Adsorption and catalytic degradation of Light green SF by magnetic PEI-modified carbon nanotubes composites

Treatment of colored effluent is necessary for the textile industry. In this study, a magnetically recyclable composite (MnFe 2 O 4 @cCNTs-PEI) was prepared by coprecipitation and grafting methods, and its efficiency for removal of light green SF (LG) from solution assessed via the adsorption and advanced oxidation techniques. The experimental results indicated that the maximum adsorption capacity of MnFe 2 O 4 @cCNTs-PEI towards LG could reach 371 mg‧g −1 at solution pH 3 and 303 K. The adsorption equilibrium results could be well fitted by Koble-Corrigan, Temkin, and Freundlich isotherm models whereas the adsorption kinetic process follows the Elovich equation and Double Constant model. This implies the adsorption process be heterogeneous multimolecular layer adsorption, accompanied by heterogeneous diffusion. The adsorption process was spontaneous, endothermic and entropy increasing which was majorly controlled by the electrostatic attraction and π-π stacking mechanisms. MnFe 2 O 4 @cCNTs-PEI can catalyze and activate H 2 O 2 to achieve a heterogeneous Fenton-like degradation of LG. MnFe 2 O 4 @cCNTs-PEI as a catalyst could achieve a higher removal rate of LG (90 %) within a broad pH range (3–10) which could be ascribed to the presence of active radical species such as ‧OH and 1 O 2 . After three adsorption and degradation regeneration cycles, the removal rate of LG was still higher than 60 %. It is potential for MnFe 2 O 4 @cCNTs-PEI to be economically viable for practical applications.