JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Removal of heavy metals from aqueous solutions using Tunisian smectite clay intercalated by functionalized crown ethers

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Solid-liquid extraction is one of the most used methods for the environment protection and especially for removal of heavy metals. The solid phase used in this work was a Tunisian smectite clay saturated by Na+ , and intercalated by functionalized crown ethers: Dibenzo-14-Crown-4 (NO2)2 (1), Dibenzo-14-Crown-4(NO2)2(Br)2 (2), Dibenzo-14-Crown-4(Br)4 (3) and Dibenzo-14-Crown-4(COOH)2 (4). These new obtained hybrid materials were firstly characterized by X-ray diffraction (XRD), IR spectroscopy and thermal analysis (DSC and DTA-TGA). After that they were used to extract heavy metals (Fe, Cu, Cd, Zn, Pb ,Mn and Co). Extraction percentages by modified clays varied in the following decreasing order Fe3+ ≥ Cu2+ ≥ Pb2+ > Co2+ ≥ Mn2+ > Cd2+ ≈ Zn2+.

B. Chrayet, F. Ammari, A. Ouerghui, F. Meganem

Functionalized crown ethers, Intercalation, Removal of heavy metals, Tunisian Smectite

Pages: 256-263

Comparison of dry grinding effect on commercial quartz-free and Tunisian quartz-rich kaolin clays milled using a grinding aid

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The activation effect generated by the dry grinding of a commercial quartz-free kaolin and a natural Tunisian quartz-rich kaolin was studied. The Tunisian kaolin has a similar chemical composition to that of pyrophyllite. The grinding operation was conducted using a laboratory planetary ball mill, while adding triethanolamine as a grinding aid. The textural analyses show that the grinding does not seem to follow the three steps conventionally observed when minerals are ground without the use of a grinding aid. The latter seems to prevent the particles agglomeration when minerals are milled for a long time. Regardless of the presence of quartz, a rapid and significant alteration of the kaolinite structure during the first 30 min of grinding was observed. Beyond those 30 min, alteration attenuates clearly. The distortion of the quartz structure follows a different evolution. Thermal events show classical evolution of the kaolinite dehydroxylation peak. However, the presence of quartz seems to affect the mullite crystallization peak: for the quartz-free sample, this peak widens but for the quartz-rich sample, it refines and its intensity increases when prolonging grinding. It is likely that Si-O-Al bonds are formed during grinding, where Si is derived from quartz and Al from kaolinite.

N. Ben Messaoud, Z. Ksibi, L. Bergaoui

Kaolinite, quartz, grinding, grinding aid, mullite

Pages: 264-275

Experimental design methodology applied to boron removal from brine by adsorption onto in-situ precipitated magnesium hydroxide

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The objective of the present study is to investigate the elimination of boron from brine (saline water), by adsorption using Mg(OH)2 precipitate in-situ as adsorbent. To optimize the experimental condition of boron removal and to evaluate statistically the important significant factors, an experimental methodology design was implemented using 23 full factorial design. The selected parameters were temperature (25°C and 70°C), molar ratio (10 and 30), stirring speed (200 and 600 rpm) and reaction time (15 min and 60 min), while Y1 (the % of boron removal) and Y2(the % of magnesium precipitate) are chosen as the responses variables. The results were analyzed statistically using the analysis of variance, F-test and the student’s t-test to check the significance of the variables effects. The model function equation for boron removal and magnesium precipitate was obtained. The obtained results showed that temperature, molar ratio, stirring speed and time affected boron removal. The optimum operating conditions were found as temperature: 25 °C, molar ratio Mg/B: 30, stirring speed: 600 rpm and time: 15 min. These optimum experimental conditions were used to eliminate 92% of boron initially present in brine in the form of Mg2B2O5.

A. Boughalmi, H. Hammi, A. M’nif

Adsorption; Boron removal, Experimental Design, Full Factorial Design, Hydroxide magnesium

Pages: 276-287

Facile synthesis of gold nanoparticles with irregular shapes in polyol and aquatic ecotoxicity effects

