Efficient and Environmentally Friendly Adsorbent Based on β-Ketoenol-Pyrazole-Thiophene for Heavy-Metal Ion Removal from Aquatic Medium: A Combined Experimental and Theoretical Study

Abstract

A new sustainable and environmentally friendly adsorbent based on a β-ketoenol-pyrazole-thiophene receptor grafted onto a silica surface was developed and applied to the removal of heavy-metal ions (Pb(II), Cu(II), Zn(II), and Cd(II)) from aquatic medium. The new material SiNPz-Th was well characterized and confirms the success of covalent binding of the receptor on the silica surface. The effect of environmental parameters on adsorption including pH, contact time, temperature, and the initial concentration were investigated. The maximum adsorption capacities of SiNPz-Th for Pb(II), Cu(II), Zn(II), and Cd(II) ions were 102.20, 76.42, 68.95, and 32.68 mg/g, respectively, at 30 min and pH = 6. The adsorption isotherms, kinetics, and thermodynamic process were investigated and showed efficiency and selectivity toward Pb(II) and good regeneration performance. Density functional theory, noncovalent-interaction, and quantum theory of atoms in molecules calculations were used to study and to gain a deeper understanding of both the adsorption mechanism and selectivity of metal ions onto the adsorbent. Accordingly, metal ions such as Pb(II), Cu(II), and Zn(II) were bidentate coordinated with the adsorbent by nitrogen and oxygen atoms of the Schiff base C=N and hydroxyl group −OH, respectively, to form stable complexes. Whereas Cd(II) was coordinated in a monodentate fashion with oxygen atom of the hydroxyl group. Furthermore, the affinity of SiNPz-Th toward the metal ions was decreased in the order of Pb(II) > Cu(II) > Zn(II) > Cd(II), in good agreement with the experimental results. All these results highlight that SiNPz-Th has good potential to be an advanced adsorbent for the removal of lead ions from real water.

New Bis-Pyrazole-Bis-Acetate Based Coordination Complexes: Influence of Counter-Anions and Metal Ions on the Supramolecular Structures

“…Its unique thermal stability could provide stable hybrid materials upon grafting L to silica for metallic decontamination purposes, particularly towards Zn(II), Mn(II) and Cd(II) which are recognised as toxic metal ions. This technology is currently under investigation in our laboratory and already applied to real water samples (e.g., from natural rivers) [43][44][45][46][47][48][49][50][51][52].…”

A Highly Efficient Environmental-Friendly Adsorbent Based on Schiff Base for Removal of Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study

“…Quantum theory of atoms in molecules (QTAIM) analysis using the Multiwfn software was performed in this study to obtain a greater understanding of local reactivity related to the atoms of Si-p-OR and Si-o-OR and of the kind of interaction which occurs when these ligands interact with Cu(II) (non-covalent or covalent or both) [ 15 ].…”

“…Recent research has focused on mesoporous silica due to its high specific surface area, absence of swelling, and fast kinetics, as well as their thermal, mechanical stabilities and compatibilities with other materials [ 12 , 13 , 14 ]. Recently, chemical engineering of organically modified porous silica has attracted attention for the adsorption of metal ions in environmental remediation [ 15 , 16 , 17 , 18 , 19 ]. Their adsorption performances mainly depend on donor atoms within the incorporated organic moieties, which can form chelating structures with metal ions, e.g., Schiff bases with Cu(II) [ 20 , 21 , 22 , 23 , 24 ].…”

Adsorption of Zn2+ from Synthetic Wastewater Using Dried Watermelon Rind (D-WMR): An Overview of Nonlinear and Linear Regression and Error Analysis

“…where: V: the volume of synthesized wastewater in a litter (L) M: the mass of adsorbent of D-WMR in gram (g) Another way to make Kd dimensionless is to use the following equation [65]:…”