Zirconia Pillared Montmorillonite for Removal of Arsenate from Water

Zirconia pillared montmorillonite, a clean adsorbent with increased specific areas of 40.118 m²/g and high basal spacing of 2.20 nm, was prepared for the removal of arsenate from water. Zirconia pillared montmorillonite is effective for the removal of arsenate. Adsorption is favored under acid conditions. Ca^{2 +} and Mg^{2 +} in the solution slightly enhance the adsorption. Over 95% removal was observed under natural pH conditions from 20 mg/L arsenate solutions containing 5.0 mg/L Ca^{2 +} or Mg^{2 +}. High adsorption capacity of over 120 mg/g was observed from arsenate solutions with different Ca^{2 +} concentrations. The Freundlich model can describe the adsorption equilibrium data well. The column test shows that the column allows the passage of the feeding solution for approximately 225 times the bed volume if the removal percentage of arsenate was monitored not to be lower than 98%. The adsorbed arsenate can be desorbed with NaOH and the desorption efficiency reaches 85% and 88% when the concentration of NaOH reaches 0.2 and 0.5 mol/L. Zirconia pillared montmorillonite can be regenerated and the regenerated adsorbents still have good adsorption capacities.

Key Words :

• Arsenate
• Montmorillonite
• Zirconia
• Adsorption
• Water treatment