Sodium Hydroxide Concentration Research Articles

Describing the permeability of permanganate co-ions in a CEM with varying supporting electrolyte concentrations

Redox flow batteries (RFBs), a promising technology for large-scale power grid energy storage, utilize a membrane separator to facilitate an ionic current while preventing mixing of the anolyte and catholyte solutions. The anolyte and catholyte of an RFB each contain an electroactive species, and usually an additional supporting electrolyte to charge balance the anode and cathode redox reactions and reduce overall ohmic losses. This study investigates the impact of the supporting electrolyte concentration and composition on Nafion’s transport properties using permanganate as the permeant. The permanganate concentration was kept constant at 0.1m, while sodium chloride and sodium hydroxide were both studied as supporting electrolytes. The sodium chloride concentration was varied from 0.1m to 4.0m, while the sodium hydroxide concentration was varied from 0.1m to 10m. The permanganate permeability, water sorption coefficient, and salt sorption coefficients were measured for Nafion, with a peak permeability being observed at a supporting electrolyte concentration of 1m for both electrolytes. A framework to describe the observed behavior was derived using first principles to determine the transport coefficients under these conditions. It was found that at low concentrations, the permanganate permeability is controlled by Donnan exclusion and salt sorption, while at high concentrations it is controlled by salt diffusion and osmotic deswelling.

Optimising chemo-enzymatic separation of polyester cellulose blends

The study demonstrates the potential of enzymatic hydrolysis and alkaline pretreatment for sustainable blended textile recycling. The target is complete cellulose removal while preserving the polyester integrity for recovery. Interactions of sodium hydroxide concentration (10 %–30 %), urea concentration (0 %–12 %), and temperature (-20 °C–50 °C) were investigated during pretreatment using a design of experiments. Analysis revealed a bimodal pattern in polyester mass loss, with one peak at lower concentrations and temperatures, and a more prominent peak at higher concentrations and temperatures. Cellulose hydrolysis also occurred under high NaOH concentrations and elevated temperatures (50 °C, 30 % NaOH, 0 % urea). Optimal conditions, preserving polyester integrity while achieving complete cellulose elimination, were identified at temperatures between 6.2 °C and 13.3 °C, with NaOH concentrations of 20.7 %–26.6 % (0 % urea) or 13.9 % NaOH and 12 % urea. These findings pave the way for a greener, more efficient textile recycling, advancing the circularity for textiles.

Кинетические характеристики процесса регенерационной утилизации отработанного раствора химического никелирования

Galvanic production in terms of the degree of negative impact on the environment occupies a leading position in the global industrial production; therefore, the introduction of regenerative recycling technology is receiving increasing attention. The aim of the present work is to determine the kinetic characteristics of the precipitation reaction in a solution of nickel sulfate with sodium hydroxide to develop a technology for the regeneration utilization of spent solutions of chemical nickel plating (SCNPS). The object of the study was the spent solution of chemical nickel plating of one of the industrial enterprises of Izhevsk. The experiment was carried out in the temperature range 293–333 K at various concentrations of sodium hydroxide (1.25–2.60 M) and nickel sulfate (0.037–0.06 M). To determine the order of the reaction, we plot graphs in the coordinates lg w – lg C(Ni) using the experimental data, where w is the reaction rate. The tangent of the slope of the obtained linear dependences with a high degree of approximation (R2 = 0.98) is close to 2, therefore, the order of the reaction of the deposition of SCNPS with sodium hydroxide is second. With a graphical method for determining the rate constant of a second-order reaction for the dependence 1/С = f(t), the tangent of the slope of the straight line corresponds to the calculated parameter. In the investigated temperature range the rate constant takes values from 5·10-4 to 9·10-4 dm3·mol-1·s-1. The activation energy of the precipitation reaction, determined by the Arrhenius equation by graphic and calculation methods, is 16.57 kJ·mol-1 and 16.44 kJ·mol-1, respectively. The low values of Ea indicate a weak dependence of the reaction rate on temperature. Consequently, the introduction of the technology for the regeneration utilization of SCNPS will not entail large expenditures of energy resources for heating the reaction masses.

