Adsorption of low-concentration perfluorooctanoic acid on corn stover-based lignin amine by synergy of electrostatic and hydrophobic interactions†

Perfluorooctanoic acid (PFOA) has received widespread attention due to its potential carcinogenic toxicity, bioaccumulation and high environmental persistence. However, there has been insufficient attention paid to the contamination of groundwater with PFOA at the level of micrograms per liter near the primary-source sites. This study used corn stover-based lignin as a raw material to prepare a new biomass adsorbent named corn stover-based lignin amine (CSLA) using the Mannich reaction for the removal of low-concentration PFOA at the level of micrograms per liter from groundwater. The CSLA exhibited excellent adsorbability with removal rates for 250, 500, and 1000 μg L⁻¹ PFOA reaching 99.03%, 99.31%, and 98.45%, respectively, at 293 K and pH = 6. The adsorption behavior was in line with the pseudo-second-order and Langmuir model, indicating that the adsorption of low-concentration PFOA on CSLA was monolayer adsorption and depended on chemical adsorption. The CSLA could maintain a high removal rate of low-concentration PFOA in the presence of competitive ions and humic acid. The adsorption of PFOA on CSLA showed excellent regeneration ability. After five adsorption cycles, the removal rate of PFOA still reached 94.55%. In addition, CSLA has good environmental safety and actual application potential. SEM-EDS, XPS, and FTIR suggested that electrostatic interaction, hydrophobic interaction and hydrogen bonding significantly promoted the removal of PFOA. The CSLA is obtained from cheap corn stover, enabling a broader impact on sustainability and efficient removal of low-concentration PFOA from groundwater.