Page 470 - Demo

474 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYmin and then autoclaved at 121 o C for 20 min. Different volumes of GO solution (1 g/L) were added to the above gel solution to obtain GO concentrations of 0 (GO-0); 150 (GO-150); 300 (GO300) and 750 (GO-750) mg/L, respectively. The homogeneous mixture was dropped into a saturated B(OH)3 solution with 2% CaCl2 to form spherical particles. The obtained particles were gently stirred in the above solution for 1 h. The seeds were then soaked in 0.5M Na2SO4 solution for 1 h. The seeds were then washed with distilled water and dried at 60 o C for 90 min.2.2.2. Adsorption properties of gel beads on methylene blueMethylene blue (MB) adsorption experiment was conducted by gently stirring 10 mg of material in 50 mL of MB 10 mg/L, pH = 7 at room temperature for 4 h to reach adsorption equilibrium. The optical absorbance of the solution was measured at 660 nm and the MB solution standard curve was used to determine the corresponding MB concentration. HCl and NaOH solutions were used to adjust the pH of the adsorption solution. Materials with different GO contents (0, 150, 300, 750 mg/L) were tested for their adsorption capacity to evaluate the effect of GO on the adsorption efficiency. Then, the effect of adsorption time and re-adsorption capacity was studied with GO gel material having the best adsorption capacity. The adsorption capacity (q t ) and adsorption efficiency (H) were calculated according to the following formula:In which, qt is the adsorption capacity (mg/g), H is the adsorption efficiency (%), C0 is the initial MB concentration (mg/L), Ct is the MB concentration at time t (mg/L), V is the volume of MB solution (L) and m is the mass of adsorbent used (g).