Citric Acid Water Research Articles

Role of acidic hydrochar on dechlorination of waste PVC in high temperature hydrothermal treatment and fuel properties enhancement of solid residues

In this study, the chlorine mitigation from waste polyvinyl chloride (WPVC) during high temperature co-hydrothermal treatment (co-HTT) and the properties of the generated solid products were assessed. WPVC was co-fed with acidic hydrochar (AHC), which was produced via hydrothermal carbonization of pineapple waste in the presence of citric acid water solution. High temperature co-HTT experiments were performed at 300–350 °C, 0.25–4 h of reaction time, and 0–20 wt% AHC loading. Co-HTT solid products (co-HTT_SP) were characterized via proximate analysis, ultimate analyses, combustion analysis, and ash analysis. The results show that the addition of 5% AHC enhances the dechlorination efficiency (DE) of WPVC from 89.35% to 97.66% at 325 °C and 0.5 h. The highest DE, reaching 99.46%, was achieved at 350 °C and 1 h in the presence of 5 wt% AHC. Furthermore, loading 5% AHC improved the higher heat value (HHV) of the solid products from 23.09 to 31.25 MJ/kg at 325 °C and 0.5 h. The maximum HHV (34.77 MJ/kg) of a solid product was achieved at 350 °C, 4 h, in the presence of 5 wt% of AHC. The co-HTT solids shown low slagging indices, fouling indices, alkali indices, and medium chlorine contents. These findings support the viability of WPVC conversion into clean solid fuel via co-HTT.

Purification of Curcuminoids from Natural Deep Eutectic Solvents (NADES) Matrices Using Chromatography-Based Separation Methods

Curcuminoids can be successfully extracted from Curcuma zedoaria using natural deep eutectic solvents (NADES) as extraction solvents. However, a mixture of extracted curcuminoids, NADES, and impurities from C. zedoaria was obtained as a slurry at the end of the extraction process. Therefore, further separation and purification were required to obtain the extracted compound in high purity. Herein, two purification methods based on classical column chromatography (CCC) and solid-phase extraction (SPE), were evaluated for the purification of curcuminoids from NADES matrices after extraction. Choline chloride–malic acid–water (CCMA–H2O) and choline chloride–citric acid–water (CCCA–H2O) in the molar ratio of 1:1:18 were selected as NADES matrices due to their high solubility and stabilization capability for curcuminoids. Ethanol-conditioned silica gel (60–200 µm) was applied as the bed resin for CCC, and a C18 cartridge was used for SPE. Acetonitrile/0.1% acetic acid, water/0.1% acetic acid, and iso-propanol/0.1% acetic acid were used as mobile phases for CCC. For SPE, methanol/0.05% acetic acid and water/0.05% acetic acid were applied in the conditioning step, water/0.05% acetic acid in the washing step, and methanol/acetonitrile (1:1) in the eluting step. The SPE method produced higher recovery of curcuminoids from the CCCA–H2O and CCMA–H2O matrices (75.27% and 73.40%, respectively) compared to CCC (51.9% and 61.0%, respectively). After removing the NADES constituents from the crude extract of curcuminoids, recrystallization was attempted.

Citric Acid Water as an Alternative to Water Restriction for High-Yield Mouse Behavior.

Powerful neural measurement and perturbation tools have positioned mice as an ideal species for probing the neural circuit mechanisms of cognition. Crucial to this success is the ability to motivate animals to perform specific behaviors. One successful strategy is to restrict their water intake, rewarding them with water during a behavioral task. However, water restriction requires rigorous monitoring of animals’ health and hydration status and can be challenging for some mice. We present an alternative that allows mice more control over their water intake: free home-cage access to water, made slightly sour by a small amount of citric acid (CA). In a previous study, rats with free access to CA water readily performed a behavioral task for water rewards, although completing fewer trials than under water restriction (Reinagel, 2018). We here extend this approach to mice and confirm its robustness across multiple laboratories. Mice reduced their intake of CA water while maintaining healthy weights. Continuous home-cage access to CA water only subtly impacted their willingness to perform a decision-making task, in which they were rewarded with sweetened water. When free CA water was used instead of water restriction only on weekends, learning and decision-making behavior were unaffected. CA water is thus a promising alternative to water restriction, allowing animals more control over their water intake without interfering with behavioral performance.

