INFLUENCE OF OXALATE AND CITRATE ON P SORPTION PREVENTION AND THE RELEASE OF THE PRESORBED METALS BY GYPSUM-CALCITE SYSTEMS. | ||||
| Journal of Soil Sciences and Agricultural Engineering | ||||
| Article 9, Volume 32, Issue 8, August 2007, Page 6921-6934 PDF (658.38 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jssae.2007.201343 | ||||
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| Author | ||||
| A. M. Al-Shabaan | ||||
| Department of Environment and Natural Agricultural Resources, College of Agriculture and Food Sciences, King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia. | ||||
| Abstract | ||||
| Fixed weight of calcite plus gypsum (1.25g of each) were first reacted with fixed levels (20 ppm of each) of Fe, Cu, Zn and Mn chlorides for 24 hours. Then fixed level of P (20 ppm) only or 0.1, 0.5, 1.0, 5.0, 10.0 and 15.0 mM organic carbon (O.C) L-1 from either oxalic or citric acid were introduced and reacted for 48 hours. The filtrate EC and pH increased under both acids but was greater under oxalic acid systems. The final Calcium was decreasing under oxalic acid treatments where it was 589 and 321 ppm at 0.1 and 15.0 mM O.C L-1, respectively. In contrast, the final Ca was increasing due to citric acid input which was 607 and 780 ppm at 0.1 and 15.0 mM O.C L-1, respectively. Bicarbonate was increasing under both acids, but the increase was greater under citric acid where it increased from 118 to 476 and from 118 to 271 ppm HCO—3 due to 0.1 and 15.0 mM O.C L-1 of citric or oxalic acid, respectively. However, citric acid reduced 60% and 70% of the added P from sorption at 0.1 and 15.0 mM O.C L-1 of it, respectively. But, oxalic acid reduced only 55% and 15% of the added P at 0.1 and 15.0 mM O.C L-1 of it, respectively. Both acids failed to release any of the presorbed metals, but citric acid could release some of Mn in decreasing rates (the highest was 45.5% of the added). Thus, citric acid was more effective than oxalic acid toward P sorption reduction under calcite-gypsum systems. | ||||
| Keywords | ||||
| calcareous; gypsiferous; ligand exchange; organic anion sorption; desorption | ||||
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