Highly Conductive and Soluble Polymer Synthesized by Copolymerization of Thiophene with Para-Methoxybenzaldehyde Using Clay Catalyst

This present research focuses on the synthesis of a new conducting polymer based on the copolymerization of thiophene with para-methoxybenzaldehyde, using a clay as an ecologic catalyst named Maghnite-H+. The catalysis of the reaction by Maghnite-H+ can confer it important benefits, such as the green environment aspect. The reaction was carried out in dichloromethane as a solvent. The new copolymer obtained is a poly (heteroarylene methines) small bandgap polymers precursor. It can be considered as a useful model system for examining the impacts of π-conjugation length on the electronic properties of this type of conjugated polymers. The measurements of the electrical conductivity gave a value of order of 0.0120 W.cm-1, allowing its use in various important applications. The characteristics of the molecular structure and the thermal behavior of the conducting polymer obtained are also discussed using different methods of analysis, such as: proton nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, ultraviolet/visible spectroscopy, and thermal gravimetric analysis (TGA). Copyright © 2019 BCREC Group. All rights reserve

One pot preparation of CeO2@Alginate composite beads for the catalytic reduction of MB dye: Effect of cerium percentage

This study focuses on the preparation of composite beads CeO2@Alginate using a one-pot method. Ce(III) was used as a crosslinking agent and then was modified with a base to transform it into CeO2 encapsulated in the alginate matrix. To study the catalytic behavior of this material the reduction of MB dye in the presence of NaBH4 was selected as a model reaction. Several parameters affecting the reduction of the MB dye were studied such as the effect of cerium content in the composite beads, the concentration of NaBH4 and the concentration of the MB dye. The results showed that the dispersion of alginate in a solution containing Ce(III) leads to the formation of hydrogel beads. The treatment of the beads with a basic solution leads to the in-situ formation of CeO2 inside the beads with a porous structure. The catalytic activity of composite beads has shown interesting results via the reduction of MB dye. The reduction of MB dye catalyzed by CeO2@ALG(2%) was total in 2 min and the associated rate constant was 2.3 min–1. The reuse tests were studied during five successive cycles, in which it was shown that the CeO2@ALG(2%) catalyst was stable without losing its effectiveness

Catalytic behavior of surfactant-containing-MCM-41 mesoporous materials for cycloaddition of 4-nitrophenyl azide

International audienceSi-MCM-41, Ga-MCM-41 and Al-MCM-41 mesoporous catalysts (with Si/Al = 80 and Si/Ga = 80) were prepared by direct synthesis under hydrothermal crystallization method using sodium aluminate or gallium sulfate and tetraethyl orthosilicate (TEOS) as aluminum or gallium and silica sources, respectively. The structural features of the materials were determined by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, Fourier transform infrared spectroscopy (FTIR), scanning and transmission electronic microscopy (SEM, TEM) and thermogravimetric analysis ATG. The catalytic activity of the calcined and as-synthesized catalyst was evaluated through the cycloaddition reaction of 4-nitrophenyl azide with activated alkenes at room temperature under liquid-phase conditions. High yields of 1,2,3-triazole were obtained. For comparison purpose, mixtures of homogeneous and heterogeneous catalyst Et3N/M-MCM-41 (M = Al or Ga) are also tested. The catalyst was used in five consecutive experiments without important loss of activity, confirming its stability. Finally, a new method for preparing triazoles in short reaction times was developed

Catalytic behavior and antibacterial/antifungal activities of new MNPs/zeolite@alginate composite beads

