Field Emission Scanning Electron Microscopy-energy Dispersive X-ray Research Articles

Structure, Surface Topography, and Glass Transition Temperature of Dental Poly (Methyl Methacrylate) Resin Conjugated with 3,9-bisethenyl-2,4,8,10-tetraoxaspiro [5,5] Undecane as Cross-linker: An In Vitro Research.

To characterize and analyze the structural presentation of a new denture base copolymer with a spiro-acetal cross-linker at 10 and 20 wt.% concentrations by nuclear magnetic resonance (NMR) and field emission scanning electron microscopy-energy-dispersive X-ray (FESEM-EDX) spectroscopies. Also, to evaluate the glass transition temperature (TG) of the new copolymer. The investigational groups G10 and G20 were heat-cured with the new spiro-acetal cross-linker at the above-mentioned concentrations, respectively. The control group G0 was heat-cured without the new cross-linker. Nuclear magnetic resonance and EDX spectroscopies determined the copolymerization along with elemental composition. The surface characteristics were discerned by FESEM. Differential scanning calorimetry was employed to evaluate the TG of the resultant copolymer. Appropriate statistical operations were performed to compare the mean TG of the groups. The new copolymer's structure with the spiro-acetal cross-linker was configured with protons, carbons, aluminum, zirconium, yttrium, and silicon atoms. The TG of the resultant copolymer was high when compared with the G0. The 20 wt.% spiro-acetal cross-linker in the copolymer exhibited the highest TG. The spiro-acetal cross-linking comonomer incorporated in the heat-cure denture polymer produced a new denture base copolymer with elevated TG. The resultant configuration of the new copolymer was characterized, structurally presented, and confirmed. The new copolymer might exhibit augmented strength due to the copolymerized spiro-acetal cross-linker. Moreover, the smooth and regular surface of the copolymer would have minimum or negligible microbial adhesion due to the hydrophobicity of the spiro-acetal comonomer incorporated in the denture base composition. How to cite this article: Ravivarman C, Ajay R, Saatwika L, et al. Structure, Surface Topography, and Glass Transition Temperature of Dental Poly (Methyl Methacrylate) Resin Conjugated with 3,9-bisethenyl-2,4,8,10-tetraoxaspiro [5,5] Undecane as Cross-linker: An In Vitro Research. J Contemp Dent Pract 2024;25(5):486-493.

Theoretical and Experimental Study for Cross-Coupling Aldol Condensation over Mono- and Bimetallic UiO-66 Nanocatalysts

Mono- and bimetallic UiO-66 nanocatalysts were synthesized using the solvothermal synthesis method and evaluated in the aldol condensation reaction of benzaldehyde and acetone in a batch reactor. N2 physisorption, thermogravimetric analysis, temperature-programmed desorption of ammonia, X-ray diffraction, field-emission scanning electron microscopy–energy-dispersive X-ray, X-ray photoelectron spectroscopy, potentiometric titration, and Fourier transform infrared were used to characterize the nanocatalysts. The higher activity exhibited by the Zr/Hf-UiO-66 catalyst could be attributed to the lower orbital energy interaction with benzaldehyde, as shown by density functional theory. A synergetic effect is observed for the bimetallic UiO-66 nanocatalyst between Zr and Hf, obtaining a higher reaction rate than the monometallic nanocatalysts. Meanwhile, this antagonistic effect was shown in the bimetallic catalysts between Zr and Ce, which was less active than the monometallic UiO-66 catalyst due to free COOH generated during the synthesis. Finally, the selectivity results showed that incorporating Hf and Ce on Zr-UiO-66 favors benzalacetone formation by cross-coupling condensation of benzaldehyde and acetone at isoconversion conditions.

