Wang Qian, Zhu Sining, Xi Chen, Jiang Binhai, Zhang Fan
College of Chemistry and Chemical Engineering, Key Laboratory of Mineral Cleaner Production and Exploit of Green Functional Materials in Hunan Province, National Experimental Teaching Demonstration Center for Chemistry, Jishou University, Jishou 416000, China.
ACS Omega. 2022 Apr 4;7(14):12231-12241. doi: 10.1021/acsomega.2c00622. eCollection 2022 Apr 12.
In this study, the highly crosslinked hyperbranched polyamide-amines (H-PAMAMs) were first prepared via one-pot methods and then modified with thiourea to synthesize a novel adsorbent containing sulfhydryl groups (CHAP-SH), which was used to adsorb Hg(II) ions from aqueous solutions. The adsorption characteristics and mechanism of CHAP-SH for Hg(II) ions were systematically studied. As expected, CHAP-SH exhibited a rapid removal performance toward Hg(II), and the maximum adsorption capacity was 282.74 mg/g at 318 K and pH = 4.5. The whole adsorption behavior could be well described by the pseudo-second-order kinetic model and Langmuir and Redlich-Peterson adsorption isotherm models, which reflected that the adsorption process was mainly monolayer chemisorption. Meanwhile, CHAP-SH had strong selectivity for Hg(II) in the presence of multimetal ions, and it had excellent recoverability after five cycles. In order to further elucidate the adsorption mechanism, the adsorbents before and after adsorption were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and energy-dispersive X-ray spectroscopy, and the results showed that the nitrogen-containing, oxygen-containing, and sulfur-containing groups in the adsorbent molecule had synergistic complexation with Hg(II). These results indicated that the adsorbents had great potential in the future treatment of aqueous solutions containing Hg(II).
在本研究中，首先通过一锅法制备了高度交联的超支化聚酰胺 - 胺（H - PAMAMs），然后用硫脲对其进行改性，以合成一种含巯基的新型吸附剂（CHAP - SH），用于从水溶液中吸附Hg(II)离子。系统研究了CHAP - SH对Hg(II)离子的吸附特性及机理。正如预期的那样，CHAP - SH对Hg(II)表现出快速的去除性能，在318 K和pH = 4.5时最大吸附容量为282.74 mg/g。整个吸附行为可以用准二级动力学模型以及朗缪尔和雷德利希 - 彼得森吸附等温线模型很好地描述，这反映出吸附过程主要是单层化学吸附。同时，CHAP - SH在多金属离子存在下对Hg(II)具有很强的选择性，并且在五个循环后具有优异的可回收性。为了进一步阐明吸附机理，采用傅里叶变换红外光谱、扫描电子显微镜、X射线光电子能谱、热重分析和能量色散X射线光谱对吸附前后的吸附剂进行了表征，结果表明吸附剂分子中的含氮、含氧和含硫基团与Hg(II)具有协同络合作用。这些结果表明该吸附剂在未来处理含Hg(II)水溶液方面具有巨大潜力。
