• 关键词：膜态δ-MnO₂  次甲基蓝  氧化脱色  吸附脱色

• 基金项目：国家自然科学基金项目(No.40771095);浙江海洋学院科研项目(No.X08M03)

• 王征
• 1. 浙江海洋学院海科学院, 舟山 316000; 2. 中国海洋大学化学化工学院, 青岛 266100

• 朱茂旭
• 中国海洋大学化学化工学院, 青岛 266100

• 徐焕志
• 浙江海洋学院海科学院, 舟山 316000

• 摘要：合成了δ-MnO₂及不同Mn含量(4.8%、25.5%、34.9%)的3种δ-MnO₂膜-蒙脱石复合体(FHt^-1、FHT-2、FHT-3).在模拟酸性环境中(pH=4.0、4.7、5.5),通过膜分离和加入强还原剂两种实验方法定量探讨了以颗粒态和膜形态存在的δ-MnO₂的吸附和氧化作用各自在次甲基蓝脱色中的相对贡献及环境地球化学意义.结果表明,在pH=4.0～5.5范围内,膜态δ-MnO₂对次甲基蓝的氧化脱色率随pH降低而升高,吸附脱色率随pH降低而降低.蒙脱石的存在阻碍了δ-MnO₂的结晶,增加了其无定形程度,致使膜态δ-MnO₂比颗粒态δ-MnO₂具有更强的氧化活性,能更有效地氧化有机物次甲基蓝.由于锰氧化物膜在自然环境中广泛存在,以前用颗粒态锰氧化物模拟研究对有机物的非生物氧化可能在一定程度上低估了天然锰氧化物的氧化效率.

• Abstract：Discrete granular δ-MnO₂ and three δ-MnO₂-coated montmorillonite complexes(FHt^-1,FHT-2 and FHT-3) with varying Mn contents ranging from 4.8% to 34.9% were synthesized.In acidic conditions(pH = 4.0,4.7,5.5) the relative contributions of adsorptive and oxidative decolorization of methylene blue by Mn-oxide coatings and their discrete granular counterparts were quantified in batch systems using a combination of filtration separation and NH2OH·HCl reductive dissolution approaches.The results show that oxidative decolorization by δ-MnO₂ coatings increased as pH decreased from 4.0 to 5.5,while absorptive decolorization decreased with decreasing pH.The montmorillonite substrate hindered crystallization of the δ-MnO₂ coatings,resulting in poorly crystalline structures,which gave the δ-MnO₂ coatings higher oxidizing activities compared with their granular counterparts.Given the ubiquitous occurrence of Mn-oxide coatings in natural environments,previous studies using discrete granular Mn oxides with various crystallinities for abiotic oxidation of organic contaminants may have underestimated the oxidizing potential of naturally occurring Mn oxides.

• Key words：δ-MnO₂ coatings  methylene blue  oxidative decolorization  absorptive decolorizations

• 
  摘要点击次数： 2439 全文下载次数： 2410