Evaluation of physicochemical properties of anthocyanin extracts and powders from purple sweet potato (Ipomoea batatas L.)

Purple sweet potato (Ipomoea batatas L.) is one of the food commodities that contain anthocyanin. This research aimed to evaluate the physicochemical properties of anthocyanin extracts and powders from purple sweet potato. Purple sweet potato anthocyanin was extracted using a water solvent with the addition of citric acid in different concentrations (0, 2, 4, and 6 g/100 mL). Ethanol solvent was used as a control. Foam mat drying was performed using variations of egg white composition (10 and 20 mg/100 mL). The result showed that extraction using a water solvent with 2 g/100 mL of citric acid was the most effective condition to obtain the highest total anthocyanin content (p < 0.05). However, its total phenolic, flavonoid, and antioxidant activity were lower compared to others. Total anthocyanin content of foam mat dried purple sweet potato powder made from the citric acid-water extract was significantly higher than the powder made from the citric acid-ethanol extract (p < 0.05). There was no effect in the total phenolic, flavonoid, viscosity, and yellowish-red color of the powder obtained from citric acid-water extract as the increase of egg white concentration. The use of 20 g/100 mL egg white in both powders produced from citric acid-water and ethanol extracts resulted in higher total anthocyanins and solubilities than powders using 10 g/100 mL egg white. The color of the powder obtained from citric acid-water extract had a lower brightness level and higher yellowish-red color intensity compared to the powder made from citric acidethanol extract.

Optogenetic stimulation of respiratory related neurons modulates swallow and swallow‐breathing coordination

Swallow and breathing are tightly coordinated behaviors in which disruption of this coordination leads to aspiration pneumonia, the leading cause of death in many adult and pediatric diseases. Little is known about the neural coordination of these two behaviors. Previous work in the respiratory column has shown activity in swallow‐related and breathing‐related neurons, as well as neurons active during both swallow and breathing, suggesting coordination at a central network level. Evidence in the intermediate reticular nucleus (postinspiratory Complex, PiCo) suggest involvement in swallow behavior but not swallow‐breathing coordination. We hypothesize that swallow predominately occurs during the expiratory phase of breathing due to inspiratory related neurons suppressing swallow activity. Thus, inhibition of excitatory neurons within the Pre‐Bötzinger complex will increase swallow excitability, while exciting glutamatergic neurons within this network will have the opposite effect. To evaluate swallow circuitry and its coordination with respiratory related networks we use optogenetic approaches to manipulate the activity of inhibitory (Vgat‐Cre) and excitatory (Dbx1‐ERT2Cre, Vglut2‐Cre) neuron populations within the ventral respiratory centers as well as modulation of PiCo (ChAT‐Cre) in the presence of light stimulation. Optogenetic activation (blue laser, 447nm) of Dbx1 cells was performed in adult Dbx1‐ERT2Cre/Ai32(ChR2) mice after exposing the ventral surface of the brainstem in vivo, and placing bilateral glass fiber optics over the ventral surface in the region of the Pre‐Bötzinger complex. Swallow activity was measured by monopolar suction electrodes of the hypoglossal (XII) and vagus (X) nerves as well as cervical sympathetic nerve (cSNA). Phases of breathing was measured via monopolar electromyogram (EMG) of the diaphragm and swallow was stimulated orally by injection of 0.1cc of 2.5% citric acid water. Our preliminary data suggest that stimulating Dbx1 cells decreased the frequency and duration of swallows. Interestingly, we observed in the presence of light stimulation multiple swallow attempts (oral phase without the pharyngeal phase) resulting in hyoid elevation but failure to induce pharyngeal phase. The average swallow in the absence of light stimulation had a duration of 1025ms whereas swallow during light stimulation was 809ms. We believe that activation of Dbx1 neurons in the Pre‐Bötzinger complex suppresses swallow activity and decouples oral and pharyngeal phases of swallow.Support or Funding InformationNIH: P01 HL090554, R01 HL144801 and R01 HL126523

Citric acid-enhanced dissolution of polyphenols during soaking of different teas.

