Description -Chelating Resin for Boron Removal
About Chelating Resins:
Chelating resins are a subgroup of ion exchange resins that have a high selectivity of at least one particular counter-ion species. The interaction of a functional group (ligand) of chelating resin and metal (in form of cation or oxoanion) is selective with respect to the nature of the metal. In the case of chelating resins counter ions are bound to resin by coordinate covalent bond or by its combination with electrostatic interactions. In the case of ion exchange, electrostatic force between oppositely charged functional group and ion in solution plays the main role. LSC 780 is a chelating resin with N-Methylglucamine functional group with high specificity for Boron as Boric acid in water or solutions.
Boron, unlike sodium, is an essential element for plant growth. (Chloride is also essential but in such small quantities that it is frequently classed non-essential.) Boron is needed in relatively small amounts, however, and if present in amounts appreciably greater than needed, it becomes toxic. For some crops, if 0.2 mg/l boron in water is essential, 1 to 2 mg/l may be toxic. Surface water rarely contains enough boron to be toxic but well water or springs occasionally contain toxic amounts, especially near geothermal areas and earthquake faults. Boron problems originating from the water are probably more frequent than those originating in the soil. Boron toxicity can affect nearly all crops but, like salinity, there is a wide range of tolerance among crops.
Boron toxicity symptoms normally show first on older leaves as a yellowing, spotting, or drying of leaf tissue at the tips and edges. Drying and chlorosis often progress toward the centre between the veins (interveinal) as more and more boron accumulates with time. On seriously affected trees, such as almonds and other tree crops which do not show typical leaf symptoms, a gum or exudate on limbs or trunk is often noticeable.
Most crop toxicity symptoms occur after boron concentrations in leaf blades exceed 250–300 mg/kg (dry weight) but not all sensitive crops accumulate boron in leaf blades. For example, stone fruits (peaches, plums, almonds, etc.), and pome fruits (apples, pears and others) are easily damaged by boron but they do not accumulate sufficient boron in the leaf tissue for leaf analysis to be a reliable diagnostic test. With these crops, boron excess must be confirmed from soil and water analyses, tree symptoms and growth characteristics.
Boric acid is a very weak acid, with a pKa of 9.15, and therefore boric acid and the sodium borates exist predominantly as undissociated boric acid [B(OH)3] in dilute aqueous solution at pH <7; at pH >10, the metaborate anion B(OH)4 becomes the main species in solution. Between these two pH values, from about 6 to 11, and at high concentration (>0.025mol/litre), highly water soluble polyborate ions such as B3O3(OH)4-, B4O5(OH)4-, and B5O6(OH)4-are formed.
The mean daily intake of boron in the diet is judged to be near 1.2 mg/day (Anderson et al.,1994). Concentrations of boron in drinking-water have wide ranges, depending on the source of the drinking-water, but for most of the world the range is judged to be between 0.1 and 0.3 mg/litre. Based on usage data, consumer products have been estimated to contribute a geometric mean of 0.1 mg/day to the estimate of total boron exposure (WHO, in press). The contribution of boron intake from air is negligible. The total daily intake can therefore beestimated from mean concentrations and concentration ranges to be between 1.5 and 2 mg.
About LSC 780
N-Methylglucamine resin has been shown to be a good adsorbent for borate or boric acid. Above ca. pH 6, the boron adsorbability of this resin increased with a maximum around pH 9. The maximum distribution ratio was higher than 106, however, further increase in pH resulted in a decrease in the distribution ratio.