Monitoring the Geopolymerization Reaction of Geopolymer Foams Using 29Si and 27Al MAS NMR

This study aims to investigate the geopolymerization reaction of geopolymer foams produced with three different foaming agents: aluminum powder, zinc powder, and hydrogen peroxide. The geopolymerization reaction of geopolymer foam was monitored using the 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy technique. 27Al MAS-NMR was used to monitor the reaction at an early stage, while 29Si and 27Al MAS-NMR analyses were employed at specific time intervals of 3, 6, 10, 15, and 28 days to examine the changes that occurred in the formed gel over time. We discussed in detail how the type of foaming agent used and the duration of the reaction both influence the quantity of gel formed and the amount of remnant fly ash. Our findings indicate that the type of foaming agent used affects the formation and structure of the gel, with aluminum powder leading to the highest gel formation. Additionally, the duration of the reaction plays a significant role in determining the quantity of remnant fly ash, with longer reaction times resulting in decreased fly ash content. This study sheds light on the relevance of understanding the role of foaming agents in the geopolymerization reactions of geopolymer foams and the influence of reaction time on the formed gel properties

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

Physico-chemical properties and durability of a fly-ash-based geopolymer

Due to the environmental problems linked to the production of portland cement, the search for new more economic and non-polluting construction materials has become a current issue of interest. Geopolymers represent new types of “polymeric” materials of mineral nature. The aim of this work is to study the influence of the Na2SiO3/NaOH mass ratio and curing time on the mechanical and microstructural properties of fly-ash-based geopolymers GP-Fs. The samples were synthesized with different Na2SiO3/NaOH mass ratios (2.5, 4, and 6) and curing times (2, 12, and 24 h) at 60°C. The GP-F pastes elaborated were analyzed by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The sample with the highest compressive strength and density and the lowest water absorption was produced with a Na2SiO3/NaOH mass ratio of 2.5 and a curing time of 24 h, which is GP1, as confirmed by FTIR and XRD analyses; in addition, it had a compact structure attributed to a higher pozzolanic reactivity. These optimized geopolymer pastes were studied to assess the durability test, evaluating the resistance to fire and acid attack. Fire resistance was assessed by heating the GP-F pastes to 800°C for 2 h, and acid resistance was studied by immersing specimens in a solution of 6% acetic acid (GP-F-CH3COOH) and 6% hydrochloric acid (GP-F-HCl) for 2 months. Physico-chemical and microstructural changes before and after heat and acid exposure were studied using several analyses. Samples exposed to an acidic environment display a completely porous shape with some micro-cracks, inducing a decrease of the residual compressive energy. FTIR analysis showed that the geopolymer gel deformed after heating to 800°C, and pores were formed in their structure due to evaporation of water

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

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

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

Inhibition of the corrosion of iron in acidic solution by the oligomeric surfactant N, N, N′, N″, N″-pentamethyl diethyleneamine-N, N″-di-[tetradecylammonium bromide]

[Purpose] The purpose of this investigation is the evaluation of the inhibitive performance of a new "gemini" surfactant in the series of bis-quat: N, N, N′, N″, N″-pentamethyl diethyleneamine-N, N″-di-[tetradecylammonium bromide] on the corrosion of iron in 1 M HCl by gravimetric, potentiodynamic and electrochemical impedance measurements. The effect of the temperature on the corrosion behavior of iron in 1 M HCl without and with inhibitor is studied in the temperature range (298-333 K). This work also attempts to correlate thermodynamic and kinetic parameters with the inhibition effect.[Design/methodology/approach] The inhibition efficiency of gemini synthesized is investigated by weight loss, potentiodynamic polarization and impedance spectroscopy methods.[Findings] The synthesized gemini bis-quat acted as a good inhibitor in 1 M HCl, and inhibition efficiency increased with inhibitor concentration and temperature. Polarization curves showed that the surfactant was a mixed-type inhibitor in hydrochloric acid. Impedance spectroscopy measurements showed that the inhibitor acted through the formation of a multilayer film at the iron surface. The adsorption of inhibitor on the iron surface obeyed the Langmuir adsorption isotherm equation. The inhibition effect was satisfactorily explained by both thermodynamic and kinetic parameters.[Originality/value] The adsorption of surfactants in the metal surface can markedly change the corrosion resisting property of the metal. So the study of the relation between the adsorption and corrosion inhibition is of a great importance. This was the first attempt to study the inhibition properties of gemini surfactants at the host laboratory.Peer reviewe