Magnesium Oxide Nanoparticles Reinforced Electrospun Alginate-Based Nanofibrous Scaffolds with Improved Physical Properties.

Mechanically robust alginate-based nanofibrous scaffolds were successfully fabricated by electrospinning method to mimic the natural extracellular matrix structure which benefits development and regeneration of tissues. Alginate-based nanofibres were electrospun from an alginate/poly(vinyl alcohol) (PVA) polyelectrolyte complex. SEM images revealed the spinnability of the complex composite nanofibrous scaffolds, showing randomly oriented, ultrafine, and virtually defects-free alginate-based/MgO nanofibrous scaffolds. Here, it is shown that an alginate/PVA complex scaffold, blended with near-spherical MgO nanoparticles (⌀ 45 nm) at a predetermined concentration (10% (w/w)), is electrospinnable to produce a complex composite nanofibrous scaffold with enhanced mechanical stability. For the comparison purpose, chemically cross-linked electrospun alginate-based scaffolds were also fabricated. Tensile test to rupture revealed the significant differences in the tensile strength and elastic modulus among the alginate scaffolds, alginate/MgO scaffolds, and cross-linked alginate scaffolds (P < 0.05). In contrast to cross-linked alginate scaffolds, alginate/MgO scaffolds yielded the highest tensile strength and elastic modulus while preserving the interfibre porosity of the scaffolds. According to the thermogravimetric analysis, MgO reinforced alginate nanofibrous scaffolds exhibited improved thermal stability. These novel alginate-based/MgO scaffolds are economical and versatile and may be further optimised for use as extracellular matrix substitutes for repair and regeneration of tissues.Peer Reviewe

Hotel Sewage Sludge Derived Biochar as an Adsorbent for Aqueous Cadmium Removal

The hotel industry is considered to be one of the main sources of sewage sludge. Sewage sludge (by-products) of wastewater treatment is considered as water, inorganic and organic materials removed from wastewater. These by-products coming from various sources through physical, chemical, and/or biological treatments. Cadmium is a non-essential heavy metal available in water sources accumulated through both natural phenomena and anthropogenic activities. Direct and indirect accumulation of Cadmium in tissues through food and drinking water causing various diseases and disorders. Thus, developed biochar from hotel sewage sludge Sri Lanka and its applicability to remove aqueous Cadmium ions was studied. In this study, the biochar wassynthesised pyrolsing the sewage sludge in a muffle furnace at 450o C. To maintain an oxygen-free atmosphere during the process, nitrogen was supplied to the system at a 200 mL/min flow rate. The temperature increase rate was set at 17o C/min. The pH, EC, total solid (TS), total fixed solid (TFS), and total volatile solids (TVS) were determined in sewage sludge. Then the synthesised biochar was characterised by X-ray diffraction (XRD), particle size analyser, and scanning electron microscopy (SEM). Furthermore, the Cadmium removal efficiency of synthesised biochar was tested with different concentrations of Cadmium solutions, pH levels, adsorbent dosages, and contact times. Atomic adsorption spectroscopy was used to analyse the Cadmium concentrations in water samples. The results were, pH (5.46), EC (1270 µs/cm), TS (55 mg/mL), TFS (14 mg/mL) and TVS (41 mg/mL). The maximum Cadmium removal percentage of 100% was obtained with 8 pH, 50 mL of 25 mg/L Cadmium solution, and 0.150 g of the synthesised biochar. Adsorption data were fitted with the Langmuir adsorption isotherm model and adsorption kinetics were fitted with a pseudosecond-order model with R2 , 0.9924. The study presents a viable option for removing Cadmiumions in water to desirable levels as a means for controlling Cadmium related health issues while sustainably controlling the sewage sludge.Keywords: Adsorption, Biochar, Heavy metal, Sewage sludg

Nano-MgO reinforced chitosan nanocomposites for high performance packaging applications with improved mechanical, thermal and barrier properties

