KOH Concentration Research Articles

Alkaline-oxidized MXene composite membrane of ultra high flux and advanced rejection performance for water purification

MXene is a metal-carbon/nitrogen compound material with a two-dimensional layered structure. As a new form of two-dimensional material, it has great potential in the field of water purification because of its properties of high permeability and hydrophilicity. In this study, a MXene composite membrane was prepared by in-situ oxidation of titanium dioxide on the MXene surface by an alkaline oxidation method. A series of characterizations of the prepared MXene composite membrane was carried out. Scanning electron microscopy showed that with an increasing degree of oxidation, the extent of agglomeration of MXene nanosheets increased, thus generating more water channels that are conducive to the transport of water molecules, and an increasing water flux. The penetration performance, interception performance, and stability of the MXene composite membrane were tested. The effect of different concentrations of KOH on the properties of the composite membrane was investigated. It was found that the flux of the composite membrane increased with alkali concentration by 4.6–28.8 times the flux without exposure to alkali. It was found that the rejection rate of the composite membrane for pollutants (dyes, humic acid, bovine serum albumin protein) decreased only slightly with increasing alkali concentration, and was ≥94% of the pure MXene membrane rejection rate in all cases. The rejection performance of the composite membrane was related to the size and charge properties of the pollutant molecules. The results of the stability tests showed that the composite membranes had a high degree of physical and flux stability in a range of aqueous solutions.

Evaluation of bovine carbonic anhydrase for promoting CO2 capture via reaction with KOH and high-salinity reject brine

In this study, we investigate the preliminary effect of bovine carbonic anhydrase (BCA) catalyst on CO2 capture via a reaction with potassium hydroxide (KOH) and reject brine under different operational conditions. Experiments were performed at a constant gauge pressure of 2 bar, with a CO2 inlet concentration of 10% and a CO2 flow rate of 776 mL/min. First, the impact of the BCA catalyst on CO2 capture in the absence of the alkaline material (KOH) was studied. Results showed that using 3-mg/L BCA increases the CO2 capture by 181% compared with the case without BCA. Second, the effect of BCA on CO2 uptake and ions reduction was examined in the presence of KOH. At a KOH concentration of 10-g/L, BCA concentration of 50-mg/L, and temperature of 40℃, a CO2 uptake value of 0.08 g CO2/g KOH was obtained. In comparison, adding 30-g/L KOH and 50-mg/L BCA increased the CO2 uptake by 737.5% (0.67 g CO2/g KOH). Furthermore, the sodium (Na+) reduction percentage reached a maximum of 40.8% at KOH and BCA concentrations of 30 g/L and 50 mg/L, respectively. However, increasing the BCA concentration to 100 mg/L negatively impacted CO2 capture and ion removal, indicating that the BCA concentration could be better optimized to achieve maximum efficiency. Additionally, when the BCA concentration was increased from 50 to 100 mg/L, the reaction rate remained nearly constant at 0.0047 mol/L·min.

Thermochemistry of the dissolution of tetra-4-sulfophthalocyanine nickel in aqueous solutions KОН at 298.15 K

We have obtained a nickel tetra-4-sulfophthalocyanine complex, soluble in water. The standard enthalpies of formation of a compound can be considered as the sum of the additive group contributions of fragments of these molecules. We assessed this value using a method based on group systematics with a Benson-type classification of fragments, taking into account the influence of the primary environment of the atoms. In order to obtain the value of the contribution of Ecompl(N)4-Ni, we used the bomb calorimetry method. The enthalpy of combustion of tetrakis (4-methoxyphenyl) porphine and its complex with nickel tetrakis (4-methoxyphenyl) porphine nickel were experimentally determined. Thermal effects of dissolution of crystalline nickel tetra-4-sulfophthalocyanine in aqueous solutions of various KOH concentrations (from 0.002 to 0.02 mol∙L−1) at 298.15 K were determined by the direct calorimetric method. The measurements were carried out in a calorimeter with an isothermal shell equipped with a reaction vessel with a volume of 60 cm3, electric calibration at T = (293.15–308.15) ± 0.01 K and P = 100.5 ± 0.7 kPa, and automatic temperature registration. The standard enthalpy of formation of dissociation products of the tetra-4-sulfophthalocyanine complex with nickel in an aqueous solution has been calculated.

