Adsorption Thermodynamics, Isotherm and Kinetics of Cationic Dyes Using Different Synthesized Graphene Oxides

Different graphene oxides (GO) (GO1.5, GO3, GO4.5, and GO6) were synthesized and characterized. Cationic dyes, including Methylene Blue (MB) and Crystal Violet (CV) were used as organic pollutants. The amount of dye adsorbed on the synthesized adsorbents increases by increasing the contaminant concentration. The results indicated that contaminant adsorption capacity is enhanced by enhancing the adsorbent dose and then decreases to some extent. As the adsorbent dose increases, the active sites will be more accessible. The adsorbent particles are agglomerated at values ​​higher than the optimal value of the absorbent. Thus, the amount of dye removal is reduced. The adsorption thermodynamic data presented that the negative ΔG of CV and MB removal by the synthesized adsorbents presented physical and spontaneous adsorption. Also, the positive values of ΔH and ΔS showed the endothermic properties of adsorption and the increase of dye irregularity on the adsorbent surface. The isotherm data indicated that MB and CV removal obeyed the Langmuir isotherm model. It means the adsorption process was carried out in specific homogeneous areas of the adsorbent. The results showed that MB and CV adsorption followed PSO kinetic.