Silver nanoparticle based efficient colorimetric assay for carbaryl – An insecticide

Metal nanoparticles capped with polymers have been employed for multiple analytical and biomedical applications. In this study, highly stable polypropylene glycol (PPG) capped silver nanoparticles (PPG-AgNPs) were synthesized by chemical reduction method. The characterization of PPG-AgNPs was performed by zeta sizer, UV–visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy energy dispersive X-ray (FESEM-EDX), and atomic force microscopy (AFM). Moreover, PPG-AgNPs were employed as a chemosensor for an insecticide of the carbamate family, Carbaryl. PPG-AgNPs based colorimetric assay render a quantitative, rapid, selective, and efficient detection of carbaryl in an analytical range of 0.05–100 µM in the presence of several other pesticides/insecticides, salts, and drugs. The limit of detection and quantification of the proposed assay for carbaryl were as low as 0.005 µM and 0.016 µM, respectively. The major strength of the proposed PPG-AgNPs based assay is its efficiency for on-spot detection of carbaryl in ecological, biological, and food samples away from a sophisticated laboratory setup. While the quantitative performance of the proposed sensor for carbaryl is comparable with UPLC and UV–Vis spectroscopy in standard conditions, the performance of the PPG-AgNPs based CAR sensor stands out for environmental, biological, and food samples.

The synthesis of zirconium oxide (ZrO2) nanoparticles (NPs) in 1-butyl-3-methylimidazolium trifluoroacetate (BMIMCF3COO) for an amperometry phenol biosensor

A novel zirconium oxide (ZrO2) nanoparticles (NPs) was synthesised utilising 1-butyl-3-methylimidazolium trifluoroacetate (BmimCF3COO) as an effective capping agent to reduce agglomeration and further improve the size of the developed NPs. The purity and properties of the ZrO2 NPs were assessed through characterisation with Fourier-transform infra-red, ultraviolet-visible, transmission electron microscopy, field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX), and X-ray diffraction. Subsequently, the ZrO2 NPs was incorporated on the modified screen-printed carbon electrode (SPCE) via glutaraldehyde (GA) cross-linking before immobilisation of tyrosinase (Tyr). Cyclic voltammetry and FESEM-EDX were selected to investigate the electrochemical properties and surface morphology of modified carbon SPCE. The surface of a modified electrode demonstrated a larger coagulant with significant porosity due to the nano-sized of ZrO2. The electrocatalytic response of the resulting ZrO2 NPs/GA/Tyr to phenol was evaluated by employing the chronoamperometry method. The resultant current response was compared to the phenol concentration from the reduced quinone formation on the modified electrode surface. The developed biosensor exhibited excellent linearity for phenol within the 10 and 90 µM (R2 = 0.9907) range with sensitivity and limit of detection (LOD) of 10.522 µA/mM and 9.468 µM, respectively, under optimal conditions. The bioelectrode exhibits satisfactory percent recovery (75–125 %) using spiked water samples from rivers and industries. Moreover, the biosensor demonstrated reasonable repeatability, reproducibility, anti-interference properties, high sensitivity, and tremendous storage stability for at least 20 days. The accomplishment of the as-prepared phenol biosensor could pave the way for a portable diagnostics strategy for rapid detection of phenol in the water sample.

Green Synthesis, Characterization, and Catalytic Activity of Amine-multiwalled Carbon Nanotube for Biodiesel Production

An amine-functionalized multiwalled carbon nanotube (MWCNT) was prepared for use as a basic heterogeneous catalyst for the conversion of Cocos nucifera (coconut) oil and Hibiscus cannabinus (kenaf) oil to biodiesel. The 3-aminopropyltrimethoxysilane (3-APTMS) was chosen to form an amine-reactive surface to bind with hydroxyl (−OH) and carboxyl (−COOH) groups of oxidized MWCNT. Silanization took place using a green surface modification method in which supercritical carbon dioxide fluid was utilized under the following conditions: 55 °C, 9 MPa, and 1 h. The synthesized catalyst was characterized using Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Field emission scanning electron microscopy–energy dispersive x-ray (FESEM-EDX), Time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray powder diffraction (XRD), and Brunauer–Emmett-Teller (BET). Transesterification of coconut oil using 10 wt% NH2-MWCNT catalyst (3 wt% APTMS), 12:1 molar ratio of methanol and oil at 63 °C for 1 h resulted in a >95% conversion. On the other hand, the same catalyst was used in the transesterification of kenaf oil, and formation of ammonium carboxylated salt was observed. The effects of temperature, pressure, and silane concentration on surface modification of MWCNT were evaluated in terms of the catalyst’s basic site density and fatty acid methyl ester conversion. The results indicate that reaction temperature and silane concentration had the most significant effects. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Carboxylate-functionalized dragon fruit peel powder as an effective adsorbent for the removal of Rhodamine B (cationic dye) from aqueous solution: adsorption behavior and mechanism

