Ratio Of Citric Acid Research Articles

Structural and optical properties of carbon nanodots based on citric acid doped with nitrogen atoms

A study of the luminescent properties of carbon nanodots obtained by microwave and hydrothermal methods of synthesis from citric acid and urea was performed. The resulting nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. The sizes of the obtained carbon nanodots after dialysis was varied from 2 to 8 nm. FTIR spectra confirm the presence of oxygen-containing –OH, –CN and –NH groups in the resulting solutions. For all studied carbon nanodots, the maximum fluorescence intensity is observed upon excitation at a wavelength of 350 nm. The fluorescence spectrum does not change its position on the wavelength scale for the samples under study due to changes in the molar ratio of precursors and the method of synthesis. The highest fluorescence quantum yield was obtained for carbon nanodots with a ratio of citric acid and urea 1:4 obtained by the microwave synthesis method. The fluorescence lifetime of carbon nanodots doped with nitrogen atoms is ~7.4 ns. It is shown that a change in the ratio of precursors does not significantly affect the size and morphology of carbon nanodots.

Modulating the fluorescence properties of carbon dots by varying the stoichiometric ratios of citric acid and urea during the synthesis

Varying the ratios of citric acid and urea during the synthesis of carbon dots (CDs) provides a strategy to modulate their fluorescence properties. The impact of different precursor ratios on the resulting CDs' size, surface chemistry, and structure was investigated using X-ray diffraction (XRD) analysis and confirmed through transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to study the influence of precursor ratios on the types and densities of surface functional groups. The optical properties of the CDs were examined using a UV–visible absorption spectrometer, photoluminescence excitation (PLE) spectra, and photoluminescence spectroscopy (PL). Smaller CDs generally exhibit higher energy emissions, resulting in bluer light, while larger CDs tend to emit lower energy light, appearing redder. By adjusting the precursor ratios, it is possible to induce shifts in fluorescence emission, leading to CDs with different fluorescence colours. Furthermore, the antimicrobial activity of CDs against bacterial pathogens was assessed, and their potential for promoting plant growth was explored by coating seeds with concentrated and diluted CDs solutions.

Nano-CuOx for ciprofloxacin effective removal via wet peroxide oxidation catalysis and its practical application in wastewater

Using Cu(NO3)2·3H2O as active material and citric acid (CA) as complexing agent, heterogeneous catalyst nano-CuOx was prepared by sol-gel method. The catalytic wet peroxide oxidation (CWPO) reaction system was established accordingly. The system was used to treat ciprofloxacin (CIP) in simulated wastewater and real wastewater. The effects of the molar ratio of metal salt to CA, calcination temperature, H2O2 dosage, reaction temperature, and catalyst dosage on the physicochemical structure and the properties of CWPO were investigated. The results showed that when the molar ratio of CA to metal salt (Cu(NO3)2·3H2O) was 1.8, the calcination temperature was 500 °C, the concentration of H2O2 was 10 mmol · L–1, the reaction temperature was 95 °C, and the dosage of catalyst was 1 g · L–1, CWPO system has the best degradation effect on CIP. At thses optical conditions, the removal rate reached 86.8%, chemical oxygen demand (COD) removal rate reached 54.9%, and the recycling rate of the catalyst was very good. The refractory organics in actual pharmaceutical wastewater could be oxidized by this system as well, and the COD removal rate reaches 47%. The degradation mechanism of CIP showed that the main functions of the CWPO system were ·O2– and ·OH radicals. The possible degradation pathways were determined by ion chromatography to be intermediate products generated from piperazine ring cleavage, defluorination, decarboxylation, and quinoline hydroxylation of CIP. The catalyzing mechanism was investigated in detail; some useful information was obtained in this work.

