Li Xin-Gui, Feng Hao, Huang Mei-Rong
Institute of Materials Chemistry, Key Laboratory of Advanced Civil Engineering Materials, College of Materials Science & Engineering, Tongji University, 1239 Si-Ping Road, Shanghai, China.
Chemistry. 2009;15(18):4573-81. doi: 10.1002/chem.200802431.
The highest Hg-ion adsorbance so far, namely up to 2063 mg g(-1), has been achieved by poly(aniline-co-5-sulfo-2-anisidine) nanosorbents. Sorption of Hg ions occurs mainly by redox and chelation mechanisms (see scheme), but also by ion exchange and physisorption.Poly(aniline (AN)-co-5-sulfo-2-anisidine (SA)) nanoparticles were synthesized by chemical oxidative copolymerization of AN and SA monomers, and their extremely strong adsorption of mercury ions in aqueous solution was demonstrated. The reactivity ratios of AN and SA comonomers were found to be 2.05 and 0.02, respectively. While AN monomer tends to homopolymerize, SA monomer tends to copolymerize with AN monomer because of the great steric hindrance and electron-attracting effect of the sulfo groups, despite the effect of conjugation of the methoxyl group with the benzene ring. The effects of initial mercury(II) concentration, sorption time, sorption temperature, ultrasonic treatment, and sorbent dosage on mercury-ion sorption onto AN/SA (50/50) copolymer nanoparticles with a number-average diameter of around 120 nm were significantly optimized. The results show that the maximum Hg-ion sorption capacity on the particulate nanosorbents can even reach 2063 mg of Hg per gram of sorbent, which would be the highest Hg-ion adsorbance so far. The sorption data fit to the Langmuir isotherm, and the process obeys pseudo-second-order kinetics. The IR and UV/Vis spectral data of the Hg-loaded copolymer particles suggest that some mercury(II) was directly reduced by the copolymer to mercury(I) and even mercury(0). A mechanism of sorption between the particles and Hg ions in aqueous solution is proposed, and a physical/ion exchange/chelation/redox sorption ratio of around 2/3/45/50 was found. Copolymer nanoparticles may be one of the most powerful and cost-effective sorbents of mercury ions, with a wide range of potential applications for the efficient removal and even recovery of the mercury ions from aqueous solution.
聚（苯胺 - 共 - 5 - 磺酸 - 2 - 甲氧基苯胺）纳米吸附剂实现了迄今为止最高的汞离子吸附量，即高达2063 mg g⁻¹。汞离子的吸附主要通过氧化还原和螯合机制（见图）进行，但也通过离子交换和物理吸附。通过AN和SA单体的化学氧化共聚合成了聚（苯胺（AN） - 共 - 5 - 磺酸 - 2 - 甲氧基苯胺（SA））纳米颗粒，并证明了它们对水溶液中汞离子具有极强的吸附作用。发现AN和SA共聚单体的竞聚率分别为2.05和0.02。虽然AN单体倾向于均聚，但由于磺酸基团的巨大空间位阻和吸电子效应，SA单体倾向于与AN单体共聚，尽管甲氧基与苯环存在共轭效应。对初始汞（II）浓度、吸附时间、吸附温度、超声处理和吸附剂用量对平均粒径约为120 nm的AN/SA（50/50）共聚物纳米颗粒上汞离子吸附的影响进行了显著优化。结果表明，颗粒状纳米吸附剂上的最大汞离子吸附容量甚至可达每克吸附剂2063 mg汞，这将是迄今为止最高的汞离子吸附量。吸附数据符合朗缪尔等温线，该过程服从准二级动力学。负载汞的共聚物颗粒的红外和紫外/可见光谱数据表明，一些汞（II）被共聚物直接还原为汞（I）甚至汞（0）。提出了颗粒与水溶液中汞离子之间的吸附机制，发现物理/离子交换/螯合/氧化还原吸附比例约为2/3/45/50。共聚物纳米颗粒可能是最强大且最具成本效益的汞离子吸附剂之一，在从水溶液中高效去除甚至回收汞离子方面具有广泛的潜在应用。
