Overestimated role of sulfate in haze formation over Chinese megacities due to improper simulation of heterogeneous reactions

Environmental Chemistry Letters - Heterogeneous reactions involving aerosol water, i.e., haze chemistry, are responsible for high aerosol concentrations observed during severe haze events in...     

羧基甲壳素对Pb(Ⅱ)的吸附性能及机理研究

为了提高甲壳素对Pb²⁺吸附性能,采用2,2,6,6-四甲基哌啶-1-氧基（TEMPO）/次氯酸钠（NaClO）/溴化钠（NaBr）氧化体系对甲壳素羧基化改性.采用FTIR、Solid ¹³C-NMR、XRD和SEM-EDX等对羧基甲壳素结构和形貌进行表征,考察了不同NaClO用量制备的羧基甲壳素、溶液pH值、Pb（Ⅱ）初始浓度、吸附时间和离子强度对吸附量的影响,利用XPS探究其吸附机理.结果表明,氧化改性不改变甲壳素的晶型,羧基出现在甲壳素晶体表面;NaClO用量和溶液pH值对吸附量影响显著,pH值为4.0~6.0,NaClO用量为30mL制备的羧基甲壳素吸附效果好,60min达到平衡,室温下饱和吸附量达233.64mg/g;吸附动力学符合准二阶动力学方程,吸附等温线符合Freundlich等温吸附模型,吸附机理包括静电作用、络合配位和离子交换.