Facile one-step synthesis of graphitic carbon nitride-modified biochar for the removal of reactive red 120 through adsorption and photocatalytic degradation

Converting waste biomass into value-added biochar has been considered as a green and sustainable strategy for resource management and pollution control.In this study,graphitic carbon nitride(g-C_(3)N_(4))modified biochars(BCs)were produced through one-pot pyrolysis of urea and hickory chips in differential ratios at 520℃.The resulting BC/g-C_(3)N_(4)composites were evaluated in laboratory for their physicochemical,adsorptive,and photocatalytic properties.The characterization tests showed the successful synthesis of the BC/g-C_(3)N_(4)composites that introduced g-C_(3)N_(4)structure,N-containing surface func-tional groups,reduced surface area,and better thermal stability to the biochar.After modification,the BC/g-C_(3)N_(4)composites showed better adsorption ability to reactive red 120(RR120)than the pristine BC,due to the strong electrostatic attrition between N-containing functional groups of g-C_(3)N_(4)on biochar surface and anionic RR120.The BC/g-C_(3)N_(4)composites also inherited g-C_(3)N_(4)’s photocatalytic activity,which is visible light responsive to generate free radicals for RR120 degradation.In addition,the composites with higher urea modification ratios were more effective in the degradation of RR120.Overall,this study demonstrates the feasibility and promising potential of combining biochar and photocatalyst for the removal of aqueous dye.Because of the synergistic adsorption and photodegradation ability,BC/g-C_(3)N_(4)composites present a novel and cost-effective solution for the removal of aqueous dye and other photodegradable contaminants under natural conditions.

In situ synthesis of CNTs/Fe-Ni/TiO_2 nanocomposite by fluidized bed chemical vapor deposition and the synergistic effect in photocatalysis

Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV-vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe（Ⅲ） in TiO2 showed no chemical changes in the growth of CNTs. Ni（Ⅱ） was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe-Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature （500 ℃）, more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO2 nanocomposite is proposed.