TY - JOUR
T1 - Removal of Transition-Metal Ions by Metal-Complexing Polythiosemicarbazone Membranes
AU - Nickisch, Roman
AU - de Vos, Wiebe M.
AU - Meier, Michael A.R.
AU - Baig, Muhammad Irshad
N1 - Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.
PY - 2023/9/8
Y1 - 2023/9/8
N2 - Membrane technology is one of the many strategies to remove transition-metal ions from aqueous streams because of its relatively lower costs and ease of operation. Typically, adsorbent materials are added into polymeric membranes to impart chelating/complexing properties, but this often results in a limited number of adsorption sites within the membrane. In this work, polythiosemicarbazone (pTSC) is proposed as a material to prepare polymeric membranes due to its metal-complexing ligands in the backbone, providing more adsorption sites. The polymer was easily processed into membranes via the nonsolvent-induced phase separation technique and exhibited asymmetric structures with adequate mechanical strength. The porosity of the membranes was controlled by increasing the polymer concentration in the casting solution, leading to ultrafiltration- and nanofiltration-type membranes with permeabilities ranging from 30 to 0.7 L·m-2·h-1·bar-1. The resulting pTSC membranes were applied for the