Novel approach for synthesis of highly active nanostructured MgO/ZnAl2O4 catalyst via gel-combustion method used in biofuel production from sunflower oil: Effect of mixed fuel

A series of MgO/ZnAl2O4 nanocatalysts was prepared in order to conversion of sunflower oil to green fuel through transesterification reaction. The ZnAl2O4 spinel was synthesized using combustion method with different mixtures of urea and citric acid as fuel. MgO was also loaded on the catalysts as the active phase by impregnation method. the physicochemical properties of synthesized MgO/ZnAl2O4 nanocatalysts was evaluated with TGA/DTG, XRD, FESEM, EDX-dot mapping and nitrogen adsorption–desorption technique. XRD patterns of all samples showed crystalline phase of zinc aluminate without any impurities. The porous morphology as well as high degree of active phase dispersion was observed in samples prepared with mixed fuel. Using mixed fuel with urea to citric acid ratio of 0.5 led to create more pores in range of 10–20 nm. It is worth mentioning that the results of the catalytic performance test of the synthesized catalysts revealed that the highest conversion rate of 98.45 % was obtained in the synthesized sample with a ratio of urea to citric acid of 1:2. Furthermore, this sample illustrated superb stability in the reusability examination so that even over after five recovery cycles, the conversion triglyceride just decreased to 91.1 %.

An innovative screening approach for orange juice authentication using dual portable/handheld NIR spectrometers and chemometrics

In this study, we explored the feasibility of utilizing two portable/handheld near-infrared (NIR) spectrometers in combination with class modeling techniques, namely data-driven soft independent modeling of class analogy (DD-SIMCA) and soft-partial least squares-discriminant analysis (soft-PLS-DA), as well as discrimination strategies of ensemble learning and hard-PLS-DA, for developing a screening method to authenticate orange juice samples and detect the presence of adulterants (the Brix to citric acid ratio in pulp-wash). The results obtained with both NIR spectrometers (Tellspec, 900-1700 nm and Neospectra, 1350-2550 nm) coupled with DD-SIMCA exhibited perfect sensitivity and specificity of 100% in both calibration and prediction sets. Additionally, when combined with the NIR Tellspec spectrometer, ensemble learning methods including gradient boosting tree (GBT) and adaptive boosting (Adaboost) demonstrated exceptional predictive capabilities, achieving the prediction of 'Brix to citric acid' ratio in pulp-wash with high sensitivity and specificity. These results surpassed the performance of hard-PLS-DA as commonly used technique in food authentication.

Metal ion removal using a low-cost coconut shell activated carbon bioadsorbent in the recovery of lactic acid from the fermentation broth

Downstream recovery and purification of lactic acid from the fermentation broth using locally available, low-cost materials derived from agricultural residues was demonstrated herein. Surface modification of coconut shell activated carbon (CSAC) was performed by grafting with carboxymethyl cellulose (CMC) using citric acid (CA) as the crosslinking agent. A proper ratio of CMC and CA to CSAC and grafting time improved the surface functionalization of grafted nanostructured CMC-CSAC while the specific surface area and porosity remained unchanged. Lactic acid was partially purified (78%) with the recovery percentage of lactic acid at 96% in single-stage adsorption at room temperature and pH 6 with a 10:1 ratio of cell-free broth to CMC-CSAC bioadsorbent. A thermodynamic study revealed that the adsorption was exothermic and non-spontaneous while the Langmuir isotherm model explained the adsorption phenomena. The results in this study represented the potential of waste utilization as solid adsorbents in green and low-cost adsorption technology.Graphical

Acid catalyzed microwave-assisted production of full-color light emissive carbon quantum dots for CCT-tunable WLEDs

Many studies have examined the use of multicolor light emissive carbon quantum dots (CQDs) in toxic metal-free optoelectronic devices, but it is still limited to obtain desirable optical properties. Here, we present a straightforward synthetic route for producing multicolor light emissive nitrogen-doped carbon quantum dots (NCQDs) using a microwave-assisted process, thus yielding individual color emissions of NCQDs in a batch. The emissive colors from NCQDs can be controlled by adjusting the molar ratios of citric acid and urea from 1 to 6 for blue and green-light emission, respectively. When o-phenylenediamine (oPDA) was chosen as a precursor, the resulting NCQDs can emit yellow light, while the red light emissive NCQDs can be obtained in the presence of a diluted HCl as a catalyst for accelerating and extending sp2-carbon bonding. The doped nitrogen in NCQDs was found to be formed as a graphitic nitrogen in the core, leading to red-shifted photoluminescent emissions from 450 nm to 620 nm. To fabricate white-light emitting diodes (WLEDs), the mixing ratios of NCQDs with different light emissions in polydimethylsiloxane (PDMS) were varied to control the correlated color temperature (CCT) from 3386 K to 7151 K and CIE coordinates of (0.30, 0.32), (0.32, 0.36), and (0.40, 0.37).

