Fe(III)NaYnano as efficient electrocatalyst for electrodegradation of Congo Red dye

Textile dyes are one of the most important contaminants of the superficial water resources. Their removal from water bodies constitutes a priority to guaranty water quality. Electrodegradation of Congo Red dye was carried out using modified electrodes prepared by the deposition of iron(III)-zeolite on Carbon Toray. The sample iron(III)-zeolite was prepared by ion-exchange method with a solution of iron(III) using NaYnano as parent zeolite, with small particles, 150 nm. Fe(III)NaYnano was characterized by SEM/EDX and XRD techniques. The introduction of iron by ion exchange method do not modified the morphology of the zeolite but affect the zeolite structure, as prove by the structural characterization results from XRD. However, cyclic voltammetry studies show that iron-zeolite modified electrode is stable in the experimental conditions. The complete degradation of Congo Red dye was achieved by electrochemical route without the use of acid and hydrogen peroxide in reactional medium.rasmus grant. This work has been developed under the scope of the projects: BioTecNorte(operation NORTE-01-0145-FEDER-000004), PTDC/AAGTEC/5269/2014, and Centre of Chemistry (UID/QUI/00686/2013 and UID/QUI/0686/2016)info:eu-repo/semantics/publishedVersio

Evaluation of the potential of volatile organic compound (di-methyl benzene) removal using adsorption on natural minerals compared to commercial oxides

AIR:SURFACES+DBIThis study is dedicated to the investigation of the potential of volatile organic compounds (VOC) adsorption over low cost natural minerals (bentonite and diatomite). The performances of these solids, in terms of adsorption/desorption properties, were compared to commercial adsorbents, such as silica, alumina and titanium dioxide. The solids were first characterized by different physico-chemical methods and di-methyl benzene (dMB) was selected as model VOC pollutant for the investigation of adsorptive characteristics. The experiments were carried out with a fixed bed reactor under dynamic conditions using Fourier Transform InfraRed spectrometer to measure the evolution of dMB concentrations in the gaseous stream at the outlet of the reactor. The measured breakthrough curves yields to adsorbed amounts at saturation that has been used to obtain adsorption isotherms. The latters were used for determination of the heat involved in the adsorption process and estimation of its values using the isosteric method. Furthermore, the performances of the studied materials were compared considering the adsorption efficiency/cost ratio (C) 2013 Elsevier B.V. All rights reserved

A comparative study of natural Tunisian clay types in the formulation of compacted earth blocks

This study investigates the physico-chemical, mineralogical and thermal characteristics of three natural Tunisian clays collected from Gafsa (A1), Zeramdine (A2) and Nabeul (A3). The aim was to promote an appropriate formulation of materials and to obtain optimal compacted earth blocks (CEB). Results of mineralogical analysis of clays revealed the dominance of kaolinite (>13.58%), illite (>25.7%), quartz (>18%) and a minor fraction of smectite phases. Chemical analysis of the clays major elements showed a SiO2 content exceeding 50% and a percentage of Al2O3 higher than 18%. Particle size distribution showed that clay fractions varied from 10 to 20%. Plasticity index defined a plastic character while the values of specific surface area were around 60 m2/g. This discrepancy has an effect on the behavior of these clays in CEB, notably their mechanical properties. From this characterization, it appears that all the sampled clays are suitable as raw material for CEB application. The prepared CEB formulations varied according to compaction energy and binder dosages. In this work, lime served as a binder at different rates (4, 6, 8 and 10%) to ameliorate the quality of CEB. Unconfined Compressive Strength values were determined by Static method test. Then bulk density, shrinkage and porosity values of samples were determined. Compressive strength could reach 7 MPa with lime supplementation in sample A1. The static compaction onto the sand-clay mixture achieved a value of density superior to 2 g cm−3 with lime supplementation in sample A1. Overall, the Gafsa clay was the most suitable for CEB preparation. Also, lime improved the compressive strength of the matrix, in addition to its ecological merits. © 2019 Elsevier Lt

Treatment of a landfill leachate from Casablanca city by a coagulation-flocculation and adsorption process using a palm bark powder (PBP)

