Various Concentrations Of Citric Acid Research Articles

Facile combustion-synthesis, structural, morphological, vibrational, photoluminescence, dielectric, and electrical properties of ZnFe2O4 nanostructures: an effect of citric acid concentrations

In the current report, we have facilely synthesized the ZnFe2O4 nanoparticles (ZFO NPs) using the flash combustion route at 600 °C with various concentrations of citric acid (CA). The structural, vibrational, and elemental/homogeneity analyses through XRD, Raman, and energy dispersive X-ray spectroscopy/Scanning electron microscopy e-mapping confirmed the cubic phase and composition of synthesized ZFO NPs. The crystallite size was estimated using Scherrer and Williamson-Hall plot methods and noticed to be reduced with an increasing amount of CA in ZFO and found between 15 and 30 nm, which was also supported by scanning electron and transmission electron microscopic studies. X-ray photoelectron spectroscopy analysis confirmed the synthesis of ZnFe2O4. The ZFO NPs were excited at 417 nm to record the luminescence spectra and found the emission peaks at 456±2, 530±3, and 625±5 nm. The dielectric constant was found to be between 147 and 165 with low loss values, and the electrical conductivity was found to be enhanced with CA content in ZFO NPs. The magnetic properties were also studied at 300 K and disused. These outcomes indicate that the properties of ZFO NPs have been greatly influenced by crystallite/grain size variation, which resulted from different CA concentration-assisted synthesis of ZFO and possess the potential for optoelectronic and energy storage devices.

Tensile Strength Improvements of Ramie Fiber Threads through Combination of Citric Acid and Sodium Hypophosphite Cross-Linking

Ramie (Boehmeria nivea) is believed to be one of the strongest natural fibers, but it still remains behind synthetic materials in terms of tensile strength. In this study, ramie materials were prepared to evaluate the modification crosslinking effect of natural fiber. The aim is to optimize various concentrations of citric acid (CA) crosslinking by adding Sodium hypophosphite (NaPO2H2), which is activated at different temperatures, to obtain the highest tensile mechanical strength. This crosslinking effect has been confirmed by FTIR to show the esterification process in the molecular structure of cellulose. The changes in the character of the fiber surface were analyzed by SEM. The tensile strength increased from 62.33 MPa for 0% CA to 124–172.86 MPa for decorticated fiber with a CA concentration of 0.75–1.875% (w/w). A significant increase in tensile strength was observed more than 19 times when CA/SHP 1% was treated at an activation temperature of 110 °C with a superior tensile strength of 1290.63. The fiber crosslinked with CA/SHP should be recommended for application of Natural Fiber Reinforced Polymer Composite (NFRPC), which has the potential to use in functional textile and industrial sector automotive or construction.

Student explorations of calcium alginate bead formation by varying pH and concentration of acidic beverage juices

Abstract Teaching experiments involving edible, biodegradable calcium alginate beads serve as an attractive model system to introduce upper secondary age students to core chemistry topics through innovations in sustainable consumer products. A teaching experiment is described that engages students with the synthesis of calcium alginate hydrogel beads from sodium alginate and calcium lactate, two food-safe and renewable materials. The beads’ outer membranes are a result of ionic interactions between carboxylate groups from alginate strands and the divalent calcium cations between them, thus forming cross-linked polymers. Protonation of the carboxylate groups on the alginate strands decreases crosslinking density affecting bead formation. First, various concentrations of citric acid are used to lower the pH of the sodium alginate solution and the effect on the calcium alginate bead formation is observed. A correlation between pH and bead shape and firmness is derived. This information is then used to explore juices with varying natural acidities. The experiment is amenable to implementation in the classroom or as an at-home activity. Learning outcomes include acid-base reactions, chemical bonding, polymer structures, and green chemistry concepts. Students consider the environmental challenges of traditional plastics used in packaging and how innovative new commercial products are attempting to provide solutions.

