Performance Evaluation of Chitosan in the Adsorption of Antibiotic Metronidazole from Aquatic Environments: Molding Using Response Surface Methodology Based on Central Composite Design, isotherm and Kinetic Studies

Antibiotics presence in drinking waters causes health problems for humans. The present study investigated chitosan potential in the adsorption of antibiotic Metronidazole from aquatic environments. The current study was conducted in an experimental scale in a batch system. The effect of input variables including pH, operating time, chitosan dose, and Metronidazole concentration on the adsorption performance was investigated in a central composite design upon on response surface methodology. Isotherm and kinetic studies also were explored in optimum condition of inputs variables. To detect the residual concentration of Metronidazole, the DR 5000 spectrophotometer at the 320 nm wavelength was applied. The results showed that the adsorption process follows a second-order polynomial model with F-value=990.936 and P<0.0001, R2=0.9989 and Adj-R2=0.9979. The optimum level of independent variables includes pH=4.74, contact time= 60 min, chitosan dose=1.5 g/L and Metronidazole concentration=20 mg/L, in which the highest removal efficiency was obtained about 85%. In the following, it was observed that the adsorption process corresponds to Langmuir isotherm and pseudo-first-order kinetic models with R2 value of 0.9965 and 0.9859, respectively. In this study, it was observed that the chitosan has a high ability in the adsorption of Metronidazole; therefore, chitosan compound can be proposed as neutral adsorbent with major potential in adsorption of Metronidazole and other similar antibiotics from aqueous environments.