KOH Concentration Research Articles

Evaluation of the Degradation Properties of Plasma Electrolytically Oxidized Mg Alloy AZ31 Using Fluid Dynamic Accelerated Tests for Biodegradable Implants

Magnesium alloys are promising biodegradable implant materials due to their excellent biocompatibility and non-toxicity. However, their poor corrosion resistance limits their application in vivo. Plasma electrolytic oxidation (PEO) is a powerful technique to improve the corrosion resistance of magnesium alloys. In this study, we present the accelerated degradation of PEO-treated AZ31 samples using a fluid dynamic test. The samples were prepared using different concentrations of KOH as an electrolyte along with NaSiO3. The anodizing time and the biasing time were optimized to obtain the increased corrosion resistance. The analysis of the degraded samples using microscopy, SEM EDX measurements, and by calculating mass loss and corrosion rates showed a significant increase in the corrosion resistance after the polymer (Resomer© LG 855 S) coating was applied to the anodized samples. The results confirm (or convince) that PEO treatment is an effective way to improve the corrosion resistance of AZ31 magnesium alloy. The fluid dynamic test can be used as an accelerated degradation test for biodegradable alloys in simulated body fluids at a physiological temperature. The polymer coating further improves the corrosion resistance of the PEO-treated AZ31 samples.

Performance of activated carbon derived from tea twigs for carbon dioxide adsorption

Activated carbon from agro-industrial waste, namely tea twigs derived from the processing of Camellia Sinensis branches, using a potassium hydroxide activator for CO2 adsorption has been conducted in this study. Various carbonization temperatures (4000C and 5000C) and heating times of 1 hour and 3 hours were used in this study. The concentration of potassium hydroxide (40% and 60%) and the ratios of activator solutions to carbon precursor made from pyrolysis of tea twigs (2:1 and 4:1) were varied for the chemical activation process. The effectiveness results of the obtained activated carbon were characterized through using Brunauer-Emmett-Teller analyzer and Temperature Programme Desorption-CO2 to determine the surface area and capacity maximum of CO2 adsorption. The optimum condition for the synthesis of activated carbon that produces high surface area was obtained at sample CCS 400/1 A2B1 where biochar carbonized at temperature of 400°C kept for 1 hour with a ratio of activator solution and precursor 4:1 using KOH concentration of 40%. The highest surface area was obtained 1,403 m2 g-1 with pore volume 0.9 m2 g-1 and pore size 1.11 nm and proved the presence of microporous areas in produced activated carbon. The maximum CO2 adsorption capacity obtained in this study was 5.1573 mmol g-1. This result could be related to the higher amount of microporous present in the activated carbon that facilitates the access of CO2 to the active sites at the pores of activated carbon.

Effect of Adding H2O2 on the Degradation of Methylene Blue Using CuO Catalyst

Research on the synthesis of CuO has been performed. Copper oxide (CuO) was synthesized via a precipitation method using varying concentrations of KOH. The synthesized CuO was characterized using FTIR and XRD techniques. The optimal CuO was obtained at a KOH concentration of 0.3 M. Photocatalytic activity was evaluated using methylene blue degradation in the presence of H2O2. The results indicated that CuO exhibited significant photocatalytic activity, with a maximum degradation efficiency of 96.5% achieved within 60 minutes. The reaction followed second-order kinetics with a rate constant of 0.0415 M-1min-1. These findings suggest the potential application of CuO as an efficient photocatalyst for environmental remediation.

Highly Efficient and Durable Water Electrolysis at High KOH Concentration Enabled by Cationic Group-Free Ion Solvating Membranes in Free-standing Gel Form.

