Comparative Study of Isotherms of Activated Carbons Produced from Mango Kernels and Commercial Activated Carbons (ISO 9001:2000)

Abstract

Waste handling and management has been a major challenge especially in the developing nations. Mango waste, with an estimated yield of 150,000 to 400,000 tons of wastes worldwide from mango processing, may cause environmental hazards. Exploring the suitability of and subsequent use of waste to replace commercial adsorbents in the area of adsorption refrigeration will address some of the waste management issues. Experimental studies of the isotherms of mango kernel activated carbons (MKAC) and that of commercial activated carbons (CAC- ISO 9001:2000) known to have suitable adsorption properties for both liquid and gas phase adsorption were carried out and compared to explore the potential of MKAC as a possible substitute. An experimental test rig was used to determine the isotherms of both MKAC- methanol and CAC- methanol refrigerant pairs. Desorption and adsorption isotherm for MKAC and CAC were determined and were observed to have same shape of curve (concave downwards). The shape of the isotherms observed from both pairs suggested the type I isotherms which are known to be highly microporous and as such suitable for gas phase adsorption. The isotherms show maximum desorption and adsorption capacities at pressure ranges of 2.5- 3.0 bar and 0.230- 0.240 bar respectively for MKAC and 2.7- 3.0 bar and 0.227 - 0.229 bar respectively for CAC. It was concluded that MKAC could be good substitute for commercially manufactured activated carbons for the design of gas phase adsorption cooling systems.

Keywords: Activated carbons, Desorption; Adsorption, Isotherms, Mango kernels.