The synthesis of a nano-Fe@NdFeB/AC magnetic catalyst and its application in the degradation of dimethyl phthalate by a Fenton-like process

The heterogeneous catalytic Fenton-like process was selected in this study to degrade a dimethyl phthalate (DMP) solution. To enhance the efficiency and catalytic recycling ratio, a novel magnetic catalyst (nano-Fe loading on NdFeB magnetic activated carbon, Nano-Fe@NdFeB/AC) was synthesized. The results indicated that on the catalytic surface, globular Fe-0 has a size from 25 to 300 nm. This catalytic surface has sufficient magnetism to be separated by a magnetic separation method, in which the specific saturation magnetization and residual magnetization were 1.48 and 0.26 emu/g, respectively. At the optimal conditions of [pH](0) = 3.000, [H2O2](0) = 4.24 mmol/L, and [Nano-Fe@NdFeB/AC](0) = 5.0 mg/L, the chemical oxygen demand removal ratio reached 85.2% after 120 min of reaction. The intermediate products monomethyl phthalate, phthalic acid, benzoquinone, hydroquinone, malonic acid, and oxalic acid were observed during the reaction. The DMP degradation was confirmed to be a hybrid mechanism of degreasing, acidification, and ring-opening reactions. The (OH)-O-center dot addition and oxidation in the aqueous phase represent the key degradation process, even though catalytic surface reactions occur at the same time. This system provides a new method to treat degradation-resistant pollution.