They were repeatedly washed several times with tap water followed by distilled water and then left in open air for several days after they were dried in oven at 100 c¤ for 12 hour.Eggshells are crushed, powdered to small grains and then calcined at 900 ¤c for 2 hour. The residue was washed with distilled water three times and dried at 105 ¤c for 24 hour