ABSTRACT

The pollution of environmental systems with heavy metals is becoming a serious problem worldwide. These contaminants are one of the main issues in sludge (which is considered waste) and can even have harmful effects if the sludge is not treated properly. Thus, the development of a novel functional magnetic nanoadsorbent based on a derived lysine is reported here, which can be efficiently applied for metal removal from sludge. Magnetic nanoparticles were coated with silica layer and further modified by covalent bonding of derived lysine. The morphology of the nanomaterial, its nano-size and the silica layer thickness were analyzed by transmission electron microscopy. The successful silanization of the lysine derivative to the silica-coated magnetic nanostructures was investigated by several physicochemical characterization techniques, while the magnetic properties were measured with a vibrating sample magnetometer. The synthesized nanostructures were used as adsorbents for simultaneous removal of most critical heavy metals (Cr, Zn, Cu) from real complex sludge suspensions. The main practical adsorption parameters, pH of the native stabilized sludge, adsorbent amount, time, and adsorbent regeneration were investigated. The results show promising adsorption properties among currently available adsorbents (the total equilibrium adsorption capacity was 24.5 mg/g) from the sludge with satisfactory nanoadsorbent reusability and its rapid removal. The stability of the nanoadsorbent in the sludge, an important but often neglected practical parameter for efficient removal, was verified. This work opens up new possibilities for the development of high-quality magnetic nanoadsorbents for metal pollutants applied in various complicated environmental fields and enables waste recovery.

摘要

重金属对环境系统的污染正在成为世界范围内的一个严重问题。这些污染物是污泥（被认为是废物）中的主要问题之一，如果污泥处理不当，甚至会产生有害影响。因此，本文报道了一种基于衍生赖氨酸的新型功能磁性纳米吸附剂的开发，该吸附剂可有效地用于从污泥中去除金属。磁性纳米粒子涂有二氧化硅层，并通过衍生赖氨酸的共价键进一步修饰。通过透射电子显微镜分析纳米材料的形态、纳米尺寸和二氧化硅层厚度。通过几种物理化学表征技术研究了赖氨酸衍生物成功硅烷化为二氧化硅涂层磁性纳米结构，而磁性是用振动样品磁力计测量的。合成的纳米结构被用作吸附剂，用于从真正的复杂污泥悬浮液中同时去除最关键的重金属（Cr、Zn、Cu）。研究了主要的实际吸附参数、天然稳定污泥的pH值、吸附剂用量、吸附时间和吸附剂再生。结果表明，目前可用的吸附剂（总平衡吸附容量为24.5 mg / g）从污泥中具有良好的吸附性能，具有令人满意的纳米吸附剂可重复使用性和快速去除。验证了纳米吸附剂在污泥中的稳定性，这是一个重要但经常被忽视的有效去除的实用参数。