Facile one-step hydrothermal synthesis of α-Fe(2)O(3)/g-C(3)N(4) composites for the synergistic adsorption and photodegradation of dyes

With the expansion of industrialization, dye pollution has become a significant hazard to humans and aquatic ecosystems. In this study, α-Fe(2)O(3)/g-C(3)N(4)-R (where R is the relative percentage of α-Fe(2)O(3)) composites were fabricated by a one-step method. The as-prepared α-Fe(2)O(3)/g-C(3)N(4)-0.5 composites showed excellent adsorption capacities for methyl orange (MO, 69.91 mg g(−1)) and methylene blue (MB, 29.46 mg g(−1)), surpassing those of g-C(3)N(4) and many other materials. Moreover, the ionic strength and initial pH influenced the adsorption process. Relatively, the adsorption isotherms best fitted the Freundlich model, and the pseudo-second-order kinetic model could accurately describe the kinetics for the adsorption of MO and MB by α-Fe(2)O(3)/g-C(3)N(4)-0.5. Electrostatic interaction and π–π electron donor–acceptor interaction were the major mechanisms for MO/MB adsorption. In addition, the photocatalytic experiment results showed that more than 79% of the added MO/MB was removed within 150 min. The experimental results of free-radical capture revealed that holes (h(+)) were the major reaction species for the photodegradation of MO, whereas MB was reduced by the synergistic effect of hydroxyl radicals (·OH) and holes (h(+)). This study suggests that the α-Fe(2)O(3)/g-C(3)N(4) composites have an application potential for the removal of dyes from wastewater.