Synthesis, characterization, and applications of redox-mediated ion exchangers.

The technology for conversion of lignocellulosic biomass resources to fuels and chemicals has been under development for decades. There are many process configurations for conversion of biomass to ethanol, one of the well-studied technologies is to use a dilute-acid-catalyzed pretreatment followed by enzymatic hydrolysis and fermentation to produce the ethanol. However, the pretreatment product mixture, typically called hydrolysate, contains a variety of degradation products such as aliphatic and aromatic acids, phenols, and aromatic aldehydes. These degradation products formed can be considered potential fermentation inhibitors, and they can be a restricting factor in the achievability of biotechnological conversions of lignocellulosics to ethanol. This project seeks to contribute to the development of biomass conversion technologies by demonstrating a novel process enabling: 1) simultaneous extraction of organic acids and phenols through reactive ion exchange, 2) quantitative recovery of extracted components into aqueous solution, and 3) regeneration of reactive ion exchangers using redox chemistry. The organometallic complex Fe([eta]5-C5H5)([eta]5-10-C2B9H8(n-C12H25)2) is used in combination with tetra-n-heptylammonium hydroxide salt to demonstrate an improved
R2ER for the extraction of acids from aqueous solutions. The metal complex itself remains in its neutral state and only acts as a spectator during the extraction step.
New synthetic approaches to a single-component reagent have been developed in this study. The new organometallics synthesized have the principal advantage of reducing the process to a one-reagent. In this case the organometallic complex acts as an extractant instead of a spectator. Seven new compounds were synthesized and characterized, and the uses of Fe([eta]5–C5H5)([eta]5-10-(N(CH3)3)-7,8-C2B9H8(n-C12H25)2)] in a R2ER process were studied for the extraction of perchlorate from aqueous solutions.