In this study we have investigated the efficiency Cobalt (II) (Co(II)) for the activation of sulfite ions following the oxidation of paracetamol used as model contaminants. Physico-chemical parameters that can impact the paracetamol degradation (pH, initial paracetamol concentration, Co(II)/S(IV) molar ratio, oxygen concentration) and contribution of various radicals were investigated in order to elucidate the chemical mechanism. Main results show that the pH is a key factor controlling the efficiency in the system Co(II)/Sulfite. Higher efficiency is observed for pH between 9.0 and 10.0. Increasing S(IV) concentrations, until 1 mM, slightly promoted the degradation of paracetamol. In fact, an excess of sulfite ions inhibits the reaction through the scavenging of SO₄⁻ and SO₅⁻. Moreover, degradation efficiency drastically decreases from ∼ 85% to less than 5% in absence of oxygen. SO₄⁻ was confirmed to be the main oxidant responsible for the paracetamol degradation. For the first time we determined the second order rate constant between SO₄⁻ and paracetamol (1.33 ± 0.79 × 10⁹ M⁻¹ s⁻¹ (at pH 5) and 6.14 ± 0.99 × 10⁸ M⁻¹ s⁻¹ (at pH 11.0)). Moreover, radical-scavenging experiments also suggest the possible implication of SO₅⁻. Hence, this work provides a precise understanding of the overall mechanism and a new promising strategy by using sulfite and transition metal such as Co(II) to promote organic compounds degradation in water under neutral and alkaline pH conditions.

在这项研究中，我们研究了用作模型污染物的扑热息痛氧化后，钴（II）（Co（II））活化亚硫酸根离子的效率。为了阐明化学机理，研究了可能影响扑热息痛降解的理化参数（pH，扑热息痛初始浓度，Co（II）/ S（IV）摩尔比，氧浓度）和各种自由基的贡献。主要结果表明，pH是控制Co（II）/亚硫酸盐体系效率的关键因素。在9.0和10.0之间的pH值下观察到更高的效率。增加S（IV）浓度直至1 mM会轻微促进对乙酰氨基酚的降解。实际上，过量的亚硫酸根离子抑制通过SO的清除反应₄ ^-和SO ₅^-。而且，在没有氧气的情况下，降解效率从约85％急剧降低到5％以下。SO ₄ ^-被证实为负责的对乙酰氨基酚降解的主要氧化剂。首次我们测定SO之间的二级速率常数₄ ^-和对乙酰氨基酚（1.33±0.79×10 ⁹ 中号^-1 小号^-1（在pH 5）和6.14±0.99×10 ⁸ 中号^-1 小号^-1（在pH 11.0））。此外，清除自由基的实验也表明SO的可能产生的影响₅ ^-。因此，这项工作通过使用亚硫酸盐和过渡金属（例如Co（II））来促进有机化合物在中性和碱性pH条件下在水中的降解，从而提供了对整体机理的精确理解和新的有希望的策略。