Fabrication of a Sustainable Biodegradable Packaging Alternative for the Fashion Industry from Banana Waste

Packaging has both functional and aesthetic purposes. Kenya requires more sustainable biodegradable packaging options after a plastic ban was introduced in 2017 affecting numerous industries such as fashion. Banana stems and peels are part of the waste produced in Kenyan farms, suggested for the construction of biodegradable paper packaging material for the fashion industry. The objectives of this study were: to extract banana stem (BS) fibres using a decorticating machine; pulp the BS fibres using banana peel lye (KOH); and construct samples of paper packaging material from the pulp treated with KOH. The research design for this study was experimental. Kiganda banana stems collected from Kisii County were used in this study. The paper packaging material was constructed by pulping the BS using the KOH as a delignification reagent and then converting the pulp to paper by mounting it on mesh frames to dry. The findings reveal that in BS fibre extraction, decorticating one banana stem takes 10 minutes yielding 105 g of dry BS fibre. It also revealed that the handmade paper-making process takes 8 hours and 12 minutes including drying time to create an A4 size paper with the majority of the time (8 hours) being used for drying. The yield from the KOH pulped BS fibre was determined to be 68%. It was clear from the findings that KOH is comparable to commercial industrial alkalis like Sodium Hydroxide (NaOH) as a delignification reagent for BS fibres as it yields much pulp which produces good packaging material. Part of the recommendations for further research include the exploration of an industrially scaled paper-making process by the paper packaging manufacturing industry using KOH to pulp BS fibres. It is also suggested that research be done on using non-decorticated stems and varied concentrations of KOH to establish the most economical method

Effect of Concentration of KOH, H2O, Temp in In-situ Transestrification Reaction of Sesbania sesban, Capparis deciduas seed

Fatty acid methyl ester is defined as the mono-alkyl esters of fatty acids derived from vegetable oils or animal fats. In simple terms, it is renewable source of energy. Petrodiesel can be replaced by biodiesel due to its superiority. Biodiesel has more lubricity which increases lifetime of engine. It is less toxic and gives less emission of Carbon dioxide, Carbon monoxide, hydrocarbons and particulate matter. The biodiesel fraction from oil content of Sesbania sesban, Capparis deciduas are found 29% & 63.75 respectively. The percentage of biodiesel yield increases with concentration of KOH as a catalyst. The aim of this article is to demonstrate the cost effective new source of energy by single step reaction i.e. production of oil by combining extraction and reaction of extract with the mixture of alcohols. In this article the effect of catalyst concentration, time, water content and temperature on in-situ transestrification is studied to obtain optimum yield of fatty acid methyl ester (Biodiesel).Fuel characterization tests show the striking similarity of various physical & chemical properties and campers to ASTM standards.

Synthesis of Biodiesel from Refined Waste Cooking Oil with Active Natural Zeolite

This research evaluates refining waste cooking oil with active natural zeolite, utilizes it for biodiesel synthesis, and characterizes the synthesized methyl ester. This experimental laboratory research was carried out: (1) activation of natural zeolite, (2) refining waste cooking oil with active natural zeolite, (3) determination of free fatty acid (FFA) content of the oil, (4) transesterification with KOH catalyst, (5) characterization of the synthesized methyl esters according to the SNI 7182:2015, and (6) identification of the methyl ester component by GC-MS. The results showed that the FFA content of the refined waste cooking oil using active natural zeolite with concentrations of 10%, 20%, and 30% per mass of oil were 2.97, 2.0, and 1.56%, respectively. The yield of methyl ester transesterified with various concentrations of KOH (0.8, 1.0, and 2% per mass of oil), respectively, were 80.13, 85.34, and 74.98%. The synthesized methyl ester resulted in the characteristics: 0.867 g/mL of density; 5.72 cSt of viscosity; 1.449 of refractive index; 1.46 g KOH/g of acid number; and 0.023% of water content. Identification of GC-MS obtained the synthesized methyl esters, which include: 46.10% of methyl hexadecanoic, 41.68% of methyl 9-octadecanoic, 6.42% of methyl octadecanoic, and 5.80% of methyl eicosanoic.

