Optimum Conditions for the Removal of Colour from Waste Water by Mango Seed Shell Based Activated Carbon

Activated carbons (AC) were produced from seed shells of two (2) varieties of mango (Local&Dausha varieties), by varying the impregnation ratio of the shells (impregnation ratios of 1:2 and 1:3 were used) with ZnCl₂ before carbonization. Their performance was evaluated through batch studies for the purpose of obtaining optimum conditions for the removal of colour (methylene blue) from wastewater. Contact time, stirring rate, adsorbent dose, initial methylene blue (MB) concentration, particle size and pH were used as variables. Results obtained revealed the optimum carbon dose of 400mg (4g/l) and 600mg (6g/l) for Local and Dausha varieties respectively, stirring rate of 98 rpm and pH value of 3. MB removal decreased with increase in initial MB concentration for all the 4 activated carbons studied. All the carbons achieved at least 97.7% removal at initial MB concentration of 87 Pt-Co units and hence this was adopted as the optimum initial MB concentration. In general, Local Zncl₂ with the impregnation ratio of 1:2 performed better as an adsorbent due to its higher surface area and porosity of 1667.8m²/g and 69% respectively. Also Local 1:2 achieved 100% removal of MB in 30 minutes, while Dausha 1:2 achieved 100% removal in 40. Local 1:3 and Dausha 1:3 achieved 94.3% and 92% respectively within 40 minutes period. Because at least 90% MB removal was attained within 40 minutes by all the carbons and it was chosen as the optimum contact time.