Adsorption of cationic dye onto fly ash-based geopolymer: Batch and fixed bed column studies

Cationic dye adsorption from aqueous solution onto synthesized geopolymer was investigated by batch and fixed bed column experiments. The geopolymer material was elaborated by alkali solution and fly ash supplied by Jorf Lasfar power plant of Morocco. Physical and chemical characteristics of samples were determined by FX, DRX, SEM, 29Si MAS NMR and Zeta potential methods. The Brunauer, Emmett and Teller (BET) technique is used to determine the surface area. The Barrett-Joyner-Halenda (BJH) method was performed to obtain pore size distribution curves and average pore diameter. Kinetics data were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. To predict the breakthrough curves and determine the main fixed bed column parameters, three kinetic models; Tomas, Bohart–Adams and Yoon-Nelson models are applied to fitting the experimental data. The kinetic study showed that the pseudo-second-order can be used to describe the methylene blue (MB) adsorption process on the geopolymer matrix. The kinetic models of the adsorption in dynamic column are suitable to describe the continuous adsorption process of dyestuff by the geopolymer. The results of this study indicated that geopolymer derived from fly ash can be used as a low cost effective adsorbent for cationic dye removal from industrial aqueous effluent

Adsorption of cationic dye onto fly ash-based geopolymer: Batch and fixed bed column studies

Cationic dye adsorption from aqueous solution onto synthesized geopolymer was investigated by batch and fixed bed column experiments. The geopolymer material was elaborated by alkali solution and fly ash supplied by Jorf Lasfar power plant of Morocco. Physical and chemical characteristics of samples were determined by FX, DRX, SEM, 29Si MAS NMR and Zeta potential methods. The Brunauer, Emmett and Teller (BET) technique is used to determine the surface area. The Barrett-Joyner-Halenda (BJH) method was performed to obtain pore size distribution curves and average pore diameter. Kinetics data were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. To predict the breakthrough curves and determine the main fixed bed column parameters, three kinetic models; Tomas, Bohart–Adams and Yoon-Nelson models are applied to fitting the experimental data. The kinetic study showed that the pseudo-second-order can be used to describe the methylene blue (MB) adsorption process on the geopolymer matrix. The kinetic models of the adsorption in dynamic column are suitable to describe the continuous adsorption process of dyestuff by the geopolymer. The results of this study indicated that geopolymer derived from fly ash can be used as a low cost effective adsorbent for cationic dye removal from industrial aqueous effluent

Phenylalanine and Tryptophan-Based Surfactants as New Antibacterial Agents: Characterization, Self-Aggregation Properties, and DPPC/Surfactants Vesicles Formulation

Cationic surfactants based on phenylalanine (CnPC3NH3Cl) and tryptophan (CnTC3NH3Cl) were synthesized using renewable raw materials as starting compounds and a green synthetic procedure. The synthesis, acid-base equilibrium, aggregation properties, and antibacterial activity were investigated. Conductivity and fluorescence were used to establish critical micelle concentrations. Micellization of CnPC3NH3Cl and CnTC3NH3Cl occurred in the ranges of 0.42–16.2 mM and 0.29–4.6 mM, respectively. Since those surfactants have some acidic character, the apparent pKa was determined through titrations, observing increasing acidity with increasing chain length and being slightly more acidic with the phenylalanine than the tryptophan derivatives. Both families showed promising antibacterial efficacy against eight different bacterial strains. Molecular docking studies against the enzyme peptidoglycan glycosyltransferase (PDB ID:2OQO) were used to investigate the potential binding mechanism of target surfactant molecules. According to small angle X-ray scattering (SAXS) results, the surfactants incorporate into DPPC (Dipalmitoyl Phosphatidyl Choline) bilayers without strong perturbation up to high surfactant concentration. Some of the C12TC3NH3Cl/DPPC formulations (40%/60% and 20%/80% molar ratios) exhibited good antibacterial activity, while the others were not effective against the tested bacteria. The strong affinity between DPPC and surfactant molecules, as determined by the DFT (density functional theory) method, could be one of the reasons for the loss of antibacterial activity of these cationic surfactants when they are incorporated in vesicles

Antibacterial activity, structure and CMC relationships of alkanediyl α,ω-bis(dimethylammonium bromide) surfactants

