Recycled Of Waste Molybdenum Disilicide,Preparation And Photocatalytic Performance Of Molybdate

In the industrial and research fields,a great number of waste MoSi₂ were produced with theapplication of MoSi₂ materials.As a strategic rare metal,Mo has been applied in the fields of steel industry,electronics and electrics,mechanical manufacturing,biomedical industry and national defense and so on,so it is of great significance for the recovery of Mo from waste MoSi₂.MoO₃ has promising application in the fields of electricity,magnetics,optical and chemistry,polymetallic molybdate,such as copper molybdate and iron molybdate,has been widely studied and used in catalysis,medicine and magnetochemistry and other fields.In this study,a thermal evaporation method was used to collect MoO₃ from waste MoSi₂ which was used as secondary renewable resources of Mo.After that,a reactive sintering method was used to preparation the Fe₂?MoO₄?₃ and Cu₃Mo₂O₉-mullite composite,and the preparation processes were explored.The sintered products were used in the treatment of organic dyes.The results showed that when MoSi₂ was calcined at 500?for 180min,the MoSi₂ was fully converted to MoO₃ and amorphous SiO₂,there are no MoSi₂ left.When the oxidation powders were heated at 950?to evaporate MoO₃,the recycled MoO₃ has high crystallinity the highest,only SiO₂ in the remaining products which means the MoO₃ was completely recovered;Recycled MoO₃ was used as a catalyst for the degradation of methylene blue,and photocatalytic efficiency reached 42.15%after dark treatment for 30min and 99.25%within 60min.Reactive sintering was used to preparation Fe₂?MoO₄?₃ in air during 600-800?with recycled MoO₃ and analytic Fe₂O₃ as raw materials,PVA was used as a binder in this experiment.Temperature has important effect on composition,morphology and photocatalytic efficiency of sintered samples.The products sintered at 800?was pure Fe₂?MoO₄?₃ with obvious holes of 10-50?m in size;The main phase of products sintered at 600?was MoO₃ and a little amount of Fe₂?MoO₄?₃,and the product sintered in 700?were the composite phase of Fe₂?MoO₄?₃ and MoO₃.Sintered products were used as catalysts for the degradation of methylene blue.The photocatalytic efficiency of pure Fe₂?MoO₄?₃ reached 51.5%,the photocatalytic efficiency of Fe₂?MoO₄?₃ and MoO₃ composite phase sintered at 700?reached30.5%after dark treatment for 30min and 80.4%within 50min of illumination.The Fe₂?MoO₄?₃ and MoO₃ composite phase photocatalytic material still keeps favorable photocatalytic activity after four cycles,and the photocatalytic efficiency still reached over 65%.After oxidation at 500?for 240 min,waste MoSi₂ was oxidized into MoO₃ and SiO₂ completely.Reactive sintering was used to preparation Cu₃Mo₂O₉-mullite composite in air during 1300-1500?for 120min with oxidized products,analytic Al₂O₃ and CuO as raw materials and PVA as a binder.The amount of CuO and temperature have important effect on composition,morphology and photocatalytic efficiency of sintered samples,the amount of Cu₃Mo₂O₉ can be varied by aggregate addition of CuO;When sintered at 1300?,Cu₃Mo₂O₉ has the sharpest diffraction peak,when sintered at 1500?,the product was pure mullite.Sintered products were used as catalysts for the degradation of congo red.The photocatalytic efficiency of sample sintered at 1300?with 12wt.%CuO showed good photocatalytic performance which 78.49%within 50min of illumination.