Enhanced performance of coal-based adsorbents in removing phenols from highly concentrated coking wastewater: Targeting large-scale applications

Coking wastewater threatens the ecology and environment significantly, but it still has challenges in the efficient removal of organic contaminants due to its complex composition and inadequate biochemical properties. Low-cost coal-based material has potential in treating coking wastewater due to its special structure and surface oxygenic functional groups. In this work, gangue-based materials were modified in different ways and applied to coking wastewater treatment. Combined with the comprehensive analysis of the adsorbents' morphology, structure, and composition with SEM, XRD, FT-IR, XPS, etc., the adsorption behaviors and regeneration properties were extensively investigated. Notably the adsorption and regeneration capacity of the adsorbents are significantly enhanced after modification, BY-C2 exhibits a remarkable COD removal rate of 90.2 % from real coking wastewater, which remains stable at 72.0 % even after 10 cycles. The pseudo-second-order kinetic model and Freundlich isotherm model are found to fit well with the adsorption processes of phenolic compounds in coking wastewater. The adsorption mechanism involves hydrogen bonding, van der Waals' force, capillary forces and electrostatic attraction. This work paves the way for the large-scaled application of coal-based adsorbents in coking wastewater treatment and the subsequent recycling of high-valued organic pollutants.