in better stability of emulsions. Further oxidation promoted the aggregation of droplets and resulted in poor stability.

Analysis of cerium-composite polymer-electrolyte membranes during and after accelerated oxidative-stability test

Shin, Dongwon,Han, Myungseong,Shul, Yong-Gun,Lee, Hyejin,Bae, Byungchan Elsevier 2018 Journal of Power Sources Vol.378 No.-

<P><B>Abstract</B></P> <P>The oxidative stability of membranes constructed from a composite of pristine sulfonated poly(arylene ether sulfone) and cerium was investigated by conducting an accelerated oxidative-stability test at the open-circuit voltage (OCV). The membranes were analyzed in situ through OCV and impedance measurements, cyclic voltammetry, and linear-sweep voltammetry to monitor the electrochemical properties during the stability test. Although the high-frequency resistance of a composite membrane was slightly higher than that of a pristine membrane because of the exchange of protons from the sulfonic acid with cerium ions, the composite membrane maintained its potential for much longer than the pristine membrane. The effect of the cerium ions as radical scavengers was confirmed by analyzing the drain water and chemical structure after operation. These post-operation analyses confirmed that cerium ions improved the oxidative stability of the hydrocarbon-based polymer during fuel-cell operation. It is clear that the cerium-based radical scavengers prevented chemical degradation of the polymer membrane as well as the electrode in terms of hydrogen cross-over, polymer-chain scission, and the electrochemical surface area, while they rarely diffused outward from the membrane.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ce-composite PEMs were evaluated in accelerated oxidative-stability test at <I>OCV.</I> </LI> <LI> During the test, the impedance, HFR, ICs, CVs, and LSVs were measured. </LI> <LI> <SUP>1</SUP>H NMR spectroscopy, GPC, FE-SEM, and EDS were conducted after the test. </LI> <LI> The in situ and post-test analyses determined what happened during the test. </LI> <LI> Ce radical scavengers aided the PEM's oxidative stability in fuel-cell operation. </LI> </UL> </P>

Effect of 2,2-azobis (2-amidinopropane) dihydrochloride oxidized casein on the microstructure and microrheology properties of emulsions

Jianming Wang,Yaoyao Tan,Hui Xu,Sisi Niu,Jinghua Yu 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.5

The impacts of protein oxidation on the droplet size and microrheology properties of casein emulsions with 20% oil content were investigated. The degree of protein oxidation was indicated by carbonyl concentration. The droplets in the emulsions of different-oxidation-degree casein had bimodal distribution, but their size altered due to oxidation. The effects of protein oxidation on the morphology, motion type, viscoelasticity, and stability of droplets were also investigated by microrheology analysis. The droplet motion was blocked by protein oxidation due to mean square displacement slope results. Solid–liquid balance values provided the liquid behavior dominating these emulsions. Oxidation of carbonyl concentration 16.72 raised the primary droplets, increased the elasticity, decreased the viscosity, and promoted the droplet motion rate, resulting in better stability of emulsions. Further oxidation promoted the aggregation of droplets and resulted in poor stability.

Fatty Acid Composition as a Predictor for the Oxidation Stability of Korean Vegetable Oils with or without Induced Oxidative Stress

Yun, Jung-Mi,Surh, Jeong-Hee The Korean Society of Food Science and Nutrition 2012 Preventive Nutrition and Food Science Vol.17 No.2

This study was designed to investigate whether the fatty acid composition could make a significant contribution to the oxidation stability of vegetable oils marketed in Korea. Ten kinds, 97 items of vegetable oils that were produced in either an industrialized or a traditional way were collected and analyzed for their fatty acid compositions and lipid oxidation products, in the absence or presence of oxidative stress. Peroxidability index (PI) calculations based on the fatty acid composition ranged from 7.10 to 111.87 with the lowest value found in olive oils and the highest in perilla oils. In the absence of induced oxidative stress, malondialdehyde (MDA), the secondary lipid oxidation product, was generated more in the oils with higher PI (r=0.890), while the tendency was not observed when the oils were subjected to an oxidation-accelerating system. In the presence of the oxidative stress, the perilla oils produced in an industrialized manner generated appreciably higher amounts of MDA than those produced in a traditional way, although both types of oils presented similar PIs. The results implicate that the fatty acid compositions could be a predictor for the oxidation stability of the vegetable oils at the early stage of oil oxidation, but not for those at a later stage of oxidation.