Membrane electrode assembly simulation of anion exchange membrane water electrolysis

Anion exchange membrane water electrolysis (AEMWE) offers a green hydrogen production method that eliminates the need for platinum group metals (PGM) as electrocatalysts. This study employs a COMSOL® 6.0 model to simulate a 1x1 cm2 Ni fibre − Raney® Ni || X37-50RT || NiFe2O4− SS316L fibre AEMWE membrane electrode assembly (MEA). The membrane is set at a thickness of 60μm, while the anodic and cathodic porous transport layers (PTL) are modelled with a thickness of 370μm, each having an average porosity of 0.70. The half−cell overpotentials are experimentally measured to validate the half−cell model in a three−electrode setup consisting of (working electrode) || AGAR-Ag/AgCl || Pt−wire (counter electrode). Two freshly prepared MEAs validated the (i) base case and (ii) sensitivity analysis models. The base case model validated the MEA results at 20 °C and 1 atm in 1M KOH electrolyte feed at 1.56 ml min−1 cm−2. The five parameters studied with the sensitivity analysis revealed the most influential parameters based on area-specific resistance (ASR) change in the following order (＋ and − indicate increase and decrease in ASR, respectively): KOH concentration (−97%), membrane thickness (＋ 9%), temperature (−4%), cathode feed type (<+0.5%), and KOH flow rate (>−0.5%).

Activated Carbon Electrodes for Supercapacitors from Purple Corncob (Zea maysL.).

Activated carbon-based supercapacitor electrodes synthesized from biomass or waste-derived biomass have recently attracted considerable attention because of their low cost, natural abundance, and power delivery performance. In this work, purple-corncob-based active carbons are prepared by KOH activation and subsequently evaluated as a composite electrode for supercapacitors using either an acidic or an alkali solution as the electrolyte. The synthesis of the material involves mixing the purple corncob powder with different concentrations of KOH (in the range of 5% to 30%) and a thermal treatment at 700 °C under an inert atmosphere. Physicochemical characterizations were performed using scanning electron microscopy, Raman spectroscopy, N2 physisorption analysis, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, while the electrochemical characteristics were determined using cyclic voltammetry, a galvanostatic charge/discharge curve, and electrochemical impedance techniques measured in a three- and two-electrode system. Composite electrodes activated with 10% KOH had a specific surface area of 728 m2 g-1, and high capacitances of 195 F g-1 at 0.5 A g-1 in 1 mol L-1 H2SO4 and 116 F g-1 at 0.5 A g-1 in 1 mol L-1 KOH were obtained. It also presented a 76% capacitance retention after 50 000 cycles. These properties depend significantly on the microporous area and micropore volume characteristics of the activated carbon. Overall, our results indicate that purple corncob has an interesting prospect as a carbon precursor material for supercapacitor electrodes.

Separation and Spectroscopic Determination of Ge(IV) as an Ion Pair Association Complex Using DB18C6 Ligand

A solvent extraction was applied using liquid ion exchange as a sensitive method to extract Germanium (IV) as anion complex K[GeO2(OH)2]- from basic media of KOH by used DB18C6 as a ligand dissolved in chloroform to form the ion pair association complex K-DB18C6+; K[GeO2(OH)2]-, the maximum wavelength of the extracted complex was λmax=290nm, and molar absorptive 1.269and#215;103 L/mol.cm. the Beerand#39;s –lambert law was adhered to within the specified range (1-20)ppm. The limits of detection and quantity were 0.034 and 0.102 ppm, respectively. The research studied optimal conditions of extraction efficiency, such as KOH concentration, shaking time, methanol effect, and electrolyte effect. In addition, a new spectrophotometric method was utilized to determine the remain of Ge(IV) in aqueous solutions and to calculate its distribution ratio (D) using Janus green B. This method was more sensitive when comparing the results with previous studies. DB18C6 as a ligand was used to determine Germanium (IV) in some canned foods widely sold in Iraq.

