Potential of the biodegradability and characteristics of bio-plastic from microalgae residues

Abstract

Petroleum-based plastic has been widely used in many industries. However, it takes hundreds of years to degrade and causes widespread pollution to our environment. These problems led to the invention of bioplastics, which were comprised of natural biopolymers made from starch. The production of bioplastics from food-based starches such as tapioca and corn created competition between food and bioplastic production industries. Hence, this research study focuses on producing bioplastic from microalgae residue, which is a non-food based raw material that uses four different types of plasticizers: glycerol, sorbitol, glutaraldehyde and polyethylene glycol (PEG). Microalgae species for identification were obtained from the fish pond at the University Malaysia of Kelantan, before cultivating the species for 14 days. The microalgae residues were extracted through the centrifugation process. Three species were identified under the light microscope, Chlorella sp., Scenedesmus sp. and Monoraphidium sp. The production of bioplastic involved a manual stirring method using a hotplate magnetic stirrer, followed by drying the bioplastic in an oven at 60 oC. Results obtained showed that sorbitol and glycerol from microalgae are suitable to be used as a plasticizer for the production of bioplastic, however glutaraldehyde and PEG are not suitable. Bioplastics that used PEG and glutaraldehyde became cracked and brittle after the drying process. The characterization of bioplastics includes universal tensile testing machines, Fourier-transform infrared analysis and biodegradability tests being processed//undertaken on glycerol-based and sorbitol based bioplastic. Characterization of bioplastics proved that both glycerol and sorbitol have high potential for applications in daily human life. Bioplastics which used sorbitol as a plasticizer could be used in can be applied the production of plastic goods such as toys and household items due to its good resistance toward stress and minimal flexibility. Meanwhile bioplastics which used glycerol as a plasticizer could be applied to the production of plastic bags and plastic food wrap due to its elastic and flexible nature.