This study examined the dissolution kinetics and antioxidant activity of tea polyphenols during the soaking of white, yellow, green, oolong, black, and dark teas. All these teas were, respectively, soaked with either freshly boiled distilled water (DW) or 10mmol/L citric acid-water solution. The residue obtained from one extraction was used for the next extraction and this process was performed consecutively 10 times, soaking for 30s each time. UHPLC-QqQ-MS measurement identified epigallocatechin gallate as the major polyphenol in white, yellow, green, oolong, and black tea infusions. As soaking times increased, the polyphenol concentrations rose initially and then dropped. Antioxidant activity was noted to decrease as soaking times increased in all tea infusions except for the DW-soaked oolong and dark teas. These findings suggested that citric acid could increase the polyphenol content in tea infusions. Specifically, the cumulative contents of epigallocatechin gallate was noted to increase 2.1-5.1 times. PRACTICAL APPLICATIONS: After water, tea is one of the most consumed beverages in the world. Drinking tea has been linked to the reduced risk of various diseases, including cancer, cardiovascular system disease, obesity, and neurodegenerative diseases, largely due to its rich polyphenol content. Moreover, the addition of citrus to a tea infusion provides an interesting and feasible method for increasing the dissolution of tea polyphenols, a finding that offers extensive potential for applications in the development of compound tea drinks.

Recycling of Tea Waste: Simple and Effective Separation of Caffeine and Catechins by Microwave Assisted Extraction (MAE)

This study was designed to develop a cost effective green extraction method to separate valuable chemicals from black tea waste (BTW) and tea dust called “caffeine dust” (CD). These materials are totally unwanted residue and treated as rubbish. Two extraction methods were used for extraction of waste materials obtained in three collection periods. In conventional extraction method, material was subjected to hot water extraction at 80 o C for 40 minutes. In microwave assisted extraction (MAE) method, different eco-friendly aqueous solvents (water, citric acid-water or ethanol-water) were used under a controlled 600 W microwave power at 80 o C for only 4 minutes treatment in a close microwave system. MAE and conventional method gave similar extract yields for both waste materials but MAE was more successful and economical completing the extraction in shorter time. Using citric acid-water solvent in MAE significantly increased the extraction of individual catechins such as epicatechin (EC) and epigallocatechin gallate (EGCG). This study showed that tea waste could be utilized for production of valuable chemicals using nontoxic solvents at extremely short extraction periods.

New Approaches for Effective Microwave Assisted Extraction of Caffeine and Catechins from Green Tea

This study was designed to develop an effective microwave assisted extraction (MAE) method for extraction of caffeine and catechins from green tea samples. A series of solvents (water, ethanol:water mixture or citric acid:water mixture) were used for extraction of green tea samples (fresh, frozen or dried) collected in three collection periods (first, second and third collection periods). Tea samples were extracted using water in a close microwave system under the certain extraction conditions. Extraction was carried out under a controlled 600 W microwave power at 80 oC temperature for 4 min irradiation time. Alternative to water, an ethanol-water mixture (1:1) or a citric acid-water (1:1) mixture was used as extracting solvent under the same conditions. After MAE crude aqueous extract was partitioned first with chloroform to separate caffeine then ethyl acetate for catechins. Both caffeine and catechin extraction was quite successful with microwave assisted system employing only 4 minutes treatment. The highest caffeine yield was obtained in the second collection period using frozen green tea samples and ethanol-water as extracting solvent. The yield of catechin extracts was between 0.84-3.96% depending on the solvent system used for extraction. Ethanol-water mixture seems to be appropriate for effective extraction in the basis of extract yields. However, HPLC results showed that individual catechin content of each extraction is more important criteria for the evaluation of most effective extraction medium rather than the mass of the extract. Using citric acid as extracting solvent in MAE seem to be more fruitful providing 100% catechin mixture with the highest EGCG content.

