Effects Of Metal Ions / Oxide Insertion On The Interaction Behavior Of Layered Clay And Antibiotics

In recent years, montmorillonite as a new green materials can be widely used in adsorption, catalytic degradation of pollutants. This paper is an adsorption research on levofloxacin in wastewater, using metal ion or oxide modified montmorillonite as the adsorbent. Firstly, the characterization of modified montmorillonite is analyzed. Secondly, the effect on pH, adsorbent dosage, adsorption time and temperature is studied in adsorption process. Lastly, the parameters of thermodynamics and kinetics are abtained by research of kinetics and isotherms of adsorption. The main contents and conclusions of the study are as follows:(1) It is can be found in characterization of Fe-pillared montmorillonite:modified montmorillonite with increased surface area, microporous structure ratio and higher interlayer spacing than before. Adsorption experiment shows that the maximum adsorption capacity is 41.13 mg · g-1 when pH of 6 to 7 and adsorbent dosage is 0.5g·L-1; Adsorption process is divided into two processes:fast and slow adsorption. Through study of kinetics and thermodynamics of adsorption, it is fround that adsorption is monolayer chemisorptions, and the adsorption process is a spontaneous endothermic reaction. It is found that the concentration of phosphate can reduce adsorption capacity, the possible reason is bidentate (-(Fe1O)2PO2-2) and monodentate (-Fe1OPO2OH-1.5) formed by phosphate and iron ion in Fe-MT.(2) By metal ions modified montmorillonite adsorption levofloxacin experiment, the maximum adsorption capacity is 82.88,94.60,96.72 and 106.20mg · g-1 when pH is 6 to 7 and adsorbent dosage is 0.4g/L. Through detection of cation release in solution after adsorption we find that metal ion modified montmorillonite is involved in the adsorption process with varying degrees of ion exchange reaction except Fe-MT. The ability of xchanged from montmorillonite is Mg2+>Cu2+>Al3+. Combined with IR characterization, kinetics and thermodynamics of investigation, the conclusion of adsorption mechanism is that as follows:Fe-MT adsorption levofloxacin mechanism is complexation reactions between the surface or layer; Mg-MT, Al-MT and Cu-MT adsorption levofloxacin is not only complex reaction, but also between the layers of metal ion exchange reaction.(3) Manganese oxide modified montmorillonite have good adsorption capacity of levofloxacin, due to montmorillonite surface with excessive negative charge after concentrated alkali-treated, thus at a pH value in 2.00 to 3.00,the adsorption reaches a maximum is 78mg·g-1. Combined the adsorption process and study of thermodynamic parameters we find that the process fits in Langmuir isotherm and second-order kinetic models, this finds indicating that the adsorption process is a spontaneous and monolayer chemisorption.In summary, montmorillonite has good adsorption capacity for levofloxacin after modified by metal ions/oxide; furthermore, show that modified montmorillonite is an inexpensive and green adsorbent which can be used for water pollution treatment.