Simultaneous adsorption of Cd2+ and photocatalytic degradation of tris-(2-chloroisopropyl) phosphate (TCPP) by mesoporous TiO2

In this work, the prepared mesoporous TiO2 was employed to eliminate the environmental risk induced by the combined pollution (tris-(2-chloroisopropyl) phosphate (TCPP) and Cd2+). The prepared material was characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-DRS), Raman imaging spectrometer (Raman), N2 adsorption/desorption isotherm and X-ray photoelectron spectroscopy (XPS). In the combined pollution system, the prepared TiO2 simultaneously exhibited a higher adsorption and photocatalytic activity for Cd2+ and TCPP at neutral condition, respectively. The adsorption of Cd2+ and photo-degradation of TCPP by mesoporous TiO2 followed pseudo-second-order and pseudo-first-order kinetics model, respectively. The removal efficiency of TCPP was improved from 67% to 100% when the concentration of co-existed Cd2+ increased from 0.5 mg L-1 to 2 mg L-1, due to the fact that the adsorbed Cd2+ on the surface of TiO2 scavenged electron and thus inhibited the photo-generated electron-hole pairs recombination. In addition, six degradation intermediates were determined by high resolution mass spectrum (HRMS) and potential transformation pathways of TCPP under the co-existence of Cd2+ were proposed. The results suggested that rapid and high-efficient simultaneous removal of Cd2+ and TCPP was feasible, which laid the basis for the remediation of other combined pollution in the future.