Chitosan nanocomposite thin films were fabricated by incorporating MgO nanoparticles to significantly improve its physical properties for potential packaging applications. A novel in-situ method was developed to synthesise spherical shaped MgO nanoparticles by heat-treating magnesium carbonate/poly(methyl methacrylate) (PMMA) composite precursor. Optimum mechanical properties of chitosan composites were yielded at 5 (w/w%) of MgO concentration, where tensile stress and elastic modulus significantly improved by 86% and 38%, respectively, compared to those of pure chitosan films. These improvements are due to the interaction of hydroxyl and amine groups of chitosan with MgO as confirmed by FTIR spectroscopy. Fracture surface morphology indicated the interplay between MgO dispersion and aggregation on the mechanical properties at different MgO concentrations. Furthermore, the chitosan/MgO nanocomposites displayed remarkable thermal stability, flame retardant properties (satisfied V0 rating according to the UL-94 standards), UV shielding and moisture barrier properties, which could certainly add value to the packaging material

Photocatalytic activity of electrospun MgO nanofibres: Synthesis, characterization and applications

One dimensional MgO nanofibres with high photocatalytic activity were fabricated using the electrospinning method via a polyvinyl alcohol (PVA)/magnesium precursor based system and the dye degradation efficacy of MgO nanofibres was compared with MgO nanospheres. Optimum electrospinning parameters including suitable magnesium precursors were investigated and the formation of MgO nanofibres were confirmed with scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) mapping. Furthermore, the crystalline lattice structure and surface roughness of fabricated nanofibres were evaluated using transmission electron microscopic-electron diffraction mode (TEM-SAED) and atomic force microscopy (AFM), respectively. Fabricated MgO nanofibres exhibited excellent photocatalytic degradation activity against widely used model reactive dye, Reactive Yellow (RY). In contrast to MgO nanospheres, electrospun MgO nanofibres completely degraded the reactive dye under UV irradiation. These photocatalytic MgO nanofibres show a great potential to be used in efficient treatment of industrial dye effluents

Fabrication of multifunctional smart polyester fabric via electrochemical deposition of ZnO nano-/microhierarchical structures

Advanced multifunctional surfaces are widely used due to their unique surface properties and widespread applications. Developing a multifunctional fabric with a low cost, fluorine-free, and easily controllable method is a great challenge. This paper reports a multifunctional fabric with conductive, UV blocking, superhydrophobic and photosensing properties via an electrodeposition method. ZnO nano-/microarchitectures have been electrodeposited on polyester fabric with a carbon black screen-printed conductive layer. The deposition was carried out in various operating parameters. The optimized conditions for the ZnO electrodeposition are at − 1.0 V for 30 min deposition time in 5 mM Zn(NO3)2 in 0.1 M KNO3 at room temperature. The developed fabric showed 100% UV radiation blocking and a water contact angle (WCA) of 156° after self-assembly of stearic acid on the ZnO layer. The modified fabric showed fast photoresponse as a photosensor, which indicates that this can be used as flexible wearable photosensors in practical applications.</p

Akaganeite nanorices deposited muscovite mica surfaces detailed data (.pdf format)

Akaganeite nanorices deposited muscovite mica surfaces detailed data (.pdf format

Urea-Assisted Synthesis of Nanospherical and Plate-Like Magnesium Oxides for Efficient Removal of Reactive Dye Wastes

Nanospherical and plate-like magnesium oxide has been successfully synthesized by urea precipitation method for the first time. A magnesium oxide precursor was prepared by heating MgCl2 solution with urea for 12 hours at 90°C. Then the calcined precursor was analysed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). In the presence of the nonionic surfactant Triton X-100 in the system, the reaction yielded in nanospheres of MgO contrast to the plate-like MgO in the absence of the surfactant. The precursor and the calcined product appeared in similar morphologies under SEM in both cases with a slight reduction of size upon calcination. The final product was confirmed as MgO using XRD and FT-IR spectroscopic methods. In TGA, both samples showed similar mass loss values upon elimination of adsorbed water molecules and decomposition of the precursor into MgO; however, the nanospherical MgO sample showed an additional weight loss due to elimination of the associated surfactant molecules. The efficiency of removing reactive dye wastes was quantified by UV-visible spectroscopy using reactive yellow dye. Plate-like MgO showed a porous structure under HR-TEM analysis in the dye adsorption study, and both plate-like and nanospherical MgO showed good dye adsorption capability. MgO nanospheres showed higher capacity of dye adsorption compared to plate-like MgO, explained by its higher surface are-to-volume ratio, while the plate-like MgO also performed well due to having a nanoporous structure. These nanomaterials will offer high potential in purifying waste water and as well in recovering expensive dye products