Study On Preparation And Properties Of Titanium Dioxide Supported On Natural Zealite Photocatalyst

Semiconductor photocatalyst is a new fuctional material that hasbeen studied by many scholars these years.Photocatalyst can changelight energy into chemical enegy at normal tempreture and pressure,sophotocatalytic degradation has become one of the most effectivemethods to treat organic pollutants. Titanium dioxide has become animportant and developing photocatalyst for its higher stability andactivity, cheapness,intoxicity, difficulty to dissolve in the acid and alkaliconditions in so many Semiconductor photocatalysts. Many facts proveTitanium dioxide has remarkable efficiency in changing light energy. Butit has some disadvantages while treating pollutants by titanium dioxidephotocatalytic degradation, such as inclination to inactivate andagglomerate, difficulty to reuse and easiness to cause the secondpollution. All these problems has baffled practical application. So manytutors both home and abroad have devoted themselves to synthsizesupported photocatalyst which can approve efficiency while ensurephotocatalytic activity. Some things have been tried to support titaniumdioxide, such as china, glass,quartz,stainless steel,activatedcarbon,optical fiber and so on. Almost the activity of all these things islower than pure TiO₂. This paper prepared titanium dioxidephotocatalyst supported on a natural zeolite with tetrabutyl titanate astitanium source. The test result proved that the chemical combinationwas achieved between titanium dioxide and the mineral and someproblems such as agglomerate, difficulty to reuse had been overcomedby using pure TiO₂. It provides a new way for semiconductorphotocatalyst. The TiO₂/natural zeolite photocatalyst with which supported onnatural zeolite was obtained after the titanium dioxide sol wassynthesized by acid-catalyzed sol-gel method. The chemicalcombination was achieved between titanium dioxide and the mineralthat has a bigger specific surface area. Specific surface and ionexchanging amount of natural zeolite would increase obviously if treatnatural zeolite beforehand by acid of some density. It was helpful forTiO2 sol to support the surface of natural zeolite. The experimentalresults showed that titanium dioxide supported on a natural zeolitetreated at 200℃had the best photocatalytic activity for omethoate.Structure test showed it was anatase that had the best crystallizationand the biggest content at 200℃. The synthesized titanium dioxidetransformed from anatase to rutile gradually with the calcinatingtemperature increased. The electron and hole produce easier foranatase than that of rutile, so it has a high photocatalytic activity. Theorganophosphorous pesticides were photocatalytic degraded by thesynthesized titanium dioxide. Dichlorvos can be entirely decomposedwith general conditions in irradiation for 120 min and it was the easiestone, Phorate was the easier one, and Parathion was the most difficultone to break down, which had relation with their molecular structure.Since the natural zeolite had better absorption, omethoate had 5percent degradation when the blank experiment was carried out by thezeolite only. At the same time, the parallel experiment was done withvisible light and there was no degradation. That is to say, the vision lighthad no contribution to the photodegradation. The influence factors such as the initial pH, the additional hydrogenperoxide, the content of titanium dioxide and the amount of supportedTiO2 on photocatalysis degradation with omethoate as aimcontaminants were further studied. The results showed that omethoatecould be easily decomposed at strong acid conditions, Sronger acidconditions, faster degradation rate. The problem in using titaniumdioxide as a photocatalyst is recombination of electron and hole. Onestrategy for inhibiting theirs recombination is to add other electron...