Optimisation of Lutein Extraction From Gac (Momordica cochinchinensis) Fruit Peel and Evaluation of In Vitro Eye Protective Effects of the Extracts

Lutein is a macular biopigment that can protect the retina from oxidative stress induced by chronic exposure to light and oxidants. The peel of gac fruit (Momordica cochinchinensis) contains high levels of lutein, but the extraction optimisation parameters are complex, requiring saponification, and the effects on ocular bioactivity are not well understood. This study is aimed at optimising parameters for lutein extraction validated using HPLC from gac peel to determine their protective effects on oxidatively stressed retinal cells. The factors investigated for optimisation were KOH concentration, time, and temperature using (1) single factor, (2) multiple factor response surface methodology, and (3) predictive modelling. The optimum conditions for lutein extraction using single factors were 9% KOH for 3 h at 60°C, multiple factors were 9% KOH for 3 h at 45°C, and predictive modelling was 18% KOH for 1.9 h at 39.9°C, with the maximum extraction of lutein at 12.37, 15.64, and 17.4 mg/g DW, respectively. The extracted lutein purity and chemical composition were compared using HPLC and FTIR and indicated high purity and similarities in all extracts including the commercially purified lutein. Lutein extracted exhibited benefits on oxidatively stressed retinal pigment epithelium (RPE) cells that reversed damage to baseline unstressed levels exceeding 80% viability, similar to purified lutein standards. The feasibility of gac lutein and extraction optimisation were discussed for commercial translational opportunities as a medicinal bioproduct with a focus on eye benefits.

(Poster Award - Honorable Mention) Durable Polybenzimidazole Anion Exchange Membranes for Alkaline Water Electrolyzers

Water electrolysis under alkaline conditions allows the use of inexpensive non-platinum-group catalysts such as nickel.1, 2 Conventional alkaline electrolyzers usually employ a highly concentrated aq. KOH solution as electrolyte (5-7 M) with a porous diaphragm as separator. Alternatively, protolysable polymers such as polybenzimidazole (PBI) may be swollen with electrolyte and used as ion-solvating membranes.2, 3 However, the chemical stability of the polymers can become a serious issue under these harsh conditions. Operation under more dilute conditions, e.g., up to 2 M KOH, may bring the benefits of the alkaline conditions combined with a longer cell lifetime. Under these conditions, aliphatic cyclic quaternary ammonium (QA) cations, such as piperidinium, have shown excellent stability.In the present work, performed as part of the EU project “NEXTAEC”, we have designed and synthesized m-PBI grafted with mono- and bis-piperidinium functionalized side chains, respectively (Figure 1a-b). AEMs were prepared from polymers with varying ion exchange capacities and studied at 80 °C containing KOH solutions in the concentration range 0.5-2 M KOH. The membranes were characterized with respect to, e.g., electrolyte solution uptake, alkaline stability, and electrolyser performance (Figure 1c). The uptake showed a strong inverse correlation with KOH concentration, which also affected the electrochemical performance. The stability as evaluated by 1HNMR spectroscopy was excellent showing, in the worst case, less than 8 % ionic loss after 6 months storage in 2 M KOH at 80 °C. Li, D.; Park, E. J.; Zhu, W.; Shi, Q.; Zhou, Y.; Tian, H.; Lin, Y.; Serov, A.; Zulevi, B.; Baca, E. D.; Fujimoto, C.; Chung, H. T.; Kim, Y. S., Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers. Nature Energy 2020, 5 (5), 378-385.Aili, D.; Kraglund, M. R.; Rajappan, S. C.; Serhiichuk, D.; Xia, Y.; Deimede, V.; Kallitsis, J.; Bae, C.; Jannasch, P.; Henkensmeier, D.; Jensen, J. O., Electrode Separators for the Next-Generation Alkaline Water Electrolyzers. ACS Energy Letters 2023, 8 (4),1900-1910.Aili, D.; Yang, J.; Jankova, K.; Henkensmeier, D.; Li, Q., From polybenzimidazoles to polybenzimidazoliums and polybenzimidazolides. Journal of Materials Chemistry A 2020, 8 (26), 12854-12886.Marino, M. G.; Kreuer, K. D., Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids. ChemSusChem 2015, 8 (3), 513-23. Figure 1