The degradation of fixed cationic groups in most anion exchange membranes (AEMs) under alkaline environments limits their durability for alkaline water electrolysis (AWE). Ion-solvating membranes (ISMs) have emerged as a promising alternative to address this issue. Herein, a cationic group-free ion solvating membrane in a free-standing gel form (ISM-PBI-FG) is presented, created through a sol-to-gel transformation process followed by KOH imbibing. This approach yields a 3D porous microstructure composed of entangled polybenzimidazole (PBI) nanofibrils, achieving 89% porosity, which enables ultrahigh alkali uptake (346% in 6 M KOH) and exceptional ionic conductivity (763 mS cm-1 at 80 °C). The absence of cationic groups avoids the attack by OH-, thus ensures good alkaline stability with a conductivity retention rate of 91.6% over a 3120 h ex situ test in 6 M KOH. The resulting membrane delivered outstanding AWE performance with current densities of 5.5 A cm-2 using platinum-group-metal (PGM) catalysts and 2.2 A cm-2 using PGM-free catalysts at 2.0 V. Notably, the in situ electrolyzer device based on ISM-PBI-FG offers extensive operational flexibility ranging from 40-100 °C and demonstrates record durability in concentrated alkaline conditions, with a voltage decay rate of only 23.5µVh-1, outperforming most reported AEMs and ISMs.

POTASSIUM HYDROXIDE PRETREATMENT OF NAPIER GRASS: CONDITIONS FOR ENHANCED REDUCING SUGAR AND BIOETHANOL PRODUCTION

The recalcitrance of lignocellulosic feedstock needs to be altered for to produce fuels and chemicals. Pretreatment is used to enhance the reactivity of cellulose and the digestibility of biomass, resulting in the effective generation of fermentable sugars. Potassium hydroxide (KOH) is particularly effective at selectively removing lignin from biomass without excessively degrading cellulose and hemicellulose. Moreover, KOH is generally less corrosive than sodium hydroxide (NaOH), leading to lower maintenance costs for pretreatment equipment. In present study, Napier grass was utilized as the substrate for reducing sugar production. Proximate analysis indicated that Napier grass contains approximately 28.50±0.12% hemicellulose, 34.15±0.08% cellulose and 26.41±0.04% lignin. With the use of the Box-Behnken Design (BBD) method, pretreatment conditions were improved. The ideal conditions for KOH pretreatment of Napier grass were determined to be 6% KOH, 180 °C temperature, and a pretreatment time of 120 min. Higher yields of reducing sugars (43.29 g/L) were achieved by this optimized condition. By analyzing the experimental data, ANOVA helps in developing a reliable model that predicts the ideal conditions for increasing reducing sugar yield. Desirability functional studies were employed in optimization to identify ideal conditions that satisfy multiple criteria simultaneously, and the design was validated by trial experiments to ensure accuracy. Desirability studies confirmed that the optimal yield of reducing sugars, approximately 43.72 g/L, was achieved with 6.79% KOH concentration, at a temperature of 178.4°C, and a pretreatment duration of 119.6 min. The results are closely resembles the experimental values predicted by the response surface model. Substrates pretreated with higher KOH concentrations yielded more ethanol (72 g/L) from Saccharomyces cerevisiae in SSF tests compared to those pretreated with lower KOH concentrations.

Morphological and quality assessments of unary and binary base immersion-fabricated cupric/cuprous oxide nanoflake-coated copper

Mass production practicable fabrication techniques for wide-application-ranged cupric oxide (CuO) or cuprous oxide (Cu2O) nanostructures are crucial in its research-to-technology thrust. Films of CuO/Cu2O were grown onto copper as coating via a 16-day unary or binary immersion to solutions of barium hydroxide (Ba(OH)2) and/or potassium hydroxide (KOH) with varying concentration proportions. Physical inspection and Raman spectroscopy confirms the identity of the grown films to be CuO for all specimens under study except for the copper foil immersed in unary KOH wherein CuO coexists with Cu2O. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX) reveals the nanoflake morphology of the oxide layers with minimal traces of impurities (maximum impurity: 4.17 At.%) and the abundance of oxygen atoms (41.14–55.68 At.%) among the samples. Copper-to-oxygen ratio of the samples ranged from 0.7 to 1.41. Moreover, analysis of variance (ANOVA) reveals the significant differences of the film and flake thicknesses among the specimens under study. The average nanoflake thickness increases as Ba(OH)2 amount is decreased as opposed to KOH up to the binary immersed sample with equal component proportions (maximum average: 71.7 nm), then decreases as KOH concentration is increased in expense of Ba(OH)2 (minimum average: 29.5 nm). The average film thickness is highest for the 75-Ba(OH)2:25-KOH immersed foil and a decreasing trend is apparent as KOH is further increased at the expense of Ba(OH)2. Preliminary assessments may qualify the fabricated oxide nanoflakes on copper for potential applications.

