Rice Husk Nanosilica Preparation and Its Potential Application as Nanofluids

The fast development in the extraction technique of silica from biomass has resulted in the signification use of silica in the industry. Rice is one of the world’s most significant plants, which serve as a carbohydrate intake for humans. Rice husk is one of the main agro-wastes comprising big quantities of silicate. This chapter presenting the review on rice husk nanosilica production techniques by thermal and chemical methods. A direction on efficient and sustainable nanosilica extraction method will be discussed. Apart from that, method on nanofluids preparation will be accumulated with respect to the end application. Moreover, the influence of nanoparticle in nanofluids in terms of heat conductivity, rheological properties, and stability will be discussed. The potential application area of silica nanofluids such as solar, automobile, electronic cooling, and biomedical application will be explored

Sulfuric Disazo Dye Stabilized Copper Nanoparticle Composite Mixture: Synthesis and Characterization

A copper nanoparticle–sulfuric disazo dye (Cu–SD1) composite was synthesized using the sol–gel method. Cu–SD1 nanocomposite formation was monitored by ultraviolet-visible spectroscopy (UV-vis). The acquired experimental results suggested that 8 h of reaction is needed for the synthesis Cu0 nanoparticles. Transmission electron microcopy (TEM) and atomic force microscopy (AFM) were employed to elucidate the morphology of the Cu–SD1 nanocomposite. It was found that the diameter of particle sizes were in the range of 2–4 nm. The interaction of SD1 with copper was confirmed by Fourier transform infrared spectroscopy (FTIR). The peak shift of O–H and C–OH functional groups indicated the interaction between SD1 and copper nanoparticles. Moreover, the azo group (N[double bond, length as m-dash]N) peaks were suppressed after the formation of the nanocomposite, suggesting that a strong linkage was formed between the functional groups and the copper nanoparticles. The surface composition and chemical states of the as-synthesized copper nanoparticles were elucidated by X-ray photoelectron spectroscopy (XPS). In addition, photo-switching of the composites was elucidated in the solution state. It was found that the Cu–SD1 nanocomposite has a faster switching response compared to the parent, SD1, in a solution

Electrochemical Study of Copper Ferrite as a Catalyst for CO2 Photoelectrochemical Reduction

In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as photocathode catalyst for photoelectrochemical (PEC) CO2 reduction. The XRD, UV-Visible Spectroscopy (UV-Vis), and Mott-Schottky (MS) experiments were done to characterize the catalyst. Linear sweep voltammetry (LSV) was employed to evaluate the visible light (λ>400 nm) effect of this catalyst for CO2 reduction.  The band gap energy of the catalyst was calculated from the UV-Vis and was found 1.30 eV. Flat band potential of the prepared CuFe2O4 was also calculated and found 0.27 V versus Ag/AgCl. Under light irradiation in the CO2-saturated NaHCO3 solution, a remarkable current development associated with CO2 reduction was found during LSV for the prepared electrode from onset potential -0.89 V with a peak current emerged at -1.01 V (vs Ag/AgCl) representing the occurrence of CO2 reduction reaction. In addition, the mechanism of PEC was proposed for the photocathode where the necessity of a bias potential in the range of 0.27 to ~ -1.0 V vs Ag/AgCl was identified which could effectively inhibit the electron-hole (e-/h+) recombination process leading to an enhancement of CO2 reduction reactions.

Synthesis and Characterization of a CaFe2O4 Catalyst for Oleic Acid Esterification

Esterification of free fatty acid (oleic acid) with ethanol over a calcium ferrite catalyst was investigated in the present study. The calcium ferrite catalyst (CaFe2O4) was synthesized by the sol–gel method, which exhibited high catalytic activity for esterification of oleic acid. The morphology and size (500–1000 nm) of the synthesized catalyst were observed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) was used to ensure the absence of impurities. The orthorhombic structure of calcium ferrite was exposed by X-ray diffractometry (XRD). The effects of reaction variables such as catalyst loading, methanol to acid ratio, reaction time and temperature on the conversion of fatty acids were studied. The optimum conditions for the esterification process was a molar ratio of alcohol to oleic acid at 12 : 1 with 5 wt% of CaFe2O4 at 70 °C with a reaction time of 2 h. XRD patterns of the recycled catalyst evidenced that the catalyst structure was unchanged up to the 3rd cycle, which indicated the long life of the catalyst

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

Facile Synthesis of Copper Nanoparticles in Glycerol at Room Temperature: Formation Mechanism

A copper sol is usually synthesized by the reduction of a copper precursor with a suitable reducing agent in the presence of a stabilizer. There are few reports regarding the preparation of copper nanoparticles in glycerol without using a stabilizing agent, but at elevated temperatures. The formation of reduced copper (Cu0) is usually verified by a UV-vis spectrophotometer where a ‘red copper sol’ was formed. In the present paper we synthesized the copper sol at room temperature in a glycerol medium using hydrazine as a reducing agent. The chemical states of copper in the sol and their composition were analyzed by X-ray absorption near edge structure spectroscopy (XANES) with the linear composition fitting method. A series-parallel mechanism of the reaction was proposed. An average particle size of 5 ± 1 nm was visualized via transmission electron microscopy (TEM)

