Removal of Chlortetracycline Hydrochloride from Aqueous Solution by Microbial Cells Supported onto Granular Pozzolana

The present research aims to investigate the biosorption capacity of microbial biomass supported onto granular pozzolana toward Chlortetracycline hydrochloride (CTC). Biosorption studies were carried out in a discontinuous system and various experimental conditions that may affect the biosorption process were evaluated including particle size of the support, the speed of agitation, the mass of the support, contact time, initial pH of the solution, and the initial concentration of CTC. At 25°C, the optimum conditions for maximum removal of CTC by immobilized microbial cells were as follows: grain size of pozzolana was between 4 and 5 mm, a stirring speed (SS) was 160 rpm, pozzolana masse was 45 g, initial pH was 7.44, the initial CTC concentration was 40 mg/L, and the equilibrium time was 5 h. Under the optimal process parameters, a maximum CTC removal rate of 93.76% was obtained. Langmuir, Freundlich and Temkin models have been applied to describe isothermal equilibrium studies of biosorption. The Freundlich model was well-fitted with the equilibrium data (R² = 0.99). The isotherm behaviour indicated that the biosorbent surface was heterogeneous, and the biosorption capacity of the microbial biomass calculated from the Langmuir model was 118.98 mg/g. The kinetic behaviour showed that the CTC biosorption followed pseudo-second-order kinetics, which suggested a chemisorption process.