Standalone green hydrogen production powered by photovoltaic panels and solar atmospheric water harvesting hybrid system: Experimental investigation

The current study experimentally investigates the performance of a hybrid standalone solar system of atmospheric water harvesting (AWH) and solar photovoltaic powering electrolyzer for green water and green hydrogen production. The system prototype is designed, constructed, and tested under outdoor summer and winter climate conditions of Alexandria, Egypt at different operating and design enhancement conditions. Water electrolyzes concept for green hydrogen production system driven by a photovoltaic panel and silica gel absorption/desorption atmospheric water harvesting solar still concept with insertion of porous sheet metals for freshwater production is performed and evaluated. The results show a rise of the AWH freshwater production of (60% and 120%) and (146% and 260%) in summer and winter, respectively with the insertion of one and two porous metal sheets, respectively. The maximum rise of the AWH efficiency is 82% in summer and 53.4% in winter by using 2 porous metal sheets. The hydrogen production rate of the system in summer is higher than that of winter by about 25%. System efficiency is almost doubled when electrolyzer KOH concentration increased from 4 gm/kg to 12 gm/kg water. The average daily system efficiency of the AWH, electrolyzer, and overall system reaches 11.6%, 65.1%, and 2.6% when operating at a KOH concentration of 12 gm/kg with two porous metal sheets. The study contributes to achieving mainly SDG goals 6, 7, and 13.

Exploring Two-Dimensional MOF-Derived Co/Ni Species for Efficient Electrocatalytic Hydrogen Evolution Reaction

Hydrogen evolution reaction (HER) has received a lot of attention due to its promising advantages in producing “green hydrogen” via electrocatalysis with low cost and high efficiency. Until now, developing transition metal-based electrocatalysts for HER has been a great challenge. In this regard, we reported a facile strategy to fabricate Co/Ni species encapsulated by carbon structure (CoNi@C) through annealing two-dimensional (2D) metal-organic framework (MOF) nanosheets. The CoNi@C that was prepared under 600 °C achieved the highest catalytic performance in 1.0 M KOH electrolyte with an overpotential of 330 mV to acquire 100 mA cm−2. In addition, the effect of KOH concentrations on the HER performance of CoNi@C-600 was explored. In 3.0 M KOH electrolyte, the current density of 100 mA cm−2 has been attained at a bias potential of 80 mV. The alkaline environment can improve the electrocatalytic performance and further enhance the stability of the as-prepared catalysts. This work would endow promising opportunities for manipulating MOF-based structures through pyrolysis to fabricate highly efficient electrocatalysts.

Prediction, modeling, and optimization studies of eco-friendly gold extraction using alpha-cyclodextrin and the RSM and CCD methods

In the Democratic Republic of the Congo, gold extraction from ore in South Kivu utilized alpha-cyclodextrin (α-CD) as an eco-friendly method to replace harmful methods. Analysis of variance and response surface methodology were employed for prediction, modeling, and optimization studies. Atomic absorption spectroscopy revealed a 0.06% gold content in a randomly taken ore sample. Leaching with modified aqua regia was optimized with the following parameters: 7.27 h, 50 g/L HBr concentration, pH 1, and 200 rpm stirring speed, resulting in 98.5% removal. Neutralization tests with potassium hydroxide (KOH) followed leaching to prepare the solution medium with appropriate pH for extraction test, by varying parameters such as time, KOH concentration, and pH. Following neutralization, extraction tests with α-CD were carried out and optimized with the following parameters: 40 min, α-CD concentration of 11.6166 g/L, and a pH of 5, resulting in a percent removal of 98.9%. α-CD’s eco-friendly nature, cost-effectiveness, and high percent removal make it a promising and sustainable alternative for gold recovery, appealing to the mining industry.

