El-Wakil Ahmad M, Waly Saadia M, Abou El-Maaty Weam M, Waly Mohamed M, Yılmaz Murat, Awad Fathi S
Chemistry Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt.
Department of Chemical Engineering, Faculty of Engineering, Osmaniye Korkut Ata University, 80000 Osmaniye, Turkey.
ACS Omega. 2022 Feb 11;7(7):6058-6069. doi: 10.1021/acsomega.1c06441. eCollection 2022 Feb 22.
A novel chelating adsorbent, based on the functionalization of activated carbon (AC) derived from water hyacinth (WH) with melamine thiourea (MT) to form melamine thiourea-modified activated carbon (MT-MAC), is used for the effective removal of Hg, Pb, and Cd from aqueous solution. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) theory confirm the successful functionalization of AC with the melamine thiourea chelating ligand through the amidation reaction between the carboxyl groups of oxidized activated carbon (OAC) and the amino groups of melamine thiourea (MT) in the presence of dicyclohexylcarbodiimide (DCC) as a coupling agent. The prepared MT-MAC exhibited extensive potential for the adsorption of the toxic metal ions Hg, Pb, and Cd from wastewater. The MT-MAC showed high capacities for the adsorption of Hg (292.6 mg·g), Pb (237.4 mg·g), and Cd (97.9 mg·g) from aqueous solution. Additionally, 100% removal efficiency of Hg at pH 5.5 was observed at very low initial concentrations (25-1000 ppb).The experimental sorption data could be fitted well with the Langmuir isotherm model, suggesting a monolayer adsorption behavior. The kinetic data of the chemisorption mechanism realized by the melamine thiourea groups grafted onto the activated carbon surface have a perfect match with the pseudo-second-order (PSO) kinetic model. In a mixed solution of metal ions containing 50 ppm of each ion, MT-MAC showed a removal of 97.0% Hg, 68% Pb, 45.0% Cd, 17.0% Cu, 7.0% Ni, and 5.0% Zn. Consequently, MT-MAC has exceptional selectivity for Hg ions from the mixed metal ion solutions. The MT-MAC adsorbent showed high stability even after three adsorption-desorption cycles. According to the results obtained, the use of the MT-MAC adsorbent for the adsorption of Pb, Hg, and Cd metal ions from polluted water is promising.
一种新型螯合吸附剂，基于水葫芦（WH）衍生的活性炭（AC）用三聚氰胺硫脲（MT）功能化形成三聚氰胺硫脲改性活性炭（MT-MAC），用于从水溶液中有效去除汞、铅和镉。傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和布鲁诺尔-埃米特-特勒（BET）理论证实，在二环己基碳二亚胺（DCC）作为偶联剂的存在下，通过氧化活性炭（OAC）的羧基与三聚氰胺硫脲（MT）的氨基之间的酰胺化反应，活性炭成功地用三聚氰胺硫脲螯合配体进行了功能化。制备的MT-MAC在从废水中吸附有毒金属离子汞、铅和镉方面表现出巨大潜力。MT-MAC对水溶液中汞（292.6 mg·g）、铅（237.4 mg·g）和镉（97.9 mg·g）的吸附容量很高。此外，在非常低的初始浓度（25 - 1000 ppb）下，在pH 5.5时观察到汞的去除效率为100%。实验吸附数据能很好地拟合朗缪尔等温线模型，表明为单层吸附行为。通过接枝到活性炭表面的三聚氰胺硫脲基团实现的化学吸附机制的动力学数据与伪二级（PSO）动力学模型完美匹配。在每种离子浓度为50 ppm的金属离子混合溶液中，MT-MAC对汞的去除率为97.0%，铅为68%，镉为45.0%，铜为17.0%，镍为7.0%，锌为5.0%。因此，MT-MAC对混合金属离子溶液中的汞离子具有优异的选择性。即使经过三次吸附 - 解吸循环，MT-MAC吸附剂仍表现出高稳定性。根据所得结果，使用MT-MAC吸附剂从污染水中吸附铅、汞和镉金属离子具有广阔前景。
