Effect Of Citric Acid Addition Research Articles

Remarkably efficient and stable Ni/Y2O3 catalysts for CO2 methanation: Effect of citric acid addition

Citric acid has been investigated for preparing the highly dispersed nickel catalysts on Y2O3 support. A highly enhanced methanation activity with the high CO2 conversion of 92 % and CH4 selectivity of 100 % was obtained over Ni/Y2O3 with optimum addition of citric acid at 350 °C. The citric acid additives during the preparation are found to influence the size of nickel nanoparticles and the interaction of metal and support, as estimated by various techniques, which, in turn, to correlated with the catalytic performance. In situ DRIFTS spectra further indicate the importance of small Ni particles on formation of carbonates and formate species as key intermediates and the subsequent hydrogenation of those species into methane. This study proposes that the Y-O-Ni interfacial structure formed by the strong Ni and Y2O3 interaction at high citric acid addition is of prime importance for the formation of methane, benefiting from the more abundant basic sites and metallic Ni to enable CO2 activation and hydrogenation of key intermediates by effective H2 dissociation respectively. This work provides a new design strategy for developing highly efficient composite CO2 methanation catalysts by control of the metal particle size and charge transfer via metal/support interface.

Elimination of representative fluoroquinolones, penicillins, and cephalosporins by solar photo-Fenton: degradation routes, primary transformations, degradation improvement by citric acid addition, and antimicrobial activity evolution.

This work studies the degradation of seven representative antibiotics (ciprofloxacin, norfloxacin, levofloxacin, oxacillin, cloxacillin, cefalexin, and cefadroxil) by solar photo-Fenton process. The removal of antibiotics by the individual components (i.e., light, H2O2, or Fe (II)) and the complete photochemical system (light/H2O2/Fe (II)) was initially evaluated. Then, the effect of citric acid addition to the photo-Fenton system was assessed. In the third place, the primary transformation products for two illustrative cases (ciprofloxacin and oxacillin treated by photo-Fenton) were determined. Also, photo-Fenton in the presence of citric acid was applied to remove antibiotics from a simulated hospital wastewater. It was found that the solar light component induced degradation of ciprofloxacin, norfloxacin, and levofloxacin, but the rest of the considered antibiotics were not reduced by photolysis. In turn, the photo-Fenton system showed a degrading action on all the tested antibiotics. The addition of citric acid to the system significantly increased the removal of antibiotics. Initial degradation products indicated that hydroxyl radical attacked moieties of antibiotics responsible for their antimicrobial activity. Finally, the treatment of hospital wastewater evidenced the high potentiality of photo-Fenton process for degrading antibiotics in aqueous matrices containing elevated concentrations of citric acid.

Effect of citric acid addition on functional properties of pasteurized liquid whole eggs.

The aim of this study was to examine the influence of different concentrations of citric acid (0, 300, 400 and 500mg/L) on the physical and functional properties of pasteurized liquid whole eggs (LWE) over 4weeks of storage. The properties tested include pH, conductivity, colour, particle size, rheological, and textural properties, as well as protein solubility, foaming and emulsification. The 4weeks of storage had a statistically significant (P < 0.05) effect on every tested parameter, while the addition of citric acid had a statistically significant (P < 0.05) effect on pH, conductivity, L* and b* values, protein solubility, emulsion activity index, emulsion capacity, emulsion stability, and an increase in foaming and texture parameters, but not on rheological parameters. Citric acid addition and a storage period of 4weeks resulted in a change of pH and an increase in protein solubility. It also led to a lower foaming capacity and a larger drainage of the system, which causes a lower power (work load) requirement to break formed gels. Apparent viscosity did not change significantly in the samples with citric acid.

Effect of fineness and citric acid addition on the hydration of ye’elimite

The first purpose of this article is to investigate the effect of fineness on the hydration of highly pure ye’elimite powders prepared by solid state reaction or by a chemical route. The second purpose is to examine the role of fineness on the hydration of model calcium sulfoaluminate cements (CSA) prepared by mixing our lab-made ye’elimite with gypsum. The last part concerns the effect of citric acid addition on hydration of a model cement. The main results are the following: (i) ettringite and hydrates formation can be accelerated by the presence of very fine ye’elimite powder in a CSA cement paste; (ii) the hydration rate of CSA model cement depends mainly on the dissolution rate of ye’elimite which can be delayed by the addition of citric acid in water; (iii) the surface of ye’elimite grains presents scarce etch pits when citric acid is present in the water, while the surface seems to be totally attacked with water.