Furandicarboxylic Acid (FDCA): Electrosynthesis and Its Facile Recovery From Polyethylene Furanoate (PEF) via Depolymerization.

Replacing fossil fuels with renewable, bio-based alternatives is inevitable for the modern chemical industry, in line with the 12 principles of green chemistry. 2,5-Furandicarboxylic acid (FDCA) is a promising platform molecule that can be derived from 5-hydroxymethyl furfural (HMF) via sustainable electrochemical oxidation. Herein, we demonstrate TEMPO-mediated electrooxidation of HMF to FDCA in ElectraSyn 2.0 using inexpensive commercially available electrodes: graphite anode and stainless-steel cathode, thereby avoiding the often cumbersome electrode preparation. Key parameters such as concentration of HMF, KOH, and catalyst loading were optimized by experimental design. Under the optimized conditions, using only a low amount of TEMPO (5 mol %), high yield and Faradaic efficiency of 96 % were achieved within 2.5 h. Moreover, since FDCA is a monomer of the bio-based poly(ethylene furanoate), PEF, we aimed to investigate its recovery by depolymerization, which could be of paramount importance in the circular economy of the FDCA. For this, a new polar aprotic solvent, methyl sesamol (MeSesamol), was used, allowing the facile depolymerization of PEF at room temperature with high monomer yields (up to 85 %), while the cosolvent MeSesamol was recycled with high efficiency (95-100 %) over five reaction cycles.

Fabrication of interface with capping-bonding synergy to boost CO2 electroreduction to formate

The production of formic acid/formate from electrochemical CO2 reduction reaction (CO2RR) is fascinating but challenging due to the lack of highly active electrocatalysts. Herein, uniform PVP-capped bismuth nanospheres (PVP@Bi-NSs) with a capping-bonding synergy were optimally fabricated to enhance the CO2RR to formate. This study unveils the reaction process in Bi-based solution. It was found that the formation of PVP@Bi-NSs experienced five stages of Bi-O8 (I), Bi-O3 (II), Bi-O4 (III), Bi-Bi6 (IV), and PVP@Bi-NSs (V), corresponding to the nucleation in precursor solution, Bi(OH)3 precipitate, decomposition to KBiO2, reduction to metallic Bi, and PVP coating, respectively. By solvothermal treatment and simply modulating the KOH concentration in the precursor, the hydrophilic ends of PVP molecules can be well bonded to the Bi nanoparticles (Bi-NPs) to form a PVP-capping layer. Compared with the Bi-NPs without PVP coating, this uniform PVP@Bi-NSs displays a higher activity with a maximal Faradaic efficiency (FE) of 92.5 % and part current density (Jformate) of 158.2 mA cm−2 at −0.9 V vs. RHE in the flow cell as well as excellent stability, which is comparable to the state-of-the-art Bi-based catalysts. The maximum Jformate can reach 280 mA cm−2 with an FE of 87.3 % at −1.2 V vs. RHE, meeting the needs of industrial current density. Further characterizations show that the capping effect of PVP contributed to the uniform distribution of nanosized PVP@Bi-NSs, increasing the electrochemical surface areas (ECSAs) and the numbers of CO2RR active sites. The bonding effect of PVP to Bi-NPs enhanced the hydrophobic property of PVP@Bi-NPs, boosting the CO2 absorption and suppressing the hydrogen evolution reaction (HER). DFT calculations reveal that this fabricated structure facilitates the generation of *OCHO intermediate and benefits formate yield. This work provides a fascinating strategy for the design of Bi-based catalysts, enabling interface engineering toward high-efficiency CO2RR.