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A simple chemical route, based on a modified polyol process, is used to synthesize mono-disperse triangular gold nanoprisms (Tr-AuNPs) in triethylene glycol (TREG) with polyvinyl-pyrrolidone (PVP) as capping agent. Both the solvent and the surfactant in the solution play important roles in the formation of the Tr-Au NPs. Shape, size and optical properties of the particles were tuned by changing the molar ratio of PVP to metal salts. The formation of such large, single-crystal Tr-Au NPs is explained by the preferential adsorption of some species of molecules from the solution onto the {111} planes of Au nuclei. The anisotropy in the nanoparticles’ shape shows strong localized surface plasmon resonance (SPR) in the near infrared region of the electromagnetic spectrum. These nanostructures may be used in areas that include photonics, optoelectronics, optical sensing and also for inducing hyperthermia in tumors. For this reason, the ecotoxicological effects of the Tr-Au NPs and their interactions with marine organisms were also studied in this work. It was found that Tr-Au NPs don’t seem to have a large effect on the non-target marine organism R. decussatus. Indeed, no significant modification (p > 0.05) was observed after 2 days on the glutathione-S-transferase activity of the clams exposed to Tr-Au NPs when compared to the control, both in the gill and the digestive glands.

A. Fkiri, A. Mezni, N. Ben Saber, B. Sellami, L.S. Smiri

Gold nanoparticles, Polyol; Triethylene glycol, Surface Plasmon resonance, Aquatic ecotoxicity

Pages: 288-293

Synthesis of substituted bis(allyl) polythioethers: Application for the synthesis of crown thioethers

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Present study describes the synthesis of a novel substituted bis (allyl) thioethers by the condensation of thioetherdithiols with different allylchlorides. Representative example of the cyclization of the diallylpolythioethers via intramolecular radical reaction is presented. The corresponding crown thioetheris is obtained in good yield and high purity.

I. Gara Dallali, H.M. Sbihi, M.M. Chaabouni, M. Romdhani-Younes

Polythioethers, crown thioethers, allyl thioethers

Pages 77-82

Microwave irradiation synthesis of 3-(2-hydroxyalkyl)-2-methylquinazolin-4(3H)-ones and their functionalization using the Mitsunobu reaction

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The synthesis of quinazolinones using a microwave method and their functionalization with the Mitsunobu reaction were investigated. The microwave method was proven to be rapid, simple and efficient in the synthesis of the starting quinazolinone. The results show an increase of obtained yields when compared with the conventional thermal method and the formation of the final derivatives in one step reaction without the activation of the alcohol function. The title quinazolinones were functionalized with a variety of variously substituted phenols using the Mitsunobu reaction to produce the corresponding new ether bridged derivatives in a 57-87% yield.

T. Saïed, N. Jelaiel, M.L. Efrit, C. Comoy, Y. Fort

Quinazolinone, Mitsunobu reaction, Microwave synthesis

Pages 83-88

Design and Synthesis of new antimicrobial [1,2,4]triazolo[1,5-c]pyrimidines

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The synthesis of 14-(aryl)-14H-naphtho[2,1-b]pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine-2- acetonitriles 4a-e has been accomplished using three steps of reaction using the 2-amino-naphthopyrane-3-carbonitriles 1a-e as useful key intermediates. Compounds 4a-e are used as precursors for the preparation of new triazolopyrimidine derivatives 5, 6, 7 and 8. Structures of these compounds were established on the basis of 1H NMR, 13C NMR and HRMS. The synthesized compounds were also screened for their antimicrobial activity.

A. Ben Said, A. Rahmouni, M. Daami-Ramadi, A. Romdhane, H. Ben Jannet

Naphtopyrane, Triazolo[1,5-c]pyrimidine acetonitrile, Antibacterial activity, Antifungal activity

Pages 94-104

Methane combustion over Pd/Al-MCM-41catalysts: The effect of palladium precursors and the preparation route

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The effect of palladium precursors and the preparation route on the catalytic performance of mesoporous materials Pd/Al-MCM-41 in methane oxidation was investigated in this work. The catalysts were prepared using both methods, namely hydrothermal method (DHT) and template ion exchange method (TIE), from three different palladium precursors Pd(NH3)4Cl2, PdCl2(MeCN)2 and Pd(acac)2. All catalysts were characterized by a variety of physico-chemical techniques such as X-ray diffraction (XRD), N2 physisorption, H2 chemisorption, temperature programmed desorption of H2 , diffuse reflectance UV–visible spectroscopy andelemental analysis by ICP, and then tested in methane combustion. According to the obtained results, the use of different palladium precursors and preparation routes play an important role on the catalytic properties of materials. The use of bis(acetonitrile)palladium (II) chloride as precursor by the TIE method seems to conduct to the best catalytic performance. This is in agreement with a better dispersion of PdO nanoparticles, thus optimizing the accessibility of reactants to the active sites in the mesoporous channels of Al-MCM-41.

A. Gannouni, S. Zribi, R. Dardouri, M. Saïd Zina

Al-MCM-41, Palladium, Template ion exchange, Hydrothermal, Methane

Pages 115-123

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