Removal of 8-Hydroxyquinoline-5-Sulfonic Acid (8-HQS) by a Sequential Heterogeneous Fenton/Adsorption Process Using a Microwave-Fabricated Iron-Perlite as Catalyst

Herein, the heterogeneous Fenton degradation of 8-hydroxyquinoline-5-sulfonic acid (8-HQS) was performed using a perlite-based synthesized catalyst. Two types of iron-perlite catalysts were synthesized by precipitation according to the conventional and microwave techniques to carry out the heterogeneous oxidation process. The as-prepared catalysts were characterized by powder X-ray diffraction, FT-IR spectroscopy, thermal gravimetric and differential thermal analysis (TGA/DTA), and optical microscopy observation. Their catalytic activity depended on the synthesis method. The highest catalytic activity was reached using the microwave-fabricated catalyst. To optimize its efficiency, the effect of some operating parameters on Fenton oxidation was carried out. Compared to the conventional method, the microwave technique produced a catalyst having significant pollutant removal of about 71.32% and high stability without iron leaching after several treatment cycles. To maximize the degradation rate at mild operating conditions, while considering the highly adsorptive character of perlite and the instantaneous catalytic oxidation activity of the prepared iron-perlite catalyst, a sequential heterogeneous Fenton/adsorption treatment process was proved to be a feasible choice for the improvement of 8-HQS removal from aqueous solution. Graphical Abstract