Identifier

etd-11132007-235550

Degree

Doctor of Philosophy (PhD)

Department

Engineering Science (Interdepartmental Program)

Document Type

Dissertation

Abstract

Trans aconitic acid (TAA) is the predominant organic acid in cane leaf matter (CLM) juice. Its concentration is three to six times higher than the level found in sugarcane stalks. The variation of composition in terms of total fermentable sugars (TFS), anions, and cations of the LCP85-384 sugarcane variety during 2003-2006 seasons, as well as the ripener (Polado-L®) effect were analyzed. TAA content ranged between 2.1-3.1 kg / t CLM. The TFS in CLM juice yielded a fermentation efficiency of 92%, four points lower than with sugar molasses. Liquid-liquid extraction (LLE), solid-liquid extraction and ion exchange were evaluated for the recovery of TAA from CLM stillage. Tributyl phosphate -dodecane, ethyl acetate and butanol were evaluated for LLE. Maximum TAA extraction yield (92 g/100 g) was observed on acidification of CLM stillage to pH 2.0 with 50 % (v/v) sulfuric acid at an organic/aqueous phase ratio (OA) of 3.5 with butanol as extractant. Tributyl phosphate-dodecane had a similar extraction yield as butanol; however, in this mixed solvent formation of third phase was observed. Ethyl acetate had the lowest extraction yield. The purity of TAA extract in butanol was 32 g/100 g DS. Butanol extract was esterified with either sulfuric acid or a cation exchange resin as catalyst to yield tributyl aconitate (TBA). Resin efficiency was affected by the impurities. The overall yield using sulfuric acid was 84 %. TBA was decolorized with powder activated carbon. The attempts to esterify TAA from spray dried CLM stillage were unsuccessful. The highest conversion yield was only 2.5 %. Dowex Optipore SD-2, a non-ionic adsorbent, showed the best results among the resins and adsorbents evaluated. TBA and two citrate esters were compared to di-isononyl phthalate (DINP) as plasticizers of polyvinyl chloride (PVC). Thermal and mechanical properties were similar to those observed with DINP. CLM and leaves together represent up to 50% of the total fiber of cane. An economic model estimated that processing whole sugarcane can be a profitable business if it is transported at distance of no more than 20 miles from the field to the mill.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Michael Saska

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