In this study, we used a simple and low-toxicity chemical treatment to make a carboxylate-functionalized dragon fruit peel powder (CF-DFPP) from dragon fruit peel to improve its capacity for adsorbing Rhodamine B (RhB) from an aqueous medium. Field Emission-Scanning Electron Microscopy/Energy-Dispersive X-ray (FE-SEM/EDX), point of zero charges (pHPZC), Brunauer-Emmett-Teller (BET), and Fourier Transform Infrared (FT-IR) analyses were performed to characterize the adsorbent materials. The adsorption performance and mechanism for the removal of RhB were examined. The kinetic, isotherm and thermodynamic parameters were employed to evaluate the adsorption mechanism. Compared to other models, the Langmuir isotherm and PSO kinetic models better defined the experimental data. CF-DFPP adsorbent exhibited a maximum adsorption efficiency of 228.7 mg/g at 298 K for RhB adsorption. Thermodynamic analysis revealed that the adsorption of RhB by CF-DFPP was spontaneous (ΔGo < 0) and exothermic (ΔHo < 0) nature of the process. Different eluting agents were used in desorption tests, and NaOH was revealed to have greater desorption efficiency (96.8%). Furthermore, regeneration examinations revealed that the biosorbent could effectively retain RhB, even after six adsorption/desorption cycles. These findings demonstrated that the CF-DFPP might be a novel material for removing RhB from an aqueous medium.

A Study on the Catalytic Technology for Reduction of Naphthenic Acid Compound from Acidic Crude Oil

The existence of naphthenic acid (NA) in acidic crude oil tends to corrode the oil refinery equipment. In this study, a catalytic deacidification reaction involving the deacidifying agent and the synthesised catalyst was aimed to eliminate NA from acidic crude oil. Diethanolamine-polyethylene glycol (DEA-PEG) was introduced as a deacidifying agent. The wet impregnation method was applied for synthesizing the calcium oxide catalyst doped by copper supported on alumina (Cu/Ca/Al2O3). The potential catalyst was characterised utilising field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX), Brunauer-Emmett-Teller (BET), and X-ray diffraction spectroscopy (XRD). The parameters include deacidifying agent dosing, loading dopant ratio and catalyst calcination temperature were performed to enhance the catalytic deacidification process in this study. Data showed that the total acidic number (TAN) value for crude B met the PETRONAS requirement for the TAN value below one using 1500 mg/L of DEA-PEG assisted by Cu/Ca (10:90)/Al2O3 catalyst.

Copper(0) nanoparticles immobilized on SBA-15: A versatile recyclable heterogeneous catalyst for solvent and ligand free C–S coupling reaction from diverse substrates

Thioester is a vital part of several commercially available drugs. Consequently, development of suitable low cost catalyst for C–S bond formation is extremely necessary. In present work, we report a SBA-15 supported copper(0) nanoparticles based catalyst (Cu(0)MS) using wet impregnation method. The catalyst was thoroughly characterized by several techniques including powder X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX), transmission electron microscopy (TEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and inductively coupled plasma-optical emission spectrometry (ICP-OES). This mesoporous silica supported copper(0) nanoparticles have been exploited as a catalyst for ligand-free and solvent-free C–S cross-coupling reactions. Symmetrical/unsymmetrical aryl/alkyl sulphides have been synthesized by the S-arylation of aromatic, heteroaromatic, and aliphatic thiols with aryl, heteroaryl as well as vinyl halides. Aryl chlorides also responded the reaction very well to produce aryl sulfides. The applicability of the current protocol has also been explored for the synthesis of the starting materials of different C–S bond containing pharmaceuticals. In addition, the present catalytic system is also suitable for the synthesis of a variety of symmetrical diaryl sulphides from aryl halides using thiourea as a sulfur source. Furthermore, it was also found that the Cu(0)MS catalyst can be reused five times without substantial loss in activity. • SBA-15 supported copper(0) nanoparticle. • Ligand-free and solvent-free C–S cross-coupling reaction. • Diverse substrates scope including vinyl halides. • Gram scale synthesis of the key structures of commercially available C–S bond containing drugs. • Symmetrical diaryl sulphides from aryl halides and thiourea.

