Bio-based crotonic acid production from wastewater

Abstract

There is a pronounced growth in industrial interest for renewable and environmentally sustainable pathways to produce chemicals. Driven by the desire to move away from linear economic models based on the supply of fossil fuel-based materials, renewable sources for chemicals are being explored. In this thesis, a multistep process to produce crotonic acid (CA) from a waste/wastewater is studied. CA is used in textile, cosmetic, painting, and coating applications and as building block in the synthesis of co-polymers, for example by copolymerization with vinyl acetate. Regardless of its wide range of application, the current production pathway of CA through a petrochemical route is neither renewable nor straightforward. Thus, this research was focused on providing a bio-based pathway to produce CA using a waste/wastewater as a feedstock. First, the waste/wastewater was subjected anaerobic fermentation to produce volatile fatty acids (VFAs). We examined adsorption as an affinity separation technique to recover these VFAs from the fermentation broth using a novel superparamagnetic polymer. Then, the VFAs were fed into an aerobic bio-reactor in which the microorganisms converted the VFAs into an intracellular co-polymer, called poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). After production of the PHBV, we investigated the application of bio-based solvents to extract the PHBV from the cells. Afterwards, the thermal degradation of PHBV towards CA was studied. Pyrolysis of the PHBV results in not only CA, but also in various side products. Therefore, the last step was focused on the purification of the produced bio-based CA.