Divalent mercury (Hg (II)) is the predominant mercury species in aquatic environments. Hg (II) combines easily with human enzymes, thus causing acute diseases, even at very low concentrations. Among existing procedures to remove Hg (II) from water, adsorption is widely used, achieving high removal efficiencies. However, most actual adsorption techniques require high temperatures, long times or tedious procedures. Here we present a novel, simple and fast method to remove Hg (II) from wastewater by using magnetic-core nanoparticles coated with metallic silver and functionalized with sodium 2-mercaptoethane sulfonate. This adsorbent was characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Brunauer–Emmett–Teller analysis, which showed a contact surface area of the adsorbent equal to 116.476 m²/g. The equilibrium isotherm is characterized by the Langmuir model. Results show that 100% adsorption efficiency is achieved in 30 seconds of contact time, at pH 6.2 and room temperature, employing a low dose of adsorbent. The adsorbent can be recovered and recycled, keeping 100% adsorption efficiency for two additional cycles. The presence of other ions commonly found in aqueous media does not interfere with Hg (II) adsorption.

二价汞（Hg（II））是水生环境中的主要汞物种。汞（II）容易与人的酶结合，即使在非常低的浓度下也能引起急性疾病。在现有的从水中去除Hg（II）的方法中，吸附被广泛使用，实现了很高的去除效率。然而，大多数实际的吸附技术需要高温，长时间或繁琐的过程。在这里，我们介绍一种新颖，简单，快速的方法，该方法通过使用涂有金属银并用2-巯基乙烷磺酸钠官能化的磁芯纳米颗粒从废水中去除Hg（II）。通过场发射扫描电子显微镜，能量色散X射线光谱和Brunauer-Emmett-Teller分析表征了该吸附剂，该吸附剂的接触表面积为116.476 m² /克。平衡等温线由Langmuir模型表征。结果表明，使用低剂量的吸附剂，在pH 6.2和室温下，在30秒的接触时间内可实现100％的吸附效率。吸附剂可以回收再利用，在另外两个循环中保持100％的吸附效率。在水介质中常见的其他离子的存在不会干扰Hg（II）的吸附。