Multiple Catalytic Alcoholysis And Recovery Of SrAl₂O₄:Eu²⁺,Dy³⁺ From Waste Luminous Fibers

Rare earth luminous fiber is a kind of functional fiber formed by using polyester（PET）as the base material,rare earth SrAl₂O₄:Eu²⁺,Dy³⁺as the luminous body,which is prepared into luminous master particle through melting granulation,and then fused spinning with polyester spinning solution at a specific ratio.Because of its excellent luminous performance,as well as green,non-toxic and harmless advantages,it is widely used in textile and clothing,architectural decoration,children’s toys,navigation and anti-counterfeiting trademarks and other fields.With the continuous development of luminous fibers,a variety of luminous textiles are constantly created,which brings great convenience to people’s life.However,it also causes a large amount of waste luminous fibers.Polyester materials are difficult to decompose under natural conditions,and rare earth SrAl₂O₄:Eu²⁺,Dy³⁺luminous materials are difficult to be recycled,which leads to environmental pollution and waste of rare earth resources.Therefore,the recycling of rare earth luminescent materials and the degradation of PET are urgent problems to be solved.Previous studies have found that compared with other methods,alcohol hydrolysis can degrade polyester macromolecules into small molecules to recover luminescent materials,effectively solving the problems of pollution and resource waste.However,the recycling efficiency and luminescence performance of the currently recycled luminescent materials are low.Based on this,this paper starts from improving the process conditions.The rare earth SrAl₂O₄:Eu²⁺,Dy³⁺luminescent materials were recovered by using glycol alcoholysis luminous fiber,and the recovery rate and luminescence performance of the luminescent materials were improved.At the same time,sodium methanol and zinc acetate were proposed as co-catalysts to explore the effects of different reaction conditions on the recovery rate of luminous materials,excitation emission performance,afterglow performance,surface color and luminous color,so as to achieve high recovery rate and excellent luminous performance of SrAl₂O₄:Eu²⁺,Dy³⁺luminous materials.The luminous coating fabric was prepared from the recovered luminous material and the feasibility of its reapplication was discussed.The experimental results provide a theoretical basis for the recovery and reuse of functional materials.Specific work contents are as follows:（1）Firstly,based on the three influencing factors of zinc acetate dosage,glycol addition amount and reaction temperature,the technological conditions of glycol alcoholysis luminous fiber were improved.X-ray diffraction（XRD）and scanning electron microscopy（SEM）were used to characterize the crystal structure and surface morphology of the recovered rare earth luminous materials.The effects of different reaction conditions on luminescence properties of luminescent materials were analyzed by fluorescence spectrometer and afterglow luminance meter.The results showed that the recovery rate of the luminescent material reached 92.53%and the initial afterglow brightness reached 5.607 cd/m² under the optimized conditions.（2）Secondly,in order to further improve the recovery rate and luminescence performance of luminous materials and reduce the oligomers covered on the surface of luminous materials,sodium methanol and zinc acetate were used as co-catalysts for alcoholysis of luminous fibers.The influences of different amounts of sodium methanol,reaction time and reaction temperature on the recovery rate of luminous materials and the effects of alcoholysis effect were studied,and the reaction mechanism was proposed and clarified.The results showed that sodium methanol did not destroy the crystal structure of the luminescent materials,and sodium methanol could selectively depolymerize PET into BHET and dimer in excess glycol,which limited the existence of high oligomers in the degradation process of zinc acetate.Under the optimized conditions,the recovery of BHET monomer reached 75.65%,and the recovery rate of luminous material is 94.47%.（3）Finally,the influence of different reaction conditions on luminescence properties of luminescent materials was explored when sodium methanol and zinc acetate were used as co-catalysts.The excitation emission,afterglow,surface color and luminous color properties of luminous materials were analyzed by fluorescence spectrometer,afterglow luminance instrument and spectrophotometer.The results show that when the amount of sodium methanol is 0.15g,the amount of zinc acetate is 0.1g,the reaction time is 4 h,and the reaction temperature is 170℃,the color difference of the recovered luminous material is the smallest compared with the pure SrAl₂O₄:Eu²⁺,Dy³⁺.The color purity of SrAl₂O₄:Eu²⁺,Dy³⁺is 56.371%,which is smaller than that of SrAl₂O₄:Eu²⁺,Dy³⁺.The initial afterglow brightness reaches 6.612 cd/m²,and returns to pure SrAl₂O₄:Eu²⁺,Dy³⁺,and more than 97%of initial brightness.Luminous coating fabric shows good afterglow performance,which indicates that the recovered luminous material has good reuse value.