X-ray coupled Laser Desorption Ionization assessment of layered double hydroxides for nitrate adsorption based on ion size, affinity and compromised layer height

Abstract

The adsorption of nitrates with NO3(aq) solutions ranging from 20mg/L to 400mg/L with Layered-Double-Hydroxides (LDH) PURAL 70 (Mg70) and an Erbium containing LDH (Er40) were investigated. The X-ray Diffraction measurements (XRD) are accompanied by complemented Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) measurements for prove of NO3- containing LDH. The shift in the XRD reflection angle for both Mg70 and Er40 corresponds to MALDI-TOF Data for presence of nitrate for all LDH except for Er40MW, as its nitrate adsorption capacity is the lowest. Both methods show the adsorption of nitrates for microwaved LDH and further calcined LDH, proving the memory effect. UV–vis spectroscopy was used to determine the nitrate concentration. The study shows substantial amount of nitrate adsorption for all LDH. Adsorption ranges from 2 to 5mg-NO3(aq)/g-LDH for initial NO3(aq) concentration from 20mg/L to 400mg/L. Leaching of element from the LDH structure is done by ICP-MS measurements to guarantee no further pollution of environmental waters with mentioned elements. Leaching for Mg ranges from170 to 1600mg/m3 and Al, Er and Fe leaching is less than 10mg/m3.