Convective Boundary Layer Flow of Williamson Hybrid Ferrofluid over a Moving Flat Plate with Viscous Dissipation

Specifically, the oxide ferroparticles in ferrofluid has low thermal conductivity thus limiting its potential in the application of heat transfer. Increasing the volume fraction ferroparticles is one of the ways to increase the efficiency but this will cause clogging in the flow system. The present research investigated the convective boundary layer flow of a Williamson hybrid ferrofluid over a moving flat plate with viscous dissipation effects. Magnetite (Fe3O4) and copper (Cu), taken as hybrid ferroparticles, are suspended in Williamson fluid represented by human blood are believed to improve the heat transfer capabilities of the ferrofluid. The governing equations in the form of partial differential equations are reduced to ordinary differential equations by using the similarity transformation. The Runge-Kutta-Fehlberg (RKF45) method is used to numerically solve the transformed equations obtained. The effects of the magnetic parameter, the Williamson fluid parameter, the moving plate parameter, and the Eckert number on the velocity profiles, the temperature profiles as well as the reduced skin friction coefficient and the reduced Nusselt number are analyzed and discussed. It is revealed that Williamson hybrid ferrofluid has higher heat transfer capabilities and lower skin friction compared to the Williamson ferrofluid at the same volume fraction. In addition, the magnetic parameter increases the skin friction while the moving plate parameter increases the reduced Nusselt number

Influence of ultrasound on alkaline treatment of empty fruit bunch fibre: preliminary study

This research underlines the effect of ultrasound in NaOH surface modification of empty fruit bunch (EFB) fibre. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterized the fibres. It can be seen that surface morphology treated by ultrasound assisted alkali treatment shows smooth surface with minor impurities. Additionally, the elimination of hemicellulose on EFB fibre surface can be proven by the disappearance of peak between 2900-1700 cm−1 (C-H). Furthermore, Ultrasound assisted alkali method demonstrate the admirable value (300 N/mm2) in enhancing the tensile stress of EFB fibre and comparable with alkali soaking technique (292 N/mm2). The findings indicate that ultrasound-assisted alkali treatment has the potential to be used as surface modification method in the industry

Discovering the knowledge transfers framework on aero-composite manufacturer in Malaysia

This work elucidated the knowledge transfer method used by an international first tier advanced composite multinational company supplier in transferring the technical knowledge to a Malaysian advanced composite manufacturer. Effective route of knowledge transfer could significantly improve the performance of the company. The process of the transferring knowledge is an ongoing progression of learning, adjusting, and improving. An excellent knowledge transfer could benefit both the knowledge provider and receiver. A “Backward Engineering” investigation on the relationship between the factors during the knowledge transfer process is useful, to be an ideal reference for others. This paper exhibits the technological transfer executed by the aero-composite manufacturer. Method chosen in this study is focus group discussion involving the working committee of respective programme. It was found that a systematic two stages with multi-phases of knowledge transfer has been explored during flat-curvature structures aero-composite project. Tacit and explicit knowledge is important for transferring technical knowledge in industry context. It is noticed that a useful knowledge transfer mechanism has an impact on the performance of organization such as increases in productivity, profits, and growth

Glycerol electro-oxidation to dihydroxyacetone on phosphorous-doped Pd/CNT nanoparticles in alkaline medium

In this communication report, a comparative study between P-doped Pd/CNT and bare Pd/CNT catalyst was carried out to decouple the effects of phosphorous-doping on electro-oxidation of glycerol. The initial characterization results suggested that Pd and its oxides were successfully incorporated within the pore channels of CNTs support for both catalysts by using hydrazine-assisted hydrothermal technique. The XPS results revealed that the amount of Pd2+ for bare Pd/CNT were 1.4 times higher than P-doped electrocatalysts (about 70.1% and 48.7%, respectively) which confirms that phosphorus facilitates the reduction of Pd2+ to metallic Pd (Pd0). The electrochemical results showed that the electrochemical surface area (392.22 m2 gPd−1) and current density (26 mA/cm2) for P-doped Pd/CNT catalyst were 2.84 and 1.6 times, respectively, higher than Pd/CNT catalyst. The P-doped catalyst was found to suppress the formation of carbonaceous intermediates; thus, improved the glycerol oxidation reaction. Small quantities of deep oxidation side products such as mesoxalic acid (<2%) and tartronic acid (<0.1%) were found along with the dihydroxyacetone (DHA), a major product of glycerol electro-oxidation. The best performing catalyst exhibited 1.4 folds higher DHA selectivity (90.8%) compared to the Pd/CNT