Abstract: Metal–organic frameworks exhibited high-performance since can be easily produced in organic substances/metal deposits with enlarged surface area. These properties provide the doping of metal nanocomposites into the porous structure to improve the photocatalytic performance. Therefore, in this study, in order to photodegrade the phosphorous two flame retardants namely tris–(2,3-dichloropropyl)phosphate (TDCPP) and tris–(1,3-dichloro-iso-propyl)phosphate (TDCIPP); NiFe2O4-based magnetic covalent organic framework nanocomposite (MCOF NC) was generated under laboratory conditions. SEM images showed that the NiFe2O4-MCOF nanospheres exhibited fascinating angular and crumpled surfaces with holes, cavities and hollow spaces in the nanocomposite. Both of the NiFe2O4 and NiFe2O4-MCOF NC were composed of C, N, O, Fe, and Ni elements. XPS spectrum of Ni 2p orbital contained two major peaks with binding energy values araund 873.4 eV and 15855.5 eV. A significant weight loss in the nanocomposite was not detected (~2.20%) while an optimal exothermic peak for NiFe2O4–MCOF NC occurred during photodegradation. For maximum TDCPP (99%) and TDCIPP (98%) photodegradation efficiencies the optimazed conditions for contact time, temperature, NiFe2O4–MCOF NC concentration, TDCPP and TDCIPP pollutant concentrations and pH should be 5 min, 40oC, 1.0 mg/l, 1500 mg/l and 5.0, respectively. The photodegradation occurred according to pseudo-first-order reaction kinetic with excellent reusability of NiFe2O4–MCOF NC. Pseudo-first-order photodegradation kinetic showed that the maximum photodegradation rate constants for 1500 mg/l TDCPP and TDCIPP was detected as 0.09 min-1 by 1 mg/l NiFe2O4–MCOF NC. Kinetic studies with adsorption showed although adsorption was detected the majority of pollutants were removed with protodegradation since photodegradation kinetic constants was approximately 8 time higher than that adsorption constants. This showed that photodegradation is the main removal of degradation mechanisms in the removal of TDCPP and TDCIPP under UV ligth. The chronic toxicity of TDCPP and TDCIPP converted to the ″not harmful″ range since their degradation intermediates are significantly less toxic. The aforementioned nanocomposite was reused with yields as high as 99% and 97% for TDCPP and TDCIPP photodegradation, respectively, after 15 cycles.

Keywords: Brominated flame retandants (BFRs), Density functional theory (DFT), Flame retardants, NiFe2O4 - based magnetic covalent organic framework nanocomposite (NiFe2O4-MCOF NC), Organophosphorus flame retardants (OPFRs), Photodegradation, Phosphorus-based flame retandants (PFRs), Sun light, Tris–(2, 3-dichloropropyl) phosphate (TDCPP), Tris–(1, 3-dichloro-iso-propyl) phosphate (TDCIPP).

Pages: 337-367

WSEAS Transactions on