Equilibrium,Kinetics and Thermodynamics of the Adsorption of Methylene Blue onto a Metal-Organic Frameworks Material,Copper Coordination Polymer with Dithiooxamide

The equilibrium, kinetics and thermodynamics of the adsorption of methylene blue( MB) from aqueous solution onto copper coordination polymer with dithiooxamide( H2dtoaCu),one of the metal-organic frameworks( MOFs),were investigated in a batch adsorption system as a function of initial pH, adsorbent concentration, contact time, initial dye concentration, and temperature. The Langmuir, Freundlich, and DubininRadushkevich( D-R) isotherm models were used for modeling the adsorption equilibrium. It was found that Langmuir model yielded a much better fit than the Freundlich model under different temperatures. The maximum monolayer adsorption capacities of MB were 192. 98,229. 86,and 297. 38 mg /g at 298,308,and 318 K,respectively. The calculated mean adsorption energy( 8. 26-11. 04 kJ /mol) using D-R model indicated that the adsorption process might take place by chemical adsorption mechanism.Otherwise,the kinetic studies revealed that the adsorption process could be well explained by pseudo-second-order rate kinetics and intraparticle diffusion was not the rate-limiting step.Thermodynamic studies indicated that this system was feasible,spontaneous,and endothermic process. Based on these studies,H2dtoaCu can be considered as a potential adsorbent for the removal of MB from aqueous solution.