An enhanced beta-blockers degradation method using copper-boron-ferrite supported graphite electrodes and continuous droplet flow-assisted electro-Fenton reactor

In this study, copper-boron-ferrite (Cu-B-Fe) composites were prepared and immobilized on treated graphite electrodes via rice husk silica-based sol-gel approach. The effect of different bimetallic loading ratios was relatively evaluated for fast in-situ electrogeneration of reactive oxygen species (H₂O₂ and ^[rad]OH) via a new droplet flow-assisted heterogeneous electro-Fenton reactor system. The optimum loading ratios of 20 wt% Fe³⁺ and 10% wt. Cu²⁺ greatly improved the catalytic activities towards efficient pharmaceutical beta blockers (atenolol and propranolol) degradation in hospital wastewater. By using Central Composite Design optimization, high correlation coefficients (R² and R²-(adj)) between the experimental and predicted data of 96.83% and 93.43% were realized. At optimized conditions, higher degradation efficiencies of ˃ 99.9% for both propranolol and atenolol in hospital wastewater were achieved. The critical contribution of ^[rad]OH radicals in the degradation process was assessed using radical scavengers. As a result, a surface mechanism at the integrated cathode electrode was proposed highlighting the contributions of iron and copper. It was confirmed that both copper and iron embedded in the porous graphite electrode surface catalyzed the efficient conversion of H₂O₂ to ^[rad]OH which in turn enhanced the degradation process. The fabricated cathode electrodes showed stable catalytic activities even after 20 experimental replicates at both neutral and acidic conditions.