Novel Fenton-like process (pre-magnetized Fe0/H2O2) for efficient degradation of organic pollutants

• Pre-magnetization Fe0/H2O2 enhanced degradation rate even 21 times and reduced reagent dosage.
• Pre-magnetization changed Fe0 surface characteristic, improved corrosion and Fe2+ generation.
• Fe0 magnetic memory could last 72 h and could be recovered after second pre-magnetization.
• This process was promising and highly efficient for various refractory contaminants removal.

A new modified Fenton-like process (pre-magnetization Fe0/H2O2) was employed to enhance the degradation of organic pollutants and reduce reagents dosage, using azo dye of tartrazine as the model. Compared with Fe0/H2O2 process, pre-magnetization Fe0/H2O2 process could have 1.3–11.2 folds enhancement in the degradation rate of tartrazine at different Fe0 dosages (0.5–4 mmol), initial pH levels (2–6.5) and H2O2 dosages (0.25–2 mmol) owing to the change of Fe0 characteristics after pre-magnetization. The contact angle of pre-magnetization Fe0 decreased from 58.4° to 19.8° enhancing the hydrophilicity and BET increased from 0.15 m2/g to 1.94 m2/g, which improved the corrosion of Fe0 and accelerated the generation of Fe2+. Similar to the case of tartrazine, pre-magnetization Fe0/H2O2 process had remarkable improvement on many refractory contaminants. The degradation rate constant of methyl orange, orange, methylene blue, 2,4-dichlorophenol (2,4-DCP), acetylsalicylic acid, phenol and tetracycline by pre-magnetization Fe0/H2O2 process was 5.2, 21.3, 9.2, 5.6, 12.3, 9.5 and 3 folds of that by Fe0/H2O2 process, respectively. The “magnetic memory” of pre-magnetization Fe0 could last 24 h which was suitable for off-site application, and the lost some or all “magnetic memory” could be recovered after second pre-magnetization. Pre-magnetization Fe0/H2O2 is a more promising and highly efficient Fenton process since it does not require any change of the present water and wastewater treatment process, and does not need an extra energy source and complex equipment but can widen pH range and save more than 75% Fe0 and H2O2 dosages.