Efficient Degradation of Congo Red in Water by UV-Vis Driven CoMoO/PDS Photo-Fenton System.

In order to improve the catalytic activity of cobalt molybdate (CoMoO), a PDS-activated and UV-vis assisted system was constructed. CoMoO was prepared by coprecipitation and calcination, and characterized by XRD, FTIR, Raman, SEM, TEM, XPS, TGA Zeta potential, BET, and UV-Vis DRS. The results showed that the morphology of the CoMoO nanolumps consisted of stacked nanosheets. XRD indicated the monoclinic structures with C2/m (C, #12) space group, which belong to α-CoMoO, and both Co and Mo ions occupy distorted octahedral sites. The pH of the isoelectric point (pHIEP) of CMO-8 at pH = 4.88 and the band gap of CoMoO was 1.92 eV. The catalytic activity of CoMoO was evaluated by photo-Fenton degradation of Congo red (CR). The catalytic performance was affected by calcination temperature, catalyst dosage, PDS dosage, and pH. Under the best conditions (0.8 g/L CMO-8, PDS 1 mL), the degradation efficiency of CR was 96.972%. The excellent catalytic activity of CoMoO was attributed to the synergistic effect of photo catalysis and CoMoO-activated PDS degradation. The capture experiments and the ESR showed that superoxide radical (·O), singlet oxygen (O), hole (h), sulfate (SO·), and hydroxyl (·OH) were the main free radicals leading to the degradation of CR. The results can provide valuable information and support for the design and application of high-efficiency transition metal oxide catalysts.