Synthesis and Characterization of Carboxy Methyl Cellulose-Based Hydrogel Cross-linked with Citric Acid

Hydrogel is a three-dimensional hydrophilic polymer network which is capable of absorbing large amounts of water, urine, blood, and other biological fluids. The applications of hydrogel are present in various fields such as pharmaceuticals, agriculture, food, and medical fields. Hydrogel is used as a wound dressing, in a drug release system, in diapers, in and menstrual products. The purpose of this research is to produce carboxymethyl cellulose (NaCMC) hydrogels using citric acid as the crosslinking agent, and to determine the optimum conditions to produce hydrogels with a high absorption capacity of liquids using various concentrations of citric acid. The first step of this research is to mix NaCMC and citric acid by stirring it with an agitator at room temperature until the mixture becomes homogeneous. Then, the mixture is casted in a petri dish and dried for 24 hours at 30°C. Then, the crosslinking reaction was carried out at 80°C for a certain time. After that, the gels are put out of the petri dish and tested to determine their values of water absorption capacity (swelling) and gel fractions. Lastly, the hydrogels are characterized using FTIR and SEM. The results showed that the NaCMC hydrogel with anhydrous citric acid with 10%-wt is the best with 3779.16% swelling ratio and gel fraction of 60%.

Physicochemical Properties for Food Packaging and Toxicity Behaviors Against Healthy Cells of Environmentally Friendly Biocompatible Starch/Citric Acid/Polyvinyl Alcohol Biocomposite Films

AbstractThe current study focuses on the fabrication, characterization, and cytotoxic effects of polymeric biocomposite films composed of starch, various concentrations of citric acid (3%, 6%, and 9%), and polyvinyl alcohol. The cross‐linked corn starch (S)‐polyvinyl alcohol (P) biocomposite films are prepared by casting technique using glucose (G) and fructose (F) as plasticizers. The chemical structure of obtained films is characterized by Fourier transform infrared and x‐ray diffraction. Physicochemical parameters of the films such as solubility, swelling capacity, and water vapor permeability, optical and mechanical properties are investigated. Furthermore, the cytotoxicity is evaluated to determine the biocompatibility of samples. The physicochemical properties of S‐P(Starch‐Polyvinyl alcohol) films improve with the addition of citric acid during the esterification reaction. The tensile strength for Starch‐Polyvinyl alcohol‐Glucose blend composition with 3% citric acid (SPG3) and Starch‐Polyvinyl alcohol‐Fructose blend composition with 3% citric acid (SFG3) biocomposite films is determined as 10.17 and 8.24 MPa, respectively, compared to 8.16 and 7.94 MPa for without citric acid, respectively. The cell viability values of biocomposite films towards NIH‐3T3 and L929 cells are calculated 90% compared to the control group. Thus, it demonstrates that they are also quite biocompatible materials.

Smear Layer Removal from Root Canal Dentin and Antimicrobial Effect of Citric Acid-modified Chlorhexidine.