Some alpha,omega-alkanediyl bis-dimethylammonium bromide compounds (gemini surfactants) referred as "m-s-m" have been synthesized, purified and characterized by usual spectroscopic methods. These compounds have been screened for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Their activity was compared. The compounds tested showed excellent in vitro antibacterial activity against Staphylococcus aureus ranging from 1.5 to 20 microg/ml and had variable activity against E. coli with minimum minimum inhibitory concentration (MIC) of 50 microg/ml. These compounds are less active against P. aeruginosa. On the other hand, contrary to the antibacterial activity of these products against S. aureus, a relation between the MIC and the critical micellar concentration (CMC) was found and relationship between chain's Length and antibacterial activity was found.This work was supported by the CNRPRT (Project research: PARS Chimie 008).Peer reviewe

Antifungal activity of amino-alcohols based cationic surfactants and in silico, homology modeling, docking and molecular dynamics studies against lanosterol 14-α-demethylase enzyme

Fungi are being responsible for causing serious infections in humans and animals. The opportunistic microorganisms provoke environmental contaminations in health and storage facilities to represent a serious concern to health security. The present work investigates the antifungal activity of two amino-alcohols based cationic surfactants such as CnEtOH, CnPrOH (with n = 14 and 16 are the carbon numbers of alkyl chain and EtOH = Ethanol and PrOH = Propanol) against a collection of different Candida species (Candida tropicalis, Candida albicans, Candida auris, Cyberlindnera jadinii, Candida parapsilosis, Candida glabrata and Candida rugosa) respectively. The amino-alcohols based cationic surfactants exhibited good antifungal activity against all Candida strains tested with minimum inhibitory concentrations (MIC) ranging from 0.002 to 0.30 mM. The MIC evaluation shows an increase as a function of the hydrophobicity of all inhibitors against the majority of the Candida strains tested. The different location of the alcoholic OH function in the polar head shows the influence on the availability of N+ responsible for electrostatic interactions with the candidate’s cell walls, which remains a very important step in the mode of action of quaternary ammonium cationic surfactants. Hence, a 3D structure of lanosterol 14-α-demethylase enzyme from C. auris was constructed by homology modeling using an online SWISS-MODEL server. The predicted model was analyzed by serval servers. Furthermore, a molecular docking study was carried out to better understand the binding mechanism of lanosterol homologous protein with surfactant ligands. Then, the docked complexes lanosterol–surfactants were refined by the molecular dynamic simulation to analyze their interaction behavior during the simulation.This study is linked to the Consejo Superior de Investigaciones Científicas (CSIC) i-coop+2018 grant (COOPA20264). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance code 001: The present work was accomplished with the support of the National Program of Cooperation in the Amazon - PROCAD/Amazon of Coordination of Superior Level Staff Improvement – CAPES/Brazil.Peer reviewe

Influence of the Nature and Rate of Alkaline Activator on the Physicochemical Properties of Fly Ash-Based Geopolymers

The influence of alkali cations on mix design of geopolymers is essential for their mechanical, thermal, and electrical performance. This research investigated the influence of alkali cation type on microscale characteristics and mechanical, dielectric, and thermal properties of fly ash-based geopolymer matrices. The geopolymers were elaborated via class F fly ash from the thermal plant Jorf Lasfar, El Jadida (Morocco), and several alkaline solutions. Morphological, structural, mechanical, dielectric, and thermal characteristics of materials synthesized via fly ash with different proportions of KOH and NaOH aged 28 days were evaluated. The physicochemical properties of class F fly ash-based geopolymers were assessed using X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) analyses. Based on readings of the results obtained, XRD and FTIR analysis detected the creation of semicrystalline potassium/sodium aluminate-silicate hydrate (KASH/NASH) gel in the elaborated matrices after the geopolymerization reaction. The SEM analysis proved the formation of alkali alumina-silicate hydrate gel in the raw material particles after the polycondensation stage. Experimental compressive strength data indicated that the highest compressive strength (39 MPa) was produced by the alkaline activator (75% KOH/25% NaOH). The dielectric parameters values of the elaborated materials changed depending of the mass ratios KOH/NaOH. Dielectric findings demonstrated that geopolymers containing 100% NaOH have better dielectric performances. The fire resistance study revealed that the geopolymer binders induced by KOH are stable up to 600°C. Based on these results, it can be deduced that the formulated geopolymer concrete possesses good mechanical, dielectric, and fire resistance properties

Photocatalytic Degradation of Methylene Blue from Aqueous Medium onto Perlite-Based Geopolymer

