Efficient Separation of Levulinic Acid Using Fly Ash from Sugar Beet Processing

Levulinic acid (LA) is a significant building block in industry. It can be produced by the hydrolysis of lignocellulosic feedstocks and needs to be separated from the aqueous production medium. This study focuses on evaluating fly ash, a waste byproduct from a sugar factory, for use in the adsorption of LA from aqueous media. The sugar beet processing fly ash (SBFA) was characterized using XRD, FTIR, SEM, and N2 adsorption-desorption analysis. The data fit the pseudo-second-order kinetic model, with good agreement between the experimentally measured (454.55 mg g–1) and calculated (452.40 mg g–1) adsorption capacities. It was observed that the efficiency slightly decreased with increasing temperature, with the effect more pronounced at lower concentrations. Calculated thermodynamic parameters demonstrated that the process was exergonic and exothermic. The capacity of LA adsorption reduced with SBFA dose while enhanced with acid concentration, achieving a maximum of 464 mg LA/g SBFA, higher than values previously achieved with other adsorbents. The Langmuir isotherm model fit well with equilibrium data. Complete recovery of LA was achieved using 0.2 M NaOH, and SBFA could be reused with high efficiency for five consecutive cycles.