Electrochemical and Mechanical Investigation of Newly Synthesized NiO-ZrO2 Nanoparticle–Grafted Polyurethane Nanocomposite Coating on Mild Steel in Chloride Media

NiO-ZrO2 nanoparticles were prepared and characterized by Fourier transformed infrared spectroscopy (FTIR) and x-ray diffractometer (XRD) analysis. The NiO-ZrO2 nanoparticles were incorporated into polyurethane (PU) and the resultant polyurethane (PU)/NiO-ZrO2 nanocomposite was coated on the steel sample. The anticorrosion behavior of the PU/NiO-ZrO2 nanocomposite coating was electrochemically studied and compared with pure polyurethane coating by scanning electrochemical microscopy (SECM), potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS). EIS studies showed a pronounced protection performance for PU/NiO-ZrO2 coating in natural seawater. SECM analysis measured lower current for the PU/NiO-ZrO2 at the scratch of the coated surface compared to PU coating. The surface characterization and elemental composition of the coated samples were examined by surface morphological studies (SEM/EDX). Dynamic mechanical analysis (DMA) test was also carried out to examine the coated nanocomposite. The results provided valuable information about the protective performance and failure analysis of PU/NIO-ZrO2 nanocomposite coated surface. Field emission-scanning electron microscopy/energy-dispersive x-ray (FE-SEM/EDX) analysis was used to examine the corrosion products formed on the surface of coated sample. The formation of thin films of oxides and chlorides of Ni and Zr blocks the penetration of corrosive ion in the coating/metal interface. It was revealed from the mechanical properties of the nanocomposite and pure PU coatings that mixed metal oxide nanoparticles (NiO-ZrO2) enhanced mechanical as well as protection properties of the polyurethane coating against corrosion. A possible protection mechanism is also proposed.

RTV silicone rubber composites reinforced with carbon nanotubes, titanium-di-oxide and their hybrid: Mechanical and piezoelectric actuation performance

The use of nanofillers with high surface area and extreme purity in polymer composite is an effective strategy to obtain high performance polymeric nanocomposites. Therefore, the effect of nanofillers such as carbon nanotubes (CNT), titanium dioxide (TiO 2 ), and their hybrid on rubber-based composites was studied. In this study, rubber nanocomposites were fabricated by using room temperature vulcanized (RTV) silicone rubber matrix and nanofillers (i.e. CNT, TiO 2 , and CNT-TiO 2 ) through solution casting method. Here, the purity and surface area of CNT (purity: >96% and BET surface area: 300 m 2 /g) and TiO 2 (purity: >98% and BET surface area: 165 m 2 /g) were estimated by field emission scanning electron microscopy/energy dispersive X-ray (FESEM-EDX) and adsorption isotherms. The mechanical properties of the rubber nanocomposites were enhanced by incorporating nanofillers. The compressive modulus was 2.18 MPa for unfilled composites and increased to 6.8 MPa (CNT), 3.95 MPa (CNT-TiO 2 ), and 2.44 MPa (TiO 2 ) at 5 phr, respectively. Similarly, the tensile strength was 0.54 MPa for unfilled composites and increased to 1.37 MPa (CNT), 1.33 MPa (CNT-TiO 2 ) and 0.61 MPa (TiO 2 ) at 5 phr, respectively. Further, the actuation displacement was improved with increasing input voltage and it was 2 mm for CNT, 1.6 mm for CNT-TiO 2 hybrid and 0.5 mm for TiO 2 at 10 kV. Moreover, a series of experiments show the potential application in piezoelectric actuation.

Decolorization of Methylene Blue Dye Using ZnO/ZSM-5 Photocatalyst Under UV-LED Irradiation

&lt;span id="docs-internal-guid-710aacff-7fff-63c8-d621-c027e79f6f4f"&gt;&lt;span&gt;&lt;strong&gt;ABSTRACT. &lt;/strong&gt;&lt;/span&gt;&lt;span&gt;The present research studied about decolorization of methylene blue dye using photocatalyst ZnO/ZSM-5 under UV-LED lamp. ZnO/ZSM-5 was synthesized using the impregnation method by adding two grams ZSM-5 to Zn solution 0.3 M 10 mL. Photocatalyst was characterized using X-ray diffractometer (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy-energy dispersive X-Ray (FESEM-EDX), and surface area analyzer (SAA). Analysis using XRD show addition characteristic peaks of ZnO at 2θ 31.60°, 34.21°, 36.08°, 47.35°, 56.50°, 62.73°, 67.83°, that indicates a successful impregnation process. The photocatalysis activity test was done on methylene blue dye 100 mg L-1. ZSM-5 and ZnO activities were tested under UV-LED irradiation and dark conditions. Data showed that percent removal of dye occurred on ZnO/ZSM-5 under 15 minutes irradiation is 78.32%.&lt;/span&gt;&lt;/span&gt;

