Separation free C3N4/SiO2 hybrid hydrogels as high active photocatalysts for TOC removal

• The hybrid hydrogels show synergistic effect of adsorption and photocatalytic degradation via 3 dimension network structure.
• The photocatalytic activity and TOC removal ability of C3N4/SiO2 was greatly enhanced.
• The pollution can be degraded continuously via C3N4/SiO2 hybrid hydrogels photocatalysts without separation.

The separation free graphitic carbon nitride/SiO2 (C3N4/SiO2) hybrid hydrogels with three-dimensional (3D) network structures have been prepared via alkali-solution and acid-gel process. The hybrid hydrogels perform enhanced ability to absorb and in-situ degrade refractory organic pollutants, such as coking wastewater and phenol. Due to the 3D network structures of C3N4/SiO2 hybrid hydrogels, they show efficient pollutants removal ability by synergistic effect of adsorption and in-situ photocatalytic degradation. The total organic carbon content (TOC) of coking wastewater is reduced by 33% with C3N4/SiO2 hybrid hydrogel, which is 5 times of pure g-C3N4. The removal abilities of phenol and methylene blue (MB) via hybrid hydrogels are 3.1 and 6 times of pure g-C3N4 respectively. The 3D network structures guarantee C3N4/SiO2 hybrid hydrogels to be continuously used without adsorption saturation and separation from water, avoiding the photocatalysts aggregation and secondary pollution.

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