Phosphorus Removal from Aqueous Solutions and Greek Soils using Modified Natural Minerals and Its Impact on the Morphological Characteristics of Crops

Abstract

In the present article, adsorption experiments of phosphate ions from their aqueous solutions were conducted with the use of five different materials (zeolite, bentonite, goethite, and systems I and II). The adsorption of phosphate ions were examined after mixing 2 g of each of these materials with 10 different phosphate concentrations (1.6, 3.2, 4.8, 6.5, 32.3, 193.5, 322.6, 483.9, 645.2, and 871.0 mol L-1). The experimental equilibrium adsorption data were analyzed using the Langmuir, Freundlich, and Temkin equations. Results indicate the following order to fit the isotherms equations: Freundlich > Temkin > Langmuir. Moreover, the five materials were used as soil amendments to soils that were cultivated with wheat, maize, and cotton. Forty days after germination, the plants were collected, the morphological characteristics were identified, and the available phosphorus in soil and the total phosphorus in plants were determined. Comparing the experimental results, goethite and system I present the best impact in the root length, leaf area index, and dry weight of each plant. The adsorbed amount of phosphorus per g of dry weight of plants increases as follows: bentonite < system I < zeolite < system II < goethite (for wheat), goethite < system II < zeolite < bentonite < system I (for cotton), and system I < system II < bentonite < zeolite < goethite (for maize). Maize can be cultivated to soils contaminated with phosphorus with the simultaneous use of system I or II as soil amendments. Wheat can be used as phytoaccumulator crop for the phytoremediation of soils contaminated with phosphorus.