Objective:To study the effectiveness of various concentrations of citric acid (CA) added to 2% chlorhexidine (CHX) on smear layer removal from the root canal wall and antimicrobial efficacy against Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans).Methods:Fifty-three single-rooted mandibular premolars were decoronate and the root canals underwent mechanical instrumentation using MTwo rotary files to size 40/0.06. The samples were then randomly divided into 5 groups according to the root canal irrigants to be used: 17% ethylenediaminetetraacetic acid (EDTA), 2% CHX, 1%, 6%, and 10% citric acid-modified 2% chlorhexidine (CAmCHX). Three teeth irrigated with phosphate-buffered saline (PBS) were used as a negative control. The smear layer removal effectiveness was evaluated under scanning electron microscopy (SEM). Images were randomly taken at the apical, middle, and coronal third level. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests. Disc diffusion and direct exposure tests were performed along with three additional control groups consisting of 1%, 6%, and 10% CA groups to assess and compare the antimicrobial efficacy of irrigants against E. faecalis and C. albicans. Statistical analysis was conducted using one-way ANOVA and Dunnett’s T3 tests.Results:Smear layer removal effectiveness in 17% EDTA group and 6% and 10% CAmCHX groups were not significantly different in the coronal and apical third of the root canal (P>0.05), however at the middle third of the root canal, the 10% CAmCHX group had significantly less remaining smear layer than all of the other experimental groups (P<0.05). There was significantly more smear layer remnant in the CHX group (P<0.01). For antimicrobial efficacy, the largest growth inhibition zone against E. faecalis was recorded in the 10% CAmCHX group (P<0.05). For planktonic E. faecalis, 1%, 6%, and 10% CAmCHX demonstrated an insignificant difference in antimicrobial efficacy compared to CHX (P>0.05). CA demonstrated no antifungal effect against C. albicans. Whereas, 6% and 10% CAmCHX resulted in the largest growth inhibition zone. Also, adding CA to CHX resulted in an insignificant difference in antifungal effect against planktonic C. albicans compared to CHX (P>0.05).Conclusion:When CA was added into CHX, the mixed irrigant demonstrated smear layer removal ability. Additionally, its antimicrobial effect remained the same.

Citric acid decreased and humic acid increased Zn sorption in soils

Zinc (Zn) is the most limiting nutrient for plant growth in calcareous soils and its availability is controlled by both the solid and solution phase characteristics of the soil. Organic acid anions in soil solution may influence Zn sorption by soil particles and thus its availability. To evaluate the influence of humic and citric acids on sorption of Zn, batch technique was used with various concentrations of citric acid (CA) (0, 0.5 and 1mmolL−1) and humic acid (HA) (0, 200 and 500mgL−1) in three soils differing in clay and calcium carbonate contents. A range of Zn concentrations (0 to 450mgL−1) were applied at constant ionic strength (0.05molL−1 NaCl). The sorption data were fitted to Langmuir, Freundlich and Temkin models. All sorption parameters, including maximum sorption in Langmuir equation (qmax), Freundlich capacity and intensity factors (KF, n), and coefficients in Temkin equation (A, KT) increased in the HA treatments and decreased in the CA treatments. Humic acid increased Freundlich sorption capacity (KF) by 73–95%, whereas CA decreased it by 52–68%. It is concluded that CA could significantly reduce Zn sorption by soil particles, probably through formation of soluble CA-Zn complexes, but HA increased Zn sorption and decreased its mobility probably due to increased number of exchangeable sites and formation of insoluble soil-HA-Zn complexes.

Effect of Citric Acid on Prolonging the Half-life of Dissolved Ozone in Water.

To elucidate the effect of citric acid on the stability of dissolved ozone, half-lives of ozone in a citric acid solution was investigated. Prolongation of the half-life of ozone was clearly shown in the presence of citric acid in ozonized water. In the presence of ethylenediaminetetraacetic acid (EDTA), the half-life of ozone was decreased. The addition of various concentrations of citric acid to the EDTA solution, however, reversed the half-life in a concentration-dependent manner. These indicate that citric acid suppresses ozone self-decomposition in water. A citric acid-mediated suppression mechanism of ozone self-decomposition involving hydroxy radical (HO•) was proposed as follows: HO• formed by the radical chain reaction process of ozone is scavenged by a way of abstracting the hydrogen atom bound to a carbon atom located α-position of a carbonyl group. The radical chain reaction of ozone is, thus, suppressed. These findings demonstrate that the addition of citric acid to ozonized water is useful for the stabilization of ozone. This ability may contribute to the application of ozone sterilization in food production processes.

