| Dimethyl Phthalate(DMP), which is a kind of reproductive toxicity, endocrine disruptors, and belongs to the persistent organic pollutants. It has been detected in atmosphere,water, soil.It is a kind of phthalate acid esters (PAEs) material, its homologue solubility in water is better than the others, the concentration in water can reach a large value. A various of pollutants can transfer and transformation in water and soil, frequently. PAEs are used in a large number of production, life activities, it has caused a certain degree of enviro nmental pollution, it could easily transferred from the polluted water to soil migration, it will also release from contaminated soil into water, so the study on migration transformation rule of DMP in the water and soil is very important. Typical soils in Chongqing City, purple soil is the tested soil, a leaching experiment is conducted using soil column simulation to explore the adsorption characteristics of soil on DMP in contaminated water,and the influences in the process. Then, the discussion will focus on the release of DMP in contaminated soil to simulate river water, the influences of different leaching solution on soil and release into water. The results showed that:(1) The concentrations of DMP were determined by high-line liquid chromatography (HPLC-20AT). Method:C18 column, UV detection wavelength:224 nm, detector cell temperature:40℃, ishing solvent was V(methanol):V(water)=80:20, the total flow rate:1 mL/min, single sample volume:15 μL, single operation time:5 min. In this condition the detection effect was the best. Linear correlation coefficient(R) was 0.9997.(2) Parabolic equation was suited to describe adsorption kinetics of DMP by soils, the correlation coefficients were over 0.99. The concentration of DMP in the leaching solution had significantly effect on the adsorption amounts of DMP (P<0.05). With the increasing concentration of DMP, the adsorption capacities of soil increased linearly, the correlation coefficient was 0.9979. The concentrations of DMP in the leaching solution were 25,50,75,100,150 mg/L, the adsorption quantities were 50.72,83.59, 106.32,132.53,184.78 μg/g. And the adsorption rates were 32.46%,26.75%,22.68%, 21.20%,19.71%, respectively. With the increase of DMP concentrations, the adsorption rates decreased gradually.(3) The ionic strength and pH in leaching solution had a significant effects on adsorption of DMP(P<0.05), the leaching pH is similar in different ionic strengths and leachate pH values.The concentration of CaC12 in the leaching solution were 0,1,2,3, 4,5 g/L, the adsorption quantity were 204.65,184.55,176.30,132.53,188.39,172.50 μg/g, and the adsorption rates were 32.75%,30.01%,28.84%,21.20%,30.14%,27.60%, respectively.(4) The addition of exogenous organic matter and active agent in soils to the influence of the adsorbed amount of DMP reached significant level(P<0.05), and had apromoting effect on absorbent. The pH of leaching liquid had a small variation range, it has illustrated the addition of exogenous organic matter and active agent in the soils had weak effects on pH of leaching liquid. The organic matter contents in soils were 0, 5,10,15,20,30 g/kg, the concentration of DMP in leaching solutions were 100 mg/L, the adsorbance of DMP were 132.53,312.40,315.72,296.84,240.17,323.03 μg/g, the adsorption rates were 21.20%,52.48%,53.74%,50.78%,40.82%,54.82%, respectively. The contents of surfactant SDBS added into soils were 0,50,200,300,400,600,800 mg/kg, the concentration of DMP in leaching solutions were 100 mg/L, the adsorbance of the DMP were 132.53,228.71,161.30,192.24,160.57,145.11,133.11 ug/g.The adsorption rates were 21.20%,38.42%,27.32%,32.43%,26.98%,24.38%,22.20%, respectively.(5) Soil microbial in the the first leaching experiment can fix DMP. The initial sorption leaching test, leaching solution concentration, retention were significantly different in two groups. Experimental group was added microbial inhibitors, DMP retention amount was 132.23 μg/g, no added biological inhibitor group, DMP retention amount was 199.29 μg/g. The adsorption rates were 21.20%,31.89%, respectively.(6) Two constant equation was suited to describe release kinetics of DMP by soil, the correlation coefficients were over 0.98. The release test of DMP transfered from soil into water was indicated that the higher DMP contents in soils, the lower release rate was, the correlation between the soil retention capacity and release rate was-0.937,reached significant correlation (n=5, P=0.05).The research illustrated that the higher of retention capacity with the lower release rate, the adsorbent of DMP by soil was relatively stable, the release amount was limited. The concentration of DMP in the first leaching solution were 25,50,75,100,150 mg/L, the release amount were 1.13, 0.99,1.26,0.96,0.67 μg/g, the release rates were 2.41%,1.26%,1.24%,0.78%,0.38%, respectively.(7) The ionic strength of leaching solution in the absorption process has significantly affected on the release quantity of DMP (P<0.05). The correlation between the release rate and release quantity was 0.933 at different ionic strengths in the leaching solution, the correlation is significant (n=5, P=0.05). DMP leaching solution of different ionic strengths, the concentrations of CaC12 were 0,2,3,4,5 g/L, the release amounts were 1.13,0.71,0.59,1.33,0.89 μg/g,the release rates were 0.59%,0.43%, 0.48%,0.74%,0.55%, respectively. Different pH of leaching solution treatment have significantly effect on the release of DMP (P<0.05), the release amount was very significantly (P<0.01). The release rate of DMP with different pH of first leaching solution treatment, pH values were 3.0,5.0,6.0,7.0,7.6, the release amounts were 3.56, 2.34,2.00,0.90,0.59 μg/g,the release rates were 2.67%,1.52%,1.32%,0.60%,0.48%, respectively. The release rate in pH 3.0 is the highest value, which was 2.67%, the release capacity was higher than the other acidic conditions.(8) DMP release assay in the soils which had additted exogenous organic matter, all samples were not detected in DMP, the organic matter added into the soils enhanced the adsorption stability of DMP, so DMP was hardly to transport and diffusion. Exogenous surfactant SDBS in soils were 0,50,300,800 mg/kg, the release amounts were 0.59,0.09,1.18,7.04 μg/g,the release rates were 0.48%,0.04%,0.65%,5.87%, respectively. Exogenous surfactant SDBS in soil was 800mg/kg, the release rate of DMP was much higher than other treatments, the contents of active agent in the soils had significant effect on the release of DMP (P<0.01).(9) On different soil microbial activity, after the initial leaching tests, DMP release quantities of the control group (microbial unchecked) and the experimental group were 0.83,0.59 μg/g, the release rates were 0.48%. DMP loss rates were 12.28% and 6.94%, respectively. |
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