| In this study,the manganese/germanium catalysts with different active group partition ratios at 500?/600? were prepared by equal volume impregnation method.The physicochemical properties of the prepared catalysts were analyzed and analyzed by various characterization methods and activity contrast differences.At the same time,the optimal catalyst conditions for oxytetracycline degradation were screened out,and the degradation pathway and mechanism of oxytetracycline in this experiment were analyzed and inferred.Finally,the use of livestock and poultry wastewater containing antibiotics was validated for the practical application of optimal catalysts.First,the catalyst preparation and characterization experiments were carried out using the impregnation method at a final calcining temperature of 500?/600? and Mn/Ce(molar ratio)=(0.05:0.1,0.1:0.1,0.2:0.1).Depending on the characterization results of XRD,SEM,BET,ICP,etc.,Mn02 and Ce02 were successfully supported on the ? alumina carrier.Compared with 500?,the crystallinity,the BET value,the hydroxyl density,etc.of the manganese lanthanum component supported on the carrier can be improved by final temperature of 600? with same active component concentration ratio.And at the same calcination final temperature,the increase in the proportion of Mn in the distribution ratio has a negative effect on the preparation of the catalyst,reducing the degree of crystallization of the active component and the specific surface area.The catalytic ozone activity test with oxytetracycline as contaminant showed that under the condition of pH=7,the calcination temperature of 600? Mn:Ce = 0.05:0.1 catalyst was the best,and the rate constant K was 2.98 x10-3,COD removal rate up to 72%,ozone utilization reached about 2.16.In this experiment,we found that the optimal catalyst final temperature was 600?.,Mn:Ce=0.05:0.1 catalyst,and under the condition of pH=7,catalytic Ozone was used to treat oxytetracycline simulated wastewater with a COD value of 300 mg/L.When 150 mg/L ozone was added and the effective contact time was 30 minutes,the best treatment result was found.Using the best experimental conditions through repeated experiments,we can see that the catalyst has high stability,with about 80%of removal rate,and the ozone coefficient is more than 2.Alkali resistance experiments showed that the alkali solution at pH=13 significantly deactivated the catalyst.In the investigation of inorganic salt ions,with the condition of pH=7,150 mg/L sodium carbonate and sodium monohydrogen phosphate can inhibit the catalytic treatment effect by 26%or more,and the addition of equal amount of sodium phosphate does not cause the inhibitory effect.It is inferred that this process is as follows:Most oxytetracyclines are first adsorbed on the surface of the catalyst,and a small portion of oxytetracycline is directly oxidized with ozone.At the same time,the ozone adsorbs on the surface of the catalyst and binds to the surface hydroxyl groups,thereby decomposing and converting into hydroxyl radicals.The resulting hydroxyl radicals are directly mineralized with oxytetracycline on the surface of the catalyst.Excess hydroxyl radicals are released into the solution to deeply degrade by-products in the water and complete degradation of oxytetracyclineFor the treatment of the actual waste water of livestock and poultry,the removal rate of COD during the addition of the catalyst in this experiment was increased by 23%.It is proved that the catalyst treated in this experiment treats the actual wastewater as effectively.The best condition for the treatment of current livestock and poultry wastewater is 200 mg/L ozone dosage.With the condition of effective contact time is 24 min,pH=7,the removal rates of UV254,COD,and TOC are 77.4%,55.4%,and 52%.Based on the above result,it can be seen that the removal of COD and TOC in the water also significantly reduces the UV254 value of the wastewater,indicating that the antibiotics in the water are also significantly degraded. |
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