Synergistic action of hydrogen peroxide and catalysis of metastable aluminum ions for degradation of atrazine in aqueous solution

• ATZ can be completely degraded within 10 min in [Al(H 2 O) 6 3+ ]* solution at pH = 12.0. • TOC removal ratio of ATZ in [Al(H 2 O) 6 3+ ]* solution can be up to 61.4% at pH = 4.0. • Metastable [Al(H 2 O) 6 3+ ]* ions decompose H 2 O 2 into HO• radicals in pH range 2.0-12.0. • HO 2 - ions produced by H 2 O 2 contribute to main ATZ degradation in alkaline solution. • [Al(H 2 O) 6 3+ ]* ions has a good reusability for ATZ degradation up to 10 cycles. In this work, metastable aluminum cluster ions [Al(H 2 O) 6 3+ ]* and hydrogen peroxide (H 2 O 2 ) were used to degrade and mineralize atrazine (ATZ) in aqueous solution, where [Al(H 2 O) 6 3+ ]* ions can decompose H 2 O 2 into hydroxyl radicals (HO • ). It was found that ATZ has a high degradation efficiency in [Al(H 2 O) 6 3+ ]* + H 2 O 2 solution both in acidic and alkaline condition, even ATZ concentration was up to 20 mg L -1 . ATZ can be completely degraded within 2 h and 10 min in acidic solution at pH = 4.0 and alkaline solution at pH = 12, respectively. Even in neutral solution, AZT can be completely degraded if the time is long enough. However, total organic carbon (TOC) removal ratio reached the maximum (61.4%) at pH = 4.0. Furthermore, [Al(H 2 O) 6 3+ ]* + H 2 O 2 solution exhibited an excellent reusability for degradation of ATZ up to 10 cycles. Mechanism analyses revealed that H 2 O 2 spontaneously decomposes into HO 2 - ions, which can transform ATZ into nontoxic hydroxyatrazine and contribute to the most of ATZ degradation in alkaline solution. HO • radicals generated by the catalysis of [Al(H 2 O) 6 3+ ]* ions contribute to the main part of ATZ degradation in acidic solution and almost all of mineralization in the full pH range. As the optimal condition to produce HO • radicals by [Al(H 2 O) 6 3+ ]* ions is at pH = 4.0, and its TOC removal ratio is the highest. The related influence factors and possible pathways for ATZ degradation were investigated in detail. The present study provides a new route to remove ATZ in aqueous solution.