Biosorption of chromium by red algae Polysiphonia nigrescens

LUIS F. SALA; SEBASTIÁN E. BELLÚ; PATRICIA BLANES; JUAN C. GONZÁLEZ; SILVIA I. GARCÍA; MARÍA INÉS FRASCAROLI; FLORENCIA MANGIAMELI; REGINA TRIPALDI; VERÓNICA ANDREU; ANA M. ATRIA; JULIO FERRÓN; JUAN M. SALAS PEREGRIN; EMILIO RUBIN DE CELIS; LIDIA PIEHL; CRISTINA MATULEWICZ; HÉCTOR PRADO

Rosario, Santa Fe, Argentina

Workshop; 1st Argentinien Workshop on Environmental Science; 2009

Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario

The presence of toxic heavy metals in contaminated streams, arising from thedischarge of untreated effluent, is one of the most important environmentalissues. Cr VI is known to be carcinogenic and can be reduced to C III by a widevariety of biological and chemical reductants .The application of traditionaltreatment techniques implies a high cost and a continuous input of chemicalswhich cause further environmental damage. The high level of sulfation of thepolysaccharides from Polysiphonia nigrescens suggests that this inexpensive redseaweed could be used as an important biomass for removing heavy metals. Thisstudy focuses on the biosorption of chromium onto algae biomass fromaqueous solution. Native P. nigrescens was collected in Cabo Corrientes (Mar delPlata, Buenos Aires, Argentina). Experimental parameters affecting biosorptionprocess such as pH, contact time and biomass dosage were studied. Thebiosorption capacity (mg Cr / g biomass) of P. nigrescens for Cr III in the studypreliminary was 50.0 mg/g at pH 4.0 and 11.6 g/L biomass dosage, 19 hequilibrium time and 20.0 OC. EPR and XPS spectroscopy from mixtures Cr VI/biomass, pH = 1, shows the presence of Cr V + C III bound to the surface of thered algae at short contact times and Cr III at long contact times. This resultsindicate that, at pH = 1, P. nigrescens can completely remove Cr VI from aqueoussolution through an adsorption-coupled reduction mechanism to yield adsorbedCr III and the less toxic aqueous Cr III, which can be further removed at pH = 4.0.