Direct Effects and Interactions Involving Iron and Humic Acid During Formation of Colloidal Phosphorus
Precipitation and complexation reactions involving factorial treatment combinations of iron (Fe), phosphorus (P), and humic acid (HA) in aerobic, slightly alkaline (pH 8.65) media permitted differentiation of direct effects and interactions among these factors, which result in formation of colloidal (nondialyzable) P. The range of concentrations studied were 0.05 to 0.2 mg total P/1, 0.1 to 100 mg total Fe/1, and 0.05 to 50.0 mg HA (Aldrich)/1. The data showed that HA, in contrast to Fe, had no capacity to bind inorganic P directly to form a colloidal phase. However, the extent of formation of colloidal P by Fe varied inversely with the amount of HA and inorganic P added to the experimental systems. Adsorption isotherms grouped according to the Fe/HA ratio (w/w) of the treatment combinations indicated occurrence of a maximum adsorption density of 0.1 mg P/mg Fe at a ratio of approximately 0.2:1. The results suggested that HA in increasing amounts decreased the polynuclear nature of the colloidal Fe and, coincidently, changed the number of sites for adsorption of P.
KeywordsCombustion Hydrolysis Crystallization Phosphorus Hydroxyl
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- American Public Health Association (APHA), 1975. Standard Methods, ed. 14. American Public Health Association, New York, 1193 pp.Google Scholar
- Comstock, W.G., 1982. The Direct and Interactive Effects of Iron and Humic Acid on the Partitioning of Inorganic Phosphorus Between Dissolved and Colloidal States, M.S. Thesis. Department of Civil and Environmental Engineering, Clarkson University, Potsdam, NY, 225 pp.Google Scholar
- Cowen, W.F. and Lee, G.F., 1976. Phosphorus availability in particulate materials transported in urban runoff. J. Water Poll. Control Fed., 48: 580–591.Google Scholar
- Dousma, J. and de Bruyn, PC., 1976. Hydrolysis- precipitation studies of iron solutions. I. Model for hydrolysis and precipitation from Fe(III) nitrate solutions. J. Colloid Internatl. Sci., 56: 527–539.Google Scholar
- Lijklema, L., 1980. Interaction of orthophosphate with iron (III) and aluminum hydroxides. Environ. Sci. Tech- nol., 14: 537-541.Google Scholar
- Rast, W. and Lee, G.F., 1978. Summary Analysis of the North American (U.S. Portion) OECD Eutrophication Project: Nutrient Loading—Lake Responses, Relationships and Trophic State Indices. Ecological Research Series, EPA-600/3-78-008, USEPA-ORD, ERL, Corvallis, OR, 455 pp.Google Scholar
- Stumm, W. and Morgan, J.J., 1981. Aquatic Chemistry. Wiley-Interscience, New York, 780 pp.Google Scholar
- Westall, J.C., Zachary, J.L. and Morel, F.M.M., undated. MINEQL: A Computer Program for the Calculation of Chemical Equilibrium Composition of Aqueous Systems (MINEQL User’s Guide). Department of Civil Engineering, Massachusetts Institute of Technology, Boston, MA, 91 pp.Google Scholar
- Young, T.C. and De Pinto, J.V., 1982. Algal-availability of particulate phosphorus from diffuse and point sources in the lower Great Lakes basin. Hydrobiologia, 94: 111–119.Google Scholar