A facile approach for the synthesis of nanoporous cobalt oxide, anatase, rutile, and mix of rutile-anatase phase through thermal decomposition of organometallic complex compounds of phloroglucinol carboxylic acid were used for the first time in order to remove the organic-harmful compounds from water. The complex compounds and nanoparticles were characterized by X-ray diffraction (XRD), UV–vis spectroscopy, FT-IR spectroscopy, elemental analysis (metal, organic atoms), Field-Emission Scanning Electron microscopy (SEM), NMR spectroscopy, quantum chemical modeling, photoluminescence, and thermal analysis techniques. The results illustrated that TiO2 nanoparticles in three different structures/ phases (Anatase, Anatase-Rutile mixture, and Rutile) and nanoporous cobalt oxide were isolated. In order to examine the possibility of modification of the structures based on TiO2, a new method was also applied, including grinding and thermal decomposition of titanium and cobalt complexes in the different ratio (10 %-to-90 %). Titanium and cobalt complexes were mixed, and ground well and then heated to 500 °C for 2 h. Nanoparticles of titanium and cobalt oxides mixtures were studied by SEM, EDX, XRD, and photoluminescence methods. The ability of the obtained product in the environmental field was tested. The results showed it led to the formation of cobalt (II) titanate of perovskite-like structures and Ti80 %Co20 % ratio was the most proper ratio to absorb visible light. Finally, this sample was used as a photocatalyst to degrade bromophenol blue (BPB), as a harmful organic target, under visible light and it could reduce the concentration of BPB to 82 % after 120 min, which showed it to be a powerful photocatalyst to treat water.

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