The effect of the citric acid to metal nitrates molar ratio on the structural and magnetic properties of strontium hexaferrite nanoparticles synthesized by the sol-gel combustion method

Strontium hexaferrite is a hard ferrite with the chemical formula of SrFe12O19 and has a magnetoplumbite structure. Due to high anisotropy, high saturation magnetization, chemical stability, high corrosion resistance, and appropriate Curie temperature, it has been widely used as a permanent magnetic material. A novel sol-gel combustion process was used to synthesize ultrafine particles of strontium hexaferrite. The weight ratio of citric acid to the total weight of strontium and iron salts nitrate (CA/MN) is among the parameters affecting the purity of SrFe12O19 nanoparticles produced by the sol-gel method, which can improve the purity of the final product by controlling this parameter. M-type SrFe12O19 nanostructures with different citric acid to metal nitrates molar ratios (0.5, 1, 2, and 4) were prepared. The results showed that nitrate-citrate gels exhibit self-ignition behavior after combustion in the air at room temperature. The samples were then characterized by XRD, TGA/DTA, FTIR, FE-SEM, VSM. The results showed that the crystallite size of strontium hexaferrite is significantly affected by the molar ratio of citric acid to metal nitrates. As the molar ratio of citric acid to metal nitrates increases, the size of nanostructures decreases. By increasing the molar ratio of citric acid from 0.5 to 1, the saturation magnetization and magnetic remanence magnetization increase, but the coercive field decreases.

Thermoplastic starch/polyvinyl alcohol blends modification by citric acid–glycerol polyesters

Thermoplastic starch/polyvinyl alcohol (TPS/PVA) films have limitations for being used in long–term applications due to starch retrogradation. This leads to plasticizer migration, especially when low molecular weight plasticizers such as glycerol, are used. In this work, we employed mixtures of oligomers based on glycerol citrates with higher molecular weight than glycerol as plasticizers for potato–based TPS/PVA blends obtained by melt–mixing. This constitutes an alternative to reduce plasticizer migration while keeping high swelling degree, and to provide high mechanical performance. The novelty lies in the usage of these oligomers by melt-mixing technique, aspect not deeply explored previously and that represents the first step towards industrial scalability. Prior to the blending process, oligomers mixtures were prepared with different molar ratios of citric acid (0–40 mol%) and added them. This minimizes the undesirable hydrolysis effect of free carboxylic groups on starch chains. The results demonstrated that the migration of plasticizers in TPS/PVA blends decreased by up to 70 % when the citric acid content increased. This reduction was attributed to the higher molecular weight (the majority in the range 764–2060 Da) and the 3D structure of the oligomers compared to using raw glycerol. Furthermore, the films exhibited a 150 % increase in Young's modulus and tensile strength without a reduction in elongation at break, while maintaining a high gel content, due to a moderate crosslinking.

Preparation and evaluation of a novel chlorine dioxide preservative based on citric acid grafted carboxymethyl chitosan

Instrument-free chlorine dioxide (ClO2) preservative for fruit and vegetable has gained great attention due to its convenience and safety. In this study, a series of carboxymethyl chitosan (CMC) with citric acid (CA) substituents were synthesized, characterized, and further used to prepare a novel ClO2 slow-releasing preservative for longan. UV–Vis and FT-IR spectra revealed that CMC-CA#1–3 were successfully prepared. Further potentiometric titration showed that the mass ratios of CA grafted in CMC-CA#1–3 were 0.18:1, 0.42:1, and 0.42:1, respectively. The composition and concentration of ClO2 slow-releasing preservative were optimized, and the best formulation was as follows: NaClO2:CMC-CA#2:Na2SO4:starch = 3:2:1:1. The maximum ClO2 release time of this preservative reached >240 h at 5–25 °C, and the maximum release rate always occurred at 12–36 h. Longan treated with 0.15–1.2 g ClO2 preservative had significantly (p < 0.05) higher L* and a* values but lower respiration rate and total microbial colony counts than the CK group (0 g ClO2 preservative). After 17 days of storage, longan treated with 0.3 g ClO2 preservative had the highest L* value of 47.47 and lowest respiration rate of 34.42 mg·kg−1·h−1, showing the best pericarp color and pulp quality. This study provided a safe, effective, and simple solution for longan preservation.

