Study On The Preparation And Properties Of Porous Materials Based On CuO-TiO₂-P₂O₅ Glasses

Porous materials are widely applied in many fields such as catalysis,adsorption and separation because of their high specific surface area and large adsorption capacity,stable chemical properties,controllable pore size and good thermal stability.Porous glass-ceramics have not only high specific surface area,but also functional skeletons formed by controlled crystallization.In this work,based on the preparation of different CuO-TiO₂-P₂O₅ system glasses,different porous materials were prepared by crystallization followed by acid treatment process.The samples were characterized by XRD,SEM,FTIR and nitrogen adsorption.The adsorption and photocatalytic properties of the prepared porous materials were also studied.The main contents and conclusions of this paper are as follows:1)Glasses with the composition of CuO·xTiO₂·（50-x）P₂O₅（x=5,10,15,20 and 25）were obtained by high temperature melting-water quenching method using CuO,TiO₂ and H₃PO₄as raw materials.The results show that the increase of led to,the crystallization of glass and the amount of crystalline CuTi₂（PO₄）₃ phase are increased with TiO₂.According to the results of differential thermal analysis,the glasses have been heat-treated and resulted glass-ceramics were leached in 0.5 M H₂SO₄ at room temperature for three days.It is found that the sample containing 20 mol%TiO₂ led to the formation of a porous material with CuTi₂（PO₄）₃ as crystalline phase and the largest surface area of 14.86 m²/g.Acid leaching by HCl or H₂SO₄solutions at room temperature had no effect on the crystalline phase of the porous samples.However,porous materials synthesized by acid leaching with HCl solution at 80 ^oC have a main crystalline phase of Ti₂O₃（H₂PO₄）₂·2H₂O and a specific surface area of 75 m²/g.2)Parent glasses xTiO₂·（70-x）CuO·30P₂O₅（x=10³0）were successfully prepared by high temperature melting and cold pressing.The infrared spectrum analysis shows that the structure of the glass is strengthened with the increase of TiO₂ in the glass composition,which is mainly due to the obvious accumulation of titanium ion which has a large field strength.With the increase of TiO₂,the relative percentage of CuTi₂（PO₄）₃ phase in heat treated samples increases.The prepared glass-ceramics were acid leached in hydrochloric acid at 80^oC for 24 h,porous materials with a main crystalline phase of Ti₂O₃（H₂PO₄）₂·2H₂O were obtained and porous materials containing anatase TiO₂ were prepared when TiO₂ is more than20 mol%.The specific surface area of the porous material made from the glass with 15 mol%TiO₂ is the largest,reaching 122 m²/g.SEM analysis shows that the sample is composed of two dimensional flakes.Methylene blue（initial concentration 5 mg/L）adsorption experiments were carried out on the sample with the largest surface area.The results showed that the removal efficiency of methylene blue in aqueous solution is 89.76%under dark condition.The adsorption of methylene blue in aqueous solution and the photocatalytic efficiency of the porous material containing the anatase TiO₂ phase（from the glass containing 25 mol%of TiO₂）are 43.75%and 40.17%,respectively.The total removal efficiency of methylene blue is 67.49%,close to that of commercial P25（a total efficiency of 73.76%）.3)Glasses with a composition of xMO·（55-x）CuO·15TiO₂·30P₂O₅（M=Ca,Zn,x=0,15,20,25 and 30）were successfully prepared.The addition of CaO or ZnO can increase glass forming ability.Porous materials were obtained by thermal treatment of the parent glassed followed by acid–leaching in hydrochloric acid at 80 ^oC.Among the porous productss,the sample containing 20 mol%of CaO and 15 mol%of ZnO have the largest specific surface area of 60 m²/g and 119 m²/g,respectively.Methylene blue（initial concentration 5 mg/L）adsorption experiments were carried out on the samples with the largest surface areas.The results showed that the efficiency of CaO-or ZnO-containing porous samples are 69.69%and 89.53%,respectively.In addition,when these porous samples were reused for 5 times,the removal efficiency of methylene blue in aqueous solution decreased to 38.15%and 64.10%,respectively.