The Oxygen Reduction Reaction on Pt and Ag Catalysts in Alkaline Media in Rrde and Half-Cell Setups

Understanding the Oxygen Reduction Reaction (ORR) in alkaline media is essential to optimize alkaline fuel cells or metal-air batteries. The catalytic activity of various ORR catalysts has usually been evaluated via Rotating (Ring) Disk Electrode (R(R)DE) measurements. However, using an electrolyte with dissolved oxygen at low KOH concentrations measured in a microampere regime at room temperature does not reflect the real cell conditions.1 Yet, RRDE is still a valuable tool for probing the reaction pathway of catalysts in alkaline media. Our study combined traditional RRDE with Gas Diffusion Electrodes (GDEs) half-cell measurements using Pt and Ag catalysts.The polarization curve of Pt-GDE exhibits a kink near 0.8 V vs. RHE leading to a significant potential drop. This specific feature can be explained by the RRDE results, which display an increased peroxide formation in that potential region due to the adsorption/desorption of hydroxyl adsorbates.2 However, Ag does not exhibit such behavior since the peroxide formation is below typical operating potentials. Depending on the operating conditions, Ag can catalyze the ORR more effectively than Pt in alkaline conditions while significantly reducing production costs. Furthermore, our study presents a general approach for evaluating ORR catalysts under experimentally challenging conditions such as elevated temperature and high KOH molarity.

Application of response surface methodology for optimization of the test condition of oxygen evolution reaction over La0.8Ba0.2CoO3 perovskite-active carbon composite

The Experimental Design was applied to optimize the electrocatalytic activity of La0.8Ba0.2CoO3 perovskite oxide/Active Carbon composite material in the alkaline solution for the Oxygen Evolution Reaction. After the preparation of La0.8Ba0.2CoO3, and structural characterizations, the experimental design was utilized to determine the optimal amount of the composite material and testing conditions. The overpotential was defined as the response variable, and the mass ratio of perovskite/active carbon, Potassium hydroxide (KOH) concentration, and Poly(vinylidene fluoride) (PVDF) amount were considered effective parameters. The significance of model terms is demonstrated by P-values less than 0.0500. The proposed prediction model determined the optimal amounts of 0.665 mg of PVDF, a KOH concentration of 0.609 M, and A perovskite/Active Carbon mass ratio of 2.81 with 308.22 mV overpotential (2.27% greater than the actual overpotential). The stability test of the optimized electrode material over 24 h suggests that it could be a good candidate electrocatalyst for OER with reusability potential.

Sensitive determination of daunorubicin in plasma of children with leukemia using pH-switchable deep eutectic solvents and HPLC-UV analysis

An environmental friendly, fast, easy and inexpensive liquid-liquid microextraction (LLME) in combination with pH-switchable deep eutectic solvent (DES) method followed by HPLC was investigated for the separation and determination of daunorubicin (DNR) in human plasma samples. For this purpose, first, 9 DESs were prepared based on previous studies and their switchability in aqueous solution was evaluated by changing the pH. Non-switchable DESs were discarded and switchable DESs were used to extract DNR. The parameters affecting the extraction efficiency were optimized (DES type, volume of DES, concentration of KOH, volume of HCl, salt addition and extraction time). After optimizing the conditions and drawing the calibration curve, figures of merit were calculated. Relative standard deviations (%RSDs) based on 7 replicate with 50 μg L−1 of DNR in plasma were 2.7 for intra-day and 4.8 % for inter-day. A wide linear range from 0.15 to 200 μg L−1 was obtained. The detection limit of the method based on signal-to-noise 3 and the quantification limit of the method based on signal-to-noise 10 were 0.05 and 0.15, respectively. After spiking plasma samples with different concentrations of DNR, relative recoveries were obtained in the range of 91.0–107.8 %.

