Carbon Based Nanocomposites For Adsorptive Removal Of Tetracycline Antibiotics

Tetracycline antibiotics(TCs),a kind of the spectrum antibiotics,because of their strong inactivation and bactericidal ability,are often used as the treatment for human,animal and plant infections with bacteria.TCs have been used as an additive in feed by farming industries due to their high efficiency and low-cost.Howerer the animals themselves have difficulty in absorbing the TCs,and most of the TCs are excreted through excrement.Long-term use of TCs will lead to accumulate in the environment and cause serious impact on human health and the ecology.Adsorption is a promising method for the removal of TCs with high efficienc,low-cost,environmental-friendly and wide adaptability.Carbon materials are commonly used as adsorbents.Biomass are abundant,widely used,easy to obtain and can be used a precursor for the preparation of low-cost activated carbon.In this work,the hybrid nanocomposites of zero-valent iron loaded the activated carbon derived from the corn stalk(Fe~0-AC)was prepared,characterized and used to remove the TCs from aqueous solution.The main results in this work:(1)Fe~0-AC was characterized by scanning electron microscope andtransmission electron microscope,the surface of the Fe~0-AC is uneven and porous.X-ray diffraction analysis showed that zero-valent iron was successfully loaded onto Fe~0-AC.X-ray photoelectron spectroscopy indicates that the Fe~0-AC nanocomposites consist primarily of Fe,C,and O elements.The specific surface area of Fe~0-AC is 1229.1 m~2 g^-1.(2)The adsorptive conditions of TC,OTC and CTC by Fe~0-AC were investigated.The adsorption amounts of tetracycline,oxytetracycline and chlortetracycline by Fe~0-AC at 298 K are 81.5,72.9 and 103.1 mg g^-1,respectively,in the range of p H 3.3-7.7.Through the synergistic action of electrostatic adsorption,bridging and surface complexation.The equilibrium was performed within 20 min at 298 K.(3)Adsorption kinetics and thermodynamics of TCs are simulated by Fe~0-AC.The results show that the adsorption of TCs by Fe~0-AC follows the Langmuir isotherm and quasi-second order kinetic model(r~2>0.99),the adsorption thermodynamic parameters(?G^o<0 and?H^o>0)indicate that the reaction is endothermic and spontaneous.