Synthesis Of Magnetic Halloysite Composites For The Fast Removal Of Tetracycline Class Of Antibiotics From Aqueous Solutions

Tetracycline class antibiotics show an important activity towards a variety of microorganisms and thus they are widely used as broad-spectrum antibiotics in human beings, animalsand agriculture. With the widespread using of tetracycline antibiotics, the negative effects of it onenvironment had appeared, such as hazardous influences to non-target organisms and the cause ofantibiotic resistance of microorganisms and it even caused serious problems to human health.Therefore, the remove of tetracycline antibiotics from aquatic environment is necessary and vital.At present, there are several ways to deal with tetracycline antibiotics contained wastewater,including physical and chemical method, biochemical method and photocatalytic degradation.Compared with these methods, adsorption costs less, reduces secondary pollution, has a easyoperation, and it is recycled and a relatively effective method. Therefore, it is widely used.Activated carbon is conventional adsorbent for the adsorption process in wastewater treatmentbecause it has amzaing surface area and affinity with numerous organic chemicals. However, itshigh prices lead to its regeneration necessitates. Therefore, searching for alternative low-costadsorbents that have comparable capacity to activated carbon is highly desired. Recently,halloysite nanotube, as a low-cost adsorbent, has received much more attention for these purposes;halloysite nanotube is an aluminosilicate clay mineral, possessing hollow nanotube structure inthe submicrometer range and large specific surface area. In contrast with other nanosizedmaterials, HNTs are readily obtainable, much cheaper, possesses special structure and are largelyreserved in China.Usually, when the reaction of adsorbent and solvent reactions finished, we used centrifugalor precipitation to separate the adsorbent and solvent, but it was time-consuming and costly. Inorder to solve the difficulties in collecting adsorbents from their dispersing media, specialattention had been taken to the combination of ferrite magnetic nanoparticles and conventionaladsorbents.The halloysite/CoFe2O4magnetic composites (MHNTs) were prepared by an effective wayin this study. The obtained composites were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and AtomicAbsorption Spectrometer (AAS). The results indicated that MHNTs exhibited strongly magneticproperty (Ms=34.02emu/g) and low leakage property. Then the MHNTs were employed as adsorbents for the fast removal of tetracycline class antibiotics（tetracycline hydrochloride，oxytetracycline hydrochloride, doxycycline hydrochloric) from aqueous solutions. Theadsorption performances of MHNTs were investigated by batch mode experiments with respectto pH, contact time, temperature and initial concentration. The Langmuir isotherm model wasfitted to the equilibrium data better than the Freundlich model and the kinetic properties werewell described by the pesudo-second-order equation. In addition, the resulting compositesreusability without obviously deterioration in performance was demonstrated by at least threerepeated cycles.