Glass Surface Nanostructuring by Soft Lithography and Chemical Etching.

Due to its high durability and transparency, soda lime glass holds a huge potential for several applications such as photovoltaics, optical instrumentation and biomedical devices, among others. The different technologies request specific properties, which can be enhanced through the modification of the surface morphology with a nanopattern. Here, we report a simple method to nanostructure a glass surface with soft lithography and wet-chemical etching in potassium hydroxide (KOH) solutions. Glass samples etched with a polymeric mask showed a nanopattern with stripes of widths between 220 and 450 nm and modulated heights between 50 and 200 nm. For different solution concentrations or etching times, the obtained nanopatterns led to an increase or reduction of the water contact angle. The largest increment, ~20 degrees, was achieved by etching the glass for 180 min with 30% KOH concentration, while a super-hydrophilic glass (~9° contact angle) was achieved when etching for 90 min with the same concentration. Optical characterization showed a very low influence of the nanostructured pattern on glass transparency and an increment in UV transmittance for some cases.

Energy-conversion efficiency for producing oxy-hydrogen gas using a simple generator based on water electrolysis

Producing hydrogen efficiently through water electrolysis could greatly reduce fossil fuel consumption. As well as this renewable energy source will also help combat global warming and boost economic investment opportunities. This paper studied some factors affecting the performance of oxy-hydrogen/hydroxy (HHO) gas generator, such as applied voltage (from 10.5 to 13.0 V) and electrolyte solution concentration (from 0.05 to 0.20 M), using a dry fuel cell based on the electrolyzing technique of water. The results revealed that the HHO gas production rate, power consumption, and temperature change of electrolyte solution increased significantly with increasing the tested applied voltage and electrolyte concentration. This study concluded that the optimum conditions for producing HHO gas ranged from 11.5 to 12.0 V for applied voltage and from 0.05 to 0.10 M for KOH concentration according to the lowest specific energy and highest HHO gas generator efficiency. Under the previous optimum conditions, the highest productivity, specific energy, and efficiency of the HHO gas generator were 343.9 cm3 min−1, 3.43 kW h m−3, and 53.79%, respectively, using 12.0 V for applied voltage and 0.10 M for electrolyte solution concentration. These findings provide an unambiguous direction for adjusting the operational factors (applied voltage and electrolyte concentration) for efficient HHO gas production and use in different applications. Furthermore, the required energy to operate the HHO gas generator can be obtained from renewable sources.

Synergistic Interactions in a Heterobimetallic Ce(III)-Ni(II) Diimine Complex: Enhancing the Electrocatalytic Efficiency for CO2 Reduction.

In this study, we propose a practical approach for producing a heterobimetallic Ni(II)-Ce(III) diimine complex from an extended salen-type ligand (H2L) to serve as an electrocatalyst for CO2 reduction and demonstrate an outstanding overall efficiency of 99.6% of the cerium-nickel complex and integrate it into applicable cell assemblies. We optimize not only the catalyst, but the operational conditions enabling successful CO2 electrolysis over extended periods at different current densities. A comparison of electrochemical behavior in H-cell and zero-gap cell electrolyzers suggests potential applications for industrial scale-up. In the H-cell electrolyzer configuration, the most elevated efficiency in CO production was achieved with a selectivity of 56.96% at -1.01 V vs RHE, while HCOO- formation exhibited a selectivity of 32.24% at -1.11 V vs RHE. The highest TON was determined to be 14657.0 for CO formation, followed by HCOO- with a TON of 927.8 at -1.11 V vs RHE. In the zero-gap electrolyzer configuration, the most efficient setup toward CO production was identified at a current density (CD) of 75 mA cm-2, a flow rate of 10 mL min-1, operating at 60 °C and utilizing a low KOH concentration of 0.1 M to yield a maximum faradaic efficiency (FECO) of 82.1% during 24 h of stable electrocatalysis.

