Life cycle assessment of phosphoric acid based geopolymer adsorbents

• Main Authors: Argonza, Antoinette Joy L., Magsano, Niño Matthew D., Santa Ana, James Anthony S.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Inorganic polymers—Absorption and adsorption; Phosphoric acid; Product life cycle; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etdb_chemeng/11; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1017&context=etdb_chemeng
• Institution: De La Salle University

Phosphoric acid-based geopolymers (PAGPs) have been found to be porous, thermally stable, reusable, and renewable, making them a possible alternative for dye and heavy metal adsorbents in wastewater. To determine its sustainability and applicability as a potential adsorbent, PAGP was assessed in terms of its environmental impacts through an ex-ante, cradle-to-gate life cycle assessment (LCA) study of its scaled-up process. In this study, reference papers and the EcoInvent database were used for the inventory of the scaled-up parameters for the production of the adsorbents, and openLCA was used for the impact assessment. These impacts were then compared to granular activated carbon (GAC) at maximum uptake capacities of copper and methylene blue (MB). It was found that PAGP performed the best compared to coconut shell-based activated carbon (CSGAC) and coal-based activated carbon (CGAC) in the copper scenario. In the copper scenario, with CGAC as reference adsorbent for 100% impact contributed, PAGP was the best in acidification potential (AP) at 15.21%, eutrophication potential (EP) at 23.86%, global warming potential (GWP) at 11.41%, and energy resources demand (ER) at 10.29% but performed worse than CSGAC in freshwater aquatic ecotoxicity potential (FAETP) at 75.34%, human toxicity potential (HTP) at 29.83%, and terrestric ecotoxicity potential (TETP) at 21.22%. The main contributors to the impact were the aluminum oxide and phosphoric acid that were used in PAGP production. For both the GAC adsorbents, electricity contributed the most to the impacts. In the MB scenario, PAGP performed the worst in the environmental impacts due to its very low MB uptake capacity. This was especially exhibited in FAETP, where PAGP had an impact that was equivalent to 86 times that of CGAC. Future studies may focus on the inclusion of a sensitivity analysis and process optimization to fully analyze possible impact uncertainties and to lower environmental impacts on scaled-up processes.