Adsorption Power of Activated Charcoal from Coconut Shells on Lead Metal (Pb) in Well Water

This research aims to determine the results of the characterization and ability of activated charcoal (activated with KOH) to absorb lead metal (Pb). The procedure used is the process of carbonizing coconut shells in an airtight container at a temperature of 300ºC. Activation of coconut shell charcoal was carried out by immersing the charcoal powder in a KOH solution with variations of 1 M, 3 M, and 5 M. Characterization of activated charcoal powder was carried out on pore morphology using SEM-EDX, and XRD to identify the crystal phase, and AAS to determine the concentration lead metal (Pb). Based on the research results, the morphology of the charcoal before activation had a lot of impurities and the pores tended to be closed. After activation, the impurities disappeared and the pores were open. The crystal phase before and after activation was identified as 23.40% and 14.3% (calculated to be low), with the specific peak at 2θ, namely the corner area of 10º-80º. The adsorption capacity and efficiency obtained on activated charcoal with a KOH concentration of 1 M was 0.00194 mg/g and 23.66%, on activated charcoal the concentration of 3 M KOH was 0.00407 mg/g and 49.61%, the concentration of activated charcoal KOH 5 M is 0.00757 mg/g and 92.36%. Thus, the greater the KOH concentration, the greater the adsorption capacity and efficiency.

Mass transfer limitation phenomena across the separator in a zero-gap alkaline water electrolysis stack: Anion-selective polymer electrolyte membrane vs. Zirfon™ Perl UTP 500 case study

Endeavours to decrease the KOH concentration in a circulating medium represent an important target of today's research. They are connected with current efforts to increase the flexibility of alkaline water electrolysis and improve its efficiency with regard to renewable energy sources. This study reports on the impact of reduced KOH solution concentration on mass and charge transport in a laboratory alkaline water electrolysis stack with two separator types. The separators used are a homogeneous anion-selective polymer-electrolyte membrane based on chloromethylated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene copolymer functionalised by 1,4–diazabicyclo[2.2.2]octane and a commercial composite porous Zirfon™ Perl UTP 500 diaphragm. The stack was assembled in zero-gap mode and a bipolar connection of the electrodes was used. Load curves were recorded for different KOH concentrations and operational temperatures to assess the performance of the stack. Surprisingly, mass transfer limiting behaviour of the stack was observed at KOH concentrations below 2 wt% KOH for the Zirfon™ Perl UTP 500 separator. This was not the case for the stack utilising an anion-selective membrane as a separator. A 1-dimensional, single cell, stationary mathematical model was developed and implemented to clarify this phenomenon and to understand the details of the mass transport across the different types of separators in this process. This information is crucial for understanding obstacles faced once the concentration of KOH approaches zero, i.e., the final target of research in this field.

Optimisation of lutein production potential in marine biflagellate Proteomonas sulcata isolated from Indian coastal waters

The present study was conducted to isolate, identify, and extract the lutein from a biflagellate Proteomonas sulcata from the coastal waters of the Gulf of Mannar, Southern east coast of India. The targeted unicellular biflagellate P. sulcata belonging to the group Geminigeraceae was collected and isolated using 96 well plates followed by the serial dilution method and morphologically confirmed. However, the pure isolate was also confirmed based on molecular identification by PCR and sequence analysis of 18 S rRNA. The resultant sequence was analysed and reflected in phylogenetic tree. Optimised the environmental parameters to obtain the maximum cell density of 50.36 ± 0.81 × 105 cells/ml. The unique characteristic feature of the isolate was the change in colour during the culture phases. ie., red colour in growing phase up to 6th day in haffkine flask and changed into green during the stationary phase until the death phase. The reason for the colour change might be due to phycobiliprotein present in the microalga and also confirmed by FTIR analysis. The maximum chlorophyll content and carotenoid of 4.59 ± 0.38 mg/g 2.55 ± 0.12 mg/g was estimated. The conventional lutein extraction process such as saponification and solvent extraction methods was followed. The process was optimized and extracted crude lutein was analysed by using HPLC. The present study concluded that, the maximum lutein yield of 3.96 ± 0.1 mg/g was obtained at a 6 M concentration of KOH and also found that the highest amount of lutein was obtained from wet biomass (red-coloured biomass) of 4.72 ± 0.38 mg/g which is significantly higher than that of freeze-dried biomass.

