Azo Dye Adsorption onto Cobalt Oxide: Isotherm, Kinetics, and Error Analysis Studies

Abstract

The current study focused on utilizing cobalt oxide to eliminate hazardous Eriochrome Black T (EBT) dye. The impact of pH (2, 4, 7, 8, and 10) and temperature (45, 50, and 55 °C) was examined for EBT removal. The results show that the maximum sorption occurred at pH = 2 and that the removal percentage increased with increasing temperature. Five non-linear regression methods were used to predict the best isotherm and kinetic models. A coefficient of non-determination, K2, was very helpful for selecting the RMSD function as a preferable error function among the five methods. Isothermal models to illustrate equilibrium sorption information, the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models were used. The results showed that the Langmuir model (R2 = 0.99) was the most favorable, indicating monolayer sorption of EBT occurred. The kinetics models were analyzed using pseudo-first-order and pseudo-second-order whereas the sorption information was well described by the pseudo-second-order model (R2 = 0.99). The results of the thermodynamic study appeared that the adsorption of EBT was endothermic, feasible, spontaneous, and physical adsorption.

Adsorption of Methyl Orange Dyes on Oriented Co/Fe-MOF Bimetallic Organic Framework in Wastewater Treatment

“…Several methods have been used to remove chromogenic organic substances from aqueous media, such as precipitation, filtration, reverse osmosis, and adsorption. With the goal of achieving high efficiency at a reduced cost while reducing wastewater volume and improving the treatment quality, adsorption has been considered an effective method with numerous outstanding advantages [5][6][7]. Recently, the bimetallic organic framework (M/MOFs) containing the second metal (e.g., Ni, Co, Mn, and Cu) has much better adsorption capacity as compared with monometallic materials [8][9][10][11][12].…”