A novel MCDM approach to selecting a biodegradable dynamic plastic product: a probabilistic hesitant fuzzy set-based COPRAS method

The development of biodegradable polymers for both industrial and commercial uses is crucial nowadays due to the detrimental environmental effects of synthetic plastics. For a variety of uses, researchers have created numerous starch-based composites. The current study examines bioplastics made from maize and rice starch for packaging purposes. Several types of bioplastic samples are created using various ratios of gelatin, glycerol, citric acid, maize starch, and rice starch. People have discovered the value of plastics all around the world. It can be used for packaging, trash bags, liquid containers, throwaway quick service restaurant products, and other things. Regarding the negative aspect of plastics, their dumping after durability poses a serious risk to both people and wildlife. This prompted researchers to seek alternative natural resources that may be used to create flexible polymers that are recyclable, eco-friendly, and sustainable. It has been discovered that tuber and grain starches can be used to produce flexible biopolymers. The decision to choose the best among these choices is an MCDM problem because the carbohydrates from these suppliers have varying qualities. The Probabilistic Hesitant Fuzzy Set (PHFS)-based COmplex PRoportional ASsessment (COPRAS) method for solving uncertainty problems is utilized in this research study. To get the objective weights of the criteria in this case, we used the Critic method of weight determination. An example case of selecting the optimal hydrolyzes for biodegradable dynamic plastic synthesis was chosen to represent the applicability of the suggested approach. The findings demonstrate the feasibility of thermoplastic starches derived from rice and corn for packaging applications.

Optimization of Hydrophobic Coating Production by Pechini Method on Modified Aluminum Surface

To fabricate a hydrophobic coating using the sol-gel method (Pechini), an experimental design using the drying time and chemicals ratio as variables was developed. The coating was deposited on an aluminum substrate (AA6061-T6) treated by acid solution or anodization method. The surface wettability was measured using a goniometric instrument. Coatings were fabricated using different numbers of layers, heating rates, and drying temperatures, and their morphologies were observed using visual analysis and scanning electron microscopy. The use of anodization treatment with a furnace ramp of 1 °C min-1, a drying temperature of 220 °C ± 10 °C, and single-layer application, produced a coating free of visible flaws and apparent damage. The coating was obtained with a 15:1 glycerin:citric acid ratio and sample pre-polymerization in the drying oven for 1 hour at 100 °C resulted in the highest contact angle, 62° ± 2°, which meets the ASTM D-7334-08 standard for a hydrophobic surface.

Extraction and separation of vanadium (IV) by EHEHPA with citric acid complexing iron (III) from sulfate leaching solution

The recovery of vanadium from sulfate leaching solutions is crucial for resource sustainability and environmental protection. However, the leaching solution contains impurities such as Fe (III), which have a significant impact on the separation and enrichment of V because a) the separation of Fe (III) and V (IV) through solvent extraction is problematic, and b) in the presence of oxygen from the air, it is challenging to fully reduce Fe (III) to Fe (II). Citric acid was used as a complexing agent in the aqueous phase to complex the Fe (III), and the effect of V (IV) extraction using 2-Ethylhexylphosphoric acid mono-2-ethylhexyl ester (EHEHPA) after Fe (III) complexation was investigated. To determine the complexation dose necessary for complete Fe (III) complexation, the numbers of ligands in the citric acid and Fe (III) complex were estimated, and the complexation mechanism of citric acid with Fe (III) was further clarified using UV–vis and FT-IR. According to the experimental findings, citric acid exhibits better complexing action than other complexing agents. Citric acid may complex > 96 % of Fe (III) in the liquid phase when the molar ratio of citric acid to Fe (III) is 1.5. When the pH of the solution was 1.2 and the molar ratio of citric acid to Fe (III) was 2, the extraction rates of V (IV) and Fe (III) obtained through EHEHPA were > 80 % and < 1 %, respectively. Additionally, the maximum separation factor βV/Fe was 430, which helped achieve the complete removal of Fe (III).

