Simultaneous toxic Cd(II) and Pb(II) encapsulation from contaminated water using Mg/Al-LDH composite materials
Simultaneous toxic Cd(II) and Pb(II) encapsulation from contaminated water using Mg/Al-LDH composite materials
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DOI：
10.1016/j.molliq.2022.120810
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发表时间：
2022-11-21
影响因子：
6
通讯作者：
Awual, Md Rabiul
中科院分区：
文献类型：
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作者：
Hossain, Md Tofazzal;Khandaker, Shahjalal;Awual, Md Rabiul
层状双氢氧化物（LDHs）由于其功能位点和络合能力而被用于有毒金属离子的蓄积。它们与六偏磷酸钠（SHMP）等配体的嵌入可以增强对重金属的吸附活性位点。本研究采用共沉淀法将Mg/Al-LDHs内嵌SHMP，通过去除铅（Pb2+）和镉（Cd2+）来解毒废水。采用XRD、FT-IR、FE-SEM-EDX等仪器对Mg/Al LDH-SHMP复合吸附剂进行了研究，确定了吸附铅和镉阳离子的功能和形态特征。通过对pH、吸附剂用量、接触时间、吸附浓度、吸附温度等条件的优化，考察了吸附性能。研究了吸附等温线、热力学、吸附过程动力学及其机理。拟二阶模型在拟合动力学数据方面给出了最高的结果，两种阳离子的相关系数都最大。等温线趋势接近Langmuir模型，对Pb2+和Cd2+的去除率最高，分别为45.66和24.34 mg（-1）。热力学研究表明，吸附反应为自发吸热反应，具有随机性。由于温度升高，吸收能力提高了。此外，Pb2+和Cd2+在Mg/Al LDH-SHMP表面的积累可能与表面络合、同构取代、沉淀和重金属螯合有关。Mg/Al LDH-SHMP复合材料吸附量大、吸附动力学快，是吸附Pb2+和Cd2+的理想材料。(c) 2022 Elsevier B.V.版权所有
The Layered double hydroxides (LDHs) were used for the toxic diverse metal ions accumulation owing to their functional sites and complexation capabilities. Their intercalation with ligands like sodium hexametaphosphate (SHMP) can enhance the active sites for heavy metal adsorption. Here, the Mg/Al-LDHs were inscribed with SHMP using the co-precipitation method to detoxify wastewater by removing lead (Pb2+) and cadmium (Cd2+). Mg/Al LDH-SHMP composite adsorbent was investigated using several instrumentations such as XRD, FT-IR, and FE-SEM-EDX for identifying the functional and morphological properties which are accountable for lead and cadmium cations adsorption. The adsorption was studied in a batch method to investigate the adsorption performance by optimizing pH, adsorbent dose, time of contact, concentration, and adsorption temperature. The adsorption isotherm, thermodynamics, kinetics of the adsorption progress, and mechanism were thoroughly investigated. The pseudo-second-order model gave the highest outcomes in terms of fitting the kinetic data, with the greatest correlation coefficient for both cations. The trend of isotherm was adjacent to the Langmuir model with the highest removal amount of 45.66 and 24.34 mgg(-1) for Pb2+ and Cd2+, respectively. The thermodynamic investigation exhibited that the adsorption reaction was spontaneous endothermic, and random in character. The capacity for absorption improved as a result of the higher temperature. Moreover, Pb2+ and Cd2+ accumulation onto the Mg/Al LDH-SHMP surface was plausible with surface complexations, isomorphic substitution, precipitation, and heavy metal chelation. The Mg/Al LDH-SHMP composite could be an ideal material for Pb2+ and Cd2+ accumulation from the wastewater for its high adsorption capacity and fast adsorption kinetics. (c) 2022 Elsevier B.V. All rights reserved.