Optimizing Tetracycline Removal through Batch and Continuous Adsorption on Modified Activated Carbon: A Bayesian Perspective and Advanced Modeling Analysis
Júlia Toffoli de Oliveira, Letícia Reggiane de Carvalho Costa, Gustavo Dall Agnol, Liliana Amaral Féris
Abstract
This study aimed to compare two adsorption modes for tetracycline (TC) removal on granular activated carbon impregnated with copper sulfate (AC-Cu), solid modification proposed by Costa et al. (2020), these being batch, through modeling the equilibrium isotherm with applying minimum square method and Bayesian statistics, and continuous, through the breakthrough curve analysis also using Bayesian statistics. For the Bayesian statistics, the methodology used in the present work follows that proposed by Oliveira et al. (2023a). The goal was to assess the potential scalability of the process. This work showed that using a more reliable mathematical approach can change the values of the isotherm parameters and indicated that the ideal operating conditions, for continuous adsorption of TC, were C 0TC = 80 mg·L –1, Q = 6 mL·min –1, and Z = 1 cm, resulting in a 95% TC removal with an adsorption capacity of the bed equal to 6.87 mg TC ·g AC-Cu –1, around three times higher than that of the unmodified AC (2.08 mg TC ·g AC –1 ). The saturation time of 107 min shows an efficient process, making it viable for implementation on a larger scale. For the elucidation of the mechanisms, the Clark model proves to best represent the process and the Log-Gompertz model is practically favorable for industrial implementation since its parameters provide valuable information about the effectiveness of the process depending on the configuration of the system. An underestimation of the maximum adsorption capacity of the bed was observed by leaving the parameter as a random variable, by approximately 46.72% and 58.95% for the Thomas and Yan models, respectively, leading to an erroneous application of the process on a larger scale. Additionally, the Langmuir model overestimated the value of q max by approximately 21.63%. Finally, the study highlights the importance of operating conditions and precise parameter estimation in optimizing the adsorption process and that the adsorption mechanisms change depending on the type of operation, in this case for the batch mode, the Langmuir isotherm, and for the continuous mode, the Clark model. These findings provide valuable insights for the development and implementation of environmentally sustainable and effective water treatment strategies.