PEMBUATAN SERBUK PEWARNA ALAMI TEKSTIL DARI EKSTRAK DAUN JATI (TECTONA GRANDIS LINN. F.)

Anthocyanin is a dye that plays a role in providing a brownish red color that has the potential to become a natural dye for food and can be used as an alternative substitute for coloring dyes that are safer for health. Textile dyes are divided into two, namely natural dyes and synthesis dyes. Natural dyes come from animals and plants while synthetic dyes can be produced from chemicals Anthocyanins are widely found in plants with striking colors, one of which is teak leaves. Teak leaves are one part of the teak tree which can be used as a source of natural dyes for textiles by extracting the leaves. This research was conducted to obtain color powder from extracts of dyes from fresh teak leaves using the foam-mat drying method. This study was prepared to study the effect of citric acid addition on color intensity and the addition of chicken egg white to moisture content and solubility of color powder of teak leaf extract. To achieve this goal, in this study used fresh teak leaves with 95% ethanol solvent mass. At the beginning of the process, 25 grams of teak leaves are mashed first, then put into a beaker glass and macerated using a 95% ethanol mass of 250 ml and added 10 ml of citric acid from the amount of solvent with a concentration varied for 24 hours. After that filtered, the filter was taken. Powder making was carried out by foam-mat drying method using chicken egg white as foaming and maltodextrin as filler. The filtrate was added with 8% b/v maltodextrin and chicken egg white with the concentration varied stirred in the mixer until homogeneous. Then the oven is dried at a temperature of 60oC until a constant weight is reached. Using 25 grams of fresh teak leaves, 95% ethanol solvent as much as 250 ml, and 8% b/v maltodextrin obtained optimal conditions at 5% b/v egg white concentration and 30% b/v citric acid concentration, with these conditions obtained the powder results with a moisture content of 8% mass, solubility of 99.22% b/v with a reddish level of 16,625, a brightness level of 43,495, and a yellowish level of 5,925. It is hoped that this research can be used as a reference for the development of further research on anthocyanin dye powder which will then be developed as a raw material for dyes for the chemical industry, and textile industry.

Facile and green preparation of hemicellulose-based film with elevated hydrophobicity via cross-linking with citric acid.

Hemicellulose has shown great potential in food packaging due to its excellent biodegradability and low oxygen permeability. However, its strong hydrophilicity leads to poor moisture resistance and hinders its wide application. To address this issue, herein a ternary carboxylic acid, citric acid (CA), was incorporated into hemicellulose as esterifying agent to form a crosslinking structure via the esterification reaction. The CA-modified hemicellulose films showed an increased contact angle of 87.5° (vs. 40.5° for unmodified film), demonstrating that the hydrophobicity of hemicellulose had been improved significantly. In addition, the esterification/cross-linking modification enhanced oxygen barrier performance with oxygen permeability decreasing from 1053 (cm3 μm) (m2 d kPa)−1 to 1.8 (cm3 μm) (m2 d kPa)−1. Moreover, the tensile strength rose to a peak value and then fell back at higher CA content. Effect of CA addition on elongation at break exhibited an opposite trend. The modified hemicellulose films with 20% CA addition possessed the highest tensile strength and the lowest elongation at break. Morphology observation with scanning electron microscopy indicated that at CA content exceeding 20%, the modified films were dense with a smooth surface, illustrating the improvement of phase compatibility. A possible mechanism for esterification/cross-linking was proposed to elucidate the connection between CA addition and film performances.

