NaOH Solution Research Articles

Paper-based degradable, label-free microRNA sensing platform based on oxide thin-film transistor arrays.

Paper-based degradable, label-free microRNA sensing platform based on oxide thin-film transistor arrays.

Extraction behaviors of aluminum and scandium from Sc-bearing aluminum residue by cascade leaching in NaOH and HNO3 aqueous solution

Extraction behaviors of aluminum and scandium from Sc-bearing aluminum residue by cascade leaching in NaOH and HNO3 aqueous solution

Alkalized MXene/laser-induced graphene-based integrated three-electrode devices for micro-droplet detection of albendazole.

Alkalized MXene/laser-induced graphene-based integrated three-electrode devices for micro-droplet detection of albendazole.

Influence of oxysalts on plasma electrolytic oxidation (PEO) of titanium performed in NaOH solution for corrosion protection

Influence of oxysalts on plasma electrolytic oxidation (PEO) of titanium performed in NaOH solution for corrosion protection

A multi-approach study on CO2 absorption in packed beds: Theoretical, experimental, and CFD perspectives on gas phase pulsation

A multi-approach study on CO2 absorption in packed beds: Theoretical, experimental, and CFD perspectives on gas phase pulsation

Peningkatan Pemurnian Minyak Jelantah melalui Sistem Adsorben Ganda: Bleaching Earth dan Karbon dari Kulit Buah Kakao (Theobroma cacao L)

Used cooking oil (minyak jelantah) is a household and industrial waste product that poses environmental risks and undergoes significant quality degradation due to the breakdown of chemical compounds during repeated use. This study aims to evaluate the effectiveness of a combination of activated carbon derived from cocoa pod husk waste and bleaching earth in improving the quality of used cooking oil. The research was conducted experimentally in the laboratory of Universitas Negeri Padang using used cooking oil obtained from local vendors. Activated carbon was prepared by calcining cocoa pod husks at 350°C for varying durations of 30, 45, 60, and 75 minutes, followed by activation with 1M NaOH solution. The purification process was carried out in stages through the addition of activated carbon and bleaching earth under controlled heating conditions. Parameters analyzed included acid number, moisture content, density, saponification value, and functional group characterization using infrared spectroscopy (FTIR). The results indicate that the most effective adsorbent combination was achieved with activated carbon calcined for 60 minutes, which reduced the acid number from 14.92 to 5.09 mg KOH/g, decreased moisture content to 0.11%, and increased the saponification value to 75.30 mg KOH/g. The FTIR spectrum showed reduced intensity in functional groups associated with degradation, indicating effective purification. In conclusion, the combination of activated carbon from cocoa pod husk waste and bleaching earth is proven effective in improving the physicochemical quality of used cooking oil, while also demonstrating the potential for sustainable and environmentally friendly use of agricultural waste as raw material for adsorbents.

Pemanfaatan Karbon Aktif Daun Serai (Cymbopogon citratus) dan Bleaching Earth dalam Penjernihan Minyak Jelantah

Used cooking oil is a household waste with the potential to pollute the environment and pose health risks if discarded improperly or reused without adequate treatment. This study aims to purify used cooking oil through a two-stage adsorption method using activated carbon derived from lemongrass leaves and Bleaching Earth. In the first stage, activated carbon was synthesized from lemongrass leaves calcined for 60 minutes and activated with 2N NaOH solution, followed by the addition of Bleaching Earth in the second stage. The quality of the oil before and after purification was assessed through analyses of density, acid number, saponification value, moisture content, and infrared spectrum (FTIR). The results indicate that activated carbon calcined for 60 minutes (MJ-C60) yielded the best outcome, reducing density to 0.9414 g/mL, lowering moisture content from 0.34% to 0.16%, and increasing the saponification value from 41.5650 to 63.7075 mg KOH/g. The acid number also decreased from 13.2302 to 8.3288 mg KOH/g. FTIR analysis revealed the presence of ester C=O groups around 1743 cm⁻¹ and aliphatic C–H absorption bands at 2850–2950 cm⁻¹, indicating that the triglyceride structure remained intact. These findings demonstrate that the combination of activated carbon from lemongrass leaves and Bleaching Earth is effective in improving the clarity and physicochemical quality of used cooking oil, while offering an environmentally friendly solution based on organic waste utilization.