Synthesis of EMT/FAU-type zeolite with high crystallinity and high EMT yield

EMT/FAU-type zeolite was synthesized by hydrothermal synthesis (initial gel composition: 10SiO2: 1Al2O3: xNa2O: 0.5 18-crown-6: 140H2O; x = 2.3, 2.7, 3.1 and 3.5) using 18 crown-6 as the template. The samples were characterized via XRD, BET and SEM techniques. The results illustrated that sodium hydroxide concentration in the initial gel (or in other words equivalent of Na2O) markedly affected the type and yield of the phases formed, morphology and textural property of the synthesized zeolites. With 3.1 equivalent of Na2O in the initial gel, the SEM result showed regular hexagonal platelets (2–5 μm in diameter), implying formation of well crystalline EMT phase being confirmed by XRD results as well. However, with lower or higher addition of Na2O amorphous or fujasite phases formed, respectively. In addition, the increase of the amount of sodium hydroxide reagent enhanced the BET surface area and microporous volume of the obtained zeolites. The high yield Na-EMT zeolite (∼70 %) produced in a short crystallization time (8 d) could be easily recovered from the synthesis slurry by filtration and washing without needing high-speed centrifugation.

Durability Properties of Ambient Cured Geopolymer Mortar Made from Rice Husk Ash–Based Alkali Activator: A Comparative Study with Conventional Alkali Activator

Abstract Geopolymers/alkali-activated materials (AAMs) are widely regarded as ecofriendly and durable alternatives to portland-based cement concrete. However, commercial alkali activators, especially the sodium silicate used to manufacture geopolymers/AAMs, are associated with a significant amount of carbon emission during their production. In this study, the feasibility of using rice husk ash (RHA) as a source for an alternative sustainable alkali activator has been explored at ambient temperature curing, and the durability properties of the geopolymer mortars (GPM) has been investigated. Three different concentrations of sodium hydroxide (SH), i.e., 20, 24, and 27 wt. % solutions, have been taken for the synthesis of RHA alkali activator used in synthesis of GPM, and another GPM with conventional alkali activator has also been synthesized for comparative study. Durability studies such as water absorption, sorptivity, sulfate resistance, and acid resistance were evaluated extensively in terms of change in weight and compressive strength. The experimental results revealed that the GPM made with 24 wt. % SH-RHA–based activator solution (R24) has optimal performance considering all the durability parameters and has a close correlation to the results obtained for the control GPM made with conventional alkali activator (C24). The microstructural studies further revealed that the gel structure of the R24 is compact and homogeneous, similar to that of C24; however, the former has a N-A-S-H–dominated gel matrix and the latter consists of N-(C)-A-S-H–type gels.

Effects of empty fruit bunch on the structures and properties of starch-based bioplastics

This paper aimed at maximizing the application of oil palm empty fruit bunch (EFB) fibers to reinforce the starch-based bioplastics with superior mechanical and water resistance properties. EFB fibers were thermally modified with dry method by incorporating different concentrations of sodium hydroxide (NaOH). Thermal treatments with NaOH exceeding 10 wt% caused significant fiber loss. Fourier transform infrared spectroscopy (FTIR) exhibited the part removal of fatty acid, hemicellulose, and lignin and SEM observed clean surfaces for the treated fibers. The crystallinity index of the fibers increased from 13.82% to 97.60%, but their thermal stability decreased due to the treatments. The influence of treated fibers on the structure and properties of starch-based bioplastics was characterized. EFB fibers treated with 10 wt% NaOH attained the high yield of 52.44% and demonstrated the best reinforcing effects on the bioplastics. This was confirmed by higher thermal stability, tensile strength, and water resistance compared to the other starch-based bioplastics.

