Complexation Extraction For Recovery Of 3-Hydroxypropionic Acid From Fermentation Broth

3-Hydroxypropionic acid(3-HP)is an important platform compound,which can be used to produce a variety of valuable industrial chemicals.Biological fermentation for the production of 3-HP could be an alternative to chemical synthesis method,and it has attracted increasing attention in recent years.However,the commercial prodution of 3-HP is severely limited by the lack of efficient separation technology.Due to its advantages including high efficiency,high throughput,easy operation and scale-up,complexation extraction is considered as a promising technology for the recovery of highly hydrophilic compounds from aqueous solutions.In this dissertation,the complexation extraction of 3-HP from fermentation is carried out with alkylamines.Firstly,tertiary alkylamines including tri-n-octylamine(TOA),tri-n-decylamine and tri-n-dodecylamine were used as extractants to extract 3-HP from aqueous solutions and their extractabilities were investigated.Concerning the best extractant TOA,effects of several key factors such as types of diluent,pH of aqueous phase,temperature,phase ratio and volume fraction of extractant in organic phase on the extraction efficiency and distribution coefficient of 3-HP were investigated.The maximum recovery rate of 81.6%was achieved under the condition of temperature 293 K,phase ratio 1:1,volume fraction of TOA in organic phase 30%and initial concentration of 3-HP 0.330 mol/L.The extraction mechanisms of 3-HP during the complexation extraction was explored by fourier transform infrared spectroscopy(FT-IR)and mass action law.The results showed that 3-HP and TOA combined as acid-amine complexes by ion-pair or hydrogen-bond.1:1 and 2:1 acid-amine complexes were present in the organic phase,and 1:1 acid-amine complex was the main form.The extraction behaviors of 3-HP by three secondary amines i.e.di-n-octylamine,di-n-decylamine and di-n-dodecylamine were investigated.The results showed that the extractabilities of 3-HP by secondary amine extractants were better than tertiary amines with equally long alkyl chain.Furthermore,effects of diluent,temperature,pH of aqueous phase,phase ratio and concentration of extractant in organic phase on the extraction were studied.The maximum recovery rate of 98.8%and distribution coefficient 77.6 of 3-HP were achieved at the condition of phase ratio 1:1,temperature 303 K using di-n-decylamine as extractant and 1-octanol as diluent.Fourier transform infrared spectroscopy(FT-IR)and mass action law were employed to explore the extraction mechanisms of 3-HP during the complexation extraction.The results showed that 3-HP and di-n-decylamine combined as ion-pair acid-amine complex.1:1 and 2:1 acid-amine complexes were present in the organic phase.Based on the research of properties of fermentation broth,the pretreatment of broth was explored and the result showed that soluble protein which can lead to emulsion can be effectively removed by heating and acidizing.Based on these results,TOA and di-n-decylamine were used to recover 3-HP from fermentation broth.The results showed that diluent has a remarkable effect on the extraction of 3-HP by both extractants.When employing the same diluents,TOA showed better extractability towards 3-HP from fermentation broth than di-n-decylamine.Multi-stage extraction was performed using TOA as extractant and 1-butanol as diluent and the results showed that a recovery rate of 96.7%for 3-HP from fermentation broth was obtained by 4-stages extraction.