Characterization and Treatment Pharmaceutical Wastewater by Photo-Fenton Process

The characteristics of the PT X pharmaceutical wastewater influent were a pH of 7.18, a COD of 384 mg/L, and a red-brown color. The Chemical Oxygen Demand (COD) has not met the quality standards based on the Ministry of Environment and Forestry Regulation No. 5 of 2014. The red-brown color was caused by wastewater containing rifampicin as a component of the tuberculosis drug. The objectives of this study were treating the real pharmaceutical wastewater to reduce COD and color by varying the molar ratio of the Fenton reagents and to identify the influence of the neutralization process. The Fenton reagents were FeSO4.7H2O and H2O2 with a molar ratio of 1:1.5, 1:2, and 1:3. The process was conducted with the help of UV light and acidic conditions. The photo-Fenton process produced residues, which can be neutralized by using 0.1 NaOH solution and coagulated by using NaCl. The neutralization process successfully decreases the amount of Fe, H2O2, and COD on liquid. The results showed that the best molar ratio is 1:2, which can be seen from the removal efficiency of organic compounds of 89.58%, and the color decrease is seen from the decrease in absorbance value.

Asymmetric Iron Complex as a Potential Catholyte for Alkaline Aqueous Redox Flow Battery

ABSTRACTAn alkaline all‐iron complex aqueous redox flow battery (AAICARFB) is an RFB that utilizes iron complex as the active material for both its anolyte and catholyte. A key limitation of iron‐based RFBs is the use of solid Fe, which prevents full separation between the cell stack and the electrolytes, hindering scalability. This study investigates the properties and performance of iron dicarboxylic bipyridine cyanide electrolytes in alkaline conditions as potential catholytes for AAICARFB, evaluating them as alternatives to ferrocyanide (Fe(CN)6). The higher redox potential and solubility of the complexes compared with Fe(CN)6 at neutral pH mean that the AAICARFB that uses the iron dicarboxylic bipyridine cyanide catholyte has the potential to have higher cell voltage and energy potential compared with previous configurations, as energy density depends on both cell voltage and solubility. Catholytes made using Na4[Fe(Dcbpy)3], K4[Fe(Dcbpy)3], Na4[Fe(Dcbpy)2(CN)2], K4[Fe(Dcbpy)2(CN)2], and Na4[Fe(Dcbpy) (CN)4] dissolved in strongly alkaline NaOH or KOH solution were studied. As a result, the Na4[Fe(Dcbpy)(CN)4] was the only iron dicarboxylic bipyridine cyanide complex to exhibit redox activity in alkaline media. It demonstrated a higher redox potential than Fe(CN)6 and better solubility than some Fe(CN)6 electrolyte configurations in alkaline conditions. These findings suggest that the Na4[Fe(Dcbpy)(CN)4] catholyte has the potential to enhance the energy density of AAICARFB systems.

Assessing the effectiveness of bentonite-FA and bentonite-marble dust in sustainable landfill liners compared to traditional bentonite-sand liner based on swelling and permeability property subjected to permeate solution

Abstract Landfill liners are crucial barriers against environmental contamination from wastes. This paper attempted to evaluate the suitability of two alternative materials, namely waste fly ash and marble dust amended with bentonite, as potential alternatives in landfill liners, considering mainly their swelling and permeability properties against the traditional, bentonite-sand liner. Laboratory experiments performed in the present research work for evaluating permeability and swelling properties of fly ash-sand-marble dust mixtures with bentonite. Under the permeate solutions conditions of CaCl₂, HCl, and NaOH, the swelling and permeability behavior of the mixtures were studied. The experimental results and findings clearly show under the under the permeate solution of CaCl2, the mixtures 4OB+60MD, 40B+60FA, 25B+75S or 30B+70S, under the permeate solution of NaOH, the mixtures 35MD+65B, 35FA+65B, 20S+80B or 25S+75B and under the permeate solution of HCl, the mixtures 4OB+60MD, 40B+60FA, 25B+75S or 30B+70S under the concentration from 1N to 2 N gives optimum result based on requirement of EPA. Finally, the bentonite-amended waste fly ash and marble dust mixes could in the future become an effective, sustainable alternative to bentonite-amended sand in the landfill liners. Adopting these materials could reduce the environmental impact of landfill construction and promote a circular economy by repurposing industrial waste, thereby contributing to more sustainable landfill management practices.