Preparation of nano zinc oxide by alkaline treatment of industrial zinc oxide dust

A new method for the preparation of nano-zinc oxide was proposed for the effective use of zinc oxide dust (ZOD) containing complex impurities recycled and processed from local plants. Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Cu2+, and Pb2+, Sn4+, Al3+, Si4+, Bi3+ were selectively extracted from ZOD by alkaline leaching combined with precursor firing process. The effects of thermodynamic analysis of ZOD, Sodium hydroxide(NaOH) concentration(2–8 mol/L), leaching time (15–75 min), autothermal temperature of leaching reaction (43–70 °C), leaching liquid/solid ratio (L/S:5–25 mL/g), and pH were investigated during leaching process. Thermogravimetry-differential thermogravimetry (TG-DTG) analyses were carried out on Zinc carbonate hydroxide (Zn5(CO3)2(OH)6) precursor. In addition, the effects of calcination temperature(400–700 °C) and holding time (1.5–4.0 h) of precursors on average particle size of nano-ZnO were also studied. The results showed the leaching rate of Zn2+ reached 98.35% under the optimum conditions as: NaOH concentration of 6 mol/L, L/S of 20 mL/g, and leaching time of 60 min. Separation rates of Pb2+, Sn4+, Al3+, Si4+ reached 94.63%, 85.08%, 98.03%, 91.48%, respectively at pH = 5.5. Zn5 (CO3)2(OH)6 nano precursors were obtained at pH = 7–8. After the precursor of zinc carbonate was calcined at 400–600 °C for 2 h, high purity (99.53%) nano-zinc oxide was obtained with a particle size of 20 nm, a specific surface area of 23.84 m2/g, a porosity of 32.66%, and a zeta potential of −13.2 mV. This article provides an alternative new idea for the green and comprehensive utilization of industrial ZOD dusts with complex compositions.

Production of Vanillin from Pumpkin Peels via Microbiological Fermentation using Aspergillus niger

Vanilla is the main natural flavouring agent used in industries such as pharmaceuticals, food, flavouring, and fragrance, in which vanillin is the major component. Vanillin (4-hydroxy-3-methoxybenzaldehyde) is a secondary metabolite of plants and the major organoleptic aroma component of natural vanilla. The vanillin compound can be produced using the following routes: direct vanilla bean extraction, chemical synthesis, and biotechnological processes (bio-vanilla production). Nowadays, the chemical synthesis method used for vanillin production has been rejected by the United States and European legislation, while plant-derived vanillin is expensive. The current study demonstrates vanillin production from pumpkin peels (Cucurbita moschata) by Aspergillus niger via one-step fermentation approach. This study implements different concentrations of sodium hydroxide (1.0 M and 2.0 M) during alkaline hydrolysis pretreatment and different feeding volumes of hydrolysates during the biotransformation processes of ferulic acid into vanillin, classified as small feeding volumes (SFV) and large feeding volumes (LFV). Detection and quantification analysis were carried out using high performance liquid chromatography (HPLC), resulting in vanillin yield of 0.49 mg/L (1.0 M SFV), 0.5 mg/L (1.0 M LFV), 0.33 mg/L (2.0 M SFV), 0.59 mg/L (2.0 M LFV). Analysis with ultraviolet-visible (UV-VIS) spectrophotometry using thiobarbituric acid as reagent was carried out as well, resulting in vanillin yield of 2.76 µg/ml (1.0 M SFV), 3.78 µg/ml (1.0 M LFV), 2.68 µg/ml (2.0 M SFV), 3.05 µg/ml (2.0 M LFV). In conclusion, pumpkin peels can be considered a great source of ferulic acid and Aspergillus niger was reported as an efficient fungus in converting ferulic acid to vanillic acid, which will then be transformed into vanillin.

Integrated Hemicellulose Extraction and Papermaking Fiber Production from Agro-Waste Biomass.

