PREPARATION AND APPLICATIONS OF NOVEL EXTRACELLULAR BIOPOLYMERS FOR SOLID-PHASE EXTRACTION OF COBALT(II) FROM ENVIRONMENTAL SAMPLES

A novel extracellular biopolymer (B-11) produced from Bacillus sp. has been used as biosorbent for the solid phase extraction of Co(II) ions in environmental samples. The prepared B-11 was characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometer (EDX) analysis, and the results showed that hydroxyl, carboxyl, phosphate and sulphonate groups are involved in sorption of Co(II) ions. Batch experiments were performed to evaluate the adsorption kinetics, adsorption isotherm, desorption and regeneration characteristics of B-11. The kinetic data were fitted with the Lagergren first-order, pseudo-second-order and intraparticle diffusion models; the pseudo-second-order model was found to be well suited for the entire adsorption process. Moreover, the obtained data were fitted with the Langmuir and Freundlich equations, and Langmuir isotherm better fitted the adsorption data with the monolayer adsorption capacity of 17.03 mg/g at pH 4.5 and 25 degrees C. Furthermore, B-11 could be reused five times with only about 8.25% regeneration loss, and the enrichment factor was more than 10.0. The presented biosorption procedure was also successfully applied to the determination of trace Co(II) in environmental water samples with satisfactory results. The relative standard deviation of the method (R.S.D.) and the detection limit (3 sigma) were 1.37% and 0.0246, respectively.