Biosorption of cobalt(II) with sunflower biomass from aqueous solutions in a fixed bed column and neural networks modelling.

The effects of inlet cobalt(II) concentration (20-60 ppm), feed flow rate (8-19 ml/min) and bed height (5-15 cm), initial solution pH (3-5) and particle size (0.25<x<0.5, 0.5<x<1 and 1<x<2 mm) on the breakthrough curves were investigated. The highest bed capacity of 11.68 mg/g was obtained using 40 ppm inlet cobalt(II) concentration, 5 cm bed height and 8 ml/min flow rate, pH 6.5 and 0.25<x<0.5 mm particle size. According to the BET (N2) measurements, the specific surface area of the shells of sunflower biomass was found to be 1.82 m(2)/g. A relationship between the predicted results of the ANN model and experimental data was conducted. The ANN model yielded determination coefficient of (R(2) 0.972), standard deviation ratio (0.166), mean absolute error (0.0158) and root mean square error (0.0141). The results indicated that the shells of the sunflower biomass is a suitable biosorbent for the uptake of cobalt(II) in fixed bed columns.