Sustainable Water Reuse: Green Polymer, Ionic Liquid, and Peroxidase-modified Graphene Oxides Composites for Remediation of Phenolic Wastewater

Based on the results of Langmuir Qmax values at pH 6 and 40 °C, adsorption performance showed a clear dependence on adsorbent type and surface chemistry. For phenol, the adsorption capacity followed the order AC-PJ (52.35 mg/g) > AC (34.84 mg/g) > GO-PAA (11.49 mg/g) > GO-ILs (9.09 mg/g) > GO (5.46 mg/g), highlighting the superior performance of biomass-derived activated carbon and the limited capacity of pristine and modified GO. For bisphenol A, a much stronger contrast was observed, with adsorption following AC-PJ (454.55 mg/g) ≫ AC (105.26 mg/g) > GO (63.29 mg/g) > GO-ILs (38.46 mg/g) > GO-PAA (16.67 mg/g). In general, AC-PJ exhibited the highest adsorption capacities for both pollutants at pH 6 and 40 °C, with a particularly pronounced advantage for BPA, confirming the dominant role of carbon-rich surfaces and favorable pore structures under these conditions. Peroxidase-assisted degradation further improved pollutant removal, achieving up to ~95% BPA and ~80% phenol removal under optimal conditions (2mM H2O2, 0.1 U/mL enzyme, pH 6, 40 °C). The process remained effective under moderate salinity, confirming the enzyme’s tolerance to ionic strength. Overall, the study demonstrated that enzymatic oxidation significantly enhanced the removal of phenolic pollutants. Enzyme loaded GO-PJP showed a pronounced enhancement in phenol removal compared with pristine GO, achieving more than a twofold improvement at intermediate concentrations due to synergistic adsorption–enzymatic oxidation, whereas BPA removal showed only limited and concentration-dependent improvement. In continuous-flow column experiments, activated carbon sustained the longest breakthrough performance, achieving dynamic capacities of 160.00 mg/ g for phenol and 559.08 mg/g for BPA, with breakthrough times of 177.78 min and 354.91 min, respectively. Graphene oxide showed faster kinetics but earlier exhaustion, with phenol capacities of 79.37 mg/g and BPA capacities of 40.20 mg/g, and breakthrough times of 62.43 min for phenol and 39.37 min for BPA. Thomas, Yoon-Nelson, and Yan models provided strong fits (R2 up to 0.96), confirming that AC acted as a high-capacity, diffusion-dominated adsorbent, while GO functioned as a rapid-kinetic but lower-capacity material under continuous operation. These column findings corroborated the batch results and highlighted AC as the most efficient sorbent for sustained removal of phenolic pollutants. These results highlighted the complementary roles of carbon-rich adsorbents for high-capacity removal and enzyme-assisted GO systems for catalytic enhancement, offering a promising and sustainable strategy for the treatment of phenolic contaminants in complex wastewater matrices.