An environmental study on starch aerogel for drug delivery applications: effect of plant scale-up

Abstract

The aim of this work is the evaluation and minimization, using a life cycle assessment approach, of the environmental impacts of starch aerogel production on different scale plants. Aerogels are porous structures, which can be used as carriers for delivery systems; they are obtained through a supercritical drying. The impacts related to the production of 1 g of starch aerogel on two different scales (vessel internal volumes equal to 0.5 and 5.2 L) were evaluated and compared. The environmental impacts on an industrial scale plant were also simulated. All the quantities related to materials, energy consumption and emissions to air, soil and water were reported to the chosen functional unit (1 g of starch aerogel obtained on bench or pilot scale plant). Data were analysed using SimaPro 8.0.5 software, whereas the Ecoinvent 3.1 database and primary data were used for the life cycle inventory, according to the reference standard for LCA (i.e., ISO 14040-14044). A detailed analysis, following a gate-to-gate approach to quantify the emissions at plant level, which are generalizable for all polysaccharides’ aerogel productions, was performed. In order to complete the study, the results of a cradle-to-gate analysis, quantifying the emissions at overall level, which are complete but related only to corn starch aerogel production, were also proposed. The IMPACT 2002+ method was used to evaluate the effect of the production on the midpoint and damage impact categories. Scaling-up the starch aerogel production from bench to pilot scale induced a substantial reduction of the impacts on all the categories. On both scales, the analysis made using midpoint categories showed that supercritical drying step strongly affected carcinogens and mineral extraction, whereas alcogel production step strongly affected respiratory organics. Solutions aimed at minimizing these impacts were proposed. The performed analysis, using both midpoint and endpoint categories, allowed to identify the aerogel production weak points and propose improved solutions. Global emissions related to starch aerogel production were lowered passing from bench scale to pilot scale. By using damage categories, it was possible to quantify a global reduction of 40% of the emissions on human health, climate change, ecosystem quality and resources. The simulation on industrial scale led to a total reduction of 82% of the damage with respect to pilot scale plant and of 95% with respect to bench scale plant.