水溶液中新生态MnO2对苯酚的氧化作用及机理研究

pH是影响反应过程的重要因素,pH≥4的条件下,新生态MnO₂与苯酚间主要发生吸附作用,而在pH<4时,新生态MnO₂与苯酚间发生氧化还原反应.本文主要研究pH<4时新生态MnO₂与苯酚间的氧化还原反应机理,并考察反应时间、温度及高价离子对苯酚去除率及溶解锰的影响.结果表明,时间对苯酚的去除率影响较大,反应10min苯酚的去除率可达60%以上,反应70min基本达到平衡,苯酚的去除率可达95%左右,溶解锰随反应时间变化不大.苯酚的去除率随温度增加而增大,但是变化幅度较小,溶解锰随温度变化不大.推测反应过程产生苯氧自由基及中间态氧化剂Mn³⁺.GC-MS测定苯酚的氧化产物为对苯醌和联苯酚.高价正离子Al³⁺能促进苯酚的去除,负离子PO₄^3-不利于苯酚的去除.

Study on Mechanism of Phenol Oxidized by Fresh Manganese Dioxide in Aqueous

pH is the key factor to affect reaction process. Adsorption and redox take place at pH > or =4 and pH <4, respectively. Free-radical and Mn3+ was inferred to produce and participate in reaction at pH <4. The oxidizing products of phenol are p-benzoquinone and biphenol determined by GC-MS. The efficiency of phenol and soluble manganese as a function of time and temperature were examined at pH <4 in order to test the mechanism inferred. Results show removal percents of phenol increase from 65% to 95% with time varied from 10 min to 70 min, but soluble manganese changes little. Removal percents of phenol increase with temperature also, but soluble manganese doesn't change. This means fresh manganese dioxide is not the only oxidant in aqueous and other oxidant , i.e. Mn34+, appears during the reaction. High valence cation, i.e. Al3+, promoted the removal percent of phenol while anion, i.e. PO4(3-), decrease the efficiency of phehol.