1

Propylene Carbonate Extraction for Recovery of Poly-3-hydroxybutryate

Abstract Propylene Carbonate Distillation Poly -3-hydroxybutryate (PHB) is a biopolymer produced as a storage molecule for energy and carbon under Propylene Carbonate is an organic solvent produced • Waste solution recovered after PHB by combining propylene oxide with carbon dioxide. It is poor growth conditions in certain organisms. PHB is a precipitation consisted of Propylene considered a polar aprotic solvent (no proton to donate) class of polyhydroxyalkanoates (PHAs), which have Carbonate and Ethanol similar properties to plastics derived from petroleum. Due to its characteristics (low vapor pressure, stability, and high polarity) it is used in many applications. These include PHB provides an environmentally friendly alternative to • Through distillation, both the Ethanol petroleum-based plastics due to its biodegradability and production of fibers and textiles, dyeing, personal care agents and Propylene Carbonate have been method of production. It can be produced by and cosmetics, and a component of some adhesives. It is also recovered.

recombinant Escherichia coli, harvested from the cell, considered non-toxic making it more suitable to use at larger

and recovered. One of the major expenses of scales. • Recovered 70% Propylene

producing PHB is the extraction of the PHB from the Carbonate and nearly all Ethanol biomass. This study focused on evaluating different

methods of PHB extraction for their ability to effectively • Preliminary experiments show no

extract PHB from E. coli biomass and the feasibility of Propylene Carbonate Extraction Procedure difference in the yield of PHB Distillation apparatus to recover Propylene scaling up those processes. These processes provide a Carbonate and Ethanol from waste stream extracted with distilled Propylene 125 L Bioreactor way to produce PHB from growing E. coli on a waste Propylene Carbonate was first tested at the test tube scale, using 0.5 g to 1 g of dried E. Carbonate product generated from algae processing. coli biomass per sample. Confirmation that the Propylene Carbonate procedure was extracting PHB from the biomass and isolation of the PHB was possible was achieved Poly-3-hydroxybutryate Extraction Techniques by gas chromatography. Results The Propylene Carbonate extraction method was evaluated to test its effectiveness at There are several procedures published to extract PHB from biomass of different Once confirmed, the Propylene Carbonate extraction procedure was scaled up to run 40 recovering PHB from dried E. coli biomass. This was done using 0.5 g of E. coli organisms. Some procedures use toxic solvents recovering high yields and purities, g of dry E. coli biomass per run. The procedure is described in the figure and pictures biomass containing approximately 20% PHB (predetermined by GC). Yield was based but use large quantities of hazardous solvents making it difficult to scale up to handle below: on the mass of PHB recovered and the purity was based on results obtained from the larger quantities of biomass. During the course of this project various extraction GC (ratio of the mass of PHB determined by GC to mass of extract analyzed). Both procedures were tested for their ability to extract PHB from the biomass, safety of the Dry E. coli Biomass fresh Propylene Carbonate and Distilled Propylene Carbonate were tested. chemicals being used, the capability of the procedure to extract wet biomass, and Biomass mixing with 94.58% finally the feasibility of scaling up the procedure being evaluated. Propylene carbonate at 100% 94.26% 1 130oC 1 Heat Propylene 80% Carbonate and Mix in 60% 55.79% 53.00% Chloroform Sodium Hydroxide: Acetone Propylene Biomass 40%

Carbonate 20% 2 0% Failed: Failed: Failed: Successful: Filter PC (Propylene Carbonate) Solvent is toxic Difficulty Scaling Low extraction yield Non-toxic solvent Fresh PC Yield PC Distilled Yield Difficult to scale Loss of PHB High recovery/purity Solvent phase PHB extract after removing solvents 2 Fresh PC Purity PC Distilled Purity Can use wet biomass separated from the biomass by vacuum Cool and Precipitate

filtration PHB with Ethanol Future work

3 Optimize Propylene Carbonate Extraction parameters for E. coli biomass

Distill to Recover Centrifuge to Collect • Digestion time with Propylene Carbonate and temperature Evaluation of Different PHB Extraction Methods Solvents Precipitated PHB • Possible Pretreatments • Temperature • pH Method of Are materials Can use wet Is Solvent Solvent to PHB extract after removing Ethanol and • Precipitation techniques Extraction: toxic? biomass Required? Process 1 kg Propylene Carbonate Biomass Energy and Mass Balance Chloroform Yes No Yes 10 L 3 • Determine the overall effectiveness of this extraction procedure in relation to Sodium No Yes No 1 L scale up. Solvent phase collected Hydroxide (Propylene Carbonate),

Acetone No No Yes 10 L cooled, and mixed with Acknowledgements Ethanol to precipitate Propylene No Yes Yes 725 mL PHB Biological Engineering Department Carbonate Logan City Environmental Department

Brian Smith, Jordan Morely, Ashik Sathish, Asif Rahman, Ronald C. Sims, Charles D. Miller SBI Science & Technology Review 1/29/2013