Construction And Study On Organic Contaminants Removal Of Metal Oxides/Halloysite Composites

Nowadays,water pollution as one of the serious environmental problems,which not only makes the problem of water shortage more serious,but also threats human health.Therefore,it is urgent to develop effective methods to remove pollutants in water.Halloysite nanotubes（HNTs）with natural tubular morphology,opposite charge of the inner and outer surface,abundant reserves and low cost have been widely applied in the removal of organic contaminants in water.Moreover,the abundant surface hydroxyl groups of HNTs would play an important role in construction of functional mineral composites and removal of pollutants.Using HNTs as support,indium oxide/halloysite nanotubes（In₂O₃/HNTs）composites were synthesized through hydrothermal-calcination method.The composites were used as adsorbents to remove tetracycline（TC）.A series of measurements,including X-ray diffraction（XRD）,fourier transform infrared（FT-IR）,X-ray photoelectron spectroscopy（XPS）and zeta potential were conducted to characterize the as-synthesized samples.The influences of adsorbent dosage,p H value,initial TC concentration and temperature on adsorption efficiency were investigated.Adsorption mechanism studies suggested that the abundant hydroxyl groups on HNTs and strong interfacial interaction between HNTs and In₂O₃ played the important roles in enhancing the adsorption efficiency,which made adsorbents have more negative surface charges to adsorb TC molecules through electrostatic interaction.Using HNTs as support,a series of CuO/HNTs composites were prepared through hydrothermal method.The synthesized CuO/HNTs could effectively activate peroxymonosulfate（PMS）to degrade bisphenol A（BPA）.The physico-chemical structure and the main active species involved in the catalytic process were studied by XRD,FT-IR,XPS,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and electron spin resonance（ESR）techniques.The effects of PMS concentration,catalyst dosage,p H value,initial BPA concentration on degradation efficiency were investigated.The results indicated that the degradation and mineralization efficiency of 70%CuO/HNTs were 1.6 and 2.2 times as those of CuO,respectively.Singlet oxygen（¹O₂）was the main active species in the catalytic process.The mechanism studies suggested that the redox reaction of Cu²⁺/Cu⁺and the abundant hydroxyl groups of HNTs played the key roles in the degradation process.In addition,the formed Cu-O-Al bond improved the cycle performance of CuO/HNTs.