The negative values of G◦ confirm the feasibility of the process and the spontaneous nature of adsorption with a high
preference for Cr (VI) onto EMCMCR.
The standard enthalpy and entropy changes of adsorption determined from Fig. 11 were
−4.242 kJ mol−1 and 71.450 Jmol−1 K−1, respectively, with a correlation coefficient of 0.992.
The value of H◦ is negative, indicating that the adsorption reaction is exothermic.
The positive value of S ◦ reflects an increase in the randomness at the solid/solution interface during the adsorption process