The study aims to evaluate the efficiency of a combined landfill leachate treatment (coagulation with ferric chloride coupled with adsorption onto palm bark powder (PBP)) enhance a low cost bioadsorbent. The efficiency of this treatment, was assessed in terms of chemical oxygen demand (COD), color and turbidity removal. This bioadsorbent was subjected to physico-chemical and morphological characterization by different methods (Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption-desorption isotherms, pH at zero charge point (pHPZC) and Boehm titration method).The coagulation process reduced the turbidity by 90%, the COD by 50%, the color by 80% and the biological oxygen demand (BOD5) by 99% for the optimum dose of ferric chloride of 12 g Fe3+. L−1. Thereafter, the sequential treatment of a landfill leachate based on coagulation as a pre-treatment process and then adsorption onto PBP improves the removal of turbidity, COD and color to 99%, 59% and 90%, respectively.These results demonstrate that combined coagulation-flocculation and adsorption processes could be a useful option for the treatment of solid-waste landfill leachate

Green synthesis of a novel clay-based catalyst supported magnetite and application as a tertiary treatment following chemical precipitation pretreatment of municipal wastewater of Fez city-Morocco

SSCI-VIDE+ATARI+MKC:LFI:AKD:JMC:CFEInternational audienceMunicipal wastewater of Fez city (Morocco) is considered one of contamination sources of the Sebou River in Morocco [1,2]. The present study deals with the fate of phenol as a compound of emergent concerns (CECs) supposed to be persistent after secondary treatment by the conventional processes in wastewater treatment plants (WWTP). Raw wastewater sampling upstream WWTP was performed periodically, followed by an exhaustive characterization. A primary treatment using coagulation-precipitation using ferric chloride was carried out to reduce the initial organic matter load and turbidity. Different treatment factors were optimized using response surface methodology (RSM). Thereafter, the pretreated and simulated wastewaters were spiked with phenol as probe compound, and its degradation was carried out in the heterogeneous Fenton process using synthesized magnetite-supported clay material by the co-precipitation method [3]. Results obtained from wastewater characterization confirm the moderate to high contamination strength of sampled wastewaters, and the preliminary treatment has reduced over 60 % of organics load. Matrix characterization of the pretreated wastewater before coupling to the Fenton process was detailed. On the other hand, the presence of magnetite phase and its high dispersion upon natural clay was confirmed by X-ray photoelectron microscopy (XPS), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). Nitrogen adsorption-desorption and Brunauer-Emmett-Teller (BET) measurements showed an optimum clay to magnetite ratio of 2:1 (wt%). The application of heterogeneous Fenton for phenol degradation has been conducted upon simulated and pretreated wastewaters. Results showed almost total degradation of the initial phenol concentration of 50 mg.L-1 within 180 min at pH 3, and the catalyst was reused for several runs. Therefore, coagulation-precipitation coupled to heterogeneous Fenton may be a promising scheme for wastewater treatment

Fe(III)-exchanged zeolites as efficient electrocatalysts for Fenton-like oxidation of dyes in aqueous phase

Electrochemical oxidation, a powerful tool for the conversion of several of organic dye compounds using metal-exchanged zeolite modified electrodes, has shown great potential due to its capability of high efficiency degradation, a global priority for a sustainable environment. In this study, the role of the Fe(III)-exchanged-zeolite-modified electrodes using two different zeolite structures (such as FAU (Y) and MFI (ZSM-5)) on the Fenton-like oxidation of Congo Red dye (C32H22N6Na2O6S2) was investigated at room temperature. To clarify the electrocatalytic trend observed by constant potential electrolysis, the surface acidity of the catalysts prepared by ion-exchange method was determined by microcalorimetric measurements of ammonia adsorption. The different acid properties deriving from the presence of different cations (NH4+, H+ and Na+) in the case of MFI structure were found to enhance the ion-exchange capacity as well as the oxidation reaction. MFI catalysts - Fe(Na)ZSM-5, Fe(H)ZSM-5 and Fe(NH4)ZSM-5 - exhibited excellent activity and stability at the end of the electrolysis (within 60 min), with a total dye degradation and an higher mineralization on Fe(H)ZSM-5 (64% of TOC), compared with Fe(Na)Ynano, which takes twice as long (120 min) for total degradation, with 19% of TOC removal. This work provides an effective route for the development of stable Fe(III)-zeolite-modified electrodes for electro-Fenton oxidation, with a better stabilization of Fe3+ ions within the framework, without the aggregation of iron and the addition of H2O2, at room temperature