Selective adsorption of ferulic acid and furfural from acid lignocellulosic hydrolysate by novel magnetic lignin-based adsorbent

In this study, two novel adsorbents (M-0 and M-1) were obtained by one-step synthesis of magnetic nanoparticles with alkaline lignin and oxidized alkaline lignin, respectively. The core-shell structure of the two adsorbents was demonstrated by various characterization results. The adsorption performance of M-0 and M-1 for ferulic acid and furfural at different pH, contact time, initial concentration, and temperature were investigated. The results showed that the adsorbents were pH-sensitive for ferulic acid but not for furfural, and the adsorption process was rapid and thermodynamically unfavorable. Meanwhile, the simulated acid hydrolysate was detoxified by different concentrations of M-1 and its reusability was investigated under mild regeneration conditions (pH = 10, 328 K). M-1 exhibited 93.41 % removal of ferulic acid and 53.12 % removal of furfural with almost no sugar loss during the adsorption process, as well as excellent reusability. The adsorbent M-1 (before and after adsorption) was determined by suitable characterization techniques and the results illustrated pi-pi interactions and hydrogen bonding as the major forces. Above all, adsorbents have promising applications for the detoxification of acidic lignocellulosic hydrolysates.