Assessment of Titratable Acidity in Fruit Using Short Wave near Infrared Spectroscopy. Part A: Establishing a Detection Limit Based on Model Solutions

Spectra (700–2500 nm) of citric acid dissolved in water possess features interpreted as being due to the dilution and perturbation of water OH stretching and combination bands (with the second and first overtones of OH stretching at 960 nm and 1420 nm, respectively, and a combination band of OH vibration at 2132 nm) and also to citric acid OH stretching and combination bands and citric acid CH2 bands (first overtone of CH2 stretching at 1680 nm and a combination band of CH2 at 2284 nm). A searching window method was used to optimise the wavelength region for a partial least squares (PLS) regression model development (around 743–904 nm for the region below 1100 nm). Despite the apparent lack of information below 1100 nm, a PLS regression model based on transmission spectra (743–904 nm) of pure citric acid—water mixtures (standard deviation = 6.65g citric acid 100 mL−1) yielded a root mean square error of cross-validation ( RMSECV) of 0.34% and correlation coefficient of determination ( Rcv2) = 0.998. However, if the matrix was varied with 0, 10 and 13% sucrose or fruit juice, RMSECV increased to 0.79%. This RMSECV value is proposed as a benchmark for attempts to assess titratable acidity of juice based on shortwave (700–1100 nm) near infrared spectra of intact fruit collected using silicon diode array instrumentation.

Low-temperature synthesis of fine BaMgAl 10O 17:Eu 2+ phosphor based on the solubility isotherms

A homogeneous and stoichiometric BaMgAl 10O 17:Eu 2+ (BAM) phosphor powder has been prepared by the citrate route. Solubility isotherms have been calculated for metal–citric acid–water system at 25 °C to predict the optimum pH condition, which was found to be pH=7 for preparing pure and stable metal citrate complexes. Well crystallized and sub-micrometer-sized BAM particles could be obtained by thermal decomposition of the optimally prepared citrate precursor at a temperature as low as 1150 °C. Though the luminescent properties of the present samples under UV excitation well reflect the bulk properties, VUV excitation has exhibited the luminescent properties greatly influenced by the surface, which might be due to the fine particle. The maximum luminance of the samples heat treated at 1350 °C was 105% in comparison with that of the commercial BAM under VUV excitation.

Novel strategies for optimization of batch, semi-batch and heating/cooling evaporative crystallization

A novel optimization framework based on a stochastic optimization algorithm is proposed for optimizing batch, semi-batch and non-isothermal evaporative crystallizations. The mathematical models for these dynamic processes are highly non-linear and hence involve prominent non-convexities in the solution space of optimization. The framework not only significantly reduces the likelihood of being trapped into local optima and convergence problems in optimization and simulations, but also employs a novel and efficient algorithm for optimization of control profiles. A new concept in combining heating/cooling and evaporation in a batch crystallization operation is also proposed in this work. Optimization results of the citric acid–water system using this concept indicate that the maximum average crystal size obtainable is 19% and 27% larger than those attainable in the optimized unseeded evaporative and cooling operations respectively. The crystal size distribution is significantly narrower than that under seeded operations. Yield increase of more than 42% is also observed in this operating methodology. Optimization results for the batch and semi-batch evaporative crystallizations also demonstrate improvements that otherwise cannot be attained by using conventional approaches and heuristic rules.

