Crisotila na degradação de dodecilbenzenosulfonato de sodio

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

Catalytic properties of chrysotile, a mineral fibrous magnesium-silicate, were studied for sodium dodecylbenzenesulfonate (DBS) degradation, a typical pollutant in wastewater. AlI experiments were performed at least in sample and measurement triplicates. Preliminary results showed a depletion of 85% in the surfactant concentration ([DBS]0: 0.16x10 mol/L; 250mL) after 4 h in contact with 4.0 g of chrysotile with aeration and without ultraviolet radiation. The reaction was optimized by factorial planning. Major effects and principal components analysis showed that the amount of chrysotile, the surfactant initial concentration and the air flow rate are the main variables for the reaction. The catalytic role of chrysotile, as opposed to an adsorption effect, was established. Samples of chrysotile which were used in DBS degradation reactions showed CO2 evolution when in acid media. The gas was identified and quantified by membrane injection mass spectrometry .The amount of CO2 measured after 2 h reaction of 250 mL of DBS solution (3.1x10 mol/L) with 4.0 g of chrysotile using air bubbling is 2.0x10 mol. When only chrysotile and water were used (in the same experimental conditions) the value obtained is 1.0x10 mol. The catalytic efficiency of chrysotile was tested using 4 times the same 4.0 g-sample in 250 mL solutions of [DBS]0: 3.1x10 mol/L with aeration for 2 hours, getting an integral surfactant depletion of 0.9x10 mol and a final depletion of 0.15x10 mol. Turnover numbers for the reactions performed with DBS (3.1x10 mol/L) and chrysotile (4.0 g) during 4 h were up to 600. Theoretical plates necessary for a fluidized bed reactor using chrysotile were estimated as 1 (one) and 4 (four) for [DBS]0: 0.16x10 and 1.3x10 mol/L, respectively. Chrysotile also showed activity for the degradation of other surfactants containing aromatic rings in their molecular structure.

ASSUNTO(S)

asbestos

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