Where Co is the initial adsorbate concentration (mg/g) and b is the Langmuir constant (L/mg) (kimet et al, 2014). In the context, Lower R L value reflect the adsorption is more favorable. In deeper explanation, RL value indicate the adsorption nature is either unfavorable (R L >1), Linear (R L =1), favorable (0<R L >1), or irreversible (RL=0) .