Optimization of batch cooling crystallization

A novel framework has been proposed for optimizing batch cooling crystallization operation. The optimization strategy is effective for highly non-linear and dynamic mathematical systems such as batch cooling crystallization systems. The proposed framework can implement constrained multivariable optimization without the tendency of being trapped into local optima. Variables that can be optimized simultaneously include the cooling profile, seed size, mass of seeds, batch time, initial and final temperatures. Optimizations have been implemented on both seeded and unseeded processes of the citric acid–water system. The optimized operation leads to improvements that otherwise cannot be attained by using conventional approaches. Optimization results also suggest that seeding can increase the flexibility of the operation.

Analysis of Equilibrium Acid Distribution in the System of Citric Acid−Water−(Triisooctylamine + Methyl Isobutyl Ketone) Using a Quasi-Physical Approximation

Methods for predicting the equilibrium acid distribution in a reactive extraction system are proposed, and their accuracies have been tested by experimental data. Three mathematical models are formulated. The pseudo single-reaction model is derived from the idea of chemical theory of solution. Based on the theory, the equilibrium is strongly affected by chemical effects which are assumed as a single reaction with its stoichiometric coefficients as adjustable parameters. A great improvement is provided by the ideal quasi-physical approximation model which eliminates the uncertainty of the solvation reaction mechanism by postulating the chemical equilibrium in the form of physical equilibrium. The model is proven to well fit the experimental equilibrium data obtained from the system of citric acid-water-(triisoctylamine + methyl isobutyl ketone ) and gives a more flexible and relatively simpler equation of equilibrium acid distribution than the models which have been published previously. A modification made by taking the nonideality of solution into account further improves the data fitting of the ideal quasi-physical approximation model for a wider range of data. The effect of temperature on the model's parameters is also discussed.

The effect of gel composition on the uranyl ions adsorption capacity of poly(N-vinyl 2-pyrrolidone-g-citric acid) hydrogels prepared by gamma rays

Poly(N-vinyl 2-pyrrolidone-g-citric acid) (PVP-g-CA) hydrogels with varying compositions were prepared from ternary mixtures of N-vinyl 2-pyrrolidone–citric acid–water by using 60Co γ-rays. The effect of gel composition on the uranyl ions adsorption capacity of PVP-g-CA hydrogels was investigated. Uranyl adsorption capacity of these hydrogels were found to be in the range of 18–144 mg [UO]/g dry gel from the aqueous solution of uranyl nitrate and 22–156 mg [UO]/g dry gel from the aqueous solution of uranyl acetate, depending on the content of citric acid in the hydrogel, while poly(N-vinyl 2-pyrrolidone) hydrogel did not sorb any uranyl ion. The swelling of PVP-g-CA hydrogel containing 2.7 mol % CA was observed in water (1620%), in uranyl acetate solution (1450%) and in uranyl nitrate solution (1360%), as compared to 700% swelling of pure PVP hydrogels. The diffusion coefficients were varied from 12.57 up to 4.04 • 10−8 m2 s−1. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1037–1043, 2000

Citrate route to the piezoelectric Pb(Zr,Ti)O3 oxide

A homogeneous and stoichiometric Pb(Zr 1-x Ti x )O 3 (x=0.52; PZT) powder with a particle size of 20–40 nm has been prepared by the citrate route. Solubility isotherms have been calculated for metal–citric acid–water systems at 25 °C to predict the optimum pH condition, which was found to be pH=6.5 for preparing pure and stable citrate complexes. Monodispersive nanometer-sized particles could be obtained by thermal decomposition of the optimally prepared citrate precursor at a temperature as low as 800 °C. The crystallization process and particle characteristics of the citrate-derived PZT powder are described in detail along with the preliminary results on the sinterability and piezoelectricity.

