New adsorbent material based on nitrothiophene-functionalized silica particles for aqueous heavy metals removal

Polythiophene derivatives as chemical sensors: a DFT study on the influence of side groups

Conjugated polymers have been considered promising candidates for applications in chemical sensors, mainly due to their high versatility of synthesis, low cost, light weight, and suitable optoelectronic properties. In this context, polythiophene (PT) derivatives have been successfully employed. However, at the same time that the versatility of the synthesis allows the production of varied derivatives, the complexity of interactions with analytes hinders an efficient design of compounds with improved sensing properties. In the present report, electronic structure calculations were employed to identify promising PT derivatives for chemical sensor applications. Structural, optoelectronic, and reactivity properties of a set of branched PT derivatives were evaluated. Adsorption studies considering different gaseous compounds were conducted for selected systems. The results suggest that an appropriate choice of the side groups can lead to derivatives with improved sensorial properties. In particular, PT-CN derivative was identified as the most promising compound for high sensitive chemical sensors towards SO₂ and NH₃ analytes.

New hybrid adsorbent based on porphyrin functionalized silica for heavy metals removal: Synthesis, characterization, isotherms, kinetics and thermodynamics studies

The pollution of water resources due to the disposal of toxic heavy metals has been a growing global concern for the last decades. For this purpose, the search for effective and economic material based adsorbents is required, due to the efficiency of the process. In this work, a novel inorganic-organic hybrid material based on silica chemically modified with a porphyrin (SiNTPP), with a high metal removal efficiency, was developed. The new material was characterized using a set of suitable techniques such as ¹³C NMR of the solid state, elemental analysis, FTIR, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore sizes and scanning electron microscopy (SEM). The new material surface exhibits good chemical and thermal stability based on the obtained thermogravimetric curves (TGA). An adsorption study was accomplished to investigate the effect of porphyrin-silica hybrid on the removal of Pb(II), Zn(II), Cd(II) and Cu(II) from aqueous solutions using a batch method. The effect of various parameters, such as initial metal concentration, pH, temperature, as well as the kinetics and thermodynamics for sorption on SiNTPP were investigated. The studies demonstrate that adsorption is fast, as proved by the equilibrium achievement within 25min. The metals removal from aqueous solution are better adapted to the Langmuir isotherm model than to the Freundlich model. The thermodynamic parameters (ΔG°, ΔH° and ΔS°) disclose that the process was endothermic and spontaneous in nature, and the adsorption process follows a pseudo-second order kinetics. The adsorbent can be regenerated continuously without affecting its extraction percentage. Its effectiveness is highly justified compared to previous described materials.

Supramolecular Hybrid Material Based on Engineering Porphyrin Hosts for an Efficient Elimination of Lead(II) from Aquatic Medium

Porphyrins show great promise for future purification demands. This is largely due to their unique features as host binding molecules that can be modified at the synthetic level, and largely improved by their incorporation into inorganic based materials. In this study, we assessed the efficacy of a hybrid material obtained from the immobilization of 5,10,15,20-tetrakis(pentafluorophenyl)-porphyrin on silica surface to remove Pb(II), Cu(II), Cd(II), and Zn(II) ions from water. The new organic-inorganic hybrid adsorbent was fully characterized by adequate techniques and the results show that the hybrid exhibits good chemical and thermal stability. From batch assays, it was evaluated how the efficacy of the hybrid was affected by the pH, contact time, initial metal concentration, and temperature. The adsorption kinetic and isotherms showed to fit the recent developed fractal-like pseudo-second-order model and Langmuir–Freundlich model respectively. The highest adsorption capacities for Pb(II), Cu(II), Cd(II), and Zn(II) ions were 187.36, 125.17, 82.45, and 56.23 mg g⁻¹, respectively, at pH 6.0 and 25 °C. This study also shows that metal cations from real river water samples can be efficient removed in the presence of the new adsorbent material.

A novel environment-friendly hybrid material based on a modified silica gel with a bispyrazole derivative for the removal of ZnII, PbII, CdIIand CuIItraces from aqueous solutions

New surface-functionalized with bispyrazole receptor was designed for efficient removal of heavy metals. The architecture of host–guest on the surface was identified.

β-Keto-enol Tethered Pyridine and Thiophene: Synthesis, Crystal Structure Determination and Its Organic Immobilization on Silica for Efficient Solid-Liquid Extraction of Heavy Metals

Molecules bearing β-keto-enol functionality are potential candidates for coordination chemistry. Reported herein is the first synthesis and use of a novel designed ligand based on β-keto-enol group embedded with pyridine and thiophene moieties. The product was prepared in a one-step procedure by mixed Claisen condensation and was characterized by EA, m/z, FT-IR, (¹H, (13)C) NMR and single-crystal X-ray diffraction analysis. The new structure was grafted onto silica particles to afford a chelating matrix which was well-characterized by EA, FT-IR, solid-state (13)C-NMR, BET, BJH, SEM and TGA. The newly prepared organic-inorganic material was used as an adsorbent for efficient solid-phase extraction (SPE) of Cu(II), Zn(II), Cd(II) and Pb(II) from aqueous solutions and showed a capture capacity of 104.12 mg·g(-1), 98.90 mg·g(-1), 72.02 mg·g(-1), and 65.54 mg·g(-1), respectively. The adsorption capacity was investigated, in a batch method, using time of contact, pH, initial concentration, kinetics (Langmuir and Freundlich models), and thermodynamic parameters (ΔG°, ΔH° and ΔS°) of the system effects.

Fabrication and covalent modification of highly chelated hybrid material based on silica-bipyridine framework for efficient adsorption of heavy metals: isotherms, kinetics and thermodynamics studies

Adsorbent materials are essential in clean-up processes.