Study of Phosphate Adsorption Using Ferrihydrite With Diffusive Gradient in Thin Films Method

The high input of phosphate into the aquatic system results in eutrophication which leads to algae blooming. Therefore, it is necessary to measure the concentrations of phosphate pollutants that occur in surface waters. Conventional analysis techniques so far only provide an overview of the pollution situation through instant sampling, so it may not represent the current water conditions. Pollutant concentrations fluctuate due to dynamic interactions of phosphate species in natural systems, hence species concentrations may change during sample storage, making accurate analysis difficult unless performed in situ. In this study, the Diffusive gradient in thin films (DGT) method was investigated using a ferrihydrite binding gel assembly on a polyacrylamide gel sheet. The ferrihydrite gel was eluted using 0.25 N H₂SO₄ to release the adsorbed phosphate. The performance test of the method on the absorption of phosphate by ferrihydrite was assessed by testing the effect of pH, contact time, and variation of initial concentration. Determination of the concentration of adsorbed phosphate using the phosphomolidenium blue method with a UV-Visible Spectrophotometer. Characterization of functional groups in polyacrylamide diffusing gel and ferrihydrite adsorbent gel using Fourier Transform Infra Red while the surface morphology of each gel was analyzed by Scanning Electron Microscope.