bsc-project-description-adsorption-of-vfas-on-sir.docx

BSc-project description

Coach: Boelo Schuur

Acid adsorption from fermented wastewater on solvent impregnated resins

By fermenting wastewater, we can make new chemicals from waste, in this way we try to close cycles and make a circular economy possible. During the fermentation volatile fatty acids (VFAs) are formed that can act as platform chemicals: from here we can convert into other valuable chemicals. There is, however, one serious issue and that is the dilution of the acids. To extract/adsorb acetic acid from a 1wt% aqueous solution in an economic fashion is not so easy. In order to find appropriate methods to recover dilute volatile fatty acids from fermented wastewater we have developed an adsorption technique that makes use of polystyrene/divinyl benzene resin (PS-DVB), which shows a marvelous selectivity for VFAs over mineral acids, but unfortunately also a lot of water is co-adsorbed.

We think that the water is not really adsorbed on the surface of the resin as is the acid, but it sits in the pores of the resin and the effect is the same: during recovery it needs to be evaporated which is energy intensive. In an attempt to keep the adsorption of the acids, but reduce the amount of water in the pores, we would like to investigate on impregnation of the resins with a high boiling solvent. Such impregnated resins are known as solvent impregnated resins. They are usually applied to extract something in the impregnated solvent, but now we want to apply the solvent to keep the water out. If this works, it can save huge amounts of energy.

The main elements of this BSc project are:

1)

Literature study on solvent impregnated resins and acid extraction/adsorption

2)

Preparing solvent impregnated resins and doing equilibrium adsorption experiments with aqueous acetic acid solutions

3)

Column adsorption experiments with artificial fermented wastewater to determine the capacity under realistic conditions