Highly Selective Removal of Pb(II) by a Pyridylpyrazole-β-ketoenol Receptor Covalently Bonded onto the Silica Surface

Abstract

Efficient materials capable of capturing toxic metals from water are widely needed. Herein, a new pyridylpyrazole-β-ketoenol receptor, X-ray diffraction analyzed, was covalently incorporated into the silica surface to produce solid and recyclable adsorbent particles. The new material, fully characterized, revealed extremely efficient removal of toxic metals from water, with a selectivity order of Pb(II) > Zn(II) > Cu(II) > Cd(II). The adsorption was exceptionally rapid at optimum pH and concentrations, showing Pb(II) removal of 93 mg g –1 within 5 min and maximum Pb(II) adsorption of 110 mg g –1 after only 20 min. Sorption isotherms agreed well with the Langmuir model suggesting a monolayer adsorption, whereas kinetics agreed with the pseudo-second-order model suggesting a chemisorption binding mechanism. Thermodynamics of adsorption were fitted with an endothermic and spontaneous process. The material, recyclable for at least five cycles, is therefore promising for the cleanup of water polluted by toxic metals, especially lead.

Synthesis, Biochemical Characterization, and Theoretical Studies of Novel β-Keto-enol Pyridine and Furan Derivatives as Potent Antifungal Agents

“…These products are presumably in anticonformation isomeric forms as already demonstrated for similar products analyzed too by single-crystal X-ray diffraction. 21 , 33 − 41 …”

“…This trend is confirmed by single-crystal X-ray diffraction, which systematically showed the β-keto-enol in this substance class, along with a mesomeric effect. 21 , 33 − 41 We recall that there are two driving forces responsible for the formation of keto-enol isomers in solution: 42 (i) the electronic force, in which the formation of the enol isomer is controlled by the electronegativity of the R and R′ substituents fixed on the β-diketone (R′COCH 2 COR) and (ii) the resonance force (mesomeric effect), which has priority over the inductive effect when one or two substituents R and R′ are aromatic.…”

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].…”

Design and synthesis of novel chitosan–based nanocomposite containing mesoporous nanosilica MCM-41: Effective absorbent for the elimination of Pb (II) from aqueous solution

“…The lead ion concentrations in the solution were measured via AAS, after that the mixture was filtrated. 36,37 The desorption ratio (D %) was computed as Eq. 2: D% ¼ mmoles of metal ion desorbed to the HCl solution mmoles of metal ions adsorbed on to polymer  100 ð2Þ…”