The interest in the reuse of water treatment residuals (WTR) as a low-cost alternative to commercial adsorbents for metal removal from aqueous solutions has been growing in recent years. In this study, Fe-WTR and Mn-WTR from a pilot-scale groundwater treatment plant were investigated for their potential to remove As(III), Cd(II), Cu(II), Ni(II) and Pb(II) from different water matrices and at different pH values in batch tests. WTR compositions were compared with chemical and microscopic analyses, revealing that Mn-WTR had a higher Mn content and a slightly higher pHPZC than Fe-WTR. In kinetic experiments at pH 7.0, metal adsorption onto Fe-WTR was faster than adsorption onto Mn-WTR, while final loadings were higher on Mn-WTR. Ni(II) and Cd(II) showed higher affinities for Mn-WTR, while the adsorption capacity of Fe-WTR was exhausted after short contact times. The Elovich model was best suited to describe experimental data, indicating chemisorption as the dominant adsorption mechanism. Isotherm experiments in multi-solute solutions showed that As(III) and Pb(II) removals increased with decreasing pH, while Cd(II) and Ni(II) removals increased with increasing pH. Except for Pb(II), adsorption could be explained with electrostatic interactions between adsorbate and adsorbent, and precipitation likely played a role in metal removal. The Langmuir model described the data better than the Freundlich model in most cases. However, models were unable to represent competition that clearly occurred at higher initial concentrations. Fe-WTR was better suited for metal adsorption in most cases; yet Mn-WTR was more effective for the adsorption of Cd(II) and Ni(II). © 2026 The Authors
Mit der Langmuir-Blodgett-Technik ist es moeglich, polymerisierbare Monoschichten, bestehend aus Diacetylenamphiphilen, auf poroese Ultrafilter zu uebertragen. Mehrere uebereinandergelegte Monoschichten werden dann als Multischicht polymerisiert. An so hergestellten Kompositmembranen sollen Transportvorgaenge und Trenneigenschaften mit Hilfe der Druckfiltration durchgefuehrt werden. Die dichte Packung innerhalb der nur wenige nm starken Multischicht verspricht gute Retentionen bei gleichzeitig hohen Permeatfluessen.