First International Conference on MOLDAVIAN RISKS – FROM ...

Recommendations

Info

<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE 16-19 May 2012, Bacau, Romania INTERACTION BETWEEN TOXIC LEAD IONS AND MODIFIED CALCIUM BENTONITES IN ENVIRONMENT DEPOLLUTION Ana-Maria Georgescu 1, 2 , Ileana Denisa Nistor 1 , Claude Penot 2 , Francoise Nardou 2 1 “Vasile Alecsandri” University of Bacau, Romania 2 University of Limoges, France Corresponding author: Ileana Denisa Nistor, dnistor@ub.ro, denisanistor@yahoo.com Abstract: Nowadays the decontamination of waters containing heavy metals has become one of the most serious environmental problems, especially in the case of accidental pollution and uncontrolled discharges of wastewater from metallurgical, chemical, galvanic and mechanical engineering. Heavy metals are not biodegradable and therefore tend to accumulate in living organisms, many heavy metal ions being toxic and carcinogenic. Toxic heavy metals of particular concern in the treatment of industrial wastewater are: mercury, lead, cadmium, zinc, chromium (IV), nickel, arsenic, cobalt. Different methods used for heavy metals removal from wastewaters were studied in the last years, like: chemical precipitation, ionic exchange, adsorption, electrolytic recover, extraction with solvents, reverse osmosis, membrane separation, ultrafiltration, flotation etc. Adsorption is a simple and efficient operation which permits the recover of adsorbent and of retained components and its subsequent reusing. This paper presents the synthesis and characterization of porous materials using different pillars as Al (III) and Cr (III) intercalated between the layers of montmorillonite. The starting material used to prepare the pillared clays was calcium natural bentonite from Orasu Nou deposit (Romania). The adsorption studies of lead ions on the obtained bentonites were realized using discontinuous batch technique, the main parameters that were varied being: contact time between the adsorbent and the aqueous solution of Pb (II), adsorbent / adsorbat ratio, Pb (II) ions concentration of initial solution. The raw material and pillared bentonites were characterized by: BET (Brunauer-Emmet-Teller) method and XRD (X-ray diffraction) analysis. Determination of ionic metallic concentration retained on materials after the contact with the metallic ions was realized using the atomic absorption spectrophotometer. The values of correlation coefficients (R2) obtained for linear dependencies showed that adsorption of Pb (II) ions on studied materials is better described by Langmuir model, compared with Freundlich model. Freundlich model constant n > 1, suggested that adsorption of Pb (II) on bentonite is a favorable process. The textural analysis of nanomaterials obtained confirmed that pillaring process leads to the development of optimal porosity with good adsorption properties, which can be sucessfully adapted for use in the process of removal of heavy metals occuring in wastewaters. Key words: bentonite, pillaring, lead, adsorption. 82
<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE 16-19 May 2012, Bacau, Romania HETEROGENEOUS WATER PHASE CATALYSIS AS AN ENVIRONMENTAL APPLICATION Nicoleta Platon 1 , Ileana Denisa Nistor 1 , Ilie Siminiceanu 2 1 ”Vasile Alecsandri” University of Bacau, Department of Chemical and Food Engineering 2 “Gh. Asachi” Technical University of Iaşi, Department of Chemical Engineering Corresponding author: Ileana Denisa Nistor, dnistor@ub.ro, denisanistor@yahoo.com Abstract: The urban distribution of qualitative water for human consumption, domestic activities and industrial use is a fundamental objective in what concerns the sustainability of life quality for the population. However, many industrial processes generate a series of pollutants, which have a negative impact on ecosystems and on humans (toxic, carcinogenic and mutagenic properties). Particularly, phenol is considered as one of the most toxic pollutants, especially for human health but also for the aquatic fauna and flora, causing an increase in the demand of oxygen in water sources and causing unpleasant taste and smell in drinking water even when it is found in very small quantities. Catalytic wet peroxide oxidation (CWPO) is part of the advanced oxidation processes (AOP) and is an efficient process because H2O2 is a strong oxidative agent. Pillared clays are successfully used as catalysts in these processes. Study on chemically modified clays by pillaring in Fenton and Fenton type processes were investigated due to its low cost, to its mild conditions (room temperature, atmospheric pressure) and to lack of toxicity for the environment of clays, hydrogen peroxide and iron salts. In this work, catalysts based on chemically modified clays by pillaring process with Al (III) and Fe (III) using as raws materials: commercial bentonite, KSF montmorillonite and K10 montmorillonite from Aldrich were synthesized. After, these catalysts were tested in wet oxidation with peroxides using the phenol as target compound. Experimental results show that Fe chemically modified clay from bentonite presented a higher activity than the Al-Fe one. The raw materials and chemically modified clays were characterized by: BET (Brunauer- Emmet-Teller) method, XRD (X-ray diffraction) analysis and EDAX-SEM (energydispersive X-ray) spectroscopy. By testing the derived catalyst from sodium bentonite, a 100% conversation of phenol was obtained after 50 minutes; by testing the KSF catalyst, a conversion of 98 % was obtained and by testing the catalyst obtained from K10 a 28% conversion was realized. The catalytic activity was evaluated by rate constant, considering a first order reaction. Verifying the hypothesis that the reaction is of order 1, we observe that the value of the rate constant K increases with the decrease of the phenol concentration. Key words: pillared clay, montmorillonit, phenol, catalytic oxidation. 83
Page 1:
“VASILE ALECSANDRI” UNIVERSITY
Page 4 and 5:
Editors: Mioara Mandea, Gabriel Laz
Page 7 and 8:
First Inte
Page 9 and 10:
First Inte
Page 11 and 12:
First Inte
Page 13 and 14:
First Inte
Page 15 and 16:
First Inte
Page 17 and 18:
First Inte
Page 19 and 20:
First Inte
Page 21 and 22:
First Inte
Page 23 and 24:
First Inte
Page 25 and 26:
First Inte
Page 27 and 28:
First Inte
Page 29 and 30:
First Inte
Page 31 and 32: First Inte
Page 81: First Inte
Page 111 and 112: Sponsors of the conference Sodexo P
show all

First International Conference on MOLDAVIAN RISKS – FROM ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?