Study On Migration Of Nitrobenzene In Groundwater

Based on the current status of the Weihe River is badly polluted, and the impact of organic pollutants in groundwater become apparent, has affected people in the context of production and living, combined with characteristics of groundwater movement in coastal areas of the Weihe River, the Weihe River marsh choose migration of groundwater in the study of nitrobenzene object, on the characteristics of pollutant nitrobenzene in the migration of groundwater carried out in the systemUsing laboratory test simulation methods of nitrobenzene in water depth of sand of different particle size of the internal migration of media law, revealing the migration process of nitrobenzene dilution, adsorption, degradation and other behavioral characteristics, analyze and interpret the nitrobenzene sand of different sizes in the migration laws of media features. The results showed that:1. By NaCl tracer experiments in groundwater of different size sand media permeability k. The screening of the sand and the sand permeability coefficients were 4.18m/d,20.74m/d, without the screening of the Weihe River Floodplain of the original sand sample penetration coefficient 5.06 m/d.2. This study shows that the migration of nitrobenzene in the groundwater are mainly due to convection, diffusion, adsorption and biodegradation. To some extent, nitrobenzene density than water will also affect the migration characteristics, especially in the higher concentration of nitrobenzene in groundwater, Physical properties of the density of nitrobenzene has a greater impact of vertical and horizontal distribution of nitrobenzene.3. According to the model used in this experiment results showed that:Groundwater in different media size, the particle size distribution is the key factor affecting the adsorption effect. The more uniform particle size distribution, the adsorption of the more obvious, the concentration of nitrobenzene in the aquifer decline faster. In the same concentration, the adsorption capacity of the original sand sample is greater than the adsorption capacity of fine sand, fine sand is greater than the adsorption capacity of the adsorption capacity of sand. Fine sand and the original particle size distribution of sand-like sand than in the more uniform, so the migration process in nitrobenzene, fine sand and medium sand aquifer, the concentration of nitrobenzene in the sand than smaller. And because the fine sand and the sand like the original particle size distribution and porosity are relatively close, so the two of nitrobenzene in the migration of groundwater law have shown time or space, whether it is also relatively close.4. Adsorption and biodegradation in the interaction of experiment can be drawn, fine sand, medium sand and sand like the original fast adsorption time were 1.5,1.5 and 2h, the slow desorption time was 5.5,1 and 5h, the time to reach equilibrium respectively 7,2.5 and 7h.5. Three different size media aquifer, the nitrobenzene concentration in the uneven distribution in the vertical direction, as the depth increases the concentration of nitrobenzene, there are two main reasons for this phenomenon. First, the uneven distribution of groundwater flow, shallow depth of the flow velocity is greater than buried deep, so embedded in the unit of time where the depth of water on the performance of nitrobenzene in the role of convective dispersion significantly, the concentration of nitrobenzene in the aquifer rapid decline; Second, the proportion of the nitrobenzene is greater than the proportion of water, the vertical direction because of gravity, near the top of the nitrobenzene to the lower migration, resulting in decreased upper lower content of nitrobenzene increased. Interaction between the two shows this phenomenon.6. In the actual flow of groundwater under the same, the same sampling hole concentration of nitrobenzene peak time from early to late followed by medium sand, fine sand and sand like the original, this phenomenon is also associated with three different kind of block sand different capacities related. According to the experimental data, the calculated fine sand, medium sand and sand samples of the original average migration rate of nitrobenzene 33.47cm/d,37.94cm/d,30.36cm/d, well below the seepage of groundwater flow velocity 46.92cm/d.7. Using MATLAB tools to create the original steady flow of sand are the source of groundwater solute diffusion model of time, and the longitudinal diffusion coefficient Dx estimation, regression analysis of results to Dx=0.540cm2/min established one-dimensional steady source of solute with time migration model, the measured value of the test with relative errors of predicted value between 0.01 to 0.05, so that the predicted effect is good.