(215x) Optimal Process Conditions for Preparation of Porous Carbons and Methylene Blue Adsorption

Porous carbon is the most popular adsorbent that is being widely used in variety of industries for different applications. The present work focuses on the process optimization of porous carbon preparation from date seed pits. The Response Surface Methodology (RSM) technique with Box-Behnken Method (BBM) was utilized with the response variables being the yield and BET surface area. The influencing parameters selected were activation temperature, Impregnation ratio (IR), and activation time. The optimum conditions were identified to be an activation temperature of 500 ⁰C, IR of 2 and activation time of 75 min with the resulting yield and BET surface area being 46 % and 838 m²/g, with corresponding average pore volume of 1.07 cc/g and average pore diameter of 1.69 nm. It also confirms that the RSM approach is most suitable for optimization of process conditions for preparation of porous carbon.

In order to assess the suitability of the carbon for adsorption of macromolecules, methylene blue (MB) adsorption studies were assessed by varying the initial concentration and the adsorption temperature. The monolayer adsorption of MB using the Langmuir adsorption isotherm was estimated to be 345 mg/g for optimized process condition, while the maximum MB adsorption capacity of 455 mg/g, corresponds to the porous carbon with highest of BET surface area. The net positive charge on surface of porous carbon decreased with increase in pH, resulting in an increase in MB uptake, due to the reduction in repulsion between the porous carbon and MB.