Removal of Disinfection By-Products Precursor (Humic Acid) by Graphene-Silica Composites

Abstract

Graphene-silica (RGO-SiO2) was successfully synthesized by a simple hydrothermal method. The composites were used to study the adsorption properties of humic acid and disinfection by-product precursors in natural surface water. Compared with reduced graphene oxide (RGO), the specific surface area of the composites doped with silica (SiO2) increased by 31.2% to 259.43 m2/g. RGO-SiO2 could achieve 66.91% adsorption of humic acid (HA), while the maximum adsorption of HA on RGO-SiO2 reached 925.91 mg/g. The adsorption and removal rates of HA by RGO-SiO2 were significantly higher than those of RGO. The whole adsorption process was in accordance with the quasi-secondary kinetic model, the Langmuir isothermal adsorption model. RGO-SiO2 has good adsorption performance for organic matter of different water qualities. RGO-SiO2 has a better removal ability for hydrophobic organics than hydrophilic and nitrogenous organics. The adsorbent was reusable, and the organic removal efficiency of RGO-SiO2 decreased insignificantly after four cycles.