The present study deals with the valorization of corn stalks in an integrated processing strategy targeting two products: extracted hemicelluloses (HC) and papermaking fibers. Preliminary trials were conducted to assess the individual or the combined effects of biomass treatment on the quality of the obtained hemicelluloses and papermaking fibers. Depending on the hot alkaline extraction (HAE) conditions, the extracted HC had a xylan content between 44-63%. The xylan removal yield ranged between 19-35%. The recovery of HC from the extraction liquor and final black liquor was significantly affected by process conditions. The experimental approach continued with the study of HAE conditions on the obtained paper's mechanical properties. The optimization approach considered conserving paper strength properties while achieving an equilibrium with the highest possible HC extraction yield. The optimal values are sodium hydroxide concentration (1%), process time (33 min), and temperature (100 °C). The xylan content in the separated HC sample was ~55%. An extended extraction of HC from the resulting pulp under hot alkaline conditions with 5% NaOH was performed to prove the HC influence on paper strength. The xylan content in HC samples was 65%. The consequence of xylan content reduction in pulp leads to 30-50% mechanical strength loss.

Central composite design for optimization of kenaf-reinforced epoxy composite bonding performance

Kenaf fiber is gaining prominence because of its ability as a natural-based reinforced material in advanced composites. However, kenaf contains a hygroscopic natural waxy substance that covers the fiber layer, providing a low surface tension and preventing strong bonding with the polymer matrix. The goal of this study is to optimize the blending parameters of kenaf fiber-reinforced epoxy composites by alkali treatment concentration, length, and fiber-matrix loading using central composite design. The maximum tensile strength was obtained at 6.03 wt% of NaOH concentration, fiber loading of 26.02 wt%, and fiber length at 7.39 mm, which showed a strong correlation between experimental and predicted values. The analysis of variance function model indicated that fiber length, sodium hydroxide concentration, and fiber loading all play important roles in mechanical properties of composites. Based on the fracture surface observations, kenaf fiber composite strength was closely related to bonding at fiber-matrix interfaces. The most common failure modes in the samples were voids, matrix fracture, fiber breakage, weak bonding, and fiber pull-out.

Determine the Optimal Parameters for Biogas Production from Common Reed (Phragmites australis)

A series of batch assays have been conducted to investigate the optimal factors that can be adopted to improve the anaerobic digestion (AD) performance of Phragmites australis and increase biogas production. The assays were carried out using 125 mL microcosm reactors with a working volume of 80 mL and incubated at mesophilic conditions (37 ± 1ºC). The effect of particle size (10, 5, 2, and < 1 mm) and alkaline pre-treatment of P. australis using various concentrations of sodium hydroxide (0.5, 1, 2, and 4%) on biogas production was examined. Furthermore, the best pre-treatment incubation time (12, 24, 48, 72, 96, and 120 h) and the optimal inoculum to substrate ratio (ISR: 4:1, 2:1, 1:1, 1:2 and 1:4) were also assessed. The results revealed that the highest biogas production from P. australis was achieved at particle size < 1 mm (27.97 ± 0.07 and 16.67 ± 0.09 mL/g VS added, for pre-treated and untreated P. australis respectively); 2% and 4% NaOH concentration for pre-treatment (70.01 ± 3.75 and 76.14 ± 2.62 mL/g VS added, respectively); pre-treatment incubation time of 72, 96, and 120 h (71.18 ± 1.79, 72.46 ± 1.08, and 73.78 ± 1.87 mL/g VS added, respectively); and ISR of 1:2 for pre-treated P. australis (78.21 ± 0.36 mL/g VS added) and ISR 1:4 for untreated P. australis (28.93 ± 1.55 mL/g VS added). Determining optimal parameters in this work would guide further development of process configurations, such as continuous AD systems.