Enhanced Chemical Stability of D-Cycloserine via Tablet Form Containing Magnesium Oxide as an Alkali Stabilizer

Jung Suk Kim,이상민,김동식,김동욱,김경수,조관형,Dong Xun Li,진성규,최한곤 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.1

The purpose of this study was to improve the chemical stability of D-cycloserine via tablet form containing an alkali stabilizer. The influence of alkalizing agents on the stability of D-cycloserine was investigated at 60 °C/75% RH for 2?days. The drug stability was evaluated with the D-cycloserine-loaded tablets prepared with various amounts of magnesium oxide using direct compression method. Compared to D-cycloserine powder and a commercial D-cycloserine-loaded product, the long-term drug stability on the chosen tablet was assessed at 40, 60, and 40 °C/75% RH during 6?months. Amongst the stabilizers investigated, magnesium oxide most improved the stability of D-cycloserine at the accelerated stress condition. The magnesium oxide/drug ratio of 1 and 2 showed higher remaining drug concentrations than those less than 0.5; however, two formers gave no significant difference in the remaining drug concentrations. Amongst the tablets tested, the formulation composed of D-cycloserine, magnesium oxide, and talc at the weight ratio of 250/250/5 most increased the stability of D-cycloserine. Additionally, due to the alkali and water-proofing property of magnesium oxide, this tablet improved the stability of D-cycloserine compared to the drug powder and commercial product. Hence, this novel tablet with enhanced drug stability would be a candidate for oral pharmaceutical product of D-cycloserine.

Service life and stability of electrodes applied in electrochemical advanced oxidation processes: A comprehensive review

Masoud Moradi,Yasser Vasseghian,Alireza Khataee,Mehmet Kobya,Hossein Arabzade,Elena-Niculina Dragoi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

In recent years, novel advanced oxidation processes (AOPs) based on electrochemical technology knownas electrochemical advanced oxidation processes (EAOPs) have been applied to the degradation of a widerange of persistent organic pollutants (POPs). EAOPs produce in situ hydroxyl radicals ( OH) capable ofdegrading POPs and their mineralization by producing stable electrode materials (e.g., boron-dopeddiamond (BDD), doped-SnO2, PbO2, and substoichiometric- and doped-TiO2). Moreover, ozone andsulfate radicals could be produced, based on electrolyte type, which cause the degradation of POPs. Although EAOPs are promising novel technologies, various parameters related to the types of electrodesin the POPs oxidation have not been fully addressed. In order to provide a full and comprehensive pictureof the current state of the art, and improve the treatment efficiency and motivate new researches in theseareas, this study analyzed the research covering EAOPs aspects, with a focus on the comparison ofstability, lifetime and service life of electrodes. Electro-chemical stability and longer life are the majorconcerns in the EAOPs. Since electrodes must be highly efficient for long periods of time, thedetermination of their lifetime is essential. On the other hand, in real-life situations, lifetimedetermination is difficult. The oxidation ability and durability of electrodes during the reactionsdepended on the structural properties of them. Electrodes composed of intermediate compounds had ahigher lifetime than binary oxides. Another factor affecting the stability of the electrodes was thestructure of the expanded mesh style anodes to better control the bubble growth through a polygonizedstructure. Anodes with irregular shapes at the surface were more likely to discharge the bubbles andreduce the negative effects of the high pressure on the surface of the electrode. The electrodes havinghigh oxidation strength and stability, had a shorter service life value. Furthermore, the calcinationtemperature and the amount of applied current directly affected the lifetime of the electrodes. On theother hand, the electrical resistance of the synthesized electrode was effective in the lifetime. Coating ofelectrodes with noble metals such as tantalum, titanium, niobium, zirconium, hafnium, vanadium,molybdate and tungsten improved the electrode stability.

Fatty Acid Composition as a Predictor for the Oxidation Stability of Korean Vegetable Oils with or without Induced Oxidative Stress

Jung-Mi Yun,Jeonghee Surh 한국식품영양과학회 2012 Preventive Nutrition and Food Science Vol.17 No.2

This study was designed to investigate whether the fatty acid composition could make a significant contribution to the oxidation stability of vegetable oils marketed in Korea. Ten kinds, 97 items of vegetable oils that were produced in either an industrialized or a traditional way were collected and analyzed for their fatty acid compositions and lipid oxidation products, in the absence or presence of oxidative stress. Peroxidability index (PI) calculations based on the fatty acid composition ranged from 7.10 to 111.87 with the lowest value found in olive oils and the highest in perilla oils. In the absence of induced oxidative stress, malondialdehyde (MDA), the secondary lipid oxidation product, was generated more in the oils with higher PI (r=0.890), while the tendency was not observed when the oils were subjected to an oxidation-accelerating system. In the presence of the oxidative stress, the perilla oils produced in an industrialized manner generated appreciably higher amounts of MDA than those produced in a traditional way, although both types of oils presented similar PIs. The results implicate that the fatty acid compositions could be a predictor for the oxidation stability of the vegetable oils at the early stage of oil oxidation, but not for those at a later stage of oxidation.