Uniform core–shell structured magnetic mesoporous TiO₂ nanospheres as a highly efficient and stable sonocatalyst for the degradation of bisphenol-A

Abstract

The contribution is equal.Uniform core-shell structured magnetic mesoporous TiO 2 (Fe 3 O 4 @SiO 2 @mTiO 2 ) nanospheres have been fabricated via a kinetic-controlled Stöber method. A silica interlayer with a thickness of ~ 25 nm was introduced as a passivation barrier to prevent the photodissociation, as well as increase the thermal stability of the core-shell materials. After being crystallized at 600 °C under nitrogen, the resultant nanospheres (Fe 3 O 4 @SiO 2 @mTiO 2 -600) possess well-defined core-shell structures with a high magnetic susceptibility (~ 17.0 emu g -1 ) and exhibit uniform mesopores (~ 5.2 nm), large BET surface area (~ 216 m 2 g -1 ) and pore volume (~ 0.20 cm 3 g -1 ). More importantly, the magnetic mesoporous TiO 2 has been demonstrated for the first time as a high efficient and stable sonocatalyst for the degradation of bisphenol-A. The pseudo first-orderreaction constant of the magnetic mesoporous TiO 2 is measured to be 0.164 min -1 , which is 1.49 and 2.27 times higher than that of P25 and ultrasound alone, respectively. The remarkable performance is attributed to the fast mass diffusion, large adsorption rate and enhanced hydroxyl-2 radical-production rate. More importantly, the catalysts can be easily recycled within 2 minutes by using an external magnetic field and a constant catalytic activity is retained even after eight cycles. This study paves a promising way for the design and synthesis of magnetic separable sonocatalysts for the degradation of organic pollutants, which is of significant importance for practical applications from both environmental and industrial points of view.

Copper(I) sulfide (Cu 2 S) nanoparticles from Cu(II) diethyldithiocarbamate: Synthesis, characterization and its application in ultrasound-assisted catalytic degradation of organic dye pollutants

“…Although, the exact mechanism for this sonocatalytic degradation reaction over Cu2S nanoparticles is not very clear and intermediates were not observed directly; on the basis of the above observations and previously reported mechanisms [45][46][47][48][49][50][51][52], the following mechanism was…”

“…Such high temperature sufficiently breaks down some H2O2 molecules on the surface of catalyst, producing hydroxyl radicals ( • OH). These heat energies of ''hot spot" can also excite the prepared Cu2S nanoparticles like light [49,50,52]. Under the excitation of such generated lights and heats, the electrons are transited from valence band (VB) of Cu2S to conduction band (CB).…”

Solvothermal Synthesis of M-doped TiO2Nanoparticles for Sonocatalysis of Methylene Blue and Methyl Orange (M = Cd, Ag, Fe, Ce, and Cu)

“…Qiu et al . fabricated uniform core–shell structured magnetic mesoporous TiO 2 nanospheres with high surface area and large pore volume, resulting in remarkable catalytic performance …”

MIL-101(Cr)–cobalt ferrite magnetic nanocomposite: synthesis, characterization and applications for the sonocatalytic degradation of organic dye pollutants

“…Moreover, the formation of hot spots results in the generation of electrons and holes on the surface of the MIL-101(Cr)/CoFe 2 O 4 sonocatalyst. 17,31,37 Actually, the electrons in the full valence band of MIL-101(Cr) and CoFe 2 O 4 are excited to the empty conduction band separately under ultrasound irradiation, leaving an equal number of holes with a positive charge in the corresponding positions. The presence of CoFe 2 O 4 favors the sonocatalytic activity under ultrasound irradiation due to its narrow band gap.…”