Novel soil remediation technology for simultaneous organic pollutant catalytic degradation and nitrogen supplementation

This study developed a novel remediation technology based on urea-hydrogen peroxide (UHP) activated by a synthesized Fe-impregnated biochar (FB). The technology can simultaneously degrade sulfamethoxazole (SMZ) and supply nitrogen nutrition in cropland soil. Experimental results showed that 97.56% of SMZ was removed in the FB-UHP system within 24 h, whereas 7.12% and 14.65% were removed in the individual application of FB and UHP. Chemical probe and scavenger test results demonstrated that SMZ degradation mainly occurred through oxidation of hydroxyl radicals generated from the activation of UHP by FB. The effects of FB pyrolysis temperature, initial pH, and reaction temperature were investigated. The combination of UHP and FB led to efficient SMZ degradation at a wide pH range of 2-10. Catalytic durability test results showed that FB exhibited good stability even after four uses. A soil column leaching experiment showed that the addition of FB-UHP reduced the SMZ leaching from the soil by 95.06%, increased the nitrogen content on surface soil by approximately 2.5 times, and decreased the nitrogen leaching by 97.57%. Early-stage seedling growth bioassay confirmed that FB-UHP significantly enhanced the SMZ degradation, increased the soil nitrogen content, and improved the lettuce plant growth. Therefore, application of FB-activated UHP is a promising technology for agricultural soil remediation.