Photoelectroreduction CO2 to Ethanol Over BiFeO3 with Synergistic Effect of Self‐Polarization and External Electric Field

The exploitation of semiconductor self‐polarization is an effective mean of improving the efficiency of electron utilization. In this work, the synthesis of BiFeO3 (BFO) samples with varying photoelectric properties is achieved by modulating the concentration of KOH. The experimental results reveal that BFO‐4 (4 m KOH) has excellent carrier efficiency. Interestingly enough, the ethanol yield of up to 7.05 μmol cm−2 h−1 in the photoelectrocatalytic process, which is 1.4 times than that of single electrocatalysis. Based on the characterization data, the external electric field forms a multi‐electric field coupling in the BFO (external electric field can enhance the self‐polarization electric field), which enhances charge separation efficiency and facilitates surface reactions, and the CO2 reduction performance is improved. Finally, the free energy in the key step of CC coupling on the surface of BiFeO3 is calculated by DFT. This study offers a valuable reference for the application of ferroelectric materials in the photoelectrocatalytic reduction of CO2 and the design of catalysts for C2+ products.

Response surface optimization of a single-step castor oil-based biodiesel production process using a stator-rotor hydrodynamic cavitation reactor.

In order to combat environmental pollution and the depletion of non-renewable fuels, feasible, eco-friendly, and sustainable biodiesel production from non-edible oil crops must be augmented. This study is the first to intensify biodiesel production from castor oil using a self-manufactured cylindrical stator-rotor hydrodynamic cavitation reactor. In order to model and optimize the biodiesel yield, a response surface methodology based on a 1/2 fraction-three-level face center composite design of three levels and five experimental factors was used. The predicted ideal operating parameters were found to be 52.51°C, 1164.8rpm rotor speed, 27.43min, 8.4:1 methanol-to-oil molar ratio, and 0.89% KOH concentration. That yielded 95.51% biodiesel with a 99% fatty acid methyl ester content. It recorded a relatively low energy consumption and high cavitation yield of 6.09 × 105J and 12 × 10-3g/J, respectively. The generated biodiesel and bio-/petro-diesel blends had good fuel qualities that were on par with global norms and commercially available Egyptian petro-diesel. The preliminary cost analysis assured the feasibility of the applied process.

Role of Intermolecular Interactions in Deep Eutectic Solvents for CO2 Capture: Vibrational Spectroscopy and Quantum Chemical Studies.

Recent research and reviews on CO2 capture methods, along with advancements in industry, have highlighted high costs and energy-intensive nature as the primary limitations of conventional direct air capture and storage (DACS) methods. In response to these challenges, deep eutectic solvents (DESs) have emerged as promising absorbents due to their scalability, selectivity, and lower environmental impact compared to other absorbents. However, the molecular origins of their enhanced thermal stability and selectivity for DAC applications have not been explored before. Therefore, the current study focuses on a comprehensive investigation into the molecular interactions within an alkaline DES composed of potassium hydroxide (KOH) and ethylene glycol (EG). Combining Fourier transform infrared (FT-IR) and quantum chemical calculations, the study reports structural changes and intermolecular interactions induced in EG upon addition of KOH and its implications on CO2 capture. Experimental and computational spectroscopic studies confirm the presence of noncovalent interactions (hydrogen bonds) within both EG and the KOH-EG system and point to the aggregation of ions at higher KOH concentrations. Additionally, molecular electrostatic potential (MESP) surface analysis, natural bond orbital (NBO) analysis, quantum theory of atoms-in-molecules (QTAIM) analysis, and reduced density gradient-noncovalent interaction (RDG-NCI) plot analysis elucidate changes in polarizability, charge distribution, hydrogen bond types, noncovalent interactions, and interaction strengths, respectively. Evaluation of explicit and hybrid models assesses their effectiveness in representing intermolecular interactions. This research enhances our understanding of molecular interactions in the KOH-EG system, which are essential for both the absorption and desorption of CO2. The study also aids in predicting and selecting DES components, optimizing their ratios with salts, and fine-tuning the properties of similar solvents and salts for enhanced CO2 capture efficiency.

