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Authors Borchert, K. ; Steinbach, C. ; Reis, B. ; Lappan, U. ; Gerlach, N. ; Mayer, M. ; Schwarz, S. ; Schwarz, D.
Title Adsorption vs. surface precipitation of Cu2+ onto porous Poly(melamine-co-formaldehyde) particles
Date 15.01.2023
Number 61200
Abstract The application of multi-functional materials like Poly(melamine-co-formaldehyde) (PMF) for water purification pose the advantage that differing pollutants can be separated. The high nitrogen content of PMF enables potential chelation of heavy metal ions as well as electrostatic interactions with anions after protonation. Furthermore, amines can induce surface precipitation of heavy metal ions. For these reasons, it is important to investigate the complex interplay of adsorption and surface precipitation when regarding the uptake of both the metal ion as well as the anion. To investigate these processes, we synthesized mesoporous PMF particles with high specific surface areas up to 421 m2/g by dispersion polymerization in water using SiO2 nanoparticles as hard template. In subsequent adsorption experiments with these porous PMF particles and different Cu(II) salts (CuSO4, Cu(NO2)3, CuCl2), we investigated the occurrence of surface precipitation and adsorption both as superimposition and as two distinct uptake steps. The surface precipitate was identified as CuxA(OH)y hydroxide species with the respective Anion A. Investigations with WAXS, SEM-EDX and EPR spectroscopy showed the regions for adsorption and surface precipitation. With this knowledge, we were able to model the uptake with a new adsorption isotherm by combination of the Langmuir and sigmoidal Boltzmann equation.
Publisher Microporous and Mesoporous Materials
Wikidata
Citation Microporous and Mesoporous Materials 348 (2023) 112383
DOI https://doi.org/10.1016/J.MICROMESO.2022.112383
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