Efficient and selective glycerol electrolysis for the co-production of lactic acid and hydrogen with multi-component Pt/C-zeolite catalyst

Among various electrochemical reactions to produce fuels and chemicals, glycerol electrolysis to co-produce hydrogen and lactic acid has received great attention. However, studies have shown the benchmark Pt based catalysts are insufficient in selectively catalysing the glycerol to lactic acid transformation, resulting in a low yield of lactic acid. Here we report a study on glycerol electrolysis with anion-exchange membrane electrode assembly electrolyser. The reaction conditions including mass transport, temperature, current density and KOH concentration were optimised, among which temperature played a significant role in facilitating the reaction rate and thermodynamics. With the optimised condition a multicomponent Pt/C-zeolite electrocatalyst system (Pt/C-CBV600) was developed and tested, which is capable to increase the lactic acid selectivity to 57.3% from the 33.8% with standalone Pt/C. Although the detailed mechanism required further investigation, it is hypothesised that the CBV600 zeolite with abundant Lewis acid surface sites can effectively bind the dihydroxyacetone intermediate, and drive the reaction towards pyruvaldehyde heterogeneously, the key step to form lactic acid.

Boosting Biodiesel Production from Dairy-Washed Scum Oil Using Beetle Antennae Search Algorithm and Fuzzy Modelling

The major goal of this study was to develop a robust fuzzy model to mimic the generation of biodiesel from the transesterification of dairy-washed milk scum (DWMS) oil. Four process parameters were considered: the molar ratio of methanol to oil, the concentration of KOH, the reaction temperature, and the reaction time. The proposed technique was divided into two steps: fuzzy modelling and optimum parameter identification. The capability of fuzzy tools to capture and make use of linguistic variables and fuzzy sets is one of their main benefits. This means that fuzzy logic allows for the representation and manipulation of values that fall across a continuum rather than merely relying on crisp values or binary categories. When dealing with non-linear relationships, this is especially helpful since it gives a more accurate and nuanced depiction of the underlying data. As a result, an accurate fuzzy model was initially built based on collected data to simulate the biodiesel production in terms of the molar ratio of methanol to oil, the concentration of KOH, the temperature of the reaction, and the reaction duration. In the second phase, the beetle antennae search (BAS) algorithm was applied to identify the optimal values of the process parameters to boost the production of biodiesel. The BAS algorithm draws inspiration from beetle behavior, particularly how they navigate using their antennae. It employs a swarm-intelligence method by deploying virtual beetles that swarm over the problem area in search of the best solution. One of its main features is the BAS algorithm’s capacity to balance exploration and exploitation. This is accomplished through the algorithm’s adaptable step-size mechanism during the search phase. As a result, the algorithm can first investigate a large portion of the problem space before gradually moving closer to the ideal answer. Compared with ANOVA, and thanks to fuzzy, the RMSE decreased from 7 using ANOVA to 0.73 using fuzzy (a decrease of 89%). The predicted R2 increased from 0.8934 using ANOVA to 0.9614 using fuzzy (an increase of 7.6). Also, the optimisation results confirmed the superiority of the BAS algorithm. Biodiesel production increased from 92% to 98.16%.

Operational and design parameters evaluation to improve hydrogen production using a low-cost alkaline water electrolysis cell in direct combination with a photovoltaic cell

Hydrogen production from renewable sources such as photovoltaic solar energy can contribute to a more sustainable energy scenario worldwide. The present work aimed to evaluate hydrogen production via alkaline water electrolysis by finding the optimal operational conditions with electrodes, alkaline electrolyzers, and solar energy with a photovoltaic panel. Firstly, graphite, stainless steel 304, and Monel 400 electrodes were evaluated using a direct voltage source, resulting in maximum hydrogen flow rates of 4.86, 10.40, and 8.12 mL/min, respectively. Then, hydrogen generation was analyzed with electrolytes of KOH, NaOH, and LiOH in 1-10 mol/L concentrations. The highest hydrogen flow rates were found for KOH electrolytes, attributed to their higher electrical conductivity. Therefore, stainless steel electrodes and KOH electrolyte were evaluated with the photovoltaic panel. The optimized conditions were a KOH concentration of 6.18 mol/L and a solar radiation of 900 W/m2 for a hydrogen production of 71.83 mL/min. The hydrogen purity remained at 98.96 ± 0.10%.