Topic
Citric acid
About: Citric acid is a research topic. Over the lifetime, 17745 publications have been published within this topic receiving 277125 citations. The topic is also known as: citrate & H3cit.
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TL;DR: In this paper, four different carboxylic acids (1,2,3,4-butane tetracarboxyl acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA)) were used as crosslinking agents for finished cotton fabrics in the presence of nanometer titanium dioxide catalyst under the irradiation of ultraviolet (UV) light and/or an electronic field (EF).
Abstract: Four different carboxylic acids (1,2,3,4-butane tetracarboxylic acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA)) were used as crosslinking agents for finished cotton fabrics in the presence of nanometer titanium dioxide catalyst under the irradiation of ultraviolet (UV) light and/or an electronic field (EF). We find that the dry crease recovery angle, wet crease recovery angle, and softness improvement percentages of the treated fabrics for all the crosslinking agents are gradually increased with the increasing of irradiation time period, but the TSR values decreased in all cases. The crease recovery and softness properties for the various crosslinking agents are ranked as BTCA > MA > CA > SUA at a given UV irradiation time period. The addition of EF treatment on the UV-irradiated fabrics improves the catalytic effects significantly. The spectra of Fourier transform infrared spectrophotometry reveal the crosslinking reaction between the carboxylic acid group of citric acid and the hydroxyl group of methylcellulose; this reaction could form ester and ether groups in the presence of nanometer TiO 2 catalyst under UV irradiation and UV irradiation and EF treatment. The pictures of scanning electron microscopy and the electron spectroscopy for chemical analysis survey spectra show the surface deposition of acid crosslinking agents on the finished fibers and the crosslinking reaction between citric acid and cellulose molecule catalyzed with nanometer titanium dioxide under the irradiation of UV only and under the irradiation of UV and the treatment of EF separately.
77 citations
TL;DR: Spectrophotometric assay of the NADP-IDH activity in the pulp during fruit development showed that in young fruit, most of the activity was associated with the mitochondrial preparation and that, as the fruit grew, the activity shifted to the soluble fraction, which suggests that the soluble activity is regulated by the expression of the cytosolic NADP -IDH gene.
77 citations
TL;DR: The half-life value of betanine at 75°C, pH 5.0 in a phosphate buffer was 48.0 ± 1.0 min (control) while 5.9% acetic acid caused a decrease in stability (33.4 ± 0.9 min) possibly due to pH changes at elevated temperatures.
Abstract: The rate of betanine degradation as affected by monocarboxylic acids (lactic acid, acetic acid), metal cations (Fe+++, Cu++), antioxidants (ascorbic acid, α-tocopherol) and sequestrants (citric acid, Na2 EDTA) was studied. Betanine was extracted from beets using water, and purified by molecular exclusion and adsorption chromatography. Column packings used were Sephadex G-25, polyacrylamide, and polyvinylpolypyrrolidone. The effect of food additives on the rate of oxidation of betanine in buffered systems was determined using a modification of the active oxygen method. A betanine solution was placed in a reaction chamber, held at 75° C, and oxygen was passed through the solution at a rate of 3 ml/min. The half-life value of betanine at 75° C, pH 5.0 in a phosphate buffer was 48.0 ± 1.0 min (control). Addition of 100 ppm lactic acid had no effect on stability (41 ± 1.7 mm), while 5.9% acetic acid caused a decrease in stability (33.4 ± 1.9 min) possibly as a result of pH changes at elevated temperatures. Metal ions at a level of 100 ppm caused an increase in the degradation rate compared to that of the control with addition of iron resulting in a half-life value of 33 ± 1.4 min. Copper had the greatest effect, reducing the half-life value to 6.0 ± 0.2 mm. Neither 100 ppm ascorbic acid nor 100 ppm a-tocopherol affected the half-life value of betanine (45.3 ± 2.3 and 50.2 ± 3.4 min, respectively). Ascorbic acid at 1000 ppm decreased the halt-life value (32.3 ± 3.3 min), whereas 10,000 ppm citric acid and 10,000 ppm EDTA caused an increase in the half-life value of 1.5 times compared to that of the control (69.4 ± 3.1 and 70.7 ± 7.1 min). Both 100 and 1000 ppm citric acid had no effect on betanine stability.
77 citations
TL;DR: The results indicate that the activation of genes possibly encoding citrate transporters plays a critical role in Al-stimulated citrate efflux, and that de novo protein synthesis is required for Al- Stimulated citate efflux.
77 citations
TL;DR: In this article, the effects of the molar ratio of citric acid to cations and of the pH value on the chemistry of a solution prepared by the Pechini method were examined.
Abstract: Several experiments were conducted to examine the effects of the molar ratio of citric acid to cations and of the pH value on the chemistry of a solution prepared by the Pechini method. Two types of precipitates, barium titanium citrate (BTC) and barium citrate, developed, depending on the experimental conditions. Characterization of BTC by FT-IR spectroscopy and solid-state 13C-NMR spectroscopy indicated that barium and titanium ions were chelated simultaneously by the central deprotonated alcoholic ligands and by dissociated carboxylic acid groups with a unidentate type of three citric acid molecules. The possible coordinated structure of BTC was proposed. The thermal decomposition behavior of BTC was investigated by powder X-ray diffractometry, FT-IR spectroscopy, and solid-state 13C-NMR spectroscopy. During decomposition, the nature of bonding between carboxylate groups and cations changed in the order unidentate → bridging → ionic, and carbonate species were detected at 500°C. A small amount of BaCO3 and the intermediate oxycarbonate coexisted at 550°-600°C.
77 citations