ChemInform Abstract: THERMODYNAMIC PROPERTIES OF CITRIC ACID AND THE SYSTEM CITRIC ACID‐WATER

Chemischer InformationsdienstVolume 14, Issue 3 Article ChemInform Abstract: THERMODYNAMIC PROPERTIES OF CITRIC ACID AND THE SYSTEM CITRIC ACID-WATER C. G. DE KRUIF, C. G. DE KRUIFSearch for more papers by this authorJ. C. VAN MILTENBURG, J. C. VAN MILTENBURGSearch for more papers by this authorA. J. J. SPRENKELS, A. J. J. SPRENKELSSearch for more papers by this authorG. STEVENS, G. STEVENSSearch for more papers by this authorW. DE GRAAF, W. DE GRAAFSearch for more papers by this authorH. G. M. DE WIT, H. G. M. DE WITSearch for more papers by this author C. G. DE KRUIF, C. G. DE KRUIFSearch for more papers by this authorJ. C. VAN MILTENBURG, J. C. VAN MILTENBURGSearch for more papers by this authorA. J. J. SPRENKELS, A. J. J. SPRENKELSSearch for more papers by this authorG. STEVENS, G. STEVENSSearch for more papers by this authorW. DE GRAAF, W. DE GRAAFSearch for more papers by this authorH. G. M. DE WIT, H. G. M. DE WITSearch for more papers by this author First published: January 18, 1983 https://doi.org/10.1002/chin.198303094Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue3January 18, 1983 RelatedInformation

Thermodynamic properties of citric acid and the system citric acid-water

The binary system citric acid-water has been investigated with static vapour pressure measurements, adiabatic calorimetry, solution calorimetry, solubility measurements and powder X-ray measurements. The data are correlated by thermodynamics and a large part of the phase diagram is given. Molar heat capacities of citric acid are given from 90 to 330 K and for citric acid monohydrate from 120 to 300 K. The enthalpy of compound formation Δ com H (298.15 K)=(−11.8±1) kJ mole −1.

Bonded peptide stationary phases for the separation of amino acids and peptides using liquid chromatography

Bonded optically active tripeptides have been applied as stationary phases for liquid chromatography. Significant retention variations are shown for some UV absorbing amino acids when compared to a silica gel column using the same mobile phase. The separation of certain isomeric dipeptides has been accomplished using the bonded optically active tripeptide stationary phases. It is shown that these separations are superior to those possible on silica gel, although the efficiencies of the column are low. Phenylthiohydantoin (PTH)-amino acids have also been analyzed using the bonded tripeptide L-Val- L-Ala- L-Ser on silica gel CT and 1% citric acid-water as the mobile phase. No two PTH-amino acids showed the same capacity ratio out of 25 tested and the separation of 15 in one isocratic run is presented. The implications and future for the use of bonded optically active peptides as stationary phases for liquid chromatography are discussed.

Secondary nucleation of two fast growth systems in a mixed suspension crystallizer: Magnesium sulfate and citric acid water systems

AbstractSecondary nucleation of magnesium sulfate and citric acid was studied in a seeded back mixed crystallizer. The MSMPR type of exponential population density distribution was obtained above 8 μm size in quasi steady state operation. Growth rates were satisfactorily correlated with supersaturation. Nucleation rates correlated with supersaturation and slurry properties. Agitation level (RPM) did not have any significant effect on the nucleation rates, presumably implying surface regeneration limited nucleation.

Effects of Sucrose and Citric Acid on the Viscometric Behavior of Aqueous Methylcellulose Solution

The flow of the mixture of methylcellulose (MC)—sucrose—citric acid—water was essentially thixotropic. The viscometric behaviors could be expressed by the power law, S = KDn, where S was shearing stress and D rate of shear. The differential viscosity (ηd) of the mixture was strongly dropped by the addition of citric acid. Sucrose had the tendency to increase ηd of the mixtures except in the case of high sucrose concentration. From the results obtained, it has been concluded that citric acid tends to break the intermolecular hydrogen bonds of MC molecules, and that sucrose tends to keep the hydrogen bonds.