Environmentally benign chitosan-based nanofibres for potential use in water treatment

Abstract

Chitosan (CS)-based nanocomposite materials are highly prone to swelling when in contact with water. It is therefore essential to modify them to enhance their resistance to swelling, in order to be applicable in water treatment. In this study, the CS-based nanofibres were prepared using the electrospinning technique. The nanofibres were prepared from a polymer blend of CS, and other polymers (polyacrylamide (PAA) and polyethylene glycol (PEG)) added in small optimized quantities to enhance the ability to electrospun CS. Elastic polyisoprene (PIP) and functionalized multi-walled carbon nanotubes (f-MWCNTs) were incorporated in the electrospinnable solution blend of CS, PAA and PEG to reduce the swelling behaviour of the CS-based nanofibres and to improve their mechanical strength and thermal properties. PIP did not only improve the morphology of the resulting nanofibres but also reduced their swelling behaviour by twofold. The addition of f-MWCNTs was found to improve the tensile strength of the nanofibres by twofold, relative to nanofibres with no f-MWCNTs. The thermal degradation of the nanofibres was improved by a magnitude of 50°C. Antibacterial silver (Ag) and iron (Fe) nanoparticles (NPs) were embedded on the nanofibres for their possible use in disinfection processes. These NPs have demonstrated a potential to kill bacteria in water and, therefore, the prepared nanofibres can be used in disinfection water treatment processes with reduced swelling capacity.

Keywords:

• chitosan
• electrospinning
• multi-walled carbon nanotubes
• swelling
• polyisoprene

Additional information

Notes on contributors

Lebea N. Nthunya

This work was conducted by a master’s student working in the research group of Professor Sabelo Mhlanga at the University of South Africa. The research group led by Prof Mhlanga largely involves finding sustainable solutions (materials) to solve problems relating to water quality within the context of the water–energy–food nexus. The approach involves applying the principles of green chemistry, nanoscience and nanotechnology to develop materials for drinking and wastewater treatment. In particular, there is keen interest in developing energy efficient technologies for drinking water treatment in rural communities, and we recently completed a flagship project supported by the National Research Foundation (South Africa). The flagship project entailed synthesis of various nano-structured materials (such as thin films, nanofibres and nanobeads) with the desired size (nanometre dimensions) and enhanced physicochemical properties. “Green” chemical synthesis approaches were applied through careful selection of reaction conditions, e.g. appropriate choice of precursors, solvents and energy requirements.