이산화염소 자체 방출 스마트 샤쉐의 제조 및 특성 연구

Chlorine dioxide (ClO2) is widely used for post-harvest sterilization treatment. However, there are limitations in the retail application of ClO2 due to difficulties in handling, expensive facilities, and safety concerns. Therefore, it is necessary to develop a ClO2 technology that can be easily applied and continuously released for a long period. In this study, a series of ClO2 self-releasing sachets were developed. First, poly(ether-block-amide) (PEBAX) and polyethyleneglycol (PEG) composite films containing different ratios of citric acid (CA) were prepared using the solution casting method. The as-prepared PEBAX/PEG-CA composite films were evaluated using FT-IR, DSC, and TGA to confirm chemical structure and thermal properties. Subsequently, PEBAX/PEG-CA composite films were designed in the form of a sachet and NaClO2 powder was transferred into the sachet to achieve a ClO2 self-releasing system. The ClO2-releasing behavior of the sachet was investigated by measuring the release amount of the gas using UV-vis. The release amount of ClO2 increased with increasing CA contents owing to the existence of higher protons (trigger) in the polymer matrix. Further, ClO2 gas was released for a longer time. Therefore, the as-prepared smart sachet can be tuned according to applications and packaging sizes to serve an optimal sterilization effect.

Tensile properties of hyperelastic functionally graded polymer

A biomaterial is a medical revolution that improves the quality of life. The Mechanical property of biomaterial is required to be similar to replaced human part, study show that the use of functionally graded polymer can improve the mechanical property of biomaterial. A functionally graded polymer known as Poly(octanediol-co-dodecanedioate-co-citrate-co-itaconate) (PODCI) is synthesized by versatile photo printing method. When a different ratio of citric acid and itaconic acid is used, PODC25I25 and PODC30I20 are synthesized. PODCI is a hyper elastic material in which the stress–strain curve is not linear. Hence, the stress–strain curve is defined by using NeoHookean, Mooney-Rivlin, Polynomial, Yeoh, and Ogden models. Finite element analysis was performed to identify the best model to describe the mechanical property of PODCI. Ogden Model was found to be the best model. Different combination of PODCI was then assigned to coupon parts, forming eight distinct configurations and finite element analysis was performed on the coupon. The result shows each configuration has a different directional advantage. It is found that Configuration 2 and 4 have the best longitudinal support while Configuration 5 has the best lateral support.

Simulation study of citric acid effects on pyrolysis of hydrochloric acid pickling waste liquor

During pyrolysis of hydrochloric acid pickling waste liquid in a Venturi Reactor from iron and steel enterprises, the reaction products agglomera ted and hindered product recovery. Addition of citric acid to materials at the inlet improved product distribution. In this paper, a numerical simulation of the combustion, phase change, and gas-solid chemistry involved in a citric acid-added pickling waste liquid was conducted. These results showed that citric acid added to the inlet resulted in a peak concentration of carbon dioxide (CO2) in the back half of the venturi throat, and some ferric oxide (Fe2O3) underwent a secondary reaction to afford ferroferric oxide (Fe3O4). As the addition of citric acid increased, the flow of Fe2O3 at the outlet first increased and then decreased, while the flow rate of Fe3O4 first decreased and then increased. When the ratio of citric acid was 7%, the flow rate of Fe2O3 was the smallest and the flow rate of Fe3O4 was the largest.

In Situ Confining Citric Acid-Derived Carbon Dots for Full-Color Room-Temperature Phosphorescence.

Room-temperature phosphorescence has received much attention owing to its potential applications in information encryption and bioelectronics. However, the preparation of full-color single-component-derived phosphorescent materials remains a challenge. Herein, a facile in situ confining strategy is proposed to achieve full-color phosphorescent carbon dots (CDs) through rapid microwave-assisted carbonization of citric acid in NaOH. By tuning the mass ratio of citric acid and NaOH, the obtained CDs exhibit tunable phosphorescence wavelengths ranging from 483 to 635nm and alterable lifetimes from 58 to 389ms with a synthesis yield of up to 83.7% (>30g per synthesis). Theoretical calculations and experimental results confirm that the formation of high-density ionic bonds between cations and CDs leads to efficient afterglow emission via the dissociation of CD arrangement, and the evolution of the aggregation state of CDs results in redshifted phosphorescence. These findings provide a strategy for the synthesis of new insights into achieving and manipulating room-temperature phosphorescent CDs, and prospect their applications in labeling and information encryption.

