Preparation of magnetic and thermal dual-responsive zinc-tetracarboxyl-phthalocyanine-g-Fe3O4@SiO2@TiO2-g-poly(N-isopropyl acrylamide) core-shell green photocatalyst

A novel hybrid organic/inorganic magnetic and thermal dual-responsive core-shell green photocatalyst zinctetracarboxyl-phthalocyanine-g-Fe3O4@SiO2@TiO2-g-poly(N-isopropylacrylamide) had been prepared. Firstly, Fe3O4@SiO2@TiO2 (FST) was prepared with core-shell structure, then thermosensitive poly(N-isopropylacrylamide) (PNIPAM) immobilized on the surface of 3-(methacryloxypropyl)-trimethoxysilane (MPS) modified FST by radical polymerization. Below the lower critical solution temperature (LCST), PNIPAM was hydrophilic to ensure them disperse uniformly in aqueous solution, and above LCST, PNIPAM became hydrophobic to accelerate the separation of FST from water. Secondly, zinc-tetracarboxyl-phthalocyanine (ZnTcPc) grafted on the surface of FST-g-PNIPAM by ester bonds and sensitized TiO2 to broaden absorption light range from ultraviolet to visible region to enhance photocatalytic activity. The photocatalytic test revealed that the decomposition rate of Rhodamine B (RhB) came to 91.8% after 60 min with ZnTcPc-g-FST-g-PNIPAM under visible light. When exposed under sun light, the degradation efficiency reached to 96.9%. It meant ZnTcPc-g-FST-g-PNIPAM was more suitable for organic pollutant degradation in nature. In addition, ZnTcPc-g-FST-g-PNIPAM performed efficient synergistic effect of thermal ( > LCST) and magnetic responded recovery for reusing. And the degradation rate of RhB under recyclable photocatalyst was reduced 9.6% after 4 cycles. Above all, ZnTcPc-g-FST-g-PNIPAM would be an efficient photocatalyst with magnetic and thermal dual-responsive recovery used in water treatment.