Sorption of Methylene Blue from Aqueous Solution Using Carbon and Chemically Modified Carbon from Periwinkle Shell

Carbonized periwinkle shell was modified by two types of activation: alkaline modification with 1 M NaOH and acidic modification with 1 M HNO3. The three carbon samples thus produced were tested for the removal of methylene blue from solution. This test was carried out to provide a cheap and readily available dosage. Chemical treatment of the sample was aimed at increasing surface functional groups. The alkaline modified sample introduced more hydroxyl group to the sample, while the acid modified produced less OH group. The amount of adsorbate removed was shown to be pH dependent with the three samples performing best at higher pH values of 9. Optimum adsorption was achieved at an adsorbent dose of 2g. The isotherm data obeyed the Langmuir model and first order kinetics. The maximum removal of dye at 2g of adsorbent dosage for 2hrs was 56.8%ss for the alkaline modified, 48.0% for the unmodified and 34.4% for the acid modified samples.