Farzad Mohaddes

Elevation of charring level of polyamide-6,6 films via ionic introduction of phosphoric acid and boric acid esters

Phosphorus and boron containing materials have the feature of increasing char formation, which can be effectively used as flame retardants especially in textiles. This paper discusses the ionic addition of phosphorus and boron esters to polyamide-6,6 (PA66), and its effect on the charring level. A mixture of phosphoric acid–boric acid ester at different degrees of esterification (ED) was prepared and two theoretical mechanisms for the esterification reaction were suggested. Ionically grafted polymer films were prepared by introducing the ester of highest ED to PA66–formic acid solution via three different processes: open air (cold) grafting, ultraviolet irradiation grafting, and hot vacuum oven grafting. Thermogravimetry was conducted for all synthesized esters and films, and the formation of new bonds between the ester and PA66 was verified using Fourier transform infrared spectroscopy.

Purification of avian biological material to refined keratin fibres

Keratin derived from chicken feather fibres (CFFs) has many potential applications that are constrained by the quality and pathogen content after purification treatment. The pathogen activity after purification has not been evaluated elsewhere. Plucked chicken feathers are prone to impose biological hazards due to accommodating blood-borne pathogens; therefore, establishing an efficient purification process is crucial. Bactericidal performance of surfactants (anionic, non-ionic, and cationic), bleach (ozone and chlorine dioxide), ethanol extraction, and a combination method comprising surfactant-bleach-ethanol extraction on chicken feathers was investigated via (A) standard plate count and enumeration of Escherichia coli, Pseudomonas species, coagulase positive Staphylococcus, aerobic and anaerobic spore-formers and (B) Salmonella and Campylobacter detection tests. Among the purification methods, only ethanol extraction and combination methods eliminated Salmonella from the untreated feathers. Although ethanol extraction exhibited superior bactericidal impact compared to the combination method, the feathers treated through the latter method demonstrated superior morphological and mechanical properties. Scanning electron microscopy-energy dispersive spectroscopy was employed to determine the remaining content of selected purifiers on treated CFFs. Fourier-transform infrared spectroscopy confirmed the successful removal of fatty esters from CFFs using nominated purifiers. Ethanol extraction was found to be the most efficacious single treatment, while combination of surfactant and oxidative sterilizer with ethanol was superior.

Application of Victorian brown coal for removal of ammonium and organics from wastewater

ABSTRACT Brown coal is a relatively abundant and low-cost material, which has been used as an effective ion-exchanger to remove ammonium from wastewater. In this study, the influences of pH, ammonium concentration and brown coal dose were investigated for removal of ammonium content from synthetic wastewater. Raw brown coal (RBC) treated with base solution has superior ammonium removal efficiency compared to RBC, which was due to chemical alterations and thus greater attachment of ammonium molecules to base-washed brown coal (BWBC), confirmed by Fourier transform infra-red spectroscopy. Scanning electron microscopy-electron diffraction scattering has identified the augmented sodium content in BWBC, which was subsequently replaced with nitrogen upon wastewater treatment. Crystallographic analysis showed a higher crystallinity formed in BWBC compared to RBC, which was likely due to formation of sodium salt crystals during NaOH treatment. Fitting batch experimental results to adsorption kinetic models suggested that the removal of ammonium was mainly governed by the reaction process rather than the physical diffusion mechanism. Both kinetic and isotherm studies confirmed higher adsorption capacity for BWBC compared to RBC. RBC in column mode was also experimented with to show organics removal from a secondary effluent. A comparatively lower removal of organics was obtained due to inability of charge neutralization as both brown coal and organics are positively charged.

Evaluation of X-ray radiation shielding performance of barium sulphate-coated fabrics

The X-ray in the field of medical imaging is an important diagnostic tool, but it has been identified that there are potential radiation risks associated with the X-ray radiation scans. These risks have traditionally been guarded against using lead based shields. Lead has excellent radiation shielding properties, but it is also heavy and a potential health and environmental hazard due to its toxicity. Thus, there have been studies seeking to find an alternative that is as effective and yet counters the other drawbacks. In this paper, preliminary studies were conducted to assess the shielding effect of barium sulphate (BaSO4) and bismuth oxide (Bi2O3) on the coated fabric samples. X-ray transmission resulting from standard lead coated samples, uncoated fabric, BaSO4, and BaSO4/Bi2O3 coated fabrics was evaluated via measuring the penetration of primary radiation. Different properties such as mass per unit area, material thickness, and surface morphology were examined. All samples were irradiated by X-ray at 80 kVp to measure the amount of transmissions. The X-ray transmission level associated with BaSO4 ranged from 84.5 % to 70.5 %. However, this level was elevated to 55.6 % when BaSO4/Bi2O3 mixture was applied on the fabric. The theoretical attenuation coefficient values associated with different coating mixtures comprising different weight proportions of BaSO4, Bi2O3, and PVC were determined between 0 MeV and 105 MeV using XCOM code. The XCOM results implied that the X-ray attenuation coefficient among all prepared coatings should be the mixture comprising 13.3 wt% Bi2O3/20 wt% BaSO4/66.7 wt% PVC, which was in agreement with the experimental results obtained from X-ray transmission measurements.