Removal of fermentation inhibitors from lignocellulosic hydrolysate using olefin-linked covalent organic framework

Abstract

During lignocellulosic biomass pretreatment, inhibitory compounds such as furan aldehydes, phenolics, and carboxylic acids are inevitably generated. These compounds impair microbial growth, hinder sugar uptake, and increase fermentation costs. Among them, formic acid (FA) is especially harmful. To mitigate this challenge, the olefin-linked covalent organic framework NKCOF-41 was employed as an adsorbent for hydrolysate detoxification. NKCOF-41 exhibited exceptional selectivity for FA, achieving a maximum adsorption capacity of 140 mg·g⁻¹at 15 °C while leaving glucose and xylose unaffected. In simulated lignocellulose hydrolysate, adsorption equilibrium was reached rapidly within 30 min and followed a pseudo-second-order kinetic model. Most important, regeneration experiments confirmed that NKCOF-41 retained its adsorption efficiency over multiple cycles. Notably, detoxified hydrolysates treated with NKCOF-41 enabled bioethanol production within 12 h, achieving a 98% yield. These results identify NKCOF-41 as a highly effective and reusable adsorbent for selective inhibitor removal, offering a promising strategy to enhance lignocellulosic biomass conversion.