Enhanced electrocatalytic activity of Ni-Mn-Co-Fe alloys for efficient hydrogen and oxygen evolution reactions: A study on the effects of electrodeposition parameters

The synthesis of high-performance and cost-effective electrocatalysts for water splitting and fuel cell processes is crucial for hydrogen energy production and is considered one of the most significant challenges. This work produced a Ni‒Mn‒Co‒Fe electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) via electrodeposition, which is a highly efficient and cost-effective method for synthesizing electrodes. The operating deposition parameters for Ni-Mn-Co-Fe were investigated, including the bath composition; scan rates of 5, 10, and 50 mV/s; pH values of 1.5, 3.5, and 7.5; bath temperatures of 25, 40, and 60 °C; and applied potentials ranging from −0.5 to −1.4 V vs. Ag/AgCl. The electrocatalytic activity of the electrocatalyst was evaluated at various temperatures and KOH concentrations. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were employed to estimate the electrocatalytic activity. The electrocatalytic performance of various electrodes for the HER and OER in alkaline environments, including Ni, Ni‒Mn, Ni‒Co, Ni‒Mn‒Co, Ni‒Mn‒Fe, and Ni‒Mn‒Co‒Fe, was examined. The results indicate that the Ni‒Mn‒Co‒Fe electrode required overpotentials of 436 mV and 447 mV to achieve a current density of 100 mA/cm2 for the HER and OER, respectively, demonstrating outstanding electrocatalytic activity. Moreover, after 20 h of electrolysis at a current density of 100 mA/cm2, the overpotential changes were minimal (less than 4 %), indicating exceptional electrochemical stability. As a bifunctional electrode in the overall water-splitting system, a cell voltage of 1.57 V vs. RHE is required to deliver a current of 10 mA/cm2.

Adsorption of dibenzofuran by modified biochar derived from microwave gasification: Impact factors and adsorption mechanism

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to the human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating or microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques, including BET, X-ray CT, SEM-EDS, FTIR, and XPS, are performed to identify the DBF adsorption mechanism on the biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. The higher porosity (16.94 %) and lower mineral content (1.75 %) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by the HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11 %) > KOH-modified CSC (77.14 %) > unmodified CSC (49.11 %) > unmodified OC (39.70 %) > HNO3-modified CSC (36.09 %). The adsorption mechanisms of DBF on the gasified biochar encompass the pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously.

Uji Kinerja Dry Cell Electrolyzer Dengan Pengaruh Konsentrasi Elektrolit Terhadap Produksi Hidrogen sebagai Sumber Energi Fuel Cell

Hydrogen is a renewable energy source with the potential to replace fossil fuels due to its eco-friendly nature. This study aims to conduct a performance test of dry cell electrolyzer with variations in KOH electrolyte concentration so that optimal hydrogen production in fuel cells can be determined. The dry cell was chosen to mitigate explosion risks in wet cells caused by short circuits and uncontrolled gas pressure in previous studies. KOH concentrations from 0.1 M to 0.5 M were tested at 10 V and 12 V for 30 minutes. The results indicate that a 0.3 M concentration at 12 V achieved the highest hydrogen yield of 1.1829 liters. The optimum condition was found at 0.3 M and 10 V with 37% efficiency, producing 0.8206 liters of hydrogen with an SEC of 31,656.65 J/L. This hydrogen powered a PEM fuel cell, achieving a maximum efficiency of 45.2% under an LED lamp load. This modification highlights potential improvements in electrolyzer performance for clean energy applications.