Recycling Ash and Slag Waste from Thermal Power Plants to Produce Foamed Geopolymers

Ash and slag waste (ASW) from coal combustion creates significant environmental and economic challenges. A promising method of ASW recycling is alkali activation with geopolymer material formation. This study investigates the influence of activating solution components (sodium hydroxide and sodium silicate) on the formation of porous geopolymers using ASW of different origins. The sodium hydroxide content of 0–4 wt.% and the sodium silicate content of 17–25 wt.% were studied. An increase in sodium hydroxide resulted in decreased density, but it adversely affected the strength. An increase in sodium silicate led to a compromised porous structure with relatively high density and compressive strength. An optimal composition, S19N3, comprising 3 wt.% of sodium hydroxide and 19 wt.% of sodium silicate obtained porous geopolymers with uniformly distributed 1.4–2 mm pores and a corresponding density of 335 kg/m3, a compressive strength of 0.55 MPa, a porosity value of 85.6%, and a thermal conductivity value of 0.075 W/(m·K). A mechanism for porous geopolymer formation was developed, including the interaction of alkaline components with ASW and a foaming agent, foaming, curing, and densification. The mechanism was examined using ASW from the Severodvinsk CHPP-1. This study allows for the optimization of geopolymer mixtures with various waste sources and the utilization of waste materials in the construction industry.

Pipette-Free and Fully Integrated Paper Device Employing DNA Extraction, Isothermal Amplification, and Carmoisine-Based Colorimetric Detection for Determining Infectious Pathogens.

A pipette-free and fully integrated device that can be used to accurately recognize the presence of infectious pathogens is an important and useful tool in point-of-care testing, particularly when aiming to decrease the unpredictable threats posed by disease outbreak. In this study, a paper device is developed to integrate the three main processes required for detecting infectious pathogens, including DNA extraction, loop-mediated isothermal amplification (LAMP), and detection. All key reagents, including sodium dodecyl sulfate (SDS), NaOH, LAMP reagents, and carmoisine, are placed on the paper device. The paper device is operated simply via sliding and folding without using any bulky equipment, and the results can be directly observed by the naked eye. The optimized concentrations of sodium dodecyl sulfate (SDS), sodium hydroxide (NaOH), and carmoisine were found to be 0.1%, 0.1 M, and 0.5 mg/mL, respectively. The paper device was used to detect Enterococcus faecium at concentrations as low as 102 CFU/mL within 60 min. Also, E. faecium spiked in milk was successfully detected using the paper device, demonstrating the feasible application in real sample analysis.

Effect of NaOH-based deproteinisation on chemical and biological properties of Moina sp. chitosan

Chitosan is a biopolymer which is isolated from the crustacean exoskeleton of Moina sp. with particular antibacterial properties. Alkali-sodium hydroxide deproteinisation has a huge role in ensuring the chitosan quality by removing protein to enhance its dispersivity. Modification of sodium hydroxide (NaOH) concentration by 3N and 6N was performed in this study to observe the effect on chemical and biological characteristics of chitosan. The highest concentration treatment of 6N NaOH exhibited the best composition of protein, fat, and ash by 6.09%, 3.77% and 0.9%, respectively. The deacetylation degree of chitosan treated with 3N NaOH depicted the highest solubility of 73.25% compared to the solubility of 6N NaOH by 61.06%. The antibacterial activity of Moina sp. chitosan was considered as having a weak and fluctuated activity by different concentrations of NaOH. The 6N NaOH treatment chitosan showed the best antibacterial activity against the grampositive bacterial strain of Staphylococcus aureus with the widest inhibition zone diameter of 4.34±0.55 mm, while the 3N NaOH treatment chitosan showed the best antibacterial activity against the gram-negative bacterial strain of Escherichia coli with widest inhibition zone diameter of 4.47±0.78 mm.

The Effect of Different Concentration of NaOH on Mechanical Properties of Allium sativum L. Peels Thin Sheet Paper

Allium sativum L. peels were used as raw material to obtain cellulosic pulps for paper making. The peels were treated with sodium hydroxide at different concentrations (5%, 12.5%, and 20%) before the paper production. The sheets were measured for weight and thickness and evaluated for tensile, tear and bursting strength. The chemical compositions of the peels were analysed. The results indicated that the peels are suitable for papermaking due to the appropriate contents of cellulose (37.22%), hemicellulose (35.21%) and lignin (9.96%) values. The colour of the sheets varies from dark to light brown when the amount of sodium hydroxide solution was increased. It was estimated that the weight of peels was in the range of 5.0 - 6.5 % of garlic clove. All the sheet samples have uniform weight and thickness. The results showed that increasing sodium hydroxide concentration from 5% to 20% decreased tensile and bursting strength, except tearing strength. Two kinds of microscopic observations showed that peels treated with the highest sodium hydroxide concentration had a fine and thin layer of binder within the fibres. The sheets appear to be transparent with due to a decrease in the tensile and bursting strength except for the tear strength.&#x0D;

