Different routes of MgAl–LDH synthesis for tailoring the adsorption of Pb(II) pollutant from water
Mihaela Mureşeanu, Andreea Eliescu, Eugenia-Corina Ignat, Gabriela Cârjă, Nicoleta Cioateră
Abstract
In this study, new adsorbents based on MgAl–LDHs were synthesized using combined precipitation (co-precipitation) route by modifying temperature and ageing time synthesis parameters, thus tailoring the adsorption capacity of Pb(II) ions from water. The synthesized materials were characterized by SEM, FTIR, XRD and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>N</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> adsorption–desorption techniques, highlighting the specific lamellar structure of layered double hydroxides (LDHs), as well as the functional groups present on the adsorbent’s surface. The maximum adsorption capacity for Pb(II) ions was 1151.97 mg/g for the MgAl–LDH synthesized at 55 °C and aged for 24 h. Sorption of Pb(II) ions occurs not only through co-precipitation in the form of characteristic compounds, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>Pb(OH)</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>PbCO</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:math> or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>Pb</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mtext>CO</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mtext>OH</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> , but also by complexation with surface hydroxyl groups.