Superhigh and ultrafast removal of congo red and methylene blue in the evolution process of ferroan brucite with multiple mechanism

Ferroan brucite with different Fe 2+ doping amount (MgFe(OH) 2 -x, x = 0.05, 0.1, 0.15, 0.2 and 0.3) were prepared for the removal of organic dyes from wastewater. In the presence of O 2 , MgFe(OH) 2 -0.3 could realize superhigh amount of removal (2069.16 mg/g) toward congo red (CR) and ultrafast removal rate toward methylene blue (MB), reaching equilibrium in about 5 min. Removal mechanism of MgFe(OH) 2 -0.3 for CR and MB was explored to verify the treatment nature. For CR, multiple removal mechanisms, such as interlayer immobilization/electrostatic attraction/hydrogen bonding and degradation were confirmed to coexist which accounted for 47.80% and 52.20% of the total removal amount. The degradation was highly related to the evolution of Fe 2+ in MgFe(OH) 2 . While hydrogen bonding and degradation played major role in MB removal. The removal behavior of CR and MB in co-existing case and in presence of competitive ions were also measured. MgFe(OH) 2 -0.3 showed almost uninfluenced removal behavior toward CR and the reason was clarified by calculating the binding energy based on molecular simulation. Ferroan brucite not only showed excellent removal ability toward different kinds of dyes but also worked on heavy metals. This work provided an excellent strategy for application of ferroan brucite.