Activation Of Urea-hydrogen Peroxide By Engineered Biochar To Simultaneous Degradation Of Antibiotic And Reduction Of Nitrogen And Phosphorus Leaching

The soil antibiotics pollution has attracted great attention around the world.The antibiotic production and consumption in China is quite large,the problem of soil antibiotic pollution is becoming more and more urgent.The contaminants sorption by biochars is recently a popular research area in China and other countries.However,the sorption ability of original biochar is limited and the organic contaminants adsorbed on biochar have the risk of release.The engineering technology of biochar proposes the noval approach for developing original biochar.The soil pollution in China has become to multiple pollution with organic contaminants,nitrogen and phosphorus leaching.Therefore,it is of great significance to develop a novel soil remediation technology for simultaneous organic pollutant catalytic degradation and reduction for nitrogen and phosphorus leaching.In this study,the antibiotic sulfamethoxazole（SMZ）is used as the target contaminant,dung and corn straw are used as raw biomass for biochar.The study of engineered biochar activated by urea peroxide（UHP）to degrade SMZ and control soil nitrogen,phosphorus leaching was carried out.The main results are as follows:（1）The hydroxyl radical（·OH）produced by Fe-impregnated biochar（FB）/UHP was the dominant oxidant in degrading SMZ.FB/UHP showed efficient SMZ degradation at a wide p H range of 2 to 10.The catalytic durability test results showed that the degradation efficiency of SMZ was in the range of 90.5 to 97.7%in 4 runs.（2）The degradation efficiency of SMZ in soil treated by FB/UHP was 91.99%after 7 days.The urea content in leachate decreased 18.96%treated by FB/UHP.FB/UHP could increase the nitrogen content in soil surface.（3）MgO crystals on the surface of Mg engineered biochar（MB）react with PO₄^3-and HPO₄^2-through precipitation mechanism to form Mg₃（PO₄）₂ and Mg HPO₄ crystals.MB can control the leaching loss of soil available phosphorus and increase soil phosphorus nutrition.The soil column experiment indicated that the MB decreased P loss from leaching by 86.63%.（4）Mg Fe-LDH engineered biochar（LB）was successfully synthesized.LB/UHP could degrade SMZ and adsorb nitrogen and phosphorus simultaneously.The degradation efficiency of SMZ first increased and then decreased with the increasing of biochar ratio.The degradation efficiency of SMZ reached the highest value of 90.01%when biochar content is 10 mg m L^-1,and·OH is demonstrated as the main reactive oxidant.The P adsorption kinetics fitted well with the Elovich model and chemical adsorption is the main mechanism.（5）LB/UHP has the effect on simultaneous organic pollutant catalytic degradation and reduction for nitrogen and phosphorus leaching.The degradation efficiency of SMZ in the soil was 73.75%undergoing the LB/UHP after 3 days,where the initial content was 8 mg kg^-1.When the concentrations of nitrogen and phosphorus in the soil were 4 g kg^-1and 4.8 g kg^-1,the retention of nitrogen and phosphorus was 67.72%and100%,respectively.