Decolorization of Methylene Blue Dye Using ZnO/ZSM-5 Photocatalyst Under UV-LED Irradiation

&lt;span id="docs-internal-guid-710aacff-7fff-63c8-d621-c027e79f6f4f"&gt;&lt;span&gt;The present research studied about decolorization of methylene blue dye using photocatalyst ZnO/ZSM-5 under UV-LED lamp. ZnO/ZSM-5 was synthesized using the impregnation method by adding two grams ZSM-5 to Zn solution 0.3 M 10 mL. Photocatalyst was characterized using X-ray diffractometer (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy-energy dispersive X-Ray (FESEM-EDX), and surface area analyzer (SAA). Analysis using XRD show addition characteristic peaks of ZnO at 2θ 31.60°, 34.21°, 36.08°, 47.35°, 56.50°, 62.73°, 67.83°, that indicates a successful impregnation process. The photocatalysis activity test was done on methylene blue dye 100 mg L-1. ZSM-5 and ZnO activities were tested under UV-LED irradiation and dark conditions. Data showed that percent removal of dye occurred on ZnO/ZSM-5 under 15 minutes irradiation is 78.32%.&lt;/span&gt;&lt;/span&gt;

Improvement of Mechanical and Anticorrosion Coating Properties in Conducting Polymer Poly(Propyl Methacrylate) Embedded with Silane Functionalized Silica Nanoparticles

An excellent new nanocomposite coating consisting of poly(propyl methacrylate) (PPMA), silanes and SiO2 nanoparticles (i.e., PPMA/silane/SiO2 blend) for aluminium alloy (AA7178) protection in natural seawater is investigated by electrochemical techniques. Three different silanes namely, ethyltriethoxysilane (EES), (3-glycidyloxypropyl)triethoxysilane (GES), and (3-aminopropyl)triethoxysilane (AES) were used to prepare functionalized SiO2 nanoparticles which are incorporated into PPMA to form PPMA/EES/SiO2, PPMA/GES/SiO2, and PPMA/AES/SiO2 nanocomposites. Electrochemical impedance spectroscopy (EIS) displayed a pronounced increase in the charge transfer resistance and potentiodynamic polarisation studies showed a significant decrease in the corrosion current for the investigated nanocomposites. The resultant nanocomposites performed as an excellent passivation layer which prevents the diffusion of ions and slows down the corrosion process due to the inclusion of silane functionalized SiO2 nanoparticles to PPMA. Scanning electrochemical microscopic (SECM) studies showed very lower corrosion current at the scratch of the PPMA-silane/SiO2 nanocomposite coated aluminium alloy. Field emission-scanning electron microscopy/energy dispersive X-ray (FE-SEM/EDX) analysis displayed the formation of corrosion products as the passive layer that hinders the dissolution of aluminium alloy. Mechanical properties of the coated aluminium alloy were found to be enhanced by the inclusion of functionalized SiO2 nanoparticles to PPMA which complimented the electrochemical studies.

Characterization of nio-bczy as composite anode prepared by a one-step sol-gel method

A high polarization resistance (Rp) at intermediate temperature (500–800°C) operation has become one of the major challenges in the development of proton-conducting fuel cells (PCFCs). Rp is the resistance of the cell that contributes by the electrodes parts which are anode and cathode as well as their interfacial components. The present study focused on the NiO-Ba(Ce0.6Zr0.4)0.9Y0.1O3-δ (NiO-BCZY) composite anode and its interfacial parts where the oxidation process takes place. The NiO-BCZY with a ratio of 50:50 was prepared by a sol-gel method and characterized by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray (FESEM/EDX), and Electrochemical Impedance Spectroscopy (EIS). At calcination temperature of 1100°C, NiO and BCZY oxides can preserve their phases to form composite anode as proven by XRD analysis. Morphology of the composite anode as observed by FESEM was spherical with particle size in the range of 30-70 nm. XRD analysis showed the formation of Ni-BCZY after undergoing reduction process under wet H2:N2 (10%:90%). As confirmed by the EIS data, the increased conductivity of the composite anode in wet H2:N2 (10%:90%) indicates that the NiO in the composite anode was reduced to Ni metal. The fabricated NiO-BCZY composite anode has shown a good potential to be a promising anode in PCFC application.

