Recovering levulinic acid by adsorption using efficient basic anion exchangers

Levulinic acid (LA) is a versatile compound used in biofuels, resins, etc., and its efficient recovery is required for its high value-added use. This study investigates the use of four anion exchange resins -Lewatit M-500 (a strong basic anion exchanger) and three weak basic anion exchangers (WBAEs), namely Amberlite IRA-67, Lewatit MP-62, and Lewatit MP-64- for LA recovery. The effects of pH, agitation time, LA concentration, resin dosage, and temperature on the adsorption efficiency were studied via batch experiments. Solution pH significantly influenced the yield. The highest efficiency was obtained at pH 2.1 for the WBAEs and pH 5 for Lewatit M-500. The kinetic data followed the pseudo-second-order model with R² >0.99. Increasing temperature slightly decreased the efficiency, with negative values for enthalpy (ΔH°) and Gibbs free energy (ΔG°), suggesting that the process was spontaneous and exothermic. The yield increased with resin dosage but decreased with higher initial LA concentrations. The highest adsorption capacity obtained from the four resins followed the order: Lewatit MP-62 (487.7 mg/g) > Amberlite IRA-67 (418.0 mg/g) > Lewatit MP-64 (371.6 mg/g) > Lewatit M-500 (278.7 mg/g). The successive adsorption-desorption trials using Lewatit MP-62 showed a slight decline (90% to 85%) in recovery efficiency over five cycles.