Effect of citric acid, calcium lactate and low temperature prefreezing treatment on the quality of frozen strawberry

Texture degradation and color fading of frozen strawberries consider to be a serious problem affect their quality. Therefore, in the present study the fresh strawberry immersed in various concentrations of citric acid and calcium lactate alone or in combination for 5min. and kept at low temperature (5°C) for overnight before freezing or frozen directly for controlling these defects. The obtained results declared that pretreatment with citric acid dip obviously enhanced the retention of ascorbic acid and total anthocyanins content and lowered the browning index while Calcium lactate maintained the texture by reducing the drip loss and increasing the firmness after thawing. The precooling treatment did not show any enhancer affect in the quality indices of frozen berries. Compared to the other treatments, the use of 0.4% citric acid – 1% Ca lactate combination dip achieved better quality attributes, including reduction in drip loss and enhancement of firmness, retention of ascorbic acid and anthocyanin content in addition to improving in color attributes.

Fabrication of Micrometer-Scale Self-Organized Pore Arrays in Anodic Alumina

We demonstrate the fabrication of self-organized ordered porous anodic alumina (PAA) with pore spacing in the micrometer range using a solution of citric acid. More specifically, we have fabricated PAA samples with regular pore spacings of 970 nm, 1070 nm, 1260 nm and 1420 nm, respectively. While pore spacing is expected to be proportional to the anodization voltage, the proportionality factor observed here (1.94 nm/V) is slightly lower than that reported in the literature (∼2.5 nm/V). These results were obtained following a careful characterization of the burning voltages of aluminum for various concentrations of citric acid. Voltage limits of 300 V, 370 V and 425 V for concentrations of 4%, 2% and 0,5%, respectively, have been established. We also established that the maximum anodization voltage in pure citric acid at very low concentration (0.05%) is in the range of 540 V. Beyond this voltage, breakdown of the alumina barrier occurs. We discuss the phenomenon of aluminum burning, which occurs when anodizing at voltages too high for a given acid concentration. We also show that high voltage anodization produces less compact PAA than lower voltage ones, and that it is increasingly difficult to obtain a thick PAA as the anodization voltage increases.

Kinetic Analysis of Strains of Lactic Acid Bacteria and Acetic Acid Bacteria in Cocoa Pulp Simulation Media toward Development of a Starter Culture for Cocoa Bean Fermentation

The composition of cocoa pulp simulation media (PSM) was optimized with species-specific strains of lactic acid bacteria (PSM-LAB) and acetic acid bacteria (PSM-AAB). Also, laboratory fermentations were carried out in PSM to investigate growth and metabolite production of strains of Lactobacillus plantarum and Lactobacillus fermentum and of Acetobacter pasteurianus isolated from Ghanaian cocoa bean heap fermentations, in view of the development of a defined starter culture. In a first step, a selection of strains was made out of a pool of strains of these LAB and AAB species, obtained from previous studies, based on their fermentation kinetics in PSM. Also, various concentrations of citric acid in the presence of glucose and/or fructose (PSM-LAB) and of lactic acid in the presence of ethanol (PSM-AAB) were tested. These data could explain the competitiveness of particular cocoa-specific strains, namely, L. plantarum 80 (homolactic and acid tolerant), L. fermentum 222 (heterolactic, citric acid fermenting, mannitol producing, and less acid tolerant), and A. pasteurianus 386B (ethanol and lactic acid oxidizing, acetic acid overoxidizing, acid tolerant, and moderately heat tolerant), during the natural cocoa bean fermentation process. For instance, it turned out that the capacity to use citric acid, which was exhibited by L. fermentum 222, is of the utmost importance. Also, the formation of mannitol was dependent not only on the LAB strain but also on environmental conditions. A mixture of L. plantarum 80, L. fermentum 222, and A. pasteurianus 386B can now be considered a mixed-strain starter culture for better controlled and more reliable cocoa bean fermentation processes.

Salivary Expression of Taste Response to Chemical Stimulation

The salivary response to application of various concentrations of citric acid to the tongue was examined in 17 individuals. Responses were reproducible and did not appear to alter with the passage of time. The relation between response and stimulant concentration was formally described by Michaelis-Menten kinetics. The technique could be extended to the study of various stimulants and used to explore the mechanism of taste perception in man.