In this work, geopolymer synthesized with perlite and an alkaline activator medium was evaluated as a new adsorbent and photocatalyst for degradation of methylene blue (MB) dye from an aqueous medium. The functional group, the structure, and the morphology of the raw and the synthesized materials were characterized using FT-IR, XRD, and SEM analysis. The degradation of MB in the contaminated solution was examined using the spectrophotometric technique. Several analysis methods revealed the formation of the aluminosilicate gel after the geopolymerization reaction. The kinetics data with UV and without UV irradiations were well fitted with the pseudo-second-order equation. The results indicated that the degradation efficiency of cationic dye by perlite-based geopolymer without and with UV was up to 88.94% and 97.87% in 4 hours, respectively. The degradation efficiencies of methylene blue are in the following order: perlite-based geopolymer under UV irradiations is greater than perlite-based geopolymer without UV irradiations that is larger than UV irradiations. The overall experimental results suggested that the new elaborated material with synergetic adsorption and photocatalytic activities has a great potential for the treatment of water contaminated by hazardous substances

Synthesis of 1,3-bis-[(dodecanoyl oxypropyl dimethylammonium) propane] dibromide ester-quat surfactant: Micellar, thermodynamic and corrosion-inhibiting properties

[EN] Ester-quat surfactant: 1,3-bis-[(dodecanoyl oxypropyl dimethyl-ammonium) propane] dibromide referred as 12-3-3-3-12 was synthesized, purified and characterized by Elemental Analysis, 1H-NMR, 13C-NMR, IR and Mass Spectra. The thermodynamic properties of aqueous solutions of this ester-quat were investigated using Electrical Conductivity and SurfaceTension measurements. The corresponding parameters of micellisation were determined for each technique. Otherwise the inhibitive action of the ester-quat (12-3-3-3-12) on the corrosion behaviour of iron was investigated in HCl and H 2SO4 medium by means Electro-chemical Resistance and Polarisation methods. The ester-quat 12-3-3-3-12 acts as a cathodic-type inhibitor. The maximum inhibition efficiency was reached around the critical micellar concentration. The ester-quat appears to be adsorbed in the metal/liquid interface through the general mode following the Frumkin adsorption model.[DE] Das Esterquat-Tensid 1,3-Bis-[(Dodecanoyloxypropyldimethylammonium)-propan]-dibromid, bezeichnet als 12-3-3-3-12, wurde synthetisiert, gereinigt und durch Elementaranalysen, 1H-NMR, 13C-NMR, IR und Massenspektrum charakterisiert. Die thermodynamischen Eigenschaften der wässrigen Lösungen dieses Esterquats wurden durch Messung der elektrischen Leitfähigkeit und der Oberflächenspannung untersucht. Für jede Technik wurden die entsprechenden Parameter der Mizellisierung bestimmt. Weiterhin wurde für das Esterquat (12-3-3-3-12) die Inhibitionsaktivität auf das Korrosionsverhalten von Eisen in HCl- und H2SO4-Medien mittels elektrochemischen Widerstandes und Polarisationsmethoden untersucht. Das Esterquat (12-3-3-3-12) funktioniert als kathodischer Inhibitor. Die maximale Inhibitionseffizienz wurde bei der kritischen Mizellbildungskonzentration erreicht. Das Esterquat scheint an der Metall/Flüssigkeits-Grenzfläche nach dem normalen Modus des Frumkin-Adsorptionsmodells zu adsorbieren.This work was supported by The CNPRST in the framework of Protars D13/31Peer reviewe

Engineering of new hydrogel beads based conducting polymers: Metal-free catalysis for highly organic pollutants degradation

International audienceEngineering of new heterogeneous metal-free catalysts is of great importance for persulfate activation. Herein, Innovative conductive polymers Polyaniline (PANI) and Polypyrrole (PPy) were used as promising catalysts for PS activation to effectively degrade organic pollutants. In fact, PANI and PPy can provide the necessary electron transfer based on nitrogen atoms located in the conjugated chains compared to their counterparts in the defective sites. In addition, PANI and PPy were immobilized inside membrane formed by cross linking alginate biopolymer by divalent calcium ions, in order to develop a new stable hydrogel beads catalyst. The prepared hydrogels-activated PS process could maintain excellent catalytic properties, mitigate catalysts deactivation, increased chemical stability and offer hope for their application in the industrial scale. The radical scavenging experiments monitored by the electron paramagnetic resonance and functional theory calculations, indicated the role of the PANI and PPy conjugated chains and the nature of the reaction pathways