Enhanced adsorption of organic matter from coal chemical membrane concentrate by applying positive potential to mesoporous activated carbon fiber

Efficient removal of organics from reverse osmosis concentrate (ROC) in the coal chemical industry is crucial for ensuring the stable operation of the evaporation-crystallization unit within zero liquid discharge process and the purity of the crystallized salt. Activated carbon adsorption is a straightforward and effective method; however, its slow adsorption kinetics and high regeneration energy requirements limit its broader application. Herein, we prepared mesoporous activated carbon fiber (ACF) with high specific area as electrode material, and enhanced the adsorption and desorption of organics by applying an electric potential. The organics in the ROC is primarily composed of humics, which are negatively charged, and low molecular weight neutrals. Applying a positive potential to the mesoporous ACF significantly increased the adsorption amount and rate of organic matter by 30% and 90%, respectively, compared to ACF adsorption or adsorption with a negative potential. This enhancement was attributed to the electrostatic attraction and mesoporous structure of ACF. ACF with high mesopore volume showed good removal of humics, low molecular weight neutrals and building blocks. Correlation analysis revealed that the adsorption rate was predominantly linked to the mesopores. By applying the reverse potential to the ACFs loaded with organic matter, 40–70% of the adsorbed organic carbon was desorbed back into the water within 5 min.The energy consumption for desorption of organics adsorbed by ACFs was almost three orders of magnitude lower than that for GAC desorption. This study offers a novel solution for enhancing the adsorption of organic matter from ROC.