Circular economy in the sugarcane agroindustry

Abstract

The sugarcane industry in the process of producing sugar and ethanol generates bagasse in large amounts. The burning of bagasse used for steam and electricity generation produces 3 million tonnes of bagasse fly ash (BFA) annually. Handling and improper disposal of BFA cause pollution in soils, air, and water, which results in environmental challenges and human health problems. The valorization of BFA is a convenient and sustainable means to reduce solid waste generation and decrease the environmental pollution load. The purpose of this research is to investigate the application of BFA for the synthesis of zeolite. Because of three-dimensional structure and unique porous properties, zeolite is a value-added product with many applications such as adsorbent material and industrial catalysis. After separation of the coarser particles containing mainly unburned carbon, fine particles of BFA were used to synthesize zeolite by alkali fusion (550 oC; 1 h; BFA: NaOH= 1:1.2 w/w) followed by hydrothermal treatment at 100 °C for 3 h. Si/Al molar ratio of 1.0 was adjusted with an external alumina source. BFA and synthesized zeolite were characterized using XFR, XRD, and MEV. The results showed that BFA may be used effectively for the synthesis of zeolite NaA with high purity comparable with the commercial product. Zeolite NaA is employed in sugarcane mills in the dehydration processes for the removal of water from the hydrated ethanol. Thus, the application of BFA in zeolitization process strategy provides not only environmental and economic benefits for the sugarcane agroindustry but also contributes to a circular economy and towards the achievement of Sustainable Development Goal 12.