Papers by Keyword: MnO₂

Abstract: Enhanced Oil Recovery (EOR) techniques have evolved significantly to meet the demands of maximizing crude oil extraction from complex reservoirs. This study investigates the application of manganese dioxide (MnO₂) nanofluids in EOR, emphasizing the synergistic effects of electrochemical potentials and electromagnetic fields. MnO₂ nanoparticles were synthesized using a hydrothermal method at 160°C, yielding uniform spherical nanostructures approximately 50 nm in size. These nanofluids demonstrated promising properties including improved surface reactivity, wettability alteration, and interfacial tension reduction between oil and water phases. Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Analysis (EDAX) confirmed the structural and elemental purity of the nanoparticles. The experimental findings reveal that MnO₂ nanofluids can effectively mobilize trapped oil, especially under the influence of electromagnetic fields, which enhance nanoparticle dispersion and oil displacement. Pressure drop analysis during core flooding tests further confirmed increased recovery efficiency at optimal nanofluid concentrations, with 0.3% MnO₂ showing the highest performance. This research presents a viable approach to improving EOR outcomes through nanotechnology, offering a scalable and efficient method to recover residual oil in challenging reservoir conditions.

Abstract: In this study, the high specific capacitance material based on activated carbon-manganese dioxide (AC/MnO₂) composite was prepared by an impregnation method. The MnO₂ particle was synthesized via a redox reaction between KMnO₄ and lemon peel extract as a bioreductor. The steps taken in this research were the preparation of lemon peel extract, then synthesis of MnO₂ using lemon peel extract, synthesis of AC/MnO₂ composites, and electrodes characterization using powder XRD, SEM, and CV. According to the results, the AC/MnO₂ composite electrode had a higher specific capacitance compared to the synthesized MnO₂. The powder XRD test results show that the synthesized MnO₂ consisted of α, γ, and δ polymorphs. SEM data show that the average MnO₂ particle size is 482.80 nm. The CV test results show that the highest AC/MnO₂ capacitance is 188.17 F g^-1 which was obtained at an AC/MnO₂ ratio is 1:1. This suggests that the AC/MnO₂ composite material has the potential to be used as a supercapacitor electrode material.

Abstract: Attempts to study the effect of blend MnO₂ and PANI-MnO₂ nanocomposites in enhancing the productivity of an acrylic Pyramid Solar Still (PSS) is carried out. Synthesized nanocomposites assorted with black paint to improve the absorption efficiency. Size of the synthesized MnO₂ is found to be 35nm. SEM image infers particles are aggregates with random shape. Thermal analysis if distillate yield confirms the formation of nanocomposite with improved thermal stability of the PANI. Distillate yield is observed around 0.484 litre/0.25m², 0.568 litre/0.25m² and 0.615 litre/0.25m² still without and with MnO₂ and PANI-MnO₂ nanocomposites. Average efficiency is found to be 23.05%, 26.63% and 28.52% under three modes. Efficiency of the combined performance is amended due to the absorption properties of MnO₂ and PANI-MnO₂. Performance ratio under three modes are found to be 5.52 %, 6.44 % and 6.93 %. Results concluded that saturation vapour pressure and latent heat also plays a major hole in production of distillate yield.

Abstract: Application of energy storage systems such as supercapacitors can not be separated from the magnetic fields effect. In the last decade, it’s rare to find research reports about various low magnetic field effects on supercapacitor performance. Asymmetric supercapacitors based on MnO₂-Carbon were made to analyze its electrochemical performance changes by magnetic field in 0-50 mT. Magnetic field was applied in flow direction from cathode (MnO₂-C) to anode (C) during electrochemical performance test using Galvanostatic Charge-Discharge (C-D) instrument. The electrochemical performance was increasing in charging (91%) and discharging (22%) time of asymmetric supercapacitors. Impressively, the 50 mT magnetic field showed a high specific capacitance of 61.9 F/g at 0.1 A/g. The supercapacitor system delivers specific energy (17.8 Wh/kg), specific power density (329.72 W/kg), and outstanding stability (79% in 50 cycles). The electrochemical improvement by magnetic field indicates a highly promising application of this method in future supercapacitor devices.

Abstract: A facile and effective approach to assemble graphene hybridized multiple manganese oxides /graphene ((m-MnO₂/Gr) was explored. The structure varied from two-dimensional (2D) to one-dimensional (1D) club-shaped manganese oxides via blending of Gr into the molten salt precursor. Compared to the m-MnO₂ and pristine Gr electrode, the m-MnO₂/Gr composites displayed a superior synergistic effect in promoted capacitive performance, cycle performance, with capacity retention of about 90% after 2000 charge-discharge cycles. It expects to supply a promising strategy to synthesize large scalable production of hybrid supercapacitor electrode.

