Institute of Materials Chemistry, Key Laboratory of Advanced Civil Engineering Materials of the Ministry of Education, College of Materials Science and Engineering, Tongji University, 1239 Si-Ping Road, Shanghai 200092, China.
J Phys Chem B. 2010 Mar 18;114(10):3534-42. doi: 10.1021/jp910697s.
Strongly selective adsorbability of natural longan (Euphoria longan) shell as a biomacromolecular sorbent toward heavy metal ions from aqueous solutions has been discovered and successfully optimized by facilely controlling the shell dosage, sorption time, pH value, and ion concentration. The sorption well-fits the Langmuir isotherm and obeys the pseudo-second-order kinetics. The maximum adsorptivity of Pb(II) and Hg(II) is 99.3 and 99.1%, respectively, with short equilibrium sorption time. The redox sorption mechanism of Pb(II) and Hg(II) ions onto longan shell was proposed on the basis of IR and X-ray diffraction analyses. In particular, a slow but durative redox interaction between Pb(II) ions and longan shell was revealed even at a solid state, resulting in the formation of Pb(syn) crystals onto longan shell. Competitive sorption suggested that the shell demonstrated a preferential sorption to Pb(II) over Hg(II) in their mixture solution, despite higher adsorptivity of Hg(II) than Pb(II) in corresponding pure solutions. The shell displayed highly selective sorption to Pb(II) over light metal ions with an adsorbability order of Pb(II) > Hg(II) >> Zn(II) > Cu(II) > Ca(II) > Mg(II) >> Fe(III,II), indicating that the shell could efficiently purify drinking water and nutritious liquids by just eliminating the harmful metal ions and still retaining the nutritious metal ions. The printery sewage and polluted river water both meet the discharge standard after being treated once with longan shell, and even satisfy the standards for irrigation/fishery and drinking water, respectively, after being treated twice. A large amount of functional groups like hydroxyl, ether, and carbonyl in the longan shell, as well as its intrinsic hydrophilicity, are responsible for the strong adsorbability toward the heavy metal ions. Not only does the longan shell have low cost and have inherent environmental friendliness in contrast to all synthetic and even seminatural sorbents but it also has stronger adsorbability toward Pb(II) and particularly Hg(II) ions than the most natural sorbents reported, making longan shell attractive as a highly cost-efficient sorbent for the selective removal of hazardous heavy metal ions.
天然龙眼壳对重金属离子具有很强的选择性吸附能力，可从水溶液中吸附生物大分子。通过简便地控制壳用量、吸附时间、pH 值和离子浓度，成功地优化了这种吸附能力。吸附非常符合朗缪尔等温线，符合准二级动力学。Pb(II)和 Hg(II)的最大吸附率分别为 99.3%和 99.1%，平衡吸附时间短。基于红外和 X 射线衍射分析，提出了 Pb(II)和 Hg(II)离子在龙眼壳上的氧化还原吸附机理。特别是，即使在固态下，也揭示了 Pb(II)离子与龙眼壳之间缓慢但持久的氧化还原相互作用，导致 Pb(syn)晶体在龙眼壳上形成。竞争吸附表明，尽管 Hg(II)的吸附率高于相应纯溶液中的 Pb(II)，但壳对混合溶液中的 Pb(II)表现出优先吸附。壳对 Pb(II)的吸附选择性高于轻金属离子，吸附能力顺序为 Pb(II) > Hg(II) >> Zn(II) > Cu(II) > Ca(II) > Mg(II) >> Fe(III,II)，表明壳可通过仅去除有害金属离子而保留营养金属离子来高效净化饮用水和营养液。经过龙眼壳处理一次后，印刷污水和受污染河水均符合排放标准，经过两次处理后，甚至分别符合灌溉/渔业和饮用水标准。龙眼壳中大量的功能基团，如羟基、醚和羰基，以及其固有亲水性，是其对重金属离子具有强吸附能力的原因。与所有合成甚至半天然吸附剂相比，龙眼壳不仅成本低，而且固有环境友好性，并且对 Pb(II)特别是 Hg(II)离子的吸附能力比报道的大多数天然吸附剂更强，使龙眼壳成为一种极具成本效益的吸附剂，可用于选择性去除有害重金属离子。
J Hazard Mater. 2008-6-15
J Hazard Mater. 2009-10-14
Polymers (Basel). 2023-5-18
Zotero 插件