Iron, precipitated in the form of hydroxides on sand particles (-48 + 65 mesh) and stabilized by drying at 100°C for 10 hours, was utilized to remove alkyl benzene sulfonate (ABS) from aqueous solutions. Solutions containing a maximum of 5 mg/l ABS were passed through a glass column packed with treated sand. The ABS formed a complex with the iron precipitants which adhered to the sand particles.
Preliminary work, in which solutions containing 10 mg/l ABS were treated with various concentrations of FeCl2 at the equivalence point (pH about 9.5), verified the fact that ABS could be removed by this type of treatment. The concentration of ABS was reduced from 10 mg/l to a limiting value of 4.5 mg/l by treating 100 ml of the ABS solution with 10 ml of 0.0071 N FeCl2 solution under these conditions.
A glass column (1.5 inch inside diameter), filled to a depth of twelve inches with 516 gm sand treated in three runs with 10, 20, and 40 ml respectively of 0.0071 N FeCl2 solution, was used to evaluate the adsorption of ABS. The quantity of ABS adsorbed from solutions of 5 mg/l ABS, flowing through the column at rates of 100 ml/hr, was proportional to the amount of iron precipitated (0.12 gm ABS/gm iron) on the sand. The removal of the ABS is attributed solely to the influence of the precipitated iron since there was no measurable effects with an untreated column.
The desorption of ABS with water was quantitative in the case of the sands treated with the quantities of iron less than 1.5 x 10-5 gm/gm sand. Approximately one-third of the ABS remained in the complexed form on the sand surface when 3 x 10-5 gm iron/gm sand was used to treat the sand.
The specific resistance (to flow) of the sand increased from 2.87 x 107 ft/lb, for the untreated sand, to 3.75 x 107 ft/lb, for sand treated with the maximum amount of iron. The specific resistance of the treated sand saturated with ABS was slightly greater than the treated sand free of ABS (3.89 x 107 ft/lb maximum).
The techniques utilized in this investigation can be used to evaluate other similar situations --Abstract, pages ii-ii