Abstract: Nickel-doped manganese dioxide (Ni-MnO₂) as electrode materials for supercapacitors were successfully prepared by one-step chemical liquid phase coprecipitation with the different nickel doped proportions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) were used to analyze the micro-structure, morphology and composition. And electrochemical properties were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectrometry (EIS). The results revealed that MnO₂ synthesized in this work turned out to be δ-MnO₂ of homogeneous dispersion and excellent electrochemical properties. Specific capacitance of 300.85 F/g was achieved for the 2% Ni-doped MnO₂ at 2mV/s through cyclic voltammetry, and after 5000 circles the persistence rate of which still remained to 75%, exhibiting a preeminent advantage of stability and reversibility to naked MnO₂.

Abstract: Tin oxide nanotubes (STs) were synthesized by the hydrothermal process using manganese dioxide nanowires (MWs) as a template and followed by oxalic acid treatment. The effect of the stannous chloride concentration on the structure and crystallite size of the product were investigated. The phase composition was determined by XRD. Morphologies were revealed by FESEM and TEM. Firstly, manganese dioxide nanowires were fabricated from KMnO₄. Then_, tin oxide nanoparticles were coated on the wall surfaces of MWs templates. The template was then leached out by oxalic acid treatment. Nanotubular structure of the final product was formed by the agglomeration of the tin oxide nanoparticles coating on the template surfaces. On increasing the stannous chloride amount, crystallite size and the electrochemical properties increased, while the specific surface area decreased.

Abstract: CO emission is one of biggest problem in environmental sector due to increasing number of motorcycle user in every years. CO is poison gas which directly affects on the public health and earth’s atmosphere. The aim of this research to developed catalyst in catalytic converter system to oxidize CO to CO₂ by using MnO₂/zeolite NaY. Zeolite NaY was synthesized by using hydrothermal method following by wet impregnation to form MnO₂/zeolite NaY, then the composite was characterized by XRD, FTIR, SEM-EDX, N₂ physisorption, and catalytic activity oxidation of CO was carried out using 4 tag motorcycle. The XRD result represent zeolite NaY synthetic has similar diffraction peak with zeolite NaY (JCPDS 39-1380), then infrared spectrum exhibit T-O-T at fingerprint area which exhibit vibration of zeolite NaY. Octahedral crystal was successfully observe by using SEM which represent zeolite NaY crystal similar with previous study. N₂ physisorp shows that the composite has type IV of isotherm which exhibit the micropore and mesopore was form into material. Then, MnO₂/zeolite NaY has good thermal stability as well as catalytic activity for CO oxidation, where the longer reaction time successfully to reduce the concentration of CO. Conversely, CO₂ concentration dramatically increase as function of reaction time.

Abstract: A study on the effect of heat treatment condition on the characteristics of MnO₂ added-Fe₂TiO₅ ceramics for NTC thermistor has been carried out. The ceramics were produced by pressing an homogenous mixture of Fe₂O₃ (local/ yarosite), TiO₂ and MnO₂ (2.0 mole %) powders in appropriate proportions to produce Fe₂TiO₅ based ceramics and sintering the pressed powder at 1050 °C for 3 hours in oxygen gas. Some sintered pellets were heat treated by heating them at 300 °C for 5, 15 and 25 minutes in Ar + 7% H₂ gas. The XRD analyses showed that the Fe₂TiO₅ ceramics with and without heat treatment time had orthorhombic structure. No peak from second phase was observed from the XRD profiles. From the electrical characteristics data, it was known that the heat treatment could change the electrical characteristics of the Fe₂TiO₅ based-thermistor. The thermistor constant (B) and room temperature resistivity (ρ_RT) decreased with the increasing of heat treatment time. All ceramics made had thermistor characteristics namely B = 3459-7596 K and ρ_RT = 1.056-6936.062 MΩcm. Thermistor constant of the ceramics was relatively big, indicated that ceramics made from local iron oxide in this work fit the market requirement for NTC thermistor.

Abstract: Fabrication of Fe₂TiO₅ pellet/disk ceramics-based NTC thermistor has been performed, in order to know the effect of sintering tempertures on the electrical characteristic of 1.0 mole % MnO₂ doped-Fe₂TiO₅ ceramics. These ceramics were made by mixing commercial powders of Fe₂O₃, TiO₂ and MnO₂ with proportional composition to produce Fe₂TiO₅ based ceramic. The raw pellet was sintered at 1100 °C, 1200 °C and 1300 °C temperature for 2 hours in air. Analysis of the microstructure and crystal structure were performed by using a scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. XRD pattern showed that all of Fe₂TiO₅ ceramics made ​​at various sintering temperatures are orthorhombic The SEM images showed that the grain size of pellet ceramics increase with increasing sintering temperatures. From electrical data that was measured at temperature 30-300 °C, showed that the addition of sintering temperature decreased the thermistor constant (B), activation energy (E_a), thermistor sensitivity (α) and room temperature resistance (R_RT). Thermistor constant (B) of the ceramics was relatively big of 5778 K to 6707 K. The value of B indicated that ceramics made in this work fit the market requirement for NTC thermistor.