Effect of Citric Acid Addition at Anthocyanin Solubility of Red Color Melinjo Peels in Solvent Ethanol, Hehane and Petroleum Ether

The result from a research by Ermiziar, et al(2009) shows that the content of anthocyanin pigment in red colour melinjo peels with ethanol solvent is 10.87 %. Anthocyanin structure which consists of Aromatic Hydrocarbons (Benzene) and the R groups that contain OCH3 is a reason why anthocyanin can also be isolated with non-polar solvents. Nevertheless, the acid environment would be desirable to get more contains of anthocyanin and it can be more stable so it can be used as natural dyes. The research objectives are to isolate anthocyanin pigments using, Etanol, hexane solvent and Petroleum Ether (PE) and to determine the effect of using the citric acid 0.5% to the anthocyanin pigments which are produced by this research. The types of solvent that are used in this research are Etanol, Hexane and PE. The slices melinjo peels are macerated using etanol, hexane and PE, respectively for 24 hours and the separation of the solvent by means of rotary evaporator.The results were obtained the concentration of anthocyanin with ethanol solvent was 1200 ppm, hexane solvent was 0.864 ppm and PE solvent was 0.800 ppm by the addition of citric acid. Without the addition of citric acid,anthocyanin concentration was ethanolsolvent was 4.000 ppm, hexane solvent was 0.634 ppm and PE solvent was 0.415 ppm

Effect of citric acid addition on the morphology and activity of Ni2P supported on mesoporous zeolite ZSM-5 for the hydrogenation of 4,6-DMDBT and phenanthrene

Preparing small, highly dispersed Ni2P particles is important for improving the hydrogenation ability of Ni2P. Here, Ni2P nanoparticles (approximately 4.3nm) on mesoporous zeolite ZSM-5 (Ni2P/MZSM-5-CA) were prepared using citric acid (CA) as an assistant agent. The formation mechanism of small Ni2P particles when CA was added was investigated by combining UV–vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and temperature-programmed reduction with a transmission electron microscope and CO chemisorption. The results indicated that the formed CA–Ni complex with high viscosity favors the Ni precursor dispersed on the dried catalyst. After calcination, the released Ni species strongly interacted with surface acidic hydroxyl groups on MZSM-5, leading to the formation of Ni2P particles with small sizes and good dispersion under a reducing atmosphere. The reaction rate constants and TOFs over Ni2P/MZSM-5-CA (16.2×10−2μmolg−1s−1 and 9.7×10−4s−1) are much higher than over Ni2P/MZSM-5 (8.2×10−2μmolg−1s−1 and 8.3×10−4s−1) in 4,6-dimethyldibenzothiophene hydrodesulfurization. In addition, Ni2P/MZSM-5-CA catalyst shows higher activity than Ni2P catalyst without CA in phenanthrene hydrogenation.

Effect of citric acid addition on MoO3/CeO2-Al2O3 catalyst for sulfur-resistant methanation

Citric acid hold great promise to improve the Mo-based catalyst performance for hydrogenation reaction applications. MoO3/CeO2-Al2O3 catalysts were prepared by impregnation method with adding citric acid into CeO2-Al2O3 composite supports and tested for sulfur resistant methanation. The syngas methanation activity increased with the increase of citric acid additive amount, and CO conversion could reach up 60% when the molar ratio of citric acid to Ce was 3. The prepared catalysts were characterized by BET, H2-TPR, XRD and XPS. The increased catalytic performance was mainly attributed to the increased amount of Ce species on the surface of catalysts which could decreased the interaction force between MoO3 and CeO2-Al2O3 supports. Additionally, the increased specific surface of CeO2-Al2O3 composite support was also in favor of catalytic performance.

Degradation of naproxen by ferrous ion-activated hydrogen peroxide, persulfate and combined hydrogen peroxide/persulfate processes: The effect of citric acid addition

Naproxen (NPX), a widely used non-steroidal anti-inflammatory drug, has been detected extensively in different environmental systems at concentrations ranging from ng/L to μg/L, which may have a detrimental effect on human health and natural ecosystems. In this study, the degradation of NPX by citric acid (CA) chelated ferrous ion-activated hydrogen peroxide, persulfate and an innovative combined hydrogen peroxide/persulfate system was evaluated. The addition of CA at an appropriate complexation ratio considerably improved the target compound decomposition by the applied systems. Among the studied processes, the S2O82−/Fe2+/CA system showed the highest performance in NPX degradation at a wide range of pH followed by the combined H2O2/S2O82−/Fe2+/CA process. Limited elimination of non-purgeable organic carbon (NPOC) was observed during the mineralization of NPX by the examined systems. The results of radicals scavenging experiments indicated that both HO and SO4− contributed to the overall oxidation performance in the activated S2O82− and H2O2/S2O82− systems, but the former was the principal radical in the combined process. Transformation products (TPs) were identified using LC––MS analysis in the CA-Fe2+-activated systems. Potential NPX degradation mechanism was subsequently proposed revealing hydroxylation with the subsequent decarboxylation or demethoxylation as the main step of the TPs formation. The findings of this study strongly suggest that the CA-Fe2+-activated S2O82− and combined H2O2/S2O82− oxidation are promising treatment technologies for the abatement of NPX pollution in natural aqueous matrices.

