Comparative assessment of magnesium-enhanced-extraction by various sequestering derivatives of 8-hydroxyquinoline via layer-by-layer chemical deposition technique

• Published in: Journal of molecular liquids Vol. 237; pp. 455 - 465
• Main Authors: Mahmoud, Mohamed E., Amira, Mohamed F., Seleim, Seleim M., Mohamed, Asmaa K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2017
• Subjects: 5AB-8HQ; 5PA-8HQ; 8HQ; Layer-by-layer; Mg(II); Surface deposition; Mg(II); 8HQ; 5PA-8HQ; 5AB-8HQ; Layer-by-layer; Surface deposition
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2017.04.096

Design and fabrication of the most highly effective reagent for removal of the target analyte from their matrices represent a great challenge. Therefore, the present work is aimed to explore the potential contribution of different functional groups on the Mg(II) extraction process using Layer-by-layer (LbL) chemical deposition process. Two sequestering reagents, viz 5-phenyl-azo-8-hydroxyquinoline (5PA-8HQ) and 5-azo-benzoate-8-hydroxyquinoline (5AB-8HQ) were synthesized, characterized and compared with the starting 8-hydroxyquinoline (8HQ) material for removal of Mg(II) ion from aqueous solution. The extraction process was evaluated on the basis of surface coverage values (μg/cm2) under different influencing factors. The results of these studies confirmed the superiority of (5AB-8HQ) in double extraction of Mg(II) due to the presence of four reactive functional groups including the quinoline OH and N as well as the azo and carboxyl groups compared to (5PA-8HQ) and (8HQ). The surface coverage values of Mg(II) by (5AB-8HQ), (5PA-8HQ) and (8HQ) were identified as 119.9, 60.8 and 60.8μg/cm2, respectively in presence of pH9.0. Under all experimental conditions, (5PA-8HQ) was identified to similarly behave as (8HQ) without the contribution of azo group in metal binding process. The characterization of deposited Mg(II) complexes confirmed the formation of Mg(II)-(8HQ)2, Mg(II)-(5PA-8HQ)2 and Mg(II)-(5AB-8HQ) in 1:2, 1:2 and 1:1 stoichiometric ratios, respectively to account for the high surface coverage values of Mg(II) by (5AB-8HQ). The effect of reaction dipping time as well as kinetics study, initial metal ion concentration as well as adsorption isotherm models and reaction temperature as well as thermodynamics parameters were also explored in this study.
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•Highly effective reagent (5AB-8HQ) for removal of magnesium (II)•Comparison of LbL removal of Mg(II) by (5AB-8HQ) versus (5PA-8HQ) and (8HQ)•The maximum removal of Mg(II) was obtained by (5AB-8HQ) as 150.9μg/cm2.•The deposited Mg(II)-(5AB-8HQ) complex was confirmed as a 1:1 ratio.•Studies of kinetic, isotherm models and thermodynamics are explored.