Adsorption of 2, 4, 6-Trichlorophenol in Water by Nitrogen and Sulfur Co-doped Sludge Biochar

Abstract

Purposes 2, 4, 6-Trichlorophenol (2, 4, 6-TCP) has been listed in the blacklist of pollutants in water because of its strong toxicity and “three inducing” effects. It is of great significance to remove 2, 4, 6-TCP from water. Methods Nitrogen and sulfur co-doped sludge biochar (Sx-NSC800) was prepared from municipal sludge by impregnation-pyrolysis method and used to adsorb 2, 4, 6-TCP in aqueous solution. The structure and surface chemical properties of Sx-NSC800 were characterized by scanning electron microscopy, specific surface and aperture analysis, X-ray diffraction, and Fourier infrared spectrometry. The pseudo-first-order kinetic and pseudo-second-order kinetic models were used to fit the adsorption kinetic data. Findings The results show that Sx-NSC800 has a good adsorption effect on 2, 4, 6-TCP, and approaches the adsorption/desorption equilibrium at about 180 min. S10-NSC800 exhibits the best effect with the adsorption capacity of 14.424 mg/g. The adsorption data have good correlations with the pseudo-second-order kinetic model. The isothermal adsorption outcome is more consistent with Freundlich isotherm model, which shows that the adsorption behavior of Sx-NSC800 is easy to take place. Temperature rising is conducive to adsorption. And the adsorption is a spontaneous process with increasing of chaos degree. The adsorption mechanism involves pore filling, hydrogen bonding, and π-π interaction.

Keywords

• sludge
• biochar
• adsorption kinetics
• adsorption isotherms
• 2, 4, 6-trichlorophenol