The use of N HNO3 to determine copper and zinc levels in heavy-metal polluted tropical soils

This study compared N HNO3 to other methods to determine plant available heavy metals in heavy-metal polluted soils. Soil samples were obtained from an experimental field treated with industrial waste after 22 years of the amendment and employed to conduct the comparative and correlation study. Soil samples were analyzed for Cu using various methods, planted in a glass house with several plants, and analyzed for soil and plant Cu and Zn. The relative strength of the chemical extractants followed the order of N HNO3 ≈ N HCl > Buffered DTPA ≈ Unbuffered DTPA > M CaCl2 ≈ N NH4OAc pH 7. A high correlation was observed for soil extracted Cu by M CaCl2 or N NH4OAc pH 7 or N HCl vs. Buffered DTPA and N HNO3 or N NH4OAc pH 7 vs. N HCl. High correlations of plant and soil Cu extracted by N HNO3 were shown by caisim, water spinach, land spinach, and corn, while plant and soil Zn were shown by caisim, water spinach, land spinach, and lettuce.

Technological Typomorphic Associations in Caustobiolites and Methods of Their Extraction

Heavy oil is considered as a multipurpose complex mineral, and the processing of heavy oils as a “complex problem”, aimed both at increasing the yield of light fractions and “transport” ability of oil, and at extracting metals from heavy asphaltene resinous fraction. The recovery of heavy metals (such as vanadium, nickel, titanium, iron, etc.) from heavy oil was performed by cavitation extraction technology with the use of light hydrocarbon solvents and chemical extractants, including a stage of extraction in an ultrasonic field with separation of insoluble fraction of asphaltenes in which a significant part of initial heavy metals and sulfur is concentrated, followed by re-extraction of metals and magnetic separation of metal aggregates.