Characterization and photocatalytic activity of CoCr2O4/g-C3N4 nanocomposite for water treatment.

One of the materials that has recently been used to remove environmental pollution from industrial effluents with photocatalytic technology is cobalt chromate (CoCr2O4) nanoparticles. An effective way to improve the photocatalytic properties of materials is to composite them with other photocatalysts to prevent recombination of electron-holes and accelerate the transfer of oxidation/reduction agents. Graphitic carbon nitride (g-C3N4) is an excellent choice due to its unique properties. In this research, CoCr2O4 and its composite with g-C3N4 (5, 10, and 15%) were synthesized by polyacrylamide gel method and characterized by X-ray diffraction, scanning electron microscopy, FTIR, UV-Vis spectroscopy techniques. The photocatalytic behavior of synthesized nanoparticles was investigated in the degradation process of methylene blue dye. The results showed that the composite samples have higher efficiency in photocatalytic activity than the pure CoCr2O4 sample. Using CoCr2O4-15 wt%g-C3N4 nanocomposite, after 80 min, methylene blue was completely degraded. The mechanism of degradation by CoCr2O4-g-C3N4 nanocomposite was the superoxide radical produced by the reaction of electrons with oxygen absorbed on the catalyst surface, as well as optically produced holes directly.

The Effects of the Addition of Polyurethane-MgO Nanohybrids on the Mechanical Properties of Ordinary Portland Cement Paste.

One of the most important methods of controlling the properties of concrete and cement-based materials is to control the rate and kinetics of cement hydration. In the present study, novel flexible polyurethane-decorated MgO nanohybrids were synthesized using a simple chemical method, added to cement paste in different amounts, and utilized as an effective mechanical performance-enhancing factor for cement paste. It was observed that by adding 3 wt% synthesized PU-MgO nanohybrids to cement paste, its mechanical properties were improved and its compressive strength and flexural strength were increased by up to 13% and 15%, respectively, compared to the plain cement, after 45 days. The effect mechanism of adding PU-MgO nanoparticles on the properties of the cement paste was investigated. The addition of PU-MgO nanohybrids increased the pozzolanic reactions and formed more C-S-H phases.