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Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substance 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4- Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Phenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenantrene;phenanthrene, DDT, Acetanilide were chosen having Koc value range from 1.239 to 4.09.

The Log Koc value of test chemical was determined to be 1.8568 dimensionless at 25°C.This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.

Additional information

Adsorption/desorption:

Different experimental studies have been reviewed from study report and peer reviewed journal for adsorption endpoint and their results are summarized below.

 

In first study the adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substance 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4- Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Phenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenantrene;phenanthrene, DDT, Acetanilide were chosen having Koc value range from 1.239 to 4.09.

The Log Koc value of test chemical was determined to be 1.8568 dimensionless at 25°C.This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.

 

Another study was reviewed from publication from Colloid & Polymer Science journal in this study the Adsorption experiment was performed in that the apparent adsorption rate was obtained by 200 ml of test chemical solution of 200 mg. dm -3 was stirred at a high rate of 500 rpm, and 0.20 g of the adsorbent was added. Samples were taken out and filtered using 0.45 Fan membrane-filters immediately. The residual concentration of the filtrate was determined by a total organic carbon analyzer. After analyzing The test chemical adsorbed only 5 % in 30 min on montmorillonite-Na clay. On the basis of this it is concluded that test chemical showed low sorption on montmorillonite-Na clay. The apparent adsorption rate was obtained by 200 ml of test chemical solution of 200 mg. dm -3 was stirred at a high rate of 500 rpm, and 0.20 g of the adsorbent was added. Samples were taken out and filtered using 0.45 Fan membrane-filters immediately. The residual concentration of the filtrate was determined by a total organic carbon analyzer. After analyzing The test chemical adsorbed only 5 % in 30 min on montmorillonite-Na clay. On the basis of this it is concluded that test chemical showed low sorption on montmorillonite-Na clay.

 

Last study was reviewed from environmental science technology journal (1987) in this study the adsorption desorption experiment was performed to determine adsorption capacity of test chemical on sediments EPA 5 and EPA 14 the sediments were obtained from the Environmental Research Laboratory, Athens, GA . Adsorption isotherms were determined by batch equilibration. The dry sediments were equilibrated with 0.01 M CaSO4, for 5 days at 4 oC before they were used in sorption experiments. The wet sediment was weighed into 25-mL glass centrifuge tubes and 25-mL aliquots of the sorbate solutions were pipetted into the centrifuge tubes containing the sediment.The sorption tubes were rotated end-over-end for approximately 16 h in a thermostated box at 25 oC,then samples were Centrifuged for 1 hour at 10000 rpm and 25 oC. After that Differential refractometry was used to analyze the supernatant solutions of the test chemical. Langmuir Parameters and percent desorption were calculated. Adsorption capacity of test chemical on sediment EPA 5 and EPA 14 was 11.1 mg/g and 5.9 mg/g respectively. On the basis of these values it is concluded that test chemical has low sorption to soil.

 

 By considering results of all the studies mentioned above it is concluded that test chemical has low sorption potential to soil and sediment therefore has moderate migration potential to ground water.