Reduction of tar, sulfur, chlorine and CO2 in syngas produced by gasification of refuse-derived fuel pellets

Effective waste management is an increasingly urgent global challenge, with gasification emerging as promising alternative to conventional disposal methods. However, the major challenge in thermochemical waste processing is the presence of contaminants in the product streams. Therefore, this study focuses on the experimental gasification of refuse-derived fuel (RDF) pellets, with the aim of characterizing the products, analyzing contaminant distribution, and purifying the syngas from multiple contaminants simultaneously. Gasification experiments were conducted in a two-stage batch reactor, and the produced syngas was purified using two continuous packed absorption columns. Yields of gaseous, liquid, and solid products were 52.5%, 23.5%, and 7.3%, respectively. Resulting char exhibited a lower heating value (LHV) of 18.24 MJ/kg and retained 76.8% of the sulfur and 35.8% of the chlorine from the RDF. Heavy metal concentrations in the char remained below environmental limits. Syngas achieved a maximum LHV of 11.9 MJ/Nm3. Its purification using aqueous solutions of NaOH and methyl-diethanolamine achieved removal efficiencies of 97.77% for H₂S and 43.06% for COS. Efficiency of HCl removal with NaOH solution ranged from 82.15% to 89.27%, also contributing to CO₂ removal. Tar content in the syngas was significantly reduced through catalytic treatment with Ni/activated carbon, achieving a maximum removal efficiency of 85.89%. Concentrations of key contaminants in syngas were reduced to 6.13 ppm for H2S, 41.58 ppm for COS, 19.37 mg/Nm3 for HCl, and 2.11 g/Nm3 for tar. These results demonstrate the feasibility of integrated gasification and multi-contaminant purification for producing cleaner syngas from RDF, advancing sustainable waste-to-energy solutions.

Synthesis and Structural Characterization of Hydroxy Butyl-β-cyclodextrin

Hydroxy butyl-β-cyclodextrin was successfully synthesized in 1.5% NaOH solution to possess the highest yield of 75.350 ± 0.030% and degree of substitution of 5.230 ± 0.012 prior to structurally characterized. The study employed infrared radiation for main functional groups, 1H, 13C, distortionless enhancement by polarization transfer, correlation spectroscopy, heteronuclear single quantum coherence, heteronuclear multiple bond correlation nuclear magnetic resonance spectra in deuterium oxide solution and mass spectroscopy data to confirm the required structure of the hydroxy butyl-β-cyclodextrin derivatives with varying degrees of substitution.

SODIUM CYANIDE GENERATION BY COAL GASIFICATION

The aim was to assess the technological feasibility of generating sodium cyanide by coal gasification, to study the effects of the process parameters (temperature, experiment duration, coal type) on the concentration of sodium cyanide in the resulting solutions, as well as to identify optimal modes of the process. Experiments were carried out on a laboratory setup consisting of a tubular cylindrical furnace equipped with a working compartment in the form of a corundum tube. Lignite and charcoal, preliminarily crushed to increase the specific surface area, were investigated. A solution of sodium cyanide was produced by sorption of gaseous hydrocyanic acid (a syngas component) with a sodium carbonate solution. A NaOH solution (pH = 10) installed in an ice bath was used in the system of absorbers. The content of sodium cyanide in the solution was determined by the titrimetric method. The HSC Chemistry 5.1 software package was used for thermodynamic calculations. During the gasification of charcoal in the temperature range 600–800oC, sodium cyanide solutions with a concentration of 0.03–0.08 wt% were obtained. An increase in temperature from 600 to 900oC led to a 4-fold decrease in the concentration of sodium cyanide in an alkaline solution, under the same duration of the experiments. A regression equation was derived for the dependence of the NaCN concentration in solution on the temperature of coal gasification and the duration of the process. It was shown that the generation of sodium cyanide by coal gasification under laboratory conditions yields sodium cyanide concentrations in solution comparable to those used for gold cyanidation at gold recovery plants. The installation of sodium cyanide generation lines directly at the production areas of gold recovery plants will reduce the production costs by eliminating expenses for purchasing, transporting and storing reagents.

