Effective strategy for removing Congo Red from wastewater by M1-XFeX(OH)2 (M = Mg/Co/Ni/Zn, X = 0.3–0.8) via adsorption and degradation mechanism

Ferroan brucite with different Fe 2+ doping amounts (Mg 1-X Fe X (OH) 2 , x = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) was synthesized for the removal of Congo red (CR) from wastewater. As the Fe 2+ content increased, the removal efficiency initially increased and then decreased, and Mg 0.6 Fe 0.4 (OH) 2 exhibited the maximum removal amount which was 2745.96 mg/g. The high removal ability of Mg 0.6 Fe 0.4 (OH) 2 was derived from the combined removal mechanism. The removal amount of CR was highly related to the amount of Fe 2+ in MgFe(OH) 2 and its existed state. The removal behaviors of M 0.7 Fe 0.3 (OH) 2 (M = Zn, Ni, Co) were also conducted to verify the function and university of Fe 2+ in the degradation process. The influence of M 2+ in M 0.7 Fe 0.3 (OH) 2 (M = Zn, Ni, Co) on the removal efficiency was explored by experimental study and calculation of the system energy and bond length change based on molecular simulation. This work provided an outstanding approach for preparation of high efficiency materials to purify organic wastewater. Graphical Abstract