Experimental Study On Thermal Desorption And Plant Treatment Of Rhodamine B In Contaminated Soil

Rhodamine B is a kind of typical organic dyes, and people always focus on the problem of its existence and treatment in water. In recent years, the phenomenon of rhodamine B contaminated in soil is gradually increasing, but the related research is very limited, so it is very important to explore the appropriate treatment technology to solve this problem.In this paper, we used clean soil to configure different concentrations of rhodamine B contaminated soil as the research object. In thermal desorption treatment test, used the soil which concentration of rhodamine B is 90.91 to 3462.54mg/kg in orthogonal design experiment and single factor experiment to study heating time, heating temperature, soil initial moisture content, and the initial concentration of rhodamine B,s influence on the desorption rate. In plant treatment test, plant ryegrass and alfalfa to dispose contaminated soil when rhodamine B concentration is 915.08 to 6269.73mg/kg, and by monitoring the plant growth conditions, calculation the removal rate of rhodamine B to determine the appropriate plant varieties.Soil has a natural degradation effect on rhodamine B, when the simulated polluted soil of rhodamine B concentration is 100 to 8000mg/kg, due to the self purification, the concentration in soil variable from 90.91 to 6269.73mg/kg after 15 days of natural degradation.In the thermal desorption text got the best conditions: when the initial concentration of rhodamine B is 90.91 to 915.08mg/kg, the optimum temperature is 300 DEG C, time is 50 min, soil initial moisture content is 15%, and the desorption rate can reach 31.87% to 79.19%. When the initial concentration of rhodamine B is 1774.23 to 3462.54mg/kg, the optimum temperature is 350 DEG C, time is 60 min, soil initial moisture is 15%, and the desorption rate can reach 35.12% to 80.78%.In plant treatment test, selecting alfalfa and ryegrass to dispose the contaminated soil, the results show that when the concentration is 915.08 to 6269.73mg/kg, the alfalfa,s survival rate can reach to 57.50%~79.58% after 90 days of planting, the removal rate can reach to 38.24%~43.42%. Ryegrass has a higher survival rate and removal rate, the survival rate can reach to 70.00%~89.33%, and the removal rate can reach to 52.18%~62.88% after 90 days of planting.In the practical application, it is needed to choose the appropriate method according to the actual situation. For the low concentration of rhodamine B in contaminated soil, priority to plant treatment, which can take into account the beauty of the environment, and the sustainable development of the soil; for medium and high concentration of rhodamine B in contaminated soil, and in emergency contaminated soil treatment process, thermal desorption treatment is preferred, which can obtain high desorption rate in a short repair cycle.