δ-MnO_2膜-蒙脱石复合体对次甲基蓝的氧化降解与吸附去除  

Oxidative degradation and adsorptive removal of methylene blue by δ-MnO_2-coated montmorillonite complexes

作　　者：王征[1,2] 朱茂旭[2] 徐焕志[1] 

机构地区：[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

出　　处：《环境科学学报》2009年第12期2578-2584,共7页Acta Scientiae Circumstantiae

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

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.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 deeolorization 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.

关 键 词：膜态δ-MnO2 次甲基蓝 氧化脱色 吸附脱色 

分 类 号：K131[历史地理—历史学]