Computer-aided environmental and exergy analyses of a large-scale production of chitosan microbeads modified with TiO2 nanoparticles

Abstract

Chitosan is a biopolymer that has emerged as a useful material with applications in sectors such as medicine, food industry, water treatment systems, among others. This biomaterial is synthesized from shrimp exoskeleton, becoming an alternative of waste valorization. Chitosan can be used as main feedstock for production of bio-adsorbents modified with nanoparticles for pollution removal purposes. In this work, an environmental assessment and exergy analysis of a large-scale production of chitosan microbeads modified with TiO2 nanoparticles were developed with the aim of evaluating potential environmental impacts and energy/exergy performance. Aspen Plus ® software was used to develop process which allows quantification of extended mass and energy flows, property estimation, calculation of physical exergy flows, among others. The environmental evaluation was performed using the Waste Reduction Algorithm through the WAR GUI software. Environmental results showed that the presence of monovalent alcohols (propanol and ethanol) increased environmental effects related to the Photochemical Oxidation Potential category. From toxicological viewpoint, titanium tetra-isopropoxide affected Human Toxicity by Ingestion and Terrestrial Toxicity categories. Thought exergy analysis was identified that Centrifugation 2 is the process unit with highest irreversibilities, and also was founded that the overall exergy efficiency of the process was 0.0439%. These findings suggested that the proposed design requires the application of process improvement strategies in order to obtain better energy performance.