title: Adsorption and Reactive Desorption on Metal-Organic Frameworks: A Direct Strategy for Lactic Acid Recovery.
abstract: Biomass-derived lactic acid (LA) is an important platform chemical towards the sustainable production of numerous materials. However, the fermentation process currently in use is limited by the difficult recovery of the LA product from the fermentation broth and results in the generation of stoichiometric amounts of gypsum waste. Herein, we show that metal-organic frameworks (MOFs) of the UiO-66(Zr) type are effective adsorbents for the separation of LA from aqueous (buffer) solutions. These frameworks based on zirconium clusters and terephthalic acid derivatives display a tremendous uptake (up to 42 wt %) and a high affinity for LA. The latter can further be tuned by changing the hydrogen-bonding properties of the functional groups present on the organic ligand. A Rietveld refinement disclosed the specific interaction of LA with the clusters of UiO-66(Zr) and a preferential adsorption on open zirconium sites. Taking advantage of the catalytic activity of UiO-66(Zr), desorption of LA was performed in alcohols to recover up to 73 % as ester. Applied to the recovery of LA, adsorption and reactive desorption offer a direct and gypsum-free strategy as an alternative for the current multi-step process.
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F box 2461, 3001, Leuven, Belgium.
authors.forename: Timothée
authors.identifier: 0000-0002-1175-4057
authors.initials: T
authors.lastname: Stassin
authors.affiliation: Institute of Inorganic Chemistry, Christian-Albrechts University Kiel, Max-Eyth Straße 2, 24118, Kiel, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Reinsch
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F box 2461, 3001, Leuven, Belgium.
authors.forename: Ben
authors.initials: B
authors.lastname: Van de Voorde
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstraße 11, 81377, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wuttke
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstraße 11, 81377, Munich, Germany.
authors.forename: Dana D
authors.initials: DD
authors.lastname: Medina
authors.affiliation: Institute of Inorganic Chemistry, Christian-Albrechts University Kiel, Max-Eyth Straße 2, 24118, Kiel, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Stock
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstraße 11, 81377, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bein
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F box 2461, 3001, Leuven, Belgium.
authors.forename: Rob
authors.identifier: 0000-0003-3178-5480
authors.initials: R
authors.lastname: Ameloot
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F box 2461, 3001, Leuven, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: De Vos
mesh_terms: D000327:Adsorption; D000438:Alcohols / Q000737:chemistry; D018533:Biomass; D002021:Buffers; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry* / Q000302:isolation & purification*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000438:Alcohols; D002021:Buffers; D009942:Organometallic Compounds; D014867:Water; D019344:Lactic Acid; D015040:Zirconium
keywords: carboxylic acids; host-guest systems; metal-organic frameworks; separation; zirconium