Use of Adsorbents for Recovery of Acetic Acid From Aqueous Solutions Part Iii -- Solvent Regeneration

Solvent leaching was investigated as a method of regeneration for activated carbons and polymer sorbents loaded with acetic acid by contact with aqueous solutions. Both batchequilibration and fixed-bed experiments were employed. Methanol, methyl acetate, and acetone are suitable regeneration solvents for most activated carbons. Amoco GX-031 is an exception, giving incomplete regeneration. Methanol provides still more efficient regeneration for macroreticular styrene-divinylbenzenes adsorbents. Among basic sorbents, amine resins give incomplete regeneration by solvent leaching, as does a poly N oxide. Polybenzimidazole, a weaker base, gives higher recoveries of acetic acid when leached by solvents. Poly(4-vinylpyridine) is regenerated completely and efficiently by methanol, methyl acetate, and acetone in a fixed-bed geometry. It thus appears that an intermediate degree of basicity is desirable in a synthetic sorbent for acetic acid-- strong enough to give the uptake benefits of acid-base interactions, but weak enough to be regenerable.