石灰、粉煤灰改性对盐渍土吸附石油污染物行为的影响

有效调控污染物的运移是实现污染土工程再利用的前提。考虑石油污染盐渍土的特殊性及工程利用的力学需求,优选石灰和粉煤灰为改性材料,结合静态动态试验,研究石灰和粉煤灰对滨海盐渍土中石油污染物的吸附解吸行为的影响。结果表明:单独的石灰和粉煤灰,对石油污染物的吸附率分别为26%和14%,两者联合作用时,吸附率提高到39%,在盐渍土中加入石灰和粉煤灰可有效提高对石油污染物的吸附量,加快吸附稳定速率;盐渍土、石灰+盐渍土、粉煤灰+盐渍土、石灰+粉煤灰+盐渍土对石油的吸附动力学均符合Lagergren二级动力学非线性方程,联合作用可使吸附平衡时间由400min缩短至60min;石灰、粉煤灰有利于吸附赋存于土颗粒孔隙中未被盐渍土颗粒吸附的呈自由态的石油;盐渍土、石灰+盐渍土、粉煤灰+盐渍土、石灰+粉煤灰+盐渍土对石油污染物的吸附等温线均为非线性Freundlich模式;石油被解吸的能力依次为盐渍土粉煤灰+盐渍土石灰+盐渍土石灰+粉煤灰+盐渍土,石灰+粉煤灰对石油污染物的吸附以化学吸附为主,具有不可逆性,有助于缓解环境温度的影响,增强稳定性。

Influence of property-modified lime and fly ash on oil absorption behaviors of saline soil

Control of pollutant migration is the prerequisite for the reuse of contaminated soil. Considering the properties of contaminated saline soil and the mechanical demand in engineering utilization, lime and fly ash were chosen optimally as treated materials. The influence of lime and fly ash on adsorption-desorption behaviors of oil contamination in inshore saline soil were studied via static and dynamic tests. Results indicate that:under the individual action of lime and fly ash, the oil adsorption rate is increased by 26% and 14%, respectively, and it increases by 39% as combine. As a conclusion, lime and fly ash can effectively increase adsorption rate and improve adsorption rate of oil contamination. Adsorption kinetics of saline soil, lime + saline soil, fly ash + saline soil, lime + fly ash + saline soil on oil contamination conform to the dynamic nonlinear equation of Lagergren second-level dynamics. The adsorption equilibrium time of saline soil was 400 min and it reduced to 60 min for lime and fly ash. Lime and fly ash is beneficial to adsorb the free oil which cannot be adsorbed by saline soil. The adsorption isotherms of saline soil, lime + saline soil, fly ash + saline soil, lime + fly ash + saline soil are non-linear Freundlich models. Adsorption of oil contamination for lime + fly ash is an irreversible chemical process, which can help to reduce the influence of ambient temperature and enhance stability.