Avaliação do ciclo de vida de hidrogéis para aplicação na agricultura

Abstract

Superabsorbent hydrogels are crosslinked hydrophilic polymers that have the ability to absorb and retain aqueous solutions in their structure without dissolving themselves. The hydrogels may be pure or mixed with mineral fillers, creating the composites that decrease production cost and improve physical and chemical characteristics of the synthesized hydrogels. It can be found in eggshells in the form of calcite, implying their use in reducing the waste management expenses. This study aims compare the environmental impacts of two hydrogels superabsorbent production processes in laboratory scale: System A, copolymer hydrogel production of potassium acrylamide acrylate (Pam Acril) and system B, the composite production with bark egg (CalG20). This study is according to the ISO 14040 and 14044 standards for Life Cycle Assessment. The extension of this work system covers the production of hydrogels (synthesis processes, washing and drying) and inputs (water, energy and chemicals). The functional unit used was a hydrogel with the absorption of 1 liter capacity, requiring 1,368 g of hydrogel PamAcril and 0,901 g and of CalG20 as reference flows. The software used was version 8.0 Sima Pro, and the database was the Ecoinvent.The methods used for assessing the environmental impacts were: the recipe in hierarchical version, including the impacts of climate change, eutrophication, acidification; Pfister, for the study of water scarcity and USEtox for analysis of the impacts of human toxicity (carcinogenic and not carcinogenic) and ecotoxicity. The results of this study show that the hydrogel produced in the system generates greater environmental impact when compared to the system B, in all analyzed categories, causing about two times more impact. The uncertainty analysis by Monte Carlo method check out the results with a significance of more than 95% in all categories used in the study. Separately analyzing the steps in both systems, larger impacts are due to energy consumption in the drying step and the water consumption by a washing step. To reduce the impact on the two systems, it is suggested modifications in the drying step