Fast responsive anatase nanoparticles coated fiber optic pH sensor

The sol-gel method is employed to synthesize the phenol red encapsulated anatase nanoparticles (PR/ANPs) matrix at low temperature (60 °C). Field emission scanning electron microscopy/Energy Dispersive X-Ray (FESEM/EDX) analysis shows porous nanostructures, and uniform elemental distribution. Atomic Force Microscopy exhibited that after phenol red (PR) encapsulation, average surface roughness (Ra) is increased up to ∼ 20 nm than pure anatase matrix Ra ∼14 nm. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy analysis confirmed the presence of bond ∼ 1054 cm−1 which is indicative of good PR encapsulation within the anatase matrix. X-ray diffraction analysis (XRD) shows intense peak corresponding to phenol along with anatase peaks suggested the interaction of Ti and O atoms with PR species. High resolution transmission electron micrographs (HR-TEM) analysis exhibited crystalline anatase structure before and after encapsulation along (101) direction. The average particle size is observed 5 nm for ANPs matrix which reduced to 3 nm after encapsulation. Observed high surface area 218 m2/g after encapsulation is helpful to enhance the activity of the sensing device. Thermogravimetric analysis (TGA) shows that after 422 °C, no mass weight loss is observed which confirmed the thermal stability of synthesized matrices. After encapsulation, observed low refractive index 1.8 at 550 nm indicates the porous nature of the matrix. The fiber optic pH sensor shows a linear response over the dynamic pH range 1–12, sensitivity is calculated as 1.83 counts/pH at 454 nm with determination coefficient (R2) ∼ 0.97. The proposed sensing device has fast response time 1.09s–0.42s within acidic-basic media, good reversibility, and validity. Experimental findings suggested that synthesized material has great potential in photonic devices/applications.

Green synthesis of sulfonated organosilane functionalized multiwalled carbon nanotubes and its catalytic activity for one-pot conversion of high free fatty acid seed oil to biodiesel

An environmentally friendly surface modification method was applied to synthesize solid acid catalyst suitable for biodiesel production. The catalyst was prepared from multiwalled carbon nanotube (MWCNT) and 3-mercaptopropyltrimethoxysilane (3-MPTMS) oxidized in hydrogen peroxide under supercritical carbon dioxide (scCO2). The carbon dioxide under supercritical condition with ethanol as cosolvent allows swift transportation and promotes uniform distribution of organosilane groups on randomly entangled and layered orientation of MWCNT. The catalyst was characterized by using Field emission scanning electron microscopy–energy dispersive x-ray (FESEM-EDX), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), Brunauer–Emmett-Teller (BET) analysis and Time-of-Flight secondary ion mass spectrometry (TOF-SIMS). The catalytic activity of the catalyst was tested using a high free fatty acid (FFA)-containing Hibiscus cannabinus (kenaf) oil, and the fatty acid methyl esters (FAME) products from simultaneous esterification and transesterification reactions were quantified. To compare with scCO2 method, an acid catalyst was also prepared using liquid chemical deposition that resulted in only 45.11% biodiesel conversion. On the other hand, the optimum conversion of 93.10% was obtained using a scCO2 synthesized catalyst at the following transesterification conditions: temperature = 63 °C, methanol:oil ratio = 14:1, 10 wt % catalyst and time = 240 min.

