Fe3O4/Al2O3/ZrO2 TERNARY OXIDE NANOCOMPOSITE: SYNTHESIS, CHARACTERIZATION AND PHOSPHATE DESORPTION STUDY FROM ACID SOIL USING DIALYSIS MEMBRANE TUBES (DMTs)

Abstract

Phosphorus (P) is an essential element for plant and animal growth; although plant roots are capable of absorbing P from the soil solution at low P concentrations, most soils cannot supply sufficient amounts of P to the plant due to various factors. Knowledge of the effect of the P remaining in the soil (residual effect) is of great importance for fertilization recommendation. Phosphorous fixation to soil results in less P available to plants. Nano technology addresses the development of solutions to the existing environmental problems. For this purpose, Fe-Al-Zr ternary mixed oxide Nano composite adsorbent with 70, 25 and 5 percentage composition of Fe, Al, and Zr respectively was synthesized by co-precipitation method. The as-synthesized adsorbent was characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), flame atomic absorption spectroscopy (FAAS) studies and Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX). The study of phosphate desorption was carried out on four soil samples collected from West Wollega Zone, Oromia region namely, Kiltu Kara, Nedjo Boji, Dirmeji and Mana Sibu which were incubated with 0, 50, 100 and 150 ppm phosphate. Selected physicochemical properties of soil were determined. The simulation of phosphate desorption from soil to plant was predicted by dialysis membrane tube filled with Iron-aluminum-Zirconium oxide (DMT-Fe-Al-Zr). The results suggest that the phosphorus treatment and desorption time had significant effect on the amount of desorbed phosphorus from the soils. The phosphate desorbed was found to be highest at Kiltu Kara soil with 150 mg/Kg treatment which has the value ranging (4.51- 32.62.mg/Kg) and lowest in the control (1.42-15.591 mg kg-1 ) at all levels of extraction time for all soil types. The releasing rate of phosphate from soil followed first order kinetics having highest desorption rate found on day 1 for Kiltu Kara soil sample with the value of 4.63 mg/Kg day-1 and the lowest was observed on day 28th of Boji Dirmeji (B) with the value of 0.44 mg/Kg day-1 . Therefore, the DMT- Fe-Al-Zr method can serve as analytical tool to assess the availability of residual P in soil, which is essential to estimate available P for plants.