响应曲面法优化土壤镉浸提过程

Optimization of soil Cd extraction process using the response surface methodology

以温度、提取时间、土液比为研究因素,考察浸提剂乙二胺四乙酸二钠(EDTA-2Na)对土壤Cd浸提率的影响。首先,以单因素实验为基础,研究3因素单独对土壤Cd浸提率的影响,结果发现随着3因素水平的提高,土壤Cd浸提率整体呈上升趋势,在一定的范围内(温度20～25℃、提取时间50～90 min、土液比1:2～1:5),土壤Cd浸提率增大较为明显,分别上升了35%、8%、17%,而随着3因素水平的提升(温度30～35℃、提取时间130～170 min、土液比1:7～1:10),土壤Cd浸提率上升了5%、1%、4%;其次,采用响应曲面分析法中Box-Behnken中心实验设计法,建立了基于土壤Cd浸提率影响因素的二次函数预测模型,结果表明,模型预测值与实验实测值较为接近,各实验点几乎全部位于1:1线。在3因素研究范围内,当温度为30℃、提取时间为130 min、土液比约为1:6.5时,土壤Cd浸提率效果最佳。所得结论有助于进一步改进浸提剂EDTA-2Na对土壤Cd的浸提效率。

In this study, the effect of EDTA-2Na extractant on soil Cd extraction rate was investigated when the temperature, extraction time and soil-leaching solution ratio were taken as the research factors. First, the influences of the three factors on the soil Cd extraction rate were studied on the basis of the single factor test. The results showed that the soil Cd extraction rate increased with the increase of these three factors. Within a certain range of temperature from 20 to 25 ℃, extraction time from 50 to 90 min or soil-solution ratio from 1:2 to 1:5, the soil Cd extraction rate presented a remarkable increase by 35%, 8% or 17%, respectively. Then, with the increase of three factors(temperature from 30 to 35 ℃, extraction time from 130 to 170 min, soil-solution ratio from 1:7 to 1:10), the soil Cd extraction rate increased by 5%, 1% or 4%, respectively. Second, the Box-Behnken design in the response surface method was adopted to establish the quadratic prediction model for soil Cd extraction rate based on the influence factors. The results showed that the model prediction values for soil Cd extraction rate were considerably close to the test values, and the test points were almost on the 1:1 line. The best soil Cd extraction rate occurred at the temperature of 30 ℃, the extraction time of 130 min and the soil-solution ratio of about 1:6.5.At last, the aforementioned results are helpful to further improve the soil Cd leaching efficiency with the extractant EDTA-2Na.