Numerical investigations of response surface methodology for organic dye adsorption onto Mg-Al LDH -GO Nano Hybrid: An optimization, kinetics and isothermal studies

Abstract

We developed Mg-Al LDH intercalated with NO3- decorated Graphene Oxide nanohybrid with positive cationic textile dye adsorption, such as methylene blue. Contact time, initial dye concentration, and pH were among the independent variables used in the study. The Response Surface Model (RSM) was used to optimise and describe the interdependencies of the different variables. The method was evaluated using the Box-Behnken design (BBD). A second-order polynomial model was used to understand the experimental results, and the effectiveness of the chosen model was verified by its strong agreement in determination coefficient values. The adsorption results suited the best for the Langmuir isotherm than the D-R and Freundlich isotherms, resulting in efficient adsorption of 187.62 ​mg/g, proving LDH-GO is an effective dye adsorbent. Simultaneously, the kinetics were based on the pseudo-second-order model, and additional kinetic factors such as Elovich, pseudo-first-order, and intra-particular diffusion were examined. According to Thermodynamic studies, the adsorption process is spontaneous, which is exothermic and characterised by increased randomness. According to a regeneration test, even after four cycles, 37% of the removal efficiency for MB can be achieved. Based on this report, these materials can be used as an adsorbent to remove the dye.