Synthesis And Characterisation Of Monodisperse Iron Oxide Nanoparticles

Magnetite (Fe3O4) nanoparticles are being extensively researched as potential building blocks for nanoscaled structures, devices and sytems. Due to their unique properties, these nanoparticles are widely considered for numerous fields such as electronics, optoelectronics, biomedicine and medical diagnostics. Different applications will require the particles to have different sizes as their properties are size-dependent

Mathematical Modelling of As(V) Adsorption by Humic Acid-Coated Magnetite Nanoparticles

In recent years, arsenic contamination in our surface water sources has become a major problem. Therefore, water treatment is the key to alleviate this problem. Adsorption as one of the polluted water remediation methods has proven to be efficient and rapid. Its underlying mechanisms can be ascertained through the study of isotherm, kinetics and thermodynamics parameters of the adsorption process itself. Therefore, in the present paper, existing data of arsenate (As(V)) adsorption mechanisms by multiple samples of adsorbents will be interpreted by modelling the data. The data were obtained from experiments conducted previously involving humic acid-coated magnetite nanoparticles (NP). The effect of variables such as the synthesis temperatures and humic acid concentrations on the adsorption was thoroughly investigated via the experiments. In this paper, both linear and non-linear models were applied, and the results were compared. The non-linear model fitting was done with Microsoft Excel 2016 solver. The equilibrium adsorption data was fitted to the Freundlich, Langmuir and Temkin isotherms as well as the kinetic pseudo-first order (PFO) and pseudo-second order (PSO) models. Linear coefficient of determination was used for linear regression while non-linear regressions was done through the non-linear error function chi-square (χ2). The best model that fits the experimental data were decided accordingly for the different adsorbent samples

Zinc Oxide Nanoparticles for Removal of Arsenic from Water

Removal of arsenate, As(V) from water was achieved using zinc oxide nanoparticles. The nanoparticles were synthesised from zinc acetate dihydrate and sodium hydroxide (NaOH) using the wet chemical sol-gel method. Different synthesis parameters were explored; including different ratios of Zn:NaOH and calcination temperatures. The synthesised samples were subsequently characterised and tested to investigate the adsorption capabilities of ZnO towards As(V). The colourimetric approach was utilised to analyse the samples’ performance. The particles had a relatively large average size as tested by the nanoparticle size analyser and the X-Ray Diffraction (XRD) characterisation of the samples confirmed the formation of ZnO. The peaks were narrow with high intensity, which indicates a larger crystal size and stable crystallinity. The samples showed a linear trend of increased adsorption capacity with the contact time. However, as indicated by the XRD and nanoparticle size analyser results, the particles had agglomerated and this has caused the total surface area to shrink. In summary, ZnO nanoparticles were successfully synthesised and were successful in adsorbing As(V) with different percentages for each sample. The adsorption trend was clear with respect to the changing parameters

Synthesis and characterisation of zinc oxide nanoparticles for thermoelectric application

In this research, zinc oxide (ZnO) nanoparticles were prepared through a chemical co-precipitation route using zinc acetate dihydrate and sodium hydroxide as the reactants. To study the variation in the properties of the nanoparticles, namely its phase, shape and size, the reaction temperature and stirring rate were varied during the synthesis process. From the X-ray diffraction profiles, the as-synthesised samples were confirmed to be ZnO. Spherical and hexagonal-shaped particles were obtained when the temperature and stirring rate were varied. A rise in the synthesis temperature from 30 to 70°C caused insignificant changes to the average diameter of the particles, although their shape was altered from spherical to hexagonal. When the stirring rate was increased, the average diameter of the particles decreased. The average diameter of the sample calcined at 600°C for 1 hour recorded a slight increase while its X-ray diffraction profile depicted narrower peaks with higher intensity, indicating formation of a more stable phase of ZnO. Further study is needed to elucidate the effects of the particle shape and sizes on the thermoelectric transport properties

Influence of aluminum dopant on the structural and optical properties of zinc oxide colloids prepared by sol-gel spin coating method

Doped zinc oxide (ZnO) colloids have attracted significant attention recently due to its wide range of applications owing to the effective tunable properties and remarkable solution processability. In this work, low cost sol-gel spin coating technique was employed to synthesize the aluminum doped ZnO colloids (AZO). The influences of the Al doping concentration on the structural and optical properties of the AZO colloids were investigated using field-emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-Vis) spectrophotometer and photoluminescence (PL) spectroscopy. Elemental composition was confirmed using energy dispersive X-Ray spectrophotometer (EDX). The size of colloid particles decrease from approximately 400 nm to 100 nm as the Al doping concentration is increased. As the size of the colloids decrease, the position of absorption peak was blue shifted, whilst the tunable optical band gap (Eg) of the AZO colloids is profound

Functionalized electrospun biobased polymeric materials in filtration

Due to its wide range of application, high removal capacity, and low cost, membrane separation technique is considered as one of the most prominent technologies for water filtration. Nevertheless, fouling of membrane is a serious obstacle using membrane filtration process. To address fouling in membrane, researchers have explored different types of modification options, including the integration of hydrophilic inorganic components or metal oxide nanoparticles (MO) loaded onto the electrospun bio and synthetic polymer-based membrane. Zinc oxide (ZnO) nanoparticles have been used extensively as a low-cost, eco-friendly, and hydrophilic material. ZnO nanoparticles (NPs) can not only provide antifouling properties to the composite membranes but also provide a photocatalytic self-cleaning capability. It possesses strong antibacterial effects. As a result, polymer-ZnO composite membranes were identified as an appealing hot issue for waste water filtration process. The chapter highlights regarding the recent advances in electrospun polymeric (bio and synthetic polymer) materials that include MO nanoparticles for mitigation of fouling and water purification. Membrane functionalization processes using biopolymer-based nanofiber were also illustrated. The performance assessment, constraints, and possible trends for future research on synthesizing the nanofibrous composite membranes in wastewater treatment are discussed in subsequent section

Electrodeposited Iron(III) Oxide (α-Fe2O3) Thermoelectric Thin Films

α-Fe2O3 thermoelectric thin films were electrodeposited onto copper substrates using chloride-based electrolytes by means of potentiostatic electrodeposition. The influence of several electrodeposition parameters on the surface morphology, elemental composition and electrical conductivity of the deposited films was studied and analyzed. The deposits formed porous, wire-like morphology, with the smallest width measured to be ~60 nm. The wires tend to aggregate to form clusters, in addition to multi-layered growth of the wires. Between the parameters studied, electrolyte concentration and deposition time parameters have higher influences on the electrical conductivity of the deposited films, with the increment up to two fold higher. Deposition potential parameter offered the lowest capability to improve on the electrical conductivity in addition to the non-uniform distribution of the measured electrical conductivities. The tunable electrical conductivity is favorable for improving the performance of α-Fe2O3 films for thermoelectric applications