l-Proline Functionalized Dicationic Framework of Bifunctional Mesoporous Organosilica for the Simultaneous Removal of Lead and Nitrate Ions

Abstract

A novel bifunctional mesoporous organosilica, PEG-functionalized bis-prolinium chloride bridged mesoporous organosilica (BPBMO) was synthesized by reacting the precursor, PEG-functionalized bis-prolinium chloride bridged organosilane (BPRIL) with tetraethyl orthosilicate (TEOS) in the presence of surfactant. The chemical conformation of BPBMO was investigated by using Fourier transform infrared (FTIR), thermogravimentric analysis (TGA), 13C, and 29Si cross-polarization/magic angle spinning (CP/MAS) NMR techniques. The characterization represents PEG-linked-prolinium (−N+Cl–) and carboxyl (−COOH) entities, constructing the dicationic framework through siloxane (Si–O–Si) linkages. The pore-wall distribution and the periodicity of BPBMO retained during the synthesis were examined by small-angle X-ray scattering (SAXS), Brunauer-Emmett-Teller-Barrett-Joyner-Halenda (BET-BJH), and transmission electron microscopy (TEM) techniques. The results revealed BPBMO as a spherical shaped solid (50–100 nm) having mesopore channels hexagonally arranged with interparticle porosity (S BET = 487 m2/g and D BJH = 5.1 nm). The material has provided active binding sites for the simultaneous removal of NO3 – and Pb2+ ions when introduced in the aqueous solutions of Pb­(NO3)2 (50 mg/L, pH 6). The removal of NO3 – by ion-exchange with prolinium (−N+Cl–) entities and the electrostatic interaction of Pb2+ with carboxylate (−COO–) group were characterized by using Raman spectroscopy, ion chromatography, and X-ray photoelectron spectroscopy (XPS) technique. The maximum removal of NO3 – and Pb2+ ions were achieved within 1 h of the adsorption reaction. The adsorption has followed the Langmuir isotherm model with the adsorption capacities (q m) of 23.04 and 21.92 mg/g for NO3 – and Pb2+ ions, respectively. The efficiency of the adsorbent was also compared with other adsorbents. Further, the BPBMO material has depicted three consecutive adsorption/desorption cycles with negligible loss in the structural conformation.

Novel design of microsphere adsorbent for efficient heavy metals adsorption

“…From Figure 7 we can see that after adsorption, CM kept its original shape, Cu and Pb peaks became visible in the EDS spectra of CM. The binding energy of Cu is around 950 eV and that of Pb is around 140 eV, which is consistent with the binding energy of the oxidation of Cu and Pb as literatures reported 47‐48 . Figure 8 manifests that the intensity of some adsorption bands showed an obvious decrease in the FT‐IR spectra, indicating the occupation of functional groups (‐SiOH, ‐AlOH) during the adsorption which is corresponding to the results of EDS.…”

Biochar Derived from Sawdust Embedded with Molybdenum Disulfide for Highly Selective Removal of Pb2+

“…It can be found that the peak of C−C/CC (at 284.69 eV) for MoS 2 @biochar after Pb 2+ adsorption shifted by 0.1 eV, indicating the chelation of Pb 2+ ions with aromatic structure (Pb-π interaction). 54 The Pb 2+ can increase the electron density by offering electrons to the aromatic structure with decreasing the binding energy of carbon atoms. As for the high-resolution O 1s spectrum of MoS 2 @biochar-Pb (Figure 7C), the new peak (at 531.11 eV) can be ascribed to the Pb−O bond.…”

Surface Properties and Chemical Constitution as Crucial Parameters for the Sorption Properties of Ionosilicas: The Case of Chromate Adsorption

“…23,34−36 Silica-based materials have intensively been studied as adsorbents in solid−liquid separation processes. 6,37 Surfacefunctionalized materials containing cationic groups have thoroughly been used for anion sorption such as arsenate, chromate, 38−41 perruthenate, 42 perrhenate, 43 or diverse radioelements. 44,45 Ammonium-and imidazolium-functionalized silica materials display improved sorption capacities due to the high quantity of functional groups located on the surface of silica materials.…”

“…Silica-based materials have intensively been studied as adsorbents in solid–liquid separation processes. , Surface-functionalized materials containing cationic groups have thoroughly been used for anion sorption such as arsenate, chromate, − perruthenate, perrhenate, or diverse radioelements. , Ammonium- and imidazolium-functionalized silica materials display improved sorption capacities due to the high quantity of functional groups located on the surface of silica materials . Additionally, ionic liquid functionalized silica-based materials appear highly efficient anion exchange materials due to their high sorption capacity, selectivity, reusability, fast kinetics, and efficiency in the large range of pH .…”