sodium-perchlorate and potassium-nitrate

This study presents an environmental-friendly and cost effective method for the extraction of arsenic from contaminated soils. Laboratory experiments using inorganic salts, potassium phosphate (KH2PO4), potassium chloride (KCl), potassium nitrate (KNO3), potassium sulfate (K2SO4), and sodium perchlorate (NaClO4) were evaluated as arsenic extractants. An Andosol soil was artificially contaminated with arsenite [As(III)] and arsenate [As(V)]. The soil was washed in a batch process with different salt solutions in the pH range 3-11 for 24 hours at 20 degrees C. Among the various potassium and sodium salts tested, KH2PO4 was found to be highly effective in extracting arsenic from As(III)-soil attaining more than 80% and 40% from As(V)-soil in neutral pH range. Other salts were particularly ineffective in extraction of arsenic from both soils. More arsenic was extracted more from the As(III)-soil than the As(V)-soil.

Topics: Arsenates; Arsenic; Arsenites; Nitrates; Perchlorates; Phosphates; Potassium Chloride; Potassium Compounds; Sodium Compounds; Soil Pollutants; Sulfates; Waste Management

The major peak near 498 nm in the ultraviolet-visible spectrum of congo red in aqueous solution shifts toward the blue while the molar absorptivity of this peak decreases predictably with increasing ionic strength. The shift was observed for solutions in which ionic strength was varied from 0.0 to 1.8M using the uni-univalent ionic compounds, NaCl, NaClO(4), KNO(3) and KBr separately. A plot of the log of the absorbance at the peak versus ionic strength was linear as well as a plot of the log of the wavelength of the major peak (shifted from 498 nm) versus the ionic strength. The slopes of each of these plots were somewhat different depending on the ionic compound.

Topics: Bromides; Coloring Agents; Congo Red; Nitrates; Osmolar Concentration; Perchlorates; Potassium Compounds; Sodium Chloride; Sodium Compounds; Solutions; Spectrophotometry, Ultraviolet; Water