betadex and 2-4-dinitrotoluene

In this study, the effect of monopotassium phosphate (MKP) on the reduction in mobility and bioavailability of 2,4,6-trinitrotoluene (TNT) was tested. In the test soil, collected from an active firing range, of which cation binding sites were mostly exchanged with H(+) or Al(3+), potassium ions in MKP exchanged the existing cations and hence significantly increased TNT sorption. In addition, a competitive sorption experiment with hexafluorobenzene and 2,4-dinitrotoluene suggests that TNT was specifically sorbed through cation-polar interaction in the test soil. The unit-equivalent Freundlich sorption coefficient of TNT in MKP-amended soil (1370.96 mg-TNT/kg-soil) was about 13 times higher than that in untreated soil (106.23 mg-TNT/kg-soil). Finally, modified synthetic precipitation leaching procedure and hydroxypropyl-β-cyclodextrin extraction result revealed that MKP application could reduce both the leachability and bioavailability of soil TNT. The leachable and extractable fraction of TNT in untreated soil were 87.63% and 94.47% of the initial TNT, respectively, whereas these fractions decreased to 49.15% and 54.85% of the initial TNT in the presence of MKP, respectively. MKP application can be a benign technology which can reduce both mobility and bioavailability of TNT in soil.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adsorption; beta-Cyclodextrins; Calcium; Dinitrobenzenes; Fluorocarbons; Phosphates; Potassium Compounds; Soil Pollutants; Trinitrotoluene

Electrokinetic soil remediation has been proven to remove heavy metals and polar organics from low hydraulic conductivity subsurface environment. In this study, carboxymethyl-beta-cyclodextrin (CMCD) was used as a carrier to assist electrokinetic treatment for removal of low polarity organic contaminants from soils (2.2% organic carbon content). Naphthalene and 2,4-dinitrotoluene (2,4-DNT) were selected as the test compounds. The results from columns experiments showed that 46 and 43% of naphthalene and 2,4-DNT, respectively, were removed using 0.01 N NaNO(3) flushing solution with 40 V electrical potential while 70 and 72% of naphthalene and 2,4-DNT were removed using 2 g/L CMCD solution. Naphthalene and 2,4-DNT removal was enhanced to 83 and 89%, respectively, by using 2 g/L CMCD with 40 V electrical potential. Findings from this study also demonstrated that cyclodextrin assisted electrokinetics can enhance the removal rate of naphthalene and 2,4-DNT. Electric potential applied has more influence on the contaminant removal than the amount of CMCD used. Higher voltage application caused increase in the removal rate of naphthalene and 2,4-DNT, and appeared to be one of the critical factors in obtaining higher contaminant removal while increasing CMCD solution concentration above 2 g/L appeared to have little effect on the contaminant removal.

Topics: beta-Cyclodextrins; Dinitrobenzenes; Electrochemistry; Kinetics; Naphthalenes; Soil Pollutants; Solutions