Adsorption of tetracycline on La-impregnated MCM-41 materials

We prepared La-impregnated mesoporous silicates to investigate the adsorption of tetracycline in aqueous solution. Nitrogen adsorption-desorption isotherm tests confirmed the mesoporosity of the prepared materials, resulting in a decline in surface area and pore volume along with La loading amount. In adsorption tests, however, La impregnation improved the adsorption capacity of materials for tetracycline even though the surface area and the pore volumes were lower after La impregnation. Adsorption capacities for tetracycline showed a maximum value with La loading amounts. The highest adsorption capacity for tetracycline was 303.3 mg g(-1), which was acquired from the fitting of isotherm data of 10 wt% La-impregnated mesoporous silicates to the Langmuir model. Changes in FTIR patterns of tetracycline adsorbed on La-impregnated mesoporous silicates implied that the negatively charged oxygen of the tricarbonylamide group of tetracycline chemically interacted with La hydroxide species in materials in the neutral condition.