Selective Adsorption of Pb(II) from Aqueous Solution by Triethylenetetramine-Grafted Polyacrylamide/Vermiculite

Abstract

Amine groups play significant roles in polymeric composites for heavy metals removal. However, generating a composite with a large number of functional and stable amine groups based on clay is still a challenge. In this work, a new amine-functionalized adsorbent based on acid-activated vermiculite (a-Verm) was prepared by organic modification of silane coupling agent as bridge, followed by in situ polymerization of acrylamide (AM) and further grafting of triethylene tetramine (TETA). The obtained polymeric composite g-PAM/OVerm was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared (FTIR), thermal analysis (TG/DTG), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analyses, confirming that amine groups were successfully grafted onto the surface of Verm. The efficacy g-PAM/OVerm for removing Pb(II) was tested. The adsorption equilibrium data on g-PAM/OVerm was in good accordance with the Langmuir adsorption isotherms, and the adsorption maximal value of Pb(II) was 219.4 mg·g−1. The adsorption kinetic data fit the pseudo-second-order kinetic model well. Additionally, g-PAM/OVerm has better selectivity for Pb(II) ion in comparison with Zn(II), Cd(II) and Cu(II) ions. The present work shows that g-PAM/OVerm holds great potential for removing Pb(II) from wastewater, and provides a new and efficient method for the removal of heavy metal ions from industrial wastewater.

Clay mineral adsorbents for heavy metal removal from wastewater: a review

“…After separation by centrifugation, the g-polyacrylamide/vermiculite was reused. Figure 16 reveals the Pb(II) adsorption capacity by g-polyacrylamide/vermiculite, and the removal efficiency of the regenerated g-polyacrylamide/ vermiculite could obtain 90% at the fifth test cycle, which suggests that g-polyacrylamide/vermiculite adsorbents are promising for the efficient adsorption for Pb(II) (Gu et al 2018).…”

Studies of the Cationic Polyacrylamide Adsorption on the Montmorillonite Surface in the Presence of Lead(II) Ions

“…However, in the systems with lead(II) ions with concentrations of 10 or 100 ppm, a slight increase in their adsorption in the presence of CT PAM was observed. The free electron pairs located on the nitrogen atoms of PAM amide groups were probably involved in this adsorption increase due to the creation of covalent bonds between the amide groups and lead(II) ions [6,7]. This indicates that despite the electrostatic repulsion between the positively charged ionized groups of polymer and the Pb(II) cations, these heavy metals can be captured from the solution and the accumulation phenomenon can occur.…”

Removal of Mercury Ions from Aqueous Solutions by Crosslinked Chitosan‐based Adsorbents: A Mini Review

“…[38] In general, adsorption mechanisms could be tackled by studying ratecontrolling steps, kinetics, thermodynamics and isotherms in conjunction with spectroscopic analysis. [39][40][41][42] For chitosan, paired electrons of O and N from carboxyl and amino groups provide empty atomic orbitals and conditions for complexation between chitosan and heavy metal ions. [43] Modified chitosan generally has multiple functional groups such as amino groups, hydroxyl groups, carboxyl groups and thiols.…”

“…Elucidation of adsorption mechanisms is critically important to understanding adsorption processes . In general, adsorption mechanisms could be tackled by studying rate‐controlling steps, kinetics, thermodynamics and isotherms in conjunction with spectroscopic analysis . For chitosan, paired electrons of O and N from carboxyl and amino groups provide empty atomic orbitals and conditions for complexation between chitosan and heavy metal ions .…”