Kinetic equilibrium and isotherm modelling adsorbed methane assessment on synthesized peek-porous sorbent carbon of sustainable coconut shell kernel

Abstract

It is important to understand methane (CH4) adsorption onto available biomass surfaces quantitatively for its storage as Adsorbed Natural Gas (ANG). Coconut shell being among the abundant agro-waste in Malaysia has chosen with polyetheretherketone (PEEK) as a precursor for preparation of hybrid activated carbon via microwave induced potassium hydroxide activation for methane storage. M33P15 Porous carbon prepared at 300 Microwave power with 3 min irradiation and 15 wt% amount of PEEK and M33P0 was prepared under the same condition as M33P15 but without addition of PEEK. The porous carbons were used for CH4 adsorption as the interactions between carbon and methane is based the pore diffusion and partly film diffusion. The ideal CH4 adsorption capacities of the activated carbons were conducted using volumetric adsorption equipment at pressures (5-30 bar). The obtained experimental data at initial pH of 8.0 and 9.0 were correlated using linear regression analysis with common adsorption kinetic (Pseudo-first order, Pseudo-second order, Elovich) and isotherm models (Freundlich, Langmuir, Sip, and Toth). The pseudo-second-order kinetics describe the best fitness with a correlation coefficient of 0.9998 for sample M33P15. For adsorption isotherms, Sip model shows better fitness for sample M33P15 with the regression coefficient (R 2 ) 0.9800 and with lowest RSMD value (0.1438) than other models. The findings revealed the potential of kinetic and isotherm models in methane adsorption applications.