クエン酸添加が魚味噌熟成中のヒスタミン蓄積と呈味成分に与える影響

クエン酸添加が魚味噌熟成中のヒスタミン蓄積と呈味成分に与える影響

Effect of Citric Acid Addition upon the Precipitation Process on the Nanostructural Characteristics of ZnO Nanoparticles

Effect of Citric Acid Addition upon the Precipitation Process on the Nanostructural Characteristics of ZnO Nanoparticles

Effect of Citric Acid Addition upon the Precipitation Process on the Nanostructural Characteristics of ZnO Nanoparticles

Effect of Citric Acid Addition upon the Precipitation Process on the Nanostructural Characteristics of ZnO Nanoparticles

Effect of citric acid addition on disaggregation of crystalline hydroxyapatite nanoparticles under calcium-rich conditions

The effect of citric acid (CA) addition on the disaggregation of crystalline hydroxyapatite (HAp) nanoparticles under calcium-rich conditions was investigated in this study. HAp nanoparticles were prepared by a wet chemical precipitation process under calcium-rich conditions, which included an excess amount of calcium ions compared with the stoichiometric Ca/P molar ratio of HAp, with added CA. The formation of calcium citrate under calcium-rich conditions was highly effective for inhibiting the aggregation of nanosize HAp primary particles, and thus highly crystalline and disaggregated HAp nanoparticles were obtained.

Effect of citric acid addition on the hydrodesulfurization activity of MoO 3/Al 2O 3 catalysts

A series of MoO 3/Al 2O 3 catalysts was prepared using citric acid (CA) as a chelating agent by a simultaneous impregnation method or by a post-treatment method. The catalyst was tested for the HDS of thiophene. The catalysts were characterized by means of LRS, XRD, Mo K-edge EXAFS and XANES, NO adsorption capacity, and surface area measurements. The catalysts were also subjected to a chemical vapor deposition (CVD) technique using Co(CO) 3NO as a precursor of Co to prepare CVD-Co/MoS 2 catalysts. The addition of citric acid to 8.7 wt% Mo/Al 2O 3 increased neither the HDS activity nor the edge dispersion of MoS 2 particles. On the other hand, the addition of citric acid by the post-treatment to MoO 3/Al 2O 3 catalysts having a higher Mo content (>20 wt% Mo) significantly enhanced the edge dispersion of MoS 2 particles and thus the catalytic activity of MoS 2/Al 2O 3 and CVD-Co/MoS 2/Al 2O 3. The addition of citric acid by the post-treatment resulted in the formation of well-dispersed Mo species on the catalyst surface at the expense of crystalline MoO 3. The Mo K-edge XAFS and XANES showed that the sulfidation degree of Mo is greatly improved by the addition of citric acid at a high Mo content regardless of the addition procedure.

Effect of Citric Acid Addition on Co−Mo/B2O3/Al2O3Catalysts Prepared by a Post-Treatment Method

Co−Mo/B2O3/Al2O3 catalysts were prepared by a post-treatment of the calcined states with citric acid (CA) and were tested for the hydrodesulfurization (HDS) reaction of thiophene. The catalysts were characterized by LRS, UV−visible spectroscopy, Mo K-edge EXAFS, TEM, NO adsorption capacity, and surface area measurements. Catalysts obtained by simultaneous impregnation with citric acid were also prepared for comparison. Sulfided catalysts were characterized by a chemical vapor deposition (CVD) technique using Co(CO)3NO. The addition of citric acid in a post-treatment more effectively increased the catalytic activity and NO adsorption capacity than did addition by a simultaneous-impregnation method. Co-CA and Mo-CA surface complexes formed at the expense of CoMoO4 and polymolybdates. The maximum potential activity of Co−Mo/B2O3/Al2O3 was obtained by a simple post-treatment of the calcined catalyst with citric acid.

