Boron leaching

Finally, for a brine high in boron, toxicity levels can be determined by analyzing an extract of water from saturated soil. The critical threshold is around 2 mg L 1. Fortunately, boron leaches quite easily from a soil at circumneutral pH, and if a soil is reclaimed from sodium, the chances are good that the boron would also be leached and its concentration would be less than 2 mg L l. 

The reduction diffusion process has also been used for the production of powders of the magnetic neodymium-iron-boron alloy (Nd15Fe77B8). The reaction involves use of a powder mix of neodymium oxide, iron, ferroboron and calcium. The reaction is conducted by heating the powder charge mixture at 1200 °C for 4 h under vacuum. Neodymium-iron-boron alloys are much more prone to oxidation than samarium-cobalt alloys and a proprietary leaching procedure is used for the separation of the alloy and calcium oxide. 

References to sample contaimination in the literature are numerous. Abercrombie, ef. oJ.(54) have noted that the information obtainable from ICP emission analysis warrants additional care because of the increased number of elements monitored. For example, if one were looking for boron and sodium, the use of glassware should be avoided. Certain digestion vessels that are presumed to be cleaned may not be acceptable. Polyethylene bottles (acid-soaked), for example, have been shown to continue releasing zinc from the matrix for as long as seven days(92). A number of trace elements may be leached from commercial disposable test tubes. Some of the more important contaminants include Ba, Sr, Zr, Na, K, Al, Ca and Mg. 

Boron deficiency is particularly prevalent in light-textured soils in which water-soluble borates are gradually leached down the soil profile and become unavailable to plants. Heavier, more loamy soils tend to retain more boron because they contain an abundance of compounds, such as humic acids, that can complex boron. Certain crop types have higher boron requirements and benefit most from supplementation. These include soybeans, cotton, peanuts, oil palm, apples, and almonds. 

Leaching of Drax and Meaford weathered ashes produced much lower initial concentrations for the readily soluble elements, in particular for Na and K (Fig. lb). Boron, Cr, Ni, and Mo are also present at much lower concentrations in the weathered ash leachates. The higher concentrations for the Ca and S in the initial leachate... 

The Determination of Boron. After dry ashing in the manner used in the lithium, beryllium, etc., procedure, the ash is fused with sodium carbonate, leached in water, and acidified with sulfuric acid. The colorimetric carminic acid method is then used to determine the boron. 

In summary, these SIMS studies have shown that reproducible measurements of some surface chemistry changes are possible following very early attack of glass surfaces by water. Early depletions of sodium and more surprisingly, boron, are indicated even after a few minutes of leaching time. The apparent effects of surface hydration on the SIMS relative ion yields also warrants further investigation. 

Leaching Introduction of contaminants from man-made materials, such as metals from stainless steel, silicon and boron from glass, lead and tin from solder, solvents from duct tape Use of inert materials, pH control, minimization of contact time with these materials... 

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