In this paper, a new family of composite materials was prepared based on calcium alginate and metal nanoparticle-loaded zeolite omega. Different types of metal nanoparticles (NPs), namely Cu, Co and Fe, were loaded onto zeolite omega to test the performance of the resulting metal/zeolite@alginate composites towards the catalytic reduction of methylene blue dye. To examine their application field as broadly as possible, these composite beads were also tested as antibacterial and antifungal agents against several types of bacteria. Several techniques such as XRD, XRF, FTIR, XPS, SEM and TGA were used to characterize the samples. The obtained results showed that all the composite bead samples were effective in the reduction of MB dye. The composite Co/Zeolite@ALG with relatively low Co nanoparticle (NP) content was selected as the best performing catalyst due to its reduction of MB dye being completely achieved in 3 min with a rate constant of 0.02 min-1, which was attributed to its highly porous structure. The reuse tests conducted on the best-performing catalyst showed good results which persisted through five successive cycles. For antibacterial and antifungal activities, the Cu/Zeolite@ALG and Fe/Zeolite@ALG composites showed good activity with significant inhibition zones

Structural and textural features of TiO2/SAPO-34 nanocomposite prepared by the sol–gel method

This paper focuses on the synthesis of nanocomposite materials, TiO2/SAPO-34, using the sol–gel method, which involves preparing a mixture between as-synthesized or calcined SAPO-34 zeolite and TiO2 gel under hydrothermal crystallization and then calcining it at 400 °C for the formation of the TiO2 anatase phase. The structural and textural features of the obtained materials were determined by various physico-chemical techniques such as thermogravimetric analysis, X-ray diffraction, scanning electronic microscopy, nitrogen sorption at 77 K, energy dispersive X-ray analysis and ultraviolet–visible spectrometry. The DRX results showed that calcination at 400 °C of the mixture between the calcined SAPO-34 and TiO2 gel led to the collapse of the original framework of zeolite, but formed the anatase TiO2 in a nano-spherical morphology; however, the use of as-synthesized SAPO-34 supports provides a mixture phase between SAPO-34 and TiO2 anatase after calcination. The photocatalytic properties of the SAPO-34/TiO2 and TiO2-type materials were tested for the removal of methylene blue (MB) dye. The MB degradation proved to increase as a function of contact time, catalyst mass and the initial concentration of MB.The authors thank Generalitat Valenciana (PROMETEOII/2014/010) for financial support

Catalytic reduction of organic pollutants, antibacterial and antifungal activities of AgNPs@CuO nanoparticles–loaded mesoporous silica

In this work, the mesoporous silica MCM-41 was prepared by a hydrothermal method and then modified using silver and copper. The obtained samples were used as antibacterial/antifungal agents and as catalysts for the reduction of the following dyes: Methylene Blue (MB), Congo Red (CR), Methyl Orange (MO), and Orange G (OG). Several parameters affecting the reduction of dyes were investigated and discussed such as the catalyst nature, the initial concentration of the dye, the dye nature, the selectivity of the catalyst in a binary system as well as the catalyst reuse. The catalysts were characterized using XRD, nitrogen sorption measurements, XRF, FTIR, XPS, SEM/EDS, and TEM. XRD, XPS, and TEM analysis clearly showed that the calcination of copper- and silver-modified silica leads to the formation of well-dispersed CuO and AgNPs having sizes between 5 and 10 nm. As determined by XRF analysis, the content of silver nanoparticles was higher compared to CuO in all samples. It has been shown that the dye reduction is influenced by the size and the content of nanoparticles as well as by their dispersions. The catalytic activity was shown to be the highest for the Ag–Cu-MCM(0.05) catalyst with a rate constant of 0.114, 0.102, 0.093, and 0.056 s−1 for MO, MB, CR, and OG dyes in the single-dye system, respectively. In the binary system containing MB/OG or MB/MO, the catalyst Ag–Cu-MCM(0.05) was more selective toward the MB dye. The reuse of the catalyst for three consecutive cycles showed higher MB conversion in a single system with an increase in reaction time. For antifungal and antibacterial properties, the application of calcined and uncalcined materials toward six different strains showed good results, but uncalcined materials showed the best results due to the synergistic effect between CuO and unreduced species Ag+ which are considered responsible for the antibacterial and antifungal action

Synthesis and application of metal nanoparticles-loaded mesoporous silica toward the reduction of organic pollutants in a simple and binary system

