Soils with variable surface charge are reported to have high affinities for the adsorption of anions and also to selectively retain cations. A laboratory study was conducted to determine the influence of sulfate (SO 4 2-) anion on phosphate (PO 4 3-) sorption/desorption from tropical soils. Duplicate 1.0 g soil samples were shaken with 10 mL portions of varying concentrations of calcium sulfate (CaSO 4 ·2H 2 O) (0.0 to 1.5 x 10 -2 M). Subsequently, the samples were equilibrated with increasing concentrations of monocalcium phosphate [Ca(H 2 PO 4 ) 2 ·H 2 O] in 0.01M calcium chloride (CaCl 2 ) to measure PO 4 sorption and afterwards with 0.01M CaCl 2 for PO 4 desorption. Results showed that PO 4 sorption maxima increased as concentrations of SO 4 in solution increased. In the most acidic soil, SO 4 adsorption from the 0.015M CaSO 4 ·2H 2 O solution increased PO 4 sorption by 93%. There was a decrease in pH in the SO 4 extracts; this would indicate that calcium (Ca) from the SO 4 salt applied to the soils before P addition was specifically adsorbed by the exchange complex and originated new sites for binding PO 4 . On the average, about 20% of the sorbed PO 4 was removed with the CaCl 2 treatment, suggesting that PO 4 was specifically adsorbed by the variable charge soils.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.