Post-Fermentation Recovery of Biobased Carboxylic Acids

Abstract

Carboxylic acids are common products produced from the bioconversion of renewable feedstocks. In these processes the separation of the acid product from fermentation broth is the most energy and cost intensive unit operation. Thus, the development of robust, scalable separation approaches that can be applied to a variety of carboxylates is of critical importance to the development of processes that utilize carboxylic acids as platform chemicals. Here we report a batch separation method that includes cell and particulate removal, cation exchange, activated carbon treatment, dewatering with a polymer resin, and product recovery. This method is demonstrated on two unique fermentation broths both derived from corn stover hydrolysate to separate neat succinic and propionic acid. For succinic acid, a crystallization yield of 91% with a product purity of 99.93% was achieved. To our knowledge this is the highest reported crystallization yield and purity for the recovery of succinic acid. Additionally, the method requires approximately 50% less energy compared to standard evaporative crystallization approaches. For propionic acid, neat liquid product was obtained with a distillation yield of 80% and purity of 98%. These excellent results achieved in terms of yield and purity for succinic and propionic acid, two acids with widely different physical properties, from chemically complex hydrolysate broth demonstrates the effective and robust nature of this approach.

Assessing the stability and techno-economic implications for wet storage of harvested microalgae to manage seasonal variability

“…The prevalence of butyric acid in the enzyme treatments could be the result of proliferation of Clostridia species, whose growth may be enabled by the higher pH of 5.0–5.1 for these experimental conditions after 30 days compared to a pH of 4.2 in anaerobic and sulfuric acid-treated samples. Butyric acid formation during ensilage of herbaceous biomass destined for animal feed is discouraged since it results in a feed unpalatable for livestock [34]; however, butyric acid formation in biomass destined for fuel production may have economic advantages if combined with other carboxylic acid fermentations [35]. Propionic and isovaleric acid production in all treatments appeared to be time dependent, experiencing an approximate two- to threefold increase between 30 and 180 days storage depending on treatment.…”

Techno-economic, life-cycle, and socioeconomic impact analysis of enzymatic recycling of poly(ethylene terephthalate)

“…The filtrate is subsequently passed through an activated carbon column to remove additives such as dyes and pigments. 35,43,44 These steps inherently assume that rTPA at pH > 7 remains soluble in the aqueous phase. The solution is then acidified by the addition of sulfuric acid to lower the pH to 2.5 and cooled to precipitate rTPA.…”

“…The process modeled here assumes that dyes, pigments, and adhesives are removed by the solid ll OPEN ACCESS filtration and activated carbon column. 35,[42][43][44] Spent enzymes are removed by ultrafiltration in the base case, which may not be a necessary step if there is sufficient removal by the activated carbon column, 101 thereby resulting in a lower MSP. Although this design is aligned with reported practices, alternate and emergent separation techniques for product recovery can be potentially explored.…”

Outer membrane vesicles catabolize lignin-derived aromatic compounds in Pseudomonas putida KT2440

“…Aromatic compounds in the lignin-rich supernatant were analyzed by electrospray ionization (ESI) liquid chromatography (LC) mass spectrometry (MS/MS) on an Ion Trap SL (Agilent) as previously described (26). Glucose and small acids in the culture supernatants were analyzed by LC-refractive index detector (RID)/UV on a Agilent 1200 LC system as previously described (71). Aromatic compounds in the OMV in vitro assays were analyzed by ESI-LC-MS/MS on a 6470 Triple Quadrupole Mass Spectrometer (Agilent) with multiple reaction monitoring (MRM) for each analyte.…”