Facile and controllable synthesis of monodisperse gold nanoparticle bipyramid for electrochemical dopamine sensor

We demonstrated potential features of gold nanoparticle bipyramid (AuNB) for an electrochemical biosensor. The facile synthesis method and controllable shape and size of the AuNB are achieved through the optimization of cetyltrimethylammonium chloride (CTAC) surfactant over citric acid (CA) ratio determining the control of typically spherical Au seed size and its transition into a penta-twinned crystal structure. We observe that the optimized ratio of CTAC and CA facilitates flocculation control in which Au seeds with size as tiny as ∼14.8 nm could be attained and finally transformed into AuNB structures with an average length of ∼55 nm with high reproducibility. To improve the electrochemical sensing performance of a screen-printed carbon electrode, surface modification with AuNB via distinctive linking procedures effectively enhanced the electroactive surface area by 40%. Carried out for the detection of dopamine, a neurotransmitter frequently linked to the risk of Parkinson’s, Alzheimer’s, and Huntington’s diseases, the AuNB decorated-carbon electrode shows outstanding electrocatalytic activity that improves sensing performance, including high sensitivity, low detection limit, wide dynamic range, high selectivity against different analytes, such as ascorbic acid, uric acid and urea, and excellent reproducibility.

Colloidal Stability of CA, SDS and PVA Coated Iron Oxide Nanoparticles (IONPs): Effect of Molar Ratio and Salinity.

Iron Oxide Nanoparticles (IONPs) have received unprecedented interest in various applications. The main challenges in IONPs are fluid stability due to agglomeration in a saline condition. This paper aims to investigate the colloidal stability of citric acid (CA), sodium dodecyl sulphate (SDS) and polyvinyl alcohol (PVA) under various molar ratios and levels of salinity. Firstly, the IONPs were synthesized using a facile co-precipitation approach. Secondly, the IONPs were coated using a simple dip-coating method by varying the molar ratio of CA, SDS and PVA. Next, the coated IONPs were characterized by using an X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and a Field Emission Scanning Electron Microscope (FESEM) for the morphological and crystallographic study of coated IONPs. Finally, the coated IONPs were characterized for their zeta potential value and hydrodynamic size using a Zetasizer and their turbidity was measured using a turbidity meter. It was found that at a low salinity level, 0.07 M of CA-IONPs, a high zeta potential value, a smaller hydrodynamic size, and a high turbidity value of -40.9 mV, 192 nm and 159 NTU were observed, respectively. At a high salinity level, 1.0 M SDS-IONPs recorded a high zeta potential value of 23.63 mV, which corresponds to a smaller hydrodynamic size (3955 nm) and high turbidity result (639 NTU). These findings are beneficial for delivering cutting-edge knowledge, especially in enhanced oil recovery (EOR) applications.

Novel synthesis of N-doped graphene quantum dot as conductive agent for carbon based supercapacitors

Conductive agent can increase conductivity and construct pore structure in supercapacitor (SC) electrode as clean renewable energy. Carbon black (CB) is common conductive agent but its zero dimension hinders efficient charge-transfer conductive bridge. Combining CB with other carbon materials can possibly solve this issue. Graphene quantum dot (GQD) with high hydrophilicity and stable doping features is easier and cheaper to develop. Previous synthesis of GQD requires complex process and lacks large-scale production. In this study, novel one-step thermal treatment was provided to synthesize N-doped GQD. Citric acid and urea ratios were varied to synthesize N-doped GQD with different N-doping extents and electrical conductivities. CB and GQD mixtures, GQD and CB are used as conductive agent for fabricating SC electrodes. Activated carbon electrode with CB and GQD mixture shows the highest specific capacitance (CF) of 241.4 F/g at 20 mV/s, while electrodes without conductive agent and with CB conductive agent respectively shows CF of 41.5 and 108.6 F/g, due to more functional groups, defects, hydrophilic sites and electrochemical surface area of the former case. Symmetric SC with CB and GQD shows a maximum energy density of 10.54 Wh/kg at 550 W/kg, and CF retention of 85% and Coulombic efficiency of 80% after 5000 charging/discharging cycles.