Small-particle-size allophane-amidoximated polyacrylonitrile composite material for uranium extraction from seawater and its preparation method

A small-particle-size allophane-amidoximated polyacrylonitrile composite material for uranium extraction from seawater, wherein the composite material is obtained by polymerizing allophane with acrylonitrile initiated by persulfate ions, followed by an amidoximation reaction;

• the allophane is nano-sized;
• the allophane has a particle size in a range of 3.5-5.0 nanometers (nm), and the allophane has a nano-hollow spherical structure with defect pores in a range of 0.3-0.5 nm, and the allophane is derived from an allophane suspension;
• wherein the polyacrylonitrile is prepared by polymerizing acrylonitrile monomers and compounding with the allophane during polymerization, and finally performing the amidoximation reaction using a hydroxylamine hydrochloride solution;
• wherein the composite material has an average particle size in a range of 26-35 nm and a median cluster size in a range of 480-560 nm;
• and
• wherein the allophane suspension is prepared by a method comprising:
• mixing a sodium orthosilicate solution at a certain concentration with an aluminum chloride hexahydrate solution at a certain concentration to obtain a mixture;
• under a condition controlling a silicon/aluminum molar ratio to 0.6-0.9, continuously stirring the mixture for 0.5-2 hours to obtain a precursor;
• centrifuging the precursor at a speed of 3000-8000 revolutions per minute (r/min) for 10-30 minutes to obtain a white precipitate;
• subjecting the white precipitate to hydrothermal treatment at 100°C. for 2-48 hours to obtain a product;
• and
• dialyzing the product with ultrapure water until a pH approaches neutral, to obtain the allophane suspension.