Real-time signal processing via chemical reactions for a microfluidic molecular communication system

Signal processing over the molecular domain is critical for analysing, modifying, and synthesising chemical signals in molecular communication systems. However, the lack of chemical signal processing blocks and the wide use of electronic devices to process electrical signals in existing molecular communication platforms can hardly meet the biocompatible, non-invasive, and size-miniaturised requirements of applications in various fields, e.g., medicine, biology, and environment sciences. To tackle this, here we design and construct a liquid-based microfluidic molecular communication platform for performing chemical concentration signal processing and digital signal transmission over distances. By specifically designing chemical reactions and microfluidic geometry, the transmitter of our platform is capable of shaping the emitted signals, and the receiver is able to threshold, amplify, and detect the chemical signals after propagation. By encoding bit information into the concentration of sodium hydroxide, we demonstrate that our platform can achieve molecular signal modulation and demodulation functionalities, and reliably transmit text messages over long distances. This platform is further optimised to maximise data rate while minimising communication error. The presented methodology for real-time chemical signal processing can enable the implementation of signal processing units in biological settings and then unleash its potential for interdisciplinary applications.

Alkali-activated geopolymer materials prepared from coal gangue and municipal solid waste incineration byproducts

Coal gangue and municipal solid waste incineration byproducts (fly ash and bottom ash) are considered as solid and hazardous waste, respectively, and the accumulation of these wastes leads to significant environmental issues. Coal gangue is rich in Si and Al but lacks of Ca, making it challenging to create alkali-activated cementitious materials with good mechanical performances. Fly ash and bottom ash are abundant in Ca. The feasibility of using fly ash and bottom ash as calcium sources for preparing alkali-activated coal gangue-based geopolymers is investigated in the present work. The unconfined compressive strength (UCS) test and microscopic tests (XRD, FTIR, TGA, SEM and ICP-OES) are conducted to study the strength and reaction mechanism of coal gangue and fly ash/bottom ash (CGFA/BA) geopolymers. The results show that the strength of CGFA/BA geopolymers initially increases and then decreases with an increase in fly ash and bottom ash content, and the optimal dosage of fly ash and bottom ash is 15% and 30%, respectively. The liquid-solid ratio and alkali solution (NaOH/Na2SiO3) ratio have a significant influence on the strength of the CGFA/BA geopolymers and the optimal alkali solution ratio is 25:75, while the liquid-solid ratio of 0.45 and 0.60 is recommended for CGFA and CGBA geopolymers, respectively. The CGFA geopolymer with 15% fly ash, 25:75 alkali solution ratio, 0.45 liquid–solid ratio and 8 mol/L sodium hydroxide concentration obtains the highest UCS of 30.28 Mpa. The heavy metal immobilization efficiency (IE) of the CGFA geopolymer is better than that of the CGBA geopolymer. The IE of heavy metals of the CGFA geopolymer is larger than 84.66% and that of the CGFA geopolymer is larger than 55.95%. In the CGFA geopolymer, the IE is Hg>Pb>Zn>Cd>Cr>Ba, while in the CGBA geopolymer, the IE is Hg>Cd>Ba>Cr>Zn>Pb.

