Authors: Elbert M Nigri Maria Alice P Cechinel Diego A Mayer Luciana P Mazur José M Loureiro Sônia D F Rocha Vítor J P Vilar
Publish Date: 2016/11/04
Volume: 24, Issue: 3, Pages: 2364-2380
Abstract
Cow bone char was investigated as sorbent for the defluoridation of aqueous solutions The cow bone char was characterized in terms of its morphology chemical composition and functional groups present on the bone char surface using different analytical techniques SEM EDS N2BET method and FTIR Batch equilibrium studies were performed for the bone chars prepared using different procedures The highest sorption capacities for fluoride were obtained for the acid washed q = 62 ± 05 mg/g and Aldoped q = 64 ± 03 mg/g bone chars Langmuir and Freundlich models fitted well the equilibrium sorption data Fluoride removal rate in batch system is fast in the first 5 h decreasing after this time until achieving equilibrium due to pore diffusion The presence of carbonate and bicarbonate ions in the aqueous solution contributes to a decrease of the fluoride sorption capacity of the bone char by 79 and 31 respectively Regeneration of the Floaded bone char using 05 M NaOH solution leads to a sorption capacity for fluoride of 31 mg/g in the second loading cycle Fluoride breakthrough curve obtained in a fixedbed column presents an asymmetrical Sshaped form with a slow approach of C/C 0 → 10 due to pore diffusion phenomena Considering the guideline value for drinking water of 15 mg F−/L as recommended by World Health Organization the service cycle for fluoride removal was of 710 h F−feed ∼ 9 mg/L flow rate = 1 mL/min m sorbent = 126 g A mass transfer model considering the pore diffusion was able to satisfactorily describe the experimental data obtained in batch and continuous systems
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