An investigation on kinetic and thermodynamic parameters of methylene blue adsorption onto graphene-based nanocomposite

Abstract

In this work, adsorption of methylene blue (MB) onto graphene-based nanocomposite adsorbent has been evaluated on the adsorbent kinetic and thermal parameters sides. Specially, graphene (Gr) was prepared from waste dry battery electrode using a simple electrochemical method and prepared graphene has been used for fabrication of a Fe3O4/chitosan/graphene (FCG) nanocomposite by a simple co-precipitation method. Experimental results indicated the adsorption of MB onto FCG follows the pseudo-second order kinetic models as described: t/qt = 0.02162 + 0.02076.t with R2 = 0.99852. Thermodynamic parameters of the adsorption of MB onto FCG were evaluated in temperature range from 283 K to 323 K and extracted data have provided values of ΔG0, ΔH° of −9.950 ÷ 6.434 kJ mol−1 and 27.348 kJ mol−1, respectively. The negative values of ΔG0 indicate the adsorption of MB onto FCG phenomenon occurred spontaneously. The positive value of ΔH° suggests the endothermic in nature and small value of ΔH° also implies a physical adsorption. These obtained results are useful to control the adsorption of MB onto graphene-based nanocomposite adsorbents in term organic dyes removal from solution.