Uranium Leaching from Contaminated Soil Utilizing Rhamnolipid, EDTA, and Citric Acid

Table 2

The procedure followed for the sequential extraction paired with the rhamnolipid extraction. The table includes the solvent utilized and the duration and temperature of the agitation for the extraction.

Step	Solvent	Duration/temperature
	Rhamnolipid extraction	Seventy-two hr at room temp
1	Subboiling purified water (20 mL)	1 hr at 95°C.
2	1 M ammonium chloride (8 mL)	1 hr at room temp.
3	1 M ammonium acetate (20 mL) at pH 4	4 hr in 85°C hot water bath
4	Mixture of 10.9 g/mL oxalic acid and 16.2 g/L ammonium oxalate (20 mL)	4 hr at room temp. in the dark
5	Six M hydrochloric acid (30 mL)	2 hr at 85°C hot water bath
6	(a) 8.8 M hydrogen peroxide (5 mL, pH 2)	(a) room temperature for 1 hr uncovered, then 85°C uncovered until volume reduced to 2 ml
	(b) 8.8 M hydrogen peroxide (5 mL, pH2)	(b) 85°C to reduce to 2 mL
	(c) 1 M ammonium acetate (25 mL, pH 4)	(c) room temperature, covered, and stirred for 18 hr
7	(a) hydrofluoric acid/aqua regia (5 mL)	(a) 30 min. room temp
	(b) perchloric acid (5 mL)	(b) 10 min room temp

Chemicals: ammonium chloride (BDH Lot number 78688), ammonium acetate (OmniPur Lot number TF07DZEMS), oxalic acid (EMD Lot number TD30EZEMS), ammonium oxalate (J.T. Baker Lot number G46147), hydrochloric acid (BDH Lot number 87003-216), hydrogen peroxide (BDH Lot number 107402), and perchloric acid (BDH Lot number 142568).