Preparation And Photocatalytic Of Aluminum Fumarate/Titanium Dioxide Composites

Printing and dyeing wastewater has the largest discharge amount in industrial wastewater.It is highly toxic and has complex organic pollutants.As a result,printing and dyeing wastewater is difficult to treat and is extremely easy to cause harm to human health and ecological environment.Photocatalysis degradation technology is one of the more effective methods to treat this kind of wastewater.Among semiconductor materials,TiO₂ is the most widely used in the field of photocatalysis due to its non-toxic and low production cost.However,when TiO₂ is used as a photocatalyst,there are some shortcomings,such as fast recombination of electron hole pairs generated by light induction,poor adsorption of pollutants,etc.Therefore,the modification and optimization of photocatalytic performance of TiO₂ is the most important problem to consider at present.In this paper,a series of composites based on Al Fu/TiO₂ was prepared by combining aluminum fumarate（Al Fu）with TiO₂.The high adsorption capacity of Al Fu endowed the composites with good adsorption capacity.At the same time,the charge transfer between Al Fu and TiO₂could limit the combination of electron hole pairs in TiO₂ to improve the photocatalytic performance.Sodium alginate（SA）as the matrix of the composite was used to improve the recycling performance of Al Fu/TiO₂ particle composite.The results were listed as follows:（1）Al Fu particle was prepared by heating under normal pressure using fumaric acid as organic ligand,Al₂（SO₄）₃·18H₂O and Al（NO₃）₃·9H₂O as aluminum source,respectively.The influence of aluminum source,heating temperature and heating time on the morphology and crystal structure of Al Fu were discussed.The results showed that Al Fu particle with high specific surface area could be prepared by using Al₂（SO₄）₃·18H₂O as aluminum source,the molar ratio of Al₂（SO₄）₃·18H₂O to fumaric acid was 1:2,and heating at 60℃for 2h.BET test showed that Al Fu belonged to typical I-type adsorption with hysteresis loop with specific surface area 603.9458 m²/g and pore volume 0.388465 cm³/g.（2）Al Fu/TiO₂composite was prepared by sol-gel method using tetrabutyl titanate（TBT）,concentrated nitric acid and ethanol in a volume ratio of 1:0.35:30,and Al Fu:TBT in a volume ratio of 1:40.The composition,structure and morphology of Al Fu/TiO₂composite were characterized by XRD,FT-IR and SEM.The results showed that TiO₂ was successfully introduced into Al Fu.According to XRD and Raman spectra,TiO₂ in Al Fu/TiO₂ composite was mainly amorphous.The structure of Al Fu was not destroyed during the introduction of TiO₂.Methyl orange（MO）was used as a simulated dye to investigate the photocatalytic degradation abiltiy of Al Fu/TiO₂ composite,and the decolorization rate of MO was used as the evaluation index.The results showed that the Al Fu/TiO₂ composite prepared with the dosage ratio of Al Fu:TBT of 1:40 showed the removal rate of MO with 96%after 120 minutes under ultraviolet light.（3）CMCS/Al Fu/P25 composite was prepared by using carboxymethyl chitosan（CMCS）as polymer matrix to support Al Fu and P25,and its crystal structure and morphology were characterized by XRD,FT-IR and SEM.The photodegradation experiment showed that the removal rate of methyl orange（MO）was less than 20%after irradiation with UV light for 120min using CMCS/Al Fu/P25 as the photocatalyst.（4）Sodium alginate（SA）was used as polymer matrix to support Al Fu,and TiO₂ was prepared by sol-gel method to obtain a new amorphous material SA/Al Fu/TiO₂.XRD,FT-IR,SEM,EDS,TEM and Raman were used to characterize the composition,structure and morphology of SA/Al Fu/TiO₂ composite.The test results showed that TiO₂ was successfully introduced into composite SA/Al Fu/TiO₂ and mainly in amorphous state.The photocatalytic degradation of SA/Al Fu/TiO₂ composite was investigated using methyl orange（MO）as the simulated dye.With the decolorization rate of MO as the evaluation index,the influence of different content of SA,Al Fu and tetrabutyl titanate（TBT）on the photocatalytic degradation of SA-x/Al Fu-y/TiO₂-z composites was studied.The UV-DRS calculation showed that the optical band gap of SA/Al Fu/TiO₂ was 3.20e V.The result indicated the synergic effect between TiO₂ and Al Fu.With the increase of the amount of Al Fu,the adsorption performance of SA/Al Fu/TiO₂composite on MO was improved.SA/Al Fu-1.5/TiO₂showed the best adsorption ability on MO.The adsorption capacity and degradation effect of SA-x/Al Fu/TiO₂ on MO decreased gradually with the increase of the mass concentration of SA.The photocatalytic ability of SA/Al Fu/TiO₂-z samples increased first and then decreased with the increase of the amount of TBT.Under UV irradiation,SA/Al Fu/TiO₂（x=2%,y=0.5,z=4m L）showed good adsorption performance and excellent photocatalytic activity for MO solution.The removal rate of MO could reach 96%within 75min.The active substance in the degradation of MO under the presence of SA/Al Fu/TiO₂composite were discussed using ammonium oxalate,tert-butyl alcohol and benzoquinone as scavengers of h⁺,·OH and·O^2-,respectively.The results showed that superoxide radical(·O^2-)was the main active substance in the process of degradation of MO using SA/Al Fu/TiO₂composite photocatalyst.All results indicated that the improvement of the photocatalytic performance of SA/Al Fu/TiO₂ composite was the result of the synergy between Al Fu and TiO₂.