Efficient production of low molecular weight lignin from eucalyptus wood through methanol-alkali system

With the high phenolic hydroxyl content and excellent bioactivity, low molecular weight lignin (LMW-Lignin) holds tremendous potential for various applications in energy storage and antibacterial materials. However, conventional sources of lignin currently available are characterized by large molecular weights, and many of their active functional groups remain unreleased, limiting their exploitation for potential applications. In this study, we investigated the inhibition effect of methanol on the recondensation of lignin fragments under a hydrothermal system of methanol/sodium hydroxide, using eucalyptus wood flour as the raw material. Our findings revealed that, in the hydrothermal alkaline system,·OCH3 free radicals formed from methanol can effectively target and react with the active sites (Cα and Cβ) on the dissolved lignin side chains, resulting in the formation of stable methoxyl structures and preventing the formation of C-C bonds and polycondensation of dissolved lignin. Optimized conditions, including 20% CH3OH (methanol content), 14% NaOH (sodium hydroxide content), and a reaction temperature of 160 ℃, led to a weight-average molecular weight of 1478 for the lignin product, with a yield of 62.90%.

Cobalt nanoparticle synthesis through the mechanochemical and chemical reduction method as a highly active and reusable catalyst for H2 production via sodium borohydride hydrolysis process

The process of hydrolysis of sodium borohydride is a new and clean method for the production of hydrogen. In this study, cobalt nanoparticles were synthesized by the mechanochemical and chemical reduction methods, and their catalytic performance was compared. The effect of using different cobalt precursors and reducing agents was investigated for the sample prepared via the chemical reduction method. The results showed that the cobalt catalysts synthesized through the chemical reduction method possessed better catalytic performance. Also, the sample prepared using cobalt nitrate and sodium borohydride had a higher hydrogen generation rate (HGR), which was equal to 3272.7 ml min−1g−1. The kinetics of the cobalt catalyst in the process have also been investigated, revealing that the rate of hydrogen production is dependent on the concentrations of sodium borohydride and sodium hydroxide, the catalyst dosage, and the process temperature. The crystal size of this catalyst was 21.6 nm with spherical agglomerated particles. The BET area of the best sample and its activation energy was equal to 11.18 m2g-1 and 22.3 kJmol-1, respectively. This catalyst was also stable in successive cycles.

Plant protein hydrogel as a delivery system of curcumin: Characterization and in vitro release Kinetics

In recent years, non-animal protein sources have led many consumers to eat plant-based alternatives. The Green gram protein is more biocompatible, highly sustainable and safer than animal proteins. Nutraceuticals have drawbacks such as poor water solubility, chemical instability at neutral and alkaline pH, auto-oxidation and poor absorption. Hydrogels are used to enhance the efficiency of these bioactive compounds. In this study, Green gram protein hydrogel enriched with curcumin was prepared. Protein was extracted from Green gram seeds using alkaline extraction and acid precipitation. Curcumin was extracted from turmeric using a Soxhlet Apparatus. A hydrogel was prepared using a sodium hydroxide concentration of 0.5 M to efficiently encapsulate curcumin and was characterized. The physicochemical properties of green gram protein hydrogels were evaluated by entrapment efficiency, swelling degree, FTIR, XRD, DSC, SEM, in vitro release and free radical scavenging assessment method. The encapsulation efficiency was 89.02 ± 0.56% respectively. The successful incorporation of curcumin in the hydrogel was confirmed by FTIR analysis. The surface properties of hydrogels were investigated using the SEM technique. The synthesized hydrogels are highly porous in nature and form cross linked structures. Moreover, hydrogels have a high swelling capacity. The swelling behaviour was due to the presence of hydrogen bonding interaction with the aqueous media. The hydrogel possesses a hydrophilic character when investigated by the contact angle. The contact angle of curcumin-loaded green gram hydrogel was increased by 9 °. The inhibition zone of 30 ± 03 mm was effective against E. coli. bacteria. The antioxidant property of the hydrogel gets increased by 50.46% after the addition of curcumin. Slow release of curcumin from hydrogel was studied using UV–vis Spectroscopy and it was inferred that it follows Korsmeyer-Peppas Kinetics model. The hydrogel was applied to tomato and apple as a coating. Generally, the results emphasised the potential use of Green gram protein hydrogel as a coating on fruits and vegetables.