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环境污染治理技术及原理

摘要：研究了腐殖酸在水合MnO₂(S)(δMnO₂)表面的吸附行为.考察了不同分子量分布范围腐殖酸的吸附性能,探讨了阳离子对吸附行为的影响及其可能作用机理,并利用FTIR光谱对吸附行为进行了光谱学研究.结果发现,具有较高分子量的腐殖酸HAa的吸附去除率比具有较低分子量的腐殖酸HA_b高30%,表明腐殖酸分子量越大越倾向于吸附在δMnO₂表面.Ca²⁺较Mg²⁺更能促进腐殖酸在δMnO₂表面的吸附;紫外-可见吸收光谱分析表明Ca²⁺较Mg²⁺具有更强的与腐殖酸络合的能力;此外,ζ电位测定发现,10mmol·L^-1Mg²⁺使δMnO₂的ζ电位由-37mV(pH=7.9)升高至-9mV(pH=6.5),而10mmol·L^-1Ca²⁺则使ζ电位升高至+7mV(pH=7.2).FTIR光谱的结果证实了腐殖酸在δMnO₂表面的吸附,并表明腐殖酸的羧基及δMnO₂的表面羟基(MnOH)在吸附过程中起着重要作用.上述结果表明,腐殖酸性质、背景阳离子等因素对腐殖酸的吸附行为有重要影响.

Abstract：The adsorptive behavior of humic acid on hydrous MnO₂(S) (δMnO₂) is investigated. Effects of such parameters as molecular weight of humic acid and divalent cation species on adsorptive behavior are investigated, and possible mechanisms that divalent cation involves in are proposed. FTIRspectra are subsequently employed for further spectroscopy study. Results of this study show approximate 30% more adsorption of humic acid with higher moleculer weight(HA_a) on δMnO₂ than that with lower molecular weight(HA_b), indicating that humic acid with higher molecular weight exhibits more tendency of adsorbing on δMnO₂. Ca²⁺ facilitates more humic acid adsorption than Mg²⁺ does; UV-Vis spectra demonstrate that Ca²⁺ possesses higher capabilities of complexing with acidic functional groups of humic acid than Mg²⁺ does; furthermore, 1.0mmol·L^-1 Ca²⁺ increases ζ potential of δMnO₂ from -37mV (pH=7.9) to +7mV (pH=7.2), while 1.0mmol·L^-1 Mg²⁺ increases to lower value as -9mV (pH=6.5), correspondingly. FTIRspectra demonstrate humic acid adsorption on δMnO₂, showing that -COO^- functional groups within humic acid and surface Mn-OHgroups of δMnO₂ have great influence on adsorptive behavior. Such factors as humic acid characteristics and background cation have important effects on adsorption.