Sustainable nanocellulose coating for EPS geofoam extracted from agricultural waste

Expanded polystyrene (EPS) geofoam blocks are gaining acceptance across industries due to their low density, insulation properties, strength, compressibility, and shock absorption under dynamic loads. The effective application of EPS is impeded by restrictions imposed by using conventional polymer-based synthetic geomembrane insulation ought for protection. Meanwhile, the production process of the geomembrane has detrimental environmental impacts, incurs high costs, and limits the utilization of EPS blocks in various applications. This research aims to create an innovative nanocoating substance using nanocellulose derived from agricultural residues to provide an eco-friendly alternative to geomembranes. The nanocellulose was extracted from four agricultural waste materials; sugarcane bagasse, banana fibers, rice straw, and spent-ground coffee; where each had a local percentage yield of 35 %, 25 %, 19 %, and 10 %, respectively. Based upon a technical criterion provided by the transmission electron microscopy (TEM) micrographs, the TOPSIS multi-criteria decision-making method was used to rank the sustainability of waste materials. It was found that sugarcane bagasse (SCB) is the most sustainable type with the smallest nano particle size. Nanocellulose extracted from SCB was characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDX), nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FTIR). The innovative nanocellulose coating primarily consisted of a nanocellulose mixture (SCB + water), polyvinyl acetate (PVA), and zinc oxide. Fourteen distinct formulas were obtained to identify the optimal proportions suitable for application on EPS surface with respect to the nano particle size, purity, and binding energy between the elements. It was found that the optimum formula consists of 42 % SCB, 50 % PVA, and 8 % zinc oxide.