Fe-N Co-doping TiO₂/Mica Pearlescent Pigment And Its Photocatalytic Property

Since successfully developed by DuPont,the mica titanium pearlescent pigment has been rapidly developed and widely applied to various industries such as coating,ink,plastic,rubber and leather etc.,due to its excellent performances such as high chemical stability,great weather resistance,nontoxicity and abundant color.However,there are huge differences the quality and performance of mica pearlescent pigment porducts between domestic and abroad.It has been clear that the glossiness and whiteness are poor for the silver white pearlescent pigment,and the color is not pure and bright enough as well as the wettability and dispersion are not ideal for the color pearlescent pigment.Therefore,it becomes a research focus in the field of pearlescent pigment to develop new stable pearlescent pigment.The titanium-mica pearlescent pigment is an inorganic composite material obtained from mica coated with one or multy layers of titanium oxide on the surface.The study was performed as follows.1.To modify the preparing process of titanium-mica pearlescent pigment in a traditional alkaline neutralization method.Sodium carbonate was used as alkaline neutralization solution to replace sodium hydroxide,and stannic chloride was employed as a nucleator for crystallization,TiO₂ was coated on the surface of mica substrate with a heterogeneous process promoted by the liquid phase hydrolysis.The X-ray Powder Diffraction?XRD?,Scanning Electron Microscope?SEM?,particle size analysis and whiteness analysis were used to investigate the composition,structure and performance of titanium-mica pearlescent pigment respectively.The synthesis conditions were also optimized.It is clear that a silvery white mica titanium pearl pigment with an average particle size of 24.00?m and a uniform,dense TiO₂ layer can be obtained at the charging rate of 0.20 mL/min,pH value of 1.8,the reaction temperature of 78 ?,the calcination temperature of 850 ??with heating rate 5 ?/min?,and the calcination time of 1 h.The advantages of the process are to be easy to control the reaction conditions,and to cause little gonorrhea.Moreover,a series of titanium-mica pearlescent pigments with various colors of silvery,white,yellow,red,purple,blue,green and so on can be prepared by controlling the thickness of TiO₂ layer.2.The photocatalytic self-cleaning feature was introduced to the traditional titanium-mica pearlescent pigment.In the liquid phase hydrolysis deposition process,titanium oxide layer was coated on the surface of mica sheet,and pH value of the system wad adjusted to 3?6 prior to the deposition of Fe?OH?₃ quantum dots by hydrolysis of FeCl₃ precursor.The dried composite was calcinated in air with an appropriate flow rate of ammonia gas.The Fe-N co-doped titanium-mica pearlescent pigment was obtained.Moreover,transmission electron microscope?TEM?,X-ray Photoelectron Spectroscopy?XPS?,X-ray Powder Diffraction?XRD?,Scanning Electron Microscope?SEM?,and UV-VIS spectrophotometer were used to investigate the composition,structure and light response of the prepared materials.It is clear that the Fe-N co-doped titanium-mica pearlescent pigment with a good pearlescent and photocatalytic properties can be facilated at n?Fe?:n?TiO₂?=0.001:1,flow of ammonia of 15 mL/min,calcinate temperature of 650 ? and calcinate time is 3 h.3.The resultant Fe-N co-doped titanium-mica pearlescent pigment was employed as a photocatalyst to investigate the photocatalytic degradation properties of rhodamine B,salicylic acid,methyl orange,and chlorine phenol under the irradiation of ultraviolet and visible light.The results show that the degradation rate is 98.47%for RhB at 20 minutes,99.42%for salicylic acid at 160 minutes,99.57%for methyl orange at 100 minutes,and 95.80%for p-chlorophenol at 6 hours respectively,suggesting that the Fe-N co-doped titanium-mica pearlescent pigment has a good photocatalytic self-cleaning properties.