纳米二氧化钛光催化修复二苯砷酸污染土壤的研究

Application of Nano TiO_2 in Remediation of DPAA-Contaminated Soils

利用纳米二氧化钛去除土壤中的二苯砷酸(diphenylarsinicacid,DPAA),研究了纳米二氧化钛对土壤吸附DPAA能力的影响,着重比较了原位直接光解法与异位泥浆处理法在去除DPAA效率上的差异,并对纳米二氧化钛催化降解的实验室条件进行了优化。结果表明:纳米二氧化钛添加可提高土壤对DPAA的吸附能力,但由于纳米颗粒的稳定性受到土壤中有机质影响,仅能提高红壤对DPAA的固定能力。直接施加纳米颗粒的原位光降解受纳米二氧化钛用量影响较小,主要受限于光在土层中的光照厚度及土壤含水量。汞灯照射10天后,DPAA的降解率最高仅为39.5%,但加水将土壤调制成泥浆、通过搅拌提高紫外照射下土壤与纳米颗粒的受辐射几率,可显著提高降解率,其中水土比变化较纳米二氧化钛用量更显著影响催化反应效率。将水土比从1︰1提升至10︰1,光照1.5 h后DPAA的降解率从34.3%上升至72.2%。泥浆搅拌下,二氧化钛光催化降解的方法在不同土壤中均表现出良好的降解效率,在有机质含量较低的红壤中DPAA的降解率最高达78.6%。

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 degradation was limited red soil. Comparison two different utilization ways of nano TiO2 into black soil, the in-situ photocatalytic by the depth of light irradiation into soil and soil water contents. The removal efficiency was only 39.5% after lO-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.