| Antibiotics are chemical substances with anti-pathogen or other activities produced by the metabolism of bacteria,fungi and other microorganisms or higher animals and plants.The large number of antibiotic residues in water has many adverse effects on human health and the ecological environment,but conventional water treatment processes are difficult to achieve ideal purification effects.Ceramic membrane catalytic ozonation technology has been widely used in the field of water treatment in recent years.However,due to the high production cost of the ceramic membrane’s complex preparation and modification process,and the lack of a unified explanation of the catalytic mechanism,it makes the promotion of this technology greatly hindered.Therefore,the simplification of ceramic membrane modification method and the exploration of ceramic membrane catalytic ozone mechanism are of great significance for the wide application of ceramic membrane catalytic ozone technology.In the process of ceramic membrane preparation,anatase（Ti O2）and Mn O2nanoparticles were doped into preparation to realize the unity of ceramic membrane preparation and modification process,so as to simplify the ceramic membrane modification process,and alumina membrane,manganese oxide membrane and titanium oxide membrane（100nm）、titanium oxide membrane（2-3μm）were successfully prepared,and these ceramic membranes were characterized.The removal effect of norfloxacin with time by ozonation,ceramic membrane adsorption and ceramic membrane synergistic ozonation technology,and the effects of ozone dosage,flow rate,initial p H,inorganic salt concentration and humic acid concentration on the treatment effect were studied.The mechanism of ceramic membrane catalytic ozone was studied.The results are as follows:（1）Doping of nano-particles in the ceramic membrane will change the structure（morphology,pore size,porosity,roughness）of the ceramic membrane,which will affect the mechanical strength,chemical stability and membrane flux of the ceramic membrane.The ceramic membrane has strong acid corrosion resistance（<3%）and alkali corrosion resistance（<0.20%）,but compared with aluminum oxide membrane,the doping of metal oxide nanoparticles will reduce the acid etching stability of the ceramic membrane,and has almost no effect on the alkali etching stability,the high-temperature firing process will change the crystal form and valence state of the modified substance:Ti O2is converted from anatase to rutile,and Ti and Mn show a variety of valence states;The ozone concentration changes significantly before and after entering and exiting the ceramic membrane,indicating that the ceramic membrane has the ability to catalyze ozone decomposition,the doping of anatase（Ti O2）and manganese dioxide further reduces the ozone concentration after the membrane is formed,indicating that the modification of the ceramic membrane improves the catalytic effect of ozone.The catalytic ability of several ceramic membranes on ozone is shown as follows:oxidation manganese membrane>titanium oxide membrane（100nm）>titanium oxide membrane（2-3μm）>aluminum oxide membrane.（2）The modified performance of the ceramic membrane improves the adsorption effect of the ceramic membrane on norfloxacin,and after the ceramic membrane is applied to the treatment of norfloxacin in water with ozone synergistic effect,the removal effect is stronger than that of the ozone oxidation and the adsorption of the ceramic membrane alone.Increasing the dosage of ozone can improve the removal efficiency of norfloxacin and TOC,but too high dosage of ozone will weaken the role of the ceramic membrane in the reaction system.The change of flow rate has a lower effect on the removal of norfloxacin,increasing the flow rate can promote the removal effect of the ceramic membrane with adsorption as the main performance,but it is not conducive to the catalytic action of the ceramic membrane with catalysis as the main function.The increase of initial p H only strengthens the removal of TOC,and has no significant effect on the removal of norfloxacin;the increase of the concentration of inorganic salt（Ca Cl2）will reduce the influence of the ceramic membrane on the reaction system,thereby inhibiting the synergistic ozone oxidation effect of the ceramic membrane;humic acid at a low concentration（2mg/L）will inhibit the removal effect of norfloxacin,but when the concentration is higher（4mg/L）,it will have a promotion trend.（3）The degradation process of norfloxacin under ozone oxidation conforms to the zero-order reaction kinetics,while the degradation process under the ceramic membrane and ozone oxidation conforms to the first-order reaction kinetics.The addition of tert-butanol will reduce the removal efficiency of norfloxacin and the catalytic ozonolysis rate of the ceramic membrane under ozone oxidation,which proves the existence of·OH in the reaction system.By comparing the ozone decomposition rate under different ceramic membrane catalysis methods,it is found that the ceramic membrane pore circulation catalysis has the strongest catalytic performance on ozone,indicating that membrane pore catalysis is the main way for ceramic membranes to catalyze ozone. |
