COF coated Fe doped hollow carbon nanosphere for selective adsorption and photocatalytic reduction on dye pollutant by confinement effect in water management

Abstract

Herein, a novel covalent-organic framework (COF) coated Fe doped hollow carbon nanosphere (HCNS), Fe-HCNS@COF, was prepared for selective adsorption and photocatalytic reduction on dye pollutant in water. The Fe-HCNS@COF displays a high affinity to malachite green (MG) with a distribution coefficient ( K d ) of 6.931, which can be attributed to the confinement effect by the π−π stacking between the benzene ring in MG and triazine ring in COF. Pseudo second order (PSO) kinetics ( R 2 ​= ​0.9914) and Langmuir isotherm model ( R 2 ​= ​0.970 9) match better to Fe-HCNS@COF on MG adsorption indicating a chemisorption with mono-layer interface. Additionally, enhanced catalytic efficiency of the nanospheres on MG reduction at 96.3% was observed under sunlight irradiation with improved reusability after five cycles (74.4%). The catalytic mechanism investigation indicates that 1 O 2 , •O 2 − , and •OH play significant role in the catalytic process, and Fe-HCNS@COF exhibits a smaller E g at 1.53 ​eV compared to COF (1.86 ​eV), signifying enhancement for separation of hole-electron pairs. A continuous flow device was established to investigated the real application in dye removal, achieving an 88.7% removal rate for MG degradation after 40 ​h continuous operation. Moreover, an improved bacterial inhibition rate over 99% was found against both Gram-negative and Gram-positive bacteria. In conclusion, the as prepared Fe-HCNS@COF provides us a novel nano-platform with multiple-function for the potential application of dye removal in real water management.