Zinc biosorption by Seaweed Illustrated by the Zincon Colorimetric Method and the Langmuir Isotherm

MARIA MAR ARECO; ERIKA VALDMAN; MARIA DOS SANTOS AFONSO

JOURNAL OF CHEMICAL EDUCATION

AMER CHEMICAL SOC

Lugar: Washington; Año: 2007 vol. 84 p. 302 - 305

0021-9584

Heavy metals are major pollutants in marine, ground, industrial and even treated waters. Sorption of heavy metals onto live or dead biological materials (biosorption) is becoming a potential method of removing toxic metals. Zinc and two algae, Ulva sp. and Gymnogongrus Torulosus., were evaluated in this study. A linear zinc calibration curve in the range 1 - 8 mg Zn L-1 was obtained using the Zincon colorimetric method. In the biosorption assays, a rapid zinc uptake was observed and kinetic curves stabilized after 60 min. Some experiments using 50 mg Zn L-1 initial concentration showed that 20% and 60% of zinc ions were removed from solution by Ulva sp. and Gymnogongrus Torulosus, respectively, after reaching the equilibrium. Results obtained varying zinc initial concentration allowed data adjustment to Langmuir model with a good correlation. The maximum zinc uptake capacity and affinity constant obtained for Gymnogongrus Torulosus were higher than those for Ulva sp. Maximum zinc uptake capacity was 42.8 mg g-1and 26.8 mg g-1 for Gymnogongrus Torulosus and Ulva sp respectively while the affinity constant was 0.084 L mg-1 and 0.019 L mg-1 likewise. An interesting and simple experiment was developed to show the potential of algae in biosorption processes.