Study On TNT Wastewater Treatment By Modified Bentonite

In this paper, on the basis of many documents home and abroad, bentonite was modified by hexadecyl trimethyl ammonium bromide (CTMAB) as cationic surface active agent for the preparation of organbentonite which was then used for the treatment of TNT wastewater. The mechanism of TNT wastewater treatment was examined, and the results showed as follows:(1) In the selected influencing factors of preparation of organbentonite, orthogonal experimental results indicated that the influence of CTMAB concentration was the first for the modification effect, temperature, oscillation frequency and pH value being the second, the third and the fourth respectively. The single factor experiments were designed to verify the above experimental results, and finally the optimum technological condition of preparation of organbentonite was determined and was that, CTMAB concentration: 2%, Temperature: 60℃, Oscillation frequency: 120r/min, pH: neutral, Oscillation time: 2h.(2) In the selected influencing factors of simulated TNT wastewater treatments by modified bentonite, orthogonal experimental results indicated that the influence of pH value was the first for the removal rate, the dosage of modified bentonite, oscillation time and temperature being the second, the third and the fourth respectively. The single factor experiments were designed to verify the above experimental results, and finally the optimum technological condition of simulated TNT wastewater treatments by modified bentonite was determined and was that, pH: neutral, Modified bentonite dosage: 1g, Oscillation time: 60min, Temperature: 30℃, Oscillation frequency: 120r/min, TNT initial concentration: 130mg/L. In this case, the removal rate of TNT exceeded 96%, and the reduction rate of CODcr reached 79% or more. Under the optimum technological conditions, the effect of modified bentonite to disposal of TNT wastewater was better than that of the original soil, and the removal rate increased more than 10%.(3) The adsorption kinetics curve of TNT wastewater treatments by modified bentonite at 30℃indicated a balance was reached when the time is for 60 min, and the linear equation was obtained. The result that the correlation coefficient was 0.9988 which is over 0.9, showed that the Dynamical Behavior of TNT was fitted for the Langmuir adsorption equation quite well. Meanwhile the isothermal adsorption curve of TNT wastewater treatments by modified bentonite at 30℃was made. The result that the correlation coefficient was 0.9827 which is more than 0.9, demonstrated that the process was corresponding with Freundlich model. The result that empirical constant n in Freundlich isotherm adsorption equation was 1.1523 which is above 1, indicated that the adsorption process of TNT wastewater treatments by modified bentonite was easily performed.