Defluorination And Regeneration Study Of Lanthanum-Doped Sewage Sludge-Based Activated Carbon

Lanthanum-doped sewage sludge-based activated carbon (AC-La), an environment-friendly material, can effectively remove fluoride ions from water. Regeneration performance of AC-La was mainly studied in this work. The results showed that compared to other elution methods, excellent regeneration performance of AC-La was achieved by NaOH. AC-La treated with 0.5 mol/L NaOH showed a high desorption rate (> 98.5%) and fluorine removal efficiency (ca.60%) again. After three NaOH regeneration processes, the regeneration rate of AC-La was stable and higher than 73.8%. Characterization proved that NaOH caused little impact on pore structure and La loading of the carbon, meanwhile, it enhanced ion exchange and electrostatic attraction during F- desorption process. The adsorption/desorption mechanism of F- on AC-La were attributed to physical action (physical adsorption/desorption and electrostatic attraction) and chemical adsorption (inner-sphere complexation, ion exchange and chemical precipitation).