Process modeling and toxicological evaluation of adsorption of tetracycline onto the magnetized cotton dust biochar

Tetracycline, a broad-spectrum antibiotic, is a widely used pharmaceutical agent for treating common infections in humans and animals. Because of its indiscriminate overuse, tetracycline remains one of the most persistent micro-pollutants in the environment. This study explored magnetized cotton dust biochar (MCDB) and magnetized cotton dust (MCD) for their potential to adsorb tetracycline from an aqueous solution. Among the adsorbents studied, MCDB showed the maximum tetracycline adsorption capacity of 146.70 ± 4.32 mg/g. The maximum tetracycline removal efficiency observed was 92.46 ± 1.21 %. In addition, the batch adsorption studies found that the adsorption by MCDB followed Freundlich isotherm (R2 = 0.978) and second-order kinetics (R2 = 0.988), respectively. Further optimization with response surface methodology and genetic algorithm improved the overall removal efficiency of MCDB to 97.79 % at the pH of 5.55, initial tetracycline concentration of 49.91 mg/L, MCDB dosage of 1.24 g/L and treatment duration of 59.99 min. The experiments performed over the optimum condition showed the maximum removal efficiency of 96.92 ± 1.25 %. Finally, the biological toxicity of tetracycline solution before and after treatment with MCDB was studied using several model organisms. The results revealed a significant decrease (p