performance evaluation of catalytic ozonation process with pumice in removal of humic acids from aqueous solutions

background: the use of alternative disinfectants and the control of natural organic material are two approaches that are typically applied in water treatment utilities to reduce the formation of chlorinated disinfection by-products in recent years. catalytic ozonation as a new technology is used to promote the efficiency of the single ozonation processes. the purpose of this study was to investigate the feasibility application of pumice as a catalyst in ozonation process in removal of humic acids from aqueous solution.   methods: this study as an experimental study was carried out at the chemistry laboratory of water and wastewater in hamadan university. the solid structure and chemical composition of activated carbon was determined by x-ray fluorescence (xrf) and x-ray diffraction (xrd). ozonation and catalytic ozonation experiments were performed in semi-batch reactor and the mass of ozone produced was measured by iodo-metric titration methods. concentration changes of humic acid were determined using spectrophotometer at an absorbance wavelength of 254 nm. to evaluate the performance of catalytic ozonation in humic acid removal, the effects of different parameters included ph, initial concentration of phenol contact, the amount pumice and tert-butanol alcohol (tba) were examined and the results were analyzed by excel software.   findings: the results of the catalytic ozonation indicated that using pumice as a catalyst increased the humic acid’s decomposition by 8 times and the removal efficiency was increased by increasing ph (4-12) and catalyst dosage (0.25-10 g). the experimental results showed that catalytic ozonation was the most effective in less time (10 min) with considerable efficiency (90%) compared to the sole ozonation process (sop). the results indicated that the catalytic ozonation process, compared to sop, was affected less by radical scavenger.   conclusion: because of the low cost of pumice, easy access to required raw materials and its remarkable performance as catalyst, it can be used as catalyst in sole ozonation processes to remove the organic material.