Research Of The Application Of Nano-photocatalyst On Environment Protection

Photocatalytic oxidation of TiO₂ (P25) and nano-size TiO₂-Cu₂O in sanitization, algaecide, and wastewater treatment of organophosphate industry were investigated in this study.1. The biocidal effects of photocatalyst with nano-Cu₂O as main component on Phage M13 and bacteria Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Serratia marcescens under visible light were investigated. Under the illumination of 30μEm^-2V^-1, the results showed that the inactivation of microorganisms by TiO₂ was not significant. In contrast, the inactivation by Cu₂O on phage M13 and bacteria Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Serratia marcescens were 89.54%, 84.10%, 94.20%, 89.82%, 100% under visible light (p <0.05), respectively, and it was enhanced by 3mmol·L^-1 Fe²⁺. Moreover, Cu₂O has some chemical inactivation to microorganisms, especially to Serratia marcescens.2. Harmful algal blooms (HABs) frequently occurred worldwide currently due to the serious eutrophication state of water bodies. Algaecidal technology is therefore in great demand. A nanomaterial sheet was prepared for algaecidal treatment in our lab previously. This paper reports the test results of algaecidal activity of the nanomaterial sheet in lab and field experiments. It was showed that under the ratio of the area of nanomaterial sheet to volume of algal cell suspension at 0.08cm² · mL^-1 and light intensity at 60μEm^-2s^-1, the cell density of algal cell suspension of Microcystis aeruginosa, Anabaena 7120, Euglena gracilis, Chlamydomonas reinhardtii decreased by 77%, 69.1%, 89.1% and 56.9% respectively after 24h treatment, and Chl.a concentration of algal cell suspension of Navicula incerta decreased by 76%. Acute fish toxicity test (5 days) of the nanomaterial sheet showed no significant toxicity. Nanomaterial sheet appears to be a new promising algaecidal technology with advantages such as low cost, highalgaecidal activity, easy to use and environmental safety.3. A study was conducted on the treatment of wastewater of organophosphate pesticide industry by photocatlytic device using T1O2 fixed film as anode and armor plate as cathode. It is shown that COD in the treatment effluent was reduced 56.1% to 90.09%, and most of organic nitrogen and organic phosphorus are degraded to be in organic nitrogen and inorganic phosphorus. Total chlorine and dissolved phosphorus in the wastewater were significantly removed by aeration and precipitation with CaO. The results showed the reduction rate of total phosphorus and dissolved total phosphorus were 94.91% and 94.92%, respectively. The reduction rate of NO3-N and NH3-N in the wastewater were 93.27% and 51.14% by 7-day treatment of Dunaliella salina.