Azo-dye decoloration by Pseudomonas sp. immobilized in sol-gel silica matrices.

MV TUTTOLOMONDO; GS ALVAREZ; G MANFREDI; MF DESIMONE; LE DIAZ

Mar del Plata

Congreso; Congreso Argentina Ambiental 2012; 2012

Among many pollutants, textile industry effluents are the major source ofenvironmental pollution. Synthetic dyes are widely used in the textile,pharmaceutical, cosmetic, and food industries. These effluents are a serious concernbecause of their adverse effects on many organisms and ecosystem as a whole.Even small concentrations of dye are highly visible and can be toxic to aquaticorganisms. Azo dyes are the largest and most versatile class of dye but due to theirchemical properties, they are not easily degradable under natural conditions andthus, are not thoroughly removed from water by conventional wastewater treatmentsystems[1,2]. In this work we propose the use of sol-gel silica matrices obtained fromsodium silicate to immobilize Pseudomonas sp., an azo-dye decolorizing bacteria.The model dyes chosen for the experiments were: Remazol Black (RB); MethylOrange (MO) and Benzyl Orange (BO). The advantages of bacteria immobilizationare the possibility to recycle the beads, protect bacteria and reduce their presence inthe resulting fluid. Bacteria were cultured aerobically at 35 ºC in aqueous solutions ofdifferent concentrations of azo-dyes. Azo-dye remnants were measured directly byabsorption at their maximum lambda [3,4]. Immobilized P. sp. was resistant to 2% ofthe tested dyes. Furthermore, recent studies allow us estimate the reutilization andhalf-life of the immobilized bacteria. The degradation products and the ability of thesol-gel matrix to bind them is also under study.