Effect of indole functionalized nano-alumina on the corrosion protection performance of epoxy coatings in marine environment

The anticorrosive performance of epoxy-indole-modified alumina nanocomposite-coated mild steel was investigated by electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM) and pull-off adhesion method in natural seawater. The dispersibility of nano-alumina in the epoxy resin has been enhanced by the functionalization of nano-alumina by indole moiety. The resulting nanocomposite coating enhanced the anti-corrosion and adhesive properties of the coated mild steel. The corrosion protection performance of epoxy resin coating decreased significantly with increase in test time. However, the corrosion resistance and adhesion strength are not significantly decreased for the indole-modified alumina-epoxy coating. The N-O-Al bonds formed by the chemical interactions between -NH functional groups of indole and nano-alumina resulted in good resistance against corrosion. Moreover, the hydrophobic nature of modified nano-alumina prevented corrosive ions to enter into nanocomposite coatings. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) explained the improved protection against corrosion in the presence of the surface-modified nanoparticle. High protection properties and ionic resistances resulted due to the possible chemical interactions between polymeric matrix and surface-modified nanoparticles in nanocomposites. Field emission-scanning electron microscopy/energy-dispersive X-ray (FE-SEM/EDX) analysis was used to examine the surface characterization of the coated sample.

Application of Electrochemical Techniques for Determining and Extracting Natural Product (EgCg) by the Synthesized Conductive Polymer Electrode (Ppy/Pan/rGO) Impregnated with Nano-Particles of TiO2

The polypyrrole/polyaniline-based electrode (Ppy/Pan/TiO2/rGO) was fabricated via the electrophoretic deposition technique on fluorine-doped tin oxide (FTO)-coated glass. Physico-electrochemical adsorption/desorption of epigallocatechin gallate (EgCg) as an electroactive species was enhanced by the fabricated electrode compared to the electroless technique extraction using the same electrode. EgCg was electrochemically extracted using chronoamperometry by electrophoretically deposited Ppy/Pan/TiO2/rGO film. Isolated EgCg was qualified and quantified by the voltammetry and high-performance liquid chromatography (HPLC) techniques. It was found that the extracted EgCg values were 3.38 and 0.72 ppm from a 10 ppm prepared solution using the electrochemically and physically based techniques, respectively. Morphology/elemental analysis and crystal structure of the prepared electrodes were characterized by field emission scanning electron microscopy/energy-dispersive X-ray (FESEM/EDX) and X-ray diffraction (XRD), respectively. The conductivity of the fabricated electrode was investigated by electrochemical impedance spectroscopy (EIS) and was calculated as 1.124 S/cm for the electrophoretically deposited electrodes (EPD).

Carbon Nanotube-Modified MnO2 : An Efficient Electrocatalyst for Oxygen Reduction Reaction

In this work, manganese dioxide/carbon nanotube (MnO2/CNT) have been synthesized by sonochemical-coprecipitation method and demonstrated that it could be an effective electrocatalyst for oxygen reduction reaction (ORR). Moreover, the effect of CNT inclusion with MnO2 was also investigated for ORR. The physical and electrochemical properties of the MnO2/CNT were examined by powder X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray (FESEM/EDX), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky and Rotating Disk Electrode (RDE) analysis. CV showed higher currents for the ORR in MnO2/CNT than CNT; however, ORR current dropped when the MnO2 loading was increased from 20–40 %. The EIS analysis showed that charge-transfer resistance for MnO2/CNT was significantly lower compared to the MnO2 indicating that MnO2 has good contact with CNT and the composite possess high electrical conductivity. Mott-Schottky results demonstrated that incorporation of CNT into MnO2 resulted in producing larger electron density in n-type MnO2/CNT compared to MnO2 which is liable for efficient electron donation from the Mn3+ to adsorbed oxygen in the rate determining step. RDE results showed that MnO2/CNT follows 4e− transfer pathway, indicating its ability to act as an effective ORR electrocatalyst.

A Potential Waste to be Selected as Media for Metal and Nutrient Removal

This study describes the potential of application of cassava peel, banana peel, coconut shell, and coconut coir to be selected as metal removal while limestone and steel slag for nutrient removal. The media were characterized by X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscopy-Energy Dispersive X-Ray (FESEM-EDX), and X-Ray Powder Diffraction (XRD). The results of XRF analysis medias show the present of calcium oxide, CaO which confirm the high efficiency in adsorbing metal ions and nutrient which is in agreement with the result of XRD. The characteristics of medias by FTIR analysis also confirmed the involvement of alcohol, carboxylic, alkanes, amines and ethers which play important role to reduce ions while FESEM-EDX indicates the porous structures of study medias. The characterization analysis highlight that cassava peel and steel slag were selected as a potential media in this study.