Pharmaceutical pollutants adsorption onto activated carbon: isotherm, kinetic investigations and DFT modeling approaches

Abstract

In this work, significant interest has been focused on removing pharmaceutical pollutants, i.e., oxytetracycline (OTC), which was studied through adsorption onto activated carbon (ACT) produced from households or agricultural wastes under various experimental conditions. The physicochemical properties of the produced carbon were investigated using multiple techniques. The characterization analysis highlighted an essential concentration of surface functional groups and a very developed porous structure. The adsorption process onto activated carbon occurs with a high yield at a large range of pH values varying between 4 and 8 at an optimum contact time of 2 h. It was established that the pseudo-second-order kinetic model fitted well OTC adsorption onto ACT. Moreover, the adsorption isotherm data showed that the pollutant removal process followed the Langmuir model with high regression coefficients ($R^2$) values and important adsorption efficiency of 80% for $100~\text{mg}{\cdot }\text{L}^{-1}$ of OTC. The displayed results consequently, the use of ACT as an adsorbent could be considered an efficient, sustainable, and low-cost alternative for pharmaceuticals-loaded wastewater treatment.

Keywords

• Isotherm
• Adsorption
• Activated carbon
• OTC
• Physico-chemical characterization
• Kinetics
• Isotherm