Abstract:The application of nano TiO2 in the remediation of DPAA contaminated soils was studied. Results showed the addition of nano TiO2 enhanced the adsorbed amount of the DPAA onto red soil, yellow-brown soil and black soil. Due to the stability of nano TiO2 particles could be influenced by the soil organic materials, the addition nano TiO2 only increased the immobility of DPAA in red soil. Comparison two different utilization ways of nano TiO2 into black soil, the in-situ photocatalytic degradation was limited by the depth of light irradiation into soil and soil water contents. The removal efficiency was only 39.5% after 10-day irradiation, but promoted by 34.3% to 72.2% when converting soil to soil slurry by raising the water: soil ratio from 1︰1 to 10︰1, and this increasing trend were validated in red soil and yellow-brown soil with the degradation efficiency could reach 78.6% in red soil of lower organic matter content, higher than those in the other two soils.