Study of mixed binding agent La-MOF and chelex-100 by diffusive gradient in thin films (DGT) devices

Abstract

The release of phosphor in the form of high phosphate from sediments to the aquatic system triggers a eutrophication process. It occurs due to the influence of the iron redox system where phosphate bound to iron(III) oxyhydroxide is reduced to iron(II) which will be released into aquatic systems under anoxic conditions. Therefore, developing an in-situ technique to measure the release of phosphor and iron simultaneously contributes to a better analysis. The method uses Lanthanum MOF, a porous material with a high surface area to bind labile phosphate species and Chelex-100 and bind iron(II) ions in Diffusive Gradient in Thin Films (DGT). The largest value of CDGT/Csolution for Iron(II) ion was 1.12, and for the labile phosphate species, the maximum value was 1.39 within 24 hours. Tests on variations in the pH solution obtained optimum results for Iron(II) ions, namely at pH 2.5 - 4.5. Meanwhile, the labile phosphate species produced the optimum result at a pH of 2.5-8.6. This study shows that the ability of the binding agent combination in the DGT tool to bind Iron(II) ions and labile phosphate species depends on the immersion (soaking) time and pH.