| Water contamination of antibiotic has drawn widespread attention. Adsorption is a simple, fast and efficient method to remove organic contaminants and heavy metals, and the most critical technical problem is adsorbents. Carbon nanotubes(CNTs) have aroused widespread attention as a new type of adsorbents due to their outstanding ability for the removal of various inorganic and organic contaminants. CNTs have been the focus of considerable research because of their highly porous and hollow structure, large specific surface areas, and CNTs show strong interactions with organic compounds.Roxithromycin is the derivative of erythromycin, belonging to macrolide. It frequently detected from the water. Although the content is tiny, it may cause bacteria resistance to drugs and "false" persistent presence. It is likely to enter the human body through drinking water, and lead to the potential damages on human health. Seldom current research on removing roxithromycin in water is reported. Therefore, the research on roxithromycin removal in water has research worthy and practical necessity. This dissertation focuses on the removal of roxithromycin in water.The performance of using MWCNTs to adsorption roxithromycin from aqueous solution was investigated. The effects of environmental factors such as p H, temperature, dosage, humic acid and ion strength were discussed, as well as the reaction mechanism. The results demonstrate p H effect had significant effect on roxithromycin adsorption. The adsorption reached 39.75 mg/g maximum value at low p H. When the p H increased, the adsorption always decreased. Promotion of roxithromycin adsorption was observed at high humic acid concentration, however, inhibition of roxithromycin adsorption at low humic acid concentration. However, the ion strength effect was quite opposite. Ionic strength had bad effect on the roxithromycin adsorption, while increased the removal of roxithromycin. MWCNTs have good adsorption ability on roxithromycin by experiments. The sorption kinetics and thermodynamics were found to follow pseudo-first-order kinetic model, intraparticle diffusion model and Freundlich isotherm equation. The adsorption was exothermic reaction and physical adsorption, △G<0, △S<0.Magnetic MWCNTs were prepared by wet chemical method to embed iron oxide particles into MWCNTs. Using magnetic separation techniques can extract the magnetic MWCNTs from the water. It reduces pollution caused by the dispersion of MWCNTs in water for its nanometer diameter. MWCNTs and magnetic MWCNTs were characterized by microscopic analysis methods, such as: SEM, FT-IR, Zeta potential, Boehm titration and magnetic separation.Three single-factor experiments(p H, temperature, time) conducted to study the effects of magnetic MWCNTs adsorbing roxithromycin. Focus on the analysis of adsorption properties of magnetic MWCNTs and adsorption mechanism. The results showed as the p H increased, the adsorption amount raised after a decline. The adsorption reached 39.5 mg/g maximum value at p H=1, as reached 20.6 mg/g minimum value in neutral condition. The adsorption of magnetic MWCNTs at 50 mg for roxithromycin reached saturated adsorption state of around 150 min, removal rate about 85%. However, magnetic MWCNTs can quickly separate from water. Quasi first-kinetic-order equation, quasi second-kinetic-order equation and Langmuir isotherm equation can well fit the adsorption. The adsorption of magnetic MWCNTs for roxithromycin was endothermic reaction, physical and chemical adsorption, △G<0, △S>0.MWCNTs had good adsorption capacity for roxithromycin through the study. Given the studies domestic and foreign and school laboratory conditions, the adsorption property of MWCNTs on roxithromycin in water was studied by factors effect, the adsorption kinetics and thermodynamics. Magnetic MWCNTs enhance the possibility of the application in water treatment. It found that the magnetic MWCNTs have good removal capacity for roxithromycin. Hope the study can provide some help for removing antibiotics in water. |
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