Effect of NaOH Steam on Swelling and Cleaning of Food Soil Layers

AbstractIn conventional cleaning‐in‐place (CIP) processes, only a small fraction of cleaning fluids directly contacts soil layers, limiting their effectiveness. Alternatively, steam can be incorporated into CIP procedures, offering advantages such as prolonged contact time, reduced chemical and water consumption, and enhanced wetting of spray shadow areas. This study specifically investigates the effect of steam during the swelling phase of soil layers. Experiments were conducted using steam, NaOH steam, water, and NaOH solution, respectively. Steam demonstrated an over 100 times higher swelling efficiency compared to liquids. Cleaning studies demonstrated that the use of steam achieved similar cleaning times to water‐swollen soil layers, while NaOH resulted in shorter times, with steam being twice as resource‐efficient.

TECHNOGENIC WASTE AS A NEW INORGANIC BINDER

Every year 9.2 billion tonnes of industrial waste are generated worldwide. This is waste from industrial manufacturing processes that’s often a by-product with no further use.In addition to occupying huge areas for disposal of construction waste, this waste pollutes land, water and air. Responsible industrial waste management is vital to reduce such risks. The paper presents the possibility of utilizing construction waste to produce a binding material that could be used instead of cement. In this paper, the mechanical properties of geopolymer based on fly ash from the "Stanari" thermal power plant near Doboj, granulated blast furnace slag from Arcelor Mittal Zenica, quartz sand, as well as the mechanical properties of Portland cement CEM I 52.5 N and cement with the addition of granulated blast furnace slag were examined. A mixture of water glass and 12 M NaOH solution is used as an activation agent for the preparation of geopolymer. Samples of portland cement CEM I 52.5 N, cement with addition of GBFS and geopolymer were produced and tested according to standard EN 196-1:1994. Geopolymers do not have high compressive strength values like cement CEM I 52.5, but they can replace cement in constructions with lower load capacity.Please do not change the given formatting.

The effect of cupola furnace iron slag on the physical and mechanical properties of alkali-activated fly ash-based mortars

Abstract This study investigates the physical and mechanical properties of alkali-activated mortars, in which thermal power plant fly ash (FA) was partially replaced by cupola furnace iron slag (IS). An optimal mix design determined through preliminary tests consisted of an aggregate-to-binder ratio of 1.5 (by weight), NaOH solution concentration of 10 M, Na₂SiO₃ (liquid) to NaOH (solid) ratio of 2, and a water-to-binder ratio of 0.3, all maintained consistently across mixtures. Chemical compositions and phase structures of raw materials were characterized using X-ray fluorescence (XRF) and X-ray diffraction (XRD), respectively. Particle size distribution was determined by laser diffraction analysis, and microstructural morphology was examined using scanning electron microscopy (SEM). Bulk density and apparent porosity were measured using Archimedes’ method with water as the immersion medium. Mechanical properties were evaluated through compressive strength and three-point bending tests after 28 days of curing. Results showed that mortars incorporating 75 wt% cupola furnace iron slag as a fly ash replacement exhibited superior performance, achieving a bulk density of 2118 kg/m³, apparent porosity of 12.2%, compressive strength of 44 MPa, and flexural strength of 10.2 MPa. These findings highlight the potential of iron slag as an effective supplementary material in alkali-activated mortars, enhancing mechanical properties and contributing to microstructural densification.

Synthesis, molecular interactions, and antioxidant properties of a new terpolymer: formation of epoxy-based terpolymer composite on glass

A new chloroacetophenone-based acid-catalyzed terpolymer has been synthesized from vanillylidenacetone/4-hydroxystyryl methyl ketone, formaldehyde, and chloroacetophenone. Characterization of the terpolymer was done by using FTIR and 1H NMR data. Thermal stability/behavior of new terpolymers determined by DSC and TGA. Ultrasonic properties, including ultrasonic velocity, density, adiabatic compressibility, specific acoustic impedance, viscosity, intermolecular free length, and relaxation time, were studied successfully in DMSO. The average molecular weight of the polymer has been reported. The antioxidant property of acetophenone-based terpolymer is reportedly against DPPH (2,2-diphenyl-1-picrylhydrazyl), with a 1.66 mg/mL IC50 value. The synthesized terpolymer was used as an epoxy curing agent in a 50% weight ratio, along with DGEBA (diglycidyl ether of bisphenol A) resin at 453.15 K. The thermal stability of the epoxy-polymer composite was investigated using a TGA analysis. Chemical stability of the composite was estimated using strong acid (concentrated HCl), saturated NaOH, and NaCl solution. Surface morphology of the epoxy composite was examined using SEM analysis.