In this work, mesoporous silica MCM-41 was prepared by hydrothermal route, and the obtained as-synthesized material (CTA-MCM-41) was modified by two different methods using silver and cerium assisted by thermal treatment. The modified materials were characterized by XRD, FTIR, XRF, XPS, nitrogen sorption measurements at −196 °C, SEM, and TEM analyses. The modified materials were tested as catalysts in a simple and binary system via the reduction reaction of Methylene Blue (MB), Congo Red (CR), 4-Nitrophenol (4-NP), Methyl Orange (MO), Orange G (OG) in the presence of NaBH4. The effect of the nanoparticles size, their dispersions, the nature of the organic pollutant, the initial concentration of the organic pollutant, and the concentration of the reducing agent NaBH4 have been studied and discussed. The obtained results confirmed that the preparation method plays an important role in the content and nature of nanoparticles, their sizes, their dispersions, and also on their catalytic performance. The Ag-Ce-MCM-2 material was selected as the best catalyst due to the synergistic effect between AgNPs and CeO2. The rate constant calculated in the simple system for the different pollutants was as follows: 0.1829 s−1, 0.1762 s−1, 0.0606 s−1, 0.0585 s−1, 0.0556 s−1 for MO, OG, MB, 4-NP, CR, respectively. The reduction in a binary system containing CR and MB or MO and MB was in competition, in which the CR or MO degrades together with the MB dye. Whereas for the other binary systems containing 4-NP/MB or OG/MB, the catalyst Ag-Ce-MCM-2 was more selective towards the MB dye. This catalyst demonstrated efficiency and reusability across different cycles, in which the conversion of the MB dye was complete in each reuse

Mesoporous silica supported amine and amine-copper complex for CO2 adsorption: Detailed reaction mechanism of hydrophilic character and CO2 retention

International audienceMesoporous silica SBA-15 was functionalized with various amines and then doped with copper II cation (Cu2+). The modified materials were tested for the retention of CO2 at room temperature using temperature-programmed desorption (CO2-TPD). Several parameters affecting the CO2 retention capacity (CRC) such as the nature of amine groups, repetitive adsorption-desorption cycles and dispersion of copper were investigated. CO2-TPD and H2O-TPD allowed correlating the hydrophilic character with the CO2 retention capacity. The obtained results showed that amine-functionalized mesoporous materials containing their own moisture exhibit higher effectiveness in the retention of CO2. Triamine-functionalized SBA-15 displayed the highest CRC value as a result of the increase of the number of adsorption sites. Material reuse in three adsorption/desorption cycles revealed high stability with a slight decrease in CRC. The dispersion of copper induced a progressive decrease in the CRC value. The CRC decreased with increasing Cu2+ content due to competitive complexation of Cu2+ by the amino groups

Assessment of AgNPs@Cu@Alginate Composite for Efficient Water Treatment: Effect of the Content of Cu(II) Crosslinking Agent

This work concerns the preparation of multifunctional composite beads based on Cu-Alginate and AgNPs. First, the Cu-Alginate hydrogel was obtained by adding alginate at different concentrations of the crosslinking agent Cu2+ (2%, 4%, and 8%). The obtained hydrogels were modified by Ag+ species then by a chemical treatment (using NaBH4) followed by freeze-drying. The obtained aerogel beads were characterized by different methods and then were used as catalysts for the reduction of organic pollutants in a simple and binary system, and also as antibacterial and antifungal agents on different strains. The results showed the formation of a porous structure containing well-dispersed silver nanoparticles in the alginate matrix. The concentration of the Cu2+ crosslinking agent significantly influences the content of encapsulated AgNPs, the catalytic activity, and thus the antibacterial and antifungal properties of the resulting material. In the catalysis part, the Cu(2%)-ALG(AgNPs) material was selected as the most efficient catalyst due to the presence of high content of AgNPs and their good dispersion in the alginate biopolymer. High conversions of MO, 4-NP, MB, and CR were obtained in a reaction time of 2.5, 26, 23, and 29 min, respectively. Thus for binary systems, the Cu(2%)-ALG(AgNPs) catalyst was more selective with the MB dye. For antibacterial and antifungal activities all materials were effective through six strains, but it was shown that materials with unreduced Ag+ species were more effective