Preparation of Co–Mo/B 2O 3/Al 2O 3 catalysts for hydrodesulfurization: Effect of citric acid addition

The effect of citric acid (CA) addition was studied on the HDS of thiophene over Co–Mo/(B)/Al 2O 3 catalysts. The catalysts were characterized by means of LRS, Mo K-edge EXAFS, NO adsorption capacity measurements, and UV–vis spectra. The catalysts were subjected to a chemical vapor deposition (CVD) technique using Co(CO) 3NO as a precursor of Co in order to get deeper insights into the effect of citric acid addition. It was shown that the HDS activity was enhanced by the citric acid addition up to the CA/Mo mole ratio of around 1 and leveled off with further addition. The amount of Co anchored by the CVD was increased by the addition of citric acid, suggesting an increase in the dispersion of MoS 2 particles on the catalyst by the simultaneous presence of Co, Mo and citric acid, in conformity with the increase in the NO adsorption capacity. In contrast to Co–Mo catalysts, the edge dispersion of MoS 2 particles in Mo/B/Al 2O 3 was not affected by the addition of citric acid. The LRS, UV–vis spectra and Mo K-edge EXAFS showed that Co–CA and Mo–CA surface complexes are formed by the addition of citric acid. The Co–CA surface complex is more preferentially formed on CoMo/Al than on CoMo/B/Al, in agreement with a greater promoting effect of citric acid at a lower CA/Mo mole ratio for CoMo/Al than for CoMo/B/Al.

Co-Mo/(B)/Al2O3触媒のPost-treatment法によるクエン酸添加効果

Co-Mo/(B)/Al2O3触媒のPost-treatment法によるクエン酸添加効果

Improved iron bioavailability in an oat-based beverage: the combined effect of citric acid addition, dephytinization and iron supplementation

Iron deficiency in children is a major worldwide nutritional problem. An oat beverage was developed for 1- to 3-year-old children and different treatments were used to improve the iron bioavailability. To investigate the effects of citric acid addition, phytase treatment and supplementation with different iron compounds on non-heme iron absorption in human from a mineral-supplemented oat-based beverage. A 240 g portion of a 55Fe-labeled test product (T) or a 59Fe-labeled reference dose (R) was served as breakfast after overnight fasting on four consecutive days in the order of TRRT. On day 18 the retention of 59Fe was measured by a whole-body counter and the erythrocytes uptake of 55Fe and 59Fe by a liquid-scintillation counter. Forty-two healthy subjects (men and women) were randomized into four study groups, members of each being given one of the studied four products (A, B, C, and D) supplemented with Fe (1.3 mg/portion), Zn, Ca, Se and P. Ferric ammonium citrate (FeAC) was added to products A, B, and C and ferric pyrophosphate (FePP) to product D. Citric acid (60 mg/portion) was added to products B, C, and D and phytase treatment applied to products C and D. Citric acid improved iron absorption by 54% from 3.9% in product A to 6.0% in product B (p = 0.051). Phytase treatment increased iron absorption by 78% (from 6.0 to 10.7%, p = 0.003) by reducing the phytate-phosphorus content per portion from 16.3 mg in product B to 2.8 mg in product C. The two compounds gave similar iron absorption rates (p = 0.916). A combination of citric acid addition, dephytinization and iron supplementation significantly increased the iron absorption in an oat-based beverage. Such a beverage can be useful in the prevention of iron deficiency in 1- to 3-year-old children.

Mullite-zirconia composites: Effect of citric acid addition on slip and cast properties

Dispersion of mixed suspensions of zircon and α -alumina using citric acid as dispersant followed by pressure filtration produced after sintering (1600∘C—2 h) dense mullite-zirconia composites. The effect of citric acid addition and pH on the rheological behavior of the mixed suspensions (57 vol%) was examined. Most of flow curves showed a shear thinning behavior at low shear rates reaching the viscosity a plateau at high shear rates. Newtonian viscosity at high shear rates values decreased to a minimum and then increased with increasing the amount of dispersant added. Compacts prepared from well stabilized suspensions achieved a maximum relative density of 72% (theoretical) which is slightly higher than that obtained from suspensions dispersed with a polyelectrolyte. Characteristics of sintered compacts such as density and crystalline phase composition by XRD were determined.