Mechanical Properties of Surface-Treated Bamboo Strip-Reinforced Biobased Polyamide Composites.

Fully bio-based composites were obtained from continuous bamboo strips and flame-retardant polyamide 11 (PA11-FR) matrix. A mercerization treatment was performed on the bamboo strips surface to optimize fiber-matrix interactions. Composites were obtained by thermocompression molding with two pressure plateaus. The influence of the concentration of NaOH solution treatment was analyzed. The thermogravimetric analysis highlighted that the mercerization treatment removes part of hemicellulose, low molecular weight lignin and amorphous cellulose, while crystalline cellulose is preserved. Dynamic mechanical analysis performed in the shear configuration revealed the level of interactions between bamboo strips and PA11-FR matrix. The glassy modulus was improved for the composites compared to the matrix and their rubbery modulus was increased by a factor 4.6. Composites with bamboo strips treated at 1% NaOH showed the highest shear modulus across the entire temperature range with an increase by a factor of 1.39 on the glassy plateau and 1.3 on the rubbery plateau, with the untreated bamboo strips/polyamide 11-FR composite as reference. Water uptake was analogous for composites and bamboo strips, so the shear modulus at room temperature was not impacted by moisture.

THE POTENTIAL OF FALOAK BARK (STERCULIA QUADRIFIDA R.BR.) as an ACTIVATED CARBON PRODUCT THROUGH PHYSICAL-CHEMICAL ACTIVATION METHOD

Faloak is a plant species native to the East Nusa Tenggara region and Australia, widely used by the local community in NTT as an herbal medicine, particularly in treating liver disease, digestive disorders, and fatigue. However, this study presents a new application by analyzing its physical-chemical properties and evaluating its effectiveness in the synthesis of activated carbon. This study aims to explore and analyze the potential of Faloak bark as a source of activated carbon, which has not been examined in previous research. This research uses a quantitative approach by conducting controlled laboratory experiments to measure and analyze the variation in activator concentration on the water and ash content of activated carbon. The research applied the physical-chemical activation method. The physical activation process involved heating at temperatures ranging from 250°C to 450°C, while chemical activation was conducted using ZnCl₂ and NaOH at concentrations of 1 N, 2 N, and 3 N. This method was selected to determine the optimal conditions for converting Faloak bark into activated carbon, focusing on temperature and chemical activators. The findings indicate that the optimum temperature for activated carbon formation is 300°C. Additionally, tests using chemical activators showed that Faloak bark performs best with a 2 N NaOH solution, as evidenced by ash and water contents of 0.03% and 0.65%, respectively. Functional group analysis through FTIR testing identified the presence of (hydroxyl), aromatic C=C, and carbonyl C=O groups, further supporting the potential of Faloak bark as a viable material for activated carbon production. The findings suggest that Faloak bark has significant potential to be developed into an activated carbon product.

Investigation of Microstructural Effects on Electrochemical Micro-machining Behaviour of Inconel 718 Superalloy in Mixed Solution of NaNO3 and NaOH

Abstract Inconel 718 Nickel-based superalloys, pivotal in aerospace for their superior mechanical properties tied to microstructures and precipitates, are the focus of this study. In this work, microstructures and precipitates are altered through solutionizing and aging treatments. The impact of such alterations on anodic dissolution, and hence on electrochemical micromachining (ECMM) is presented. The microstructures and precipitates, and their evolution by different heat treatments are assessed using advanced microscopy techniques (EBSD, SEM, EDS, TEM). Polarization studies and dissolution tests revealed that the age heat-treated samples showed improved anodic dissolution due to a larger volume fraction of δ precipitates. During ECMM, higher machining precision was obtained in mixed NaNO3 + NaOH solutions compared to NaNO3 solutions, attributed to the presence of a thinner and compact passive layer. Machining outcomes (overcut, surface integrity) are found to be influenced by microstructures and precipitates tuned via heat-treatment processes.