Papers by Keyword: Carboxylic Acid

Abstract: Cooking oil saturation due to frequent use for frying will result in a higher fatty acid content. Activated carbon made from the banana peel (Musa acuminata) with micro-mesoporous specifications can absorb free fatty acids. Banana peels are pyrolyzed into charcoal then activated alkaline at a temperature of 650°C. Then the activated carbon is washed and mashed to obtain activated carbon powder as an adsorbent by batch. FTIR carried out adsorption analysis on cooking oil to reduce carboxylic acid in used cooking oil. The regeneration process is carried out using surfactants to save on the use of necessary materials so that they need to be recycled. The experimental results based on isothermic equilibrium show that the Freundlich model can describe the adsorption process well at 28°C with a maximum adsorption capacity of 10 mg/g. The lifespan of activated carbon can only be extended once regeneration, reaching an adsorption capacity of 65% of fresh activated carbon's ability.

Abstract: The geometric structure and electronic properties of the adsorption of organic carboxylic acids on the closed-packed Cu(111) surface have been addressed by periodic density functional theory (DFT) calculations. We also have taken into account van der Waals (vdW) interaction by the VdW-DF method. The optimized structures show that formic and acetic acids have stable structures of molecular adsorption in clean copper surfaces. We find that the adsorption energies at 1/16 ML coverage are -0.27, -0.30 and -0.10 eV for formic, acetic, and propionic acid, respectively. On the other hand, in the case of vdW-DF, their adsorption energies increased to -0.63, -0.70 and -0.73 eV.

Abstract: Carboxylic acids of various carbon chain lengths (C_n); i.e. butanoic acid (C₄), octanoic acid (C₈), dodecanoic acid (C₁₂) and hexadecanoic acid (C₁₆) have been used to organically modify silicon dioxide (SiO₂). The acid modification involve replacing the hydrogen atom of the silanol group (Si-OH) of SiO₂ with the R_nCOO-of the acid via esterification technique. SiO₂ and acid modified SiO₂ (MoC_n-SiO₂) were used as filler in preparation of polymethyl methacrylate/50% epoxidized natural rubber electrolytes containing SiO₂ (PEL-SiO₂) and MoC_n-SiO₂ (PEL-MoC_n-SiO₂) via solvent casting method with lithium tetrafluoroborate (LiBF₄) as dopant salt. Field-emission scanning electron microscopy (FESEM) analysis of PEL-SiO₂ and PEL-MoC_n-SiO₂ films show LiBF₄ accumulated to the fillers. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed formation of hydrogen bonding between LiBF₄ with fillers and polymers in the polymer electrolyte films. Interestingly, the ionic conductivity of PEL-MoC_n-SiO₂ films increases as the C_n of acids increased with the highest ionic conductivity of 5.56 x 10^-7 Scm^-1 was achieved in PEL-MoC₁₂-SiO₂ film.

Abstract: Esterification of carboxylic acids with alkyl halides were studied using dicationic ionic liquid 1,1’-decane-1,10-diylbis (3-butylpyridinium) dibromide-[C10(Bpy)2] (Br)2 in the presence of triethylamine. Good conversion rates and yields were obtained. The ionic liquid could be reused after removal of water under vacuum.

Abstract: We focused on the investigation of the influence of carboxylic acid additives on the morphology of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) particles synthesized by a homogeneous precipitation method. Three types of carboxylic acids with different number of carboxyl groups, that is, acetic acid, succinic acid and citric acid, were used as additives to control the nucleation, growth and alignment of HAp crystals. The powder properties of resulting particles were examined by powder X-ray diffractometry, fourier-transform infrared spectroscopy, and scanning electron microscopy. All resulting particles were identified to be single-phase carbonate-containing calcium-deficient HAp. The resulting particles synthesized by using acetic acid as an additive were strip-like morphology. In the case of succinic acid addition, the resulting particles exhibited irregular plate-like or spherical morphology. Wheileas, in the case of citric acid addition, the obtained particles became regular spherical shape. These results indicate the numbers of carboxyl groups of carboxylic acid give an influence of the morphology of the HAp particles.

Abstract: A new kind of triphenylene derivative sym-(OC3H6OCOC2H4COOH)6 with triphenylene at the core and carboxyl groups at the peripheral chains was synthesized and characterized by FT-IR and 1H-NMR. Thermal gravimetry analysis (TGA) and differential scanning calorimetry (DSC) showed that these compounds have a good thermal stability, which is dependent on the flexibility and interaction of the peripheral chains. Red shifts in electronic absorption spectra of the compounds were found in solution with increasing concentration.

Abstract: Uniform spherical- and rod-shaped TiO2 nanoparticles of anatase phase were prepared using decanoic acid at 300°C by reverse micelle method. The nanoparticles were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffractometry (XRD) and FT-Raman spectroscope. The content of decanoic acid and operating temperature were noted as crucial parameters, controlling the shape, size and phase of TiO2 nanoparticles. RMS roughness (1.62 nm), measured by atomic force microscope (AFM), confirmed its superiority over other methods. The DCB photodegradation reaction rate constant (first order) TiO2 nanoparticles was found superior to that of commercial TiO2, Degussa P-25.

Abstract: Bajpai et al. originally reported the formation of cements by the mixture of carboxylic acids and β-tricalcium phosphate (β-TCP). In the current study, we report and contrast four such cement systems formed from mixing citric, malic, 2-oxoglutaric or phosphoric acid with β-TCP. Cements formed from malic or 2-oxoglutaric appeared to contain crystalline phases and were determined to contain brushite, β-TCP and unreacted acid. In contrast, cement formed with citric acid was poorly crystalline, containing little evidence of brushite formation and was unstable in water and therefore does not appear to be a feasible cement system.

Abstract: Organically-modified silica xerogels from 3-aminopropyltrimethoxysilane (APTES) and 3-isocyanatepropyltriethoxysilane (ICPTES) have been synthesized through carboxylic acid (formic acid, acetic acid and valeric acid) solvolysis. The resulting hybrid materials have been characterized by powder X-ray diffraction, mid-infrared spectroscopy, 29Si and 13C nuclear magnetic resonance, and photoluminescence spectroscopy. The results show that urea cross-links have been formed in these hybrids. The luminescence features depend on the selected carboxylic acids. For example, comparatively to the hybrids derived from formic and acetic acid solvolysis, valeric acid shows a red-shift of the emission features.