Purification and recovery of phosphate wastewater via Fe-modified activated carbon derived from waste phenolic distillation residue

The purification and resource utilization of solid waste and wastewater generated during industrial processes have become a focus of extensive research. In this study, Fe-modified activated carbon adsorbents (x-Fe-RAC) were successfully synthesized using phenolic distillation residue as a carbon source treated with FeCl₃. Compared to the blank sample, the static phosphate adsorption capacity was enhanced by approximately 12 times, reaching 26.29mg/g, and the Langmuir model predicted a maximum capacity of 42.52mg/g at 298K. A series of adsorption experiments and characterization analyses confirmed that the primary mechanisms are complexation and electrostatic interactions. After five dynamic adsorption-desorption cycles without replacing the adsorbent and regenerating solution, 0.5-Fe-RAC still exhibited a good regeneration rate, while the concentration of phosphate in the regenerating solution significantly increases. In summary, this study transforms challenging solid waste into activated carbon with excellent wastewater purification capabilities, achieving a sustainable strategy of treating wastewater with industrial waste.