纳米TiO2对土壤Hg2+吸附解吸性能的影响

为了研究纳米TiO_2对土壤吸附解吸汞性能的影响,以三峡水库消落区土壤为代表,选择2种晶型(锐钛矿和金红石)的纳米TiO_2颗粒,设置3个浓度梯度(2,4,8g/kg),制成含有不同浓度纳米TiO_2颗粒的土样,配制不同浓度的Hg~(2+)溶液,进行吸附解吸试验。结果表明:纳米TiO_2颗粒可提高土壤对Hg~(2+)的吸附量,但受颗粒的晶型和浓度的影响;锐钛矿颗粒对土壤吸附解吸Hg~(2+)的影响更大,其吸附作用力更强,不易解吸,其中4g/kg处理组吸附作用最强,与对照相比,最大吸附量可提高32.65%,且其解吸率低于对照组;金红石颗粒处理组对Hg~(2+)的吸附量随颗粒浓度的升高而增大,但吸附作用力较弱,容易被解吸,8g/kg处理组影响最大,与对照相比,最大吸附量提高18.18%,但其解吸率也最大。因此,纳米TiO_2颗粒增强土壤对汞的吸附作用,从而可能影响汞在环境中的迁移转化过程,特别是锐钛矿型颗粒。

Effect of Nano-TiO2 on the Adsorption and Desorption of Hg2+in Soil

To investigate the effects of nano-TiO2 on the adsorption and desorption of Hg2+ in soil of the drawdown area of the Three Gorges Reservoir,nano-TiO2 particles of different crystal structures (anatase and rutile) were selected,and were added to soil to preparade four concentrations (0,2,4,and 8 g/kg) samples.Meanwhile,Hg2+ solutions with different Hg2+ concentrations were preparade to conduct the Hg2+ adsorption and desorption experiments.The results showed that nano-TiO2 particles increased Hg2+ adsorption capacity of soil,but it was affected by the crystal form and concentration of nano-TiO2 particles.The adsorption capacity of anatase particles was stronger than that of rutile particles,and adsorbed Hg2+ was difficult to be desorbed.In anatase particles treatments,when the concentration of nano-TiO2 particles was 4 g/kg,its Hg2+adsorption capacity was the largest,which was 32.65％ higher than that of the control group,and its desorption rate was lower than that of the control group.In the treatments with rutile particles,the amount of adsorbed Hg2+ increased with increasing of particle concentration,however Hg2+ was easily desorbed.When the particles concentration was 8 g/kg,its adsorption capacity was the maximum and was 18.18％ higher than that of the control group,but its desorption rate was the largest.Nano-TiO2 particles,especially anatase particles,enhance the Hg2+ adsorption capacity of soil,and this may impact the migration and transformation of Hg2+ in the environment.