Treatment Efficiency of Electrocoagulation Combined with Different Particle Sizes of Natural Zeolite

In a previous study, the larger size of synthetic zeolite particles was highlighted as better choice for electrocoagulation combined with zeolite (ECZ). This choice resulted in a smaller rise in pH and temperature, a more significant decline in turbidity as well as chemical oxygen demand (COD), and lower electrode wastage, but with greater damage to the electrode surface. The focus of this study was to determine whether natural zeolite of three different particle sizes has the same effect on the ECZ process. The Taguchi method L9 was employed in planning the experiments, with particle sizes of natural zeolite ranging up to 600 μm, three different electrode materials (carbon steel, aluminium alloy, and sacrificial zinc anode), current density in the range of 0.003–0.018 A cm<sup>–2</sup>, and contact time in the range 10–30 min. The Taguchi optimisation results revealed a more significant decrease in COD and turbidity with the smallest particle size of natural zeolite used (90 µm) and with Al electrodes. Evidently, the zeolite particle size, together with the zeolite composition, had a significant influence on the reduction in COD and turbidity. Anode consumption ranged from 0.0172 to 0.6469 g, with minor cathode consumption evident on all electrode materials. Optical microscopy analysis indicated significant corrosion of the anodes, particularly with the largest natural zeolite particle size of 160–600 µm, while minor corrosion damage was also observed on the cathodes.