Graphitic carbon nitride-doped sewage sludge as a novel material for photodegradation of Eriochrome Black T.

Abstract

The bio-resource utilization of sewage sludge is presented by preparation of novel waste sludge-doped graphite carbon nitride (g-C3N4) photocatalyst. The sludge flocs which constitute bacteria and organic substances served as a pore-forming framework in the catalyst, while the inorganic fractions including those transition metals and crustal metals can function as dopants for sludge-based g-C3N4 composite. The physicochemical properties of as-prepared catalyst were well analyzed by multiple characterizations. The composite catalyst showed higher surface area (50m2/g) and more mesoporous structures (8.9 × 10-2cm3/g) as compared with pristine g-C3N4 (8.4m2/g and 6.6 × 10-2cm3/g, respectively). The photoelectrochemical results showed that introduced sewage sludge impurities lowered down the photocarriers recombination efficiency and enhanced more efficient electron-hole separation by about 100 times. The photocatalytic activity was tested by degradation of typical dye Eriochrome Black T (EBT). The optimal sample improved removal of EBT by 56% in 90min under ultraviolet irradiation (λ = 254nm). According to the results of main metal ion leaching concentration and reuse tests, the composite catalyst exhibited excellent stability and repeatability.