Bakry Ayyob M, Awad Fathi S, Bobb Julian A, El-Shall M Samy
Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States.
Department of Chemistry, Faculty of Science, Jazan University, Jazan 45142, Saudi Arabia.
ACS Omega. 2020 Dec 15;5(51):33090-33100. doi: 10.1021/acsomega.0c04695. eCollection 2020 Dec 29.
Heavy metal ions represent one of the most toxic and environmentally harmful pollutants of water sources. This work reports the development of a novel chelating nitrogen-doped carboxylated porous carbon (ND-CPC) adsorbent for the effective removal of the heavy metal ions Pb(II), Hg(II), and Cr(VI) from contaminated and polluted water sources. The ND-CPC adsorbent is designed to combine four different types of nitrogen functional groups (graphitic, pyrrolic, pyridinic, and pyridine oxide) with the carboxylic acid functional groups within a high surface area of 1135 ± 20 m/g of the porous carbon structure. The ND-CPC adsorbent shows exceptionally high adsorption affinity for Pb(II) with a capacity of 721 ± 14 mg/g in addition to high uptake values of 257 ± 5 and 104 ± 2 mg/g for Hg(II) and Cr(VI), respectively. The high adsorption capacity is also coupled with fast kinetics where the equilibrium time required for the 100% removal of Pb(II) from 50 ppb and 10 ppm concentrations is 30 s and 60 min, respectively. Even with the very high concentration of 700 ppm, 74% uptake of Pb(II) is achieved within 90 min. Removal efficiencies of 100% of Pb(II), 96% of Hg(II), 91% of Cu(II), 82% of Zn(II), 25% of Cd(II), and 13% of Ni(II) are achieved from a solution containing 10 ppm concentrations of these ions, thus demonstrating excellent selectivity for Pb(II), Hg(II), and Cu(II) ions. Regeneration of the ND-CPC adsorbent shows excellent desorption efficiencies of 99 and 95% for Pb(II) and Cr(VI) ions, respectively. Because of the fast adsorption kinetics, high removal capacity and excellent regeneration, stability, and reusability, the ND-CPC is proposed as a highly efficient remediation adsorbent for the solid-phase removal of Pb(II), Hg(II), and Cr(VI) from contaminated water.
重金属离子是水源中毒性最强且对环境危害最大的污染物之一。本研究报道了一种新型螯合氮掺杂羧基化多孔碳（ND-CPC）吸附剂的研发，该吸附剂可有效去除受污染水源中的重金属离子Pb(II)、Hg(II)和Cr(VI)。ND-CPC吸附剂的设计思路是将四种不同类型的氮官能团（石墨型、吡咯型、吡啶型和吡啶氧化物型）与羧酸官能团结合在多孔碳结构中，其高比表面积为1135±20 m²/g。ND-CPC吸附剂对Pb(II)表现出极高的吸附亲和力，吸附容量为721±14 mg/g，对Hg(II)和Cr(VI)的高吸附量分别为257±5 mg/g和104±2 mg/g。高吸附容量还伴随着快速动力学，从50 ppb和10 ppm浓度的溶液中100%去除Pb(II)所需的平衡时间分别为30秒和60分钟。即使在700 ppm的极高浓度下，90分钟内仍可实现74%的Pb(II)吸附量。从含有10 ppm这些离子浓度的溶液中，Pb(II)、Hg(II)、Cu(II)、Zn(II)、Cd(II)和Ni(II)的去除效率分别达到100%、96%、91%、82%、25%和13%，从而证明了对Pb(II)、Hg(II)和Cu(II)离子具有优异的选择性。ND-CPC吸附剂的再生显示，Pb(II)和Cr(VI)离子的解吸效率分别高达99%和95%。由于其快速的吸附动力学、高去除容量以及出色的再生、稳定性和可重复使用性，ND-CPC被提议作为一种高效的修复吸附剂，用于从受污染水中固相去除Pb(II)、Hg(II)和Cr(VI)。
