Contribution of carbohydrates to the cation-exchange selectivity of aquatic humus from peat-bog water
✍ Scribed by Olav Smidsrød; Terence J. Painter
- Book ID
- 102989926
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 802 KB
- Volume
- 127
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
A sample of soluble humic acid from peat-bog water was a glycoconjugate containing 46% of a glycuronoglycan moiety and 54% of a dark-brown chromophore. These accounted for 37% and 63%, respectively, of the titratable acidity of the polymer. Cation-exchange capacities, and cationic selectivity coefficients relative to magnesium ions (KE:), were measured on the humic acid for Pb2+ , Cd ', Zn2+, Ba*+, Ca*+, and Sr2+, and compared with those of extractive-free Sphagnum and other mosses, their chlorite holocelluloses, and two soluble fragments of Sphagnum holocellulose, prepared by acidic and alkaline degradation, respectively. The humic acid showed considerably higher KKE values than most of the control materials, the enhancement being especially marked for Pbzf, Cu*+, and Ca'+. Scatchard plots showed that both parts of the glycoconjugate contributed to its selectivity, and that the selectivity of the carbohydrate part was greater in the humic acid than in the holocellulose or its soluble fragments. The results are explained by assuming that there are enhanced possibilities for cross-linking in the colloidal humic-acid complexes.