Degradation Of Non-biodegradable Organic Compounds By Combined Photocatalysis And Ozonation Processes

A review of degradation of non-biodegradable organic compounds and technique of photocatalysis combined with ozonation was firstly presented. And then the research aim was proposed. There are three parts in this paper: H-acid (1-amino-8-naphthol-3,6-disulfonic acid)degradation by combined photocatalysis of UV irradiation and ozonation processes, proposed pathway of H-acid degradation by the process and the treatment of coking wastewater by photocatalysis oxidation.(1) The experiment of H-acid degradation, by combined photocatalsis of UV irradiation and ozonation, shows that the synergistic effect exists on the decomposition of H-acid by combined photocatalsis of UV irradiation and ozonation. The effects of operating parameters, i.e. the concentration of O3, initial pH value, concentration of H-acid, concentration of sodium sulfate, were also investigated. It is found that the structure of H-acid is destroyed and its biodegradability is improved.(2) Intermediates of H-acid degradation by combined photocatalysis of UV irradiation and ozonation were analyzed by some analytic technologies (UV-vis, IC,1H NMR, HPLC-MS). Three intermediate products were identified: 1-amino-5,7,8-trihydroxynaphthalene-3,6-disulfonate, 8-hydroxy-l,2-naphthoquinone-3,6-disurfonate and 8-hydroxy-l,4-naphthoquinone -3,6-disulfonate. The pathway of H-acid degradation was discussed.(3) The degradation of coking wastewater exhausted from biochemical treatment by photocatalysis oxidation processes (O3/TiO2/UV and H2O2/TiO2/UV) was studied and compared with photocatalysis, ozone and hydrogen peroxide only. For a reaction time of 90 minutes, the CODcr of wastewater treated by the systems of photocatalysis oxidation, O3/TiO2/UV and H2O2/TiO2/UV, can be less than 80mg/L, which is far more efficient than TiO2/UV, O3 and H2O2. The effects of pH value and the concentrations of O3 and H2O2, which were controlling factors in O3/TiO2/UV and H2O2/TiO2/UV oxidation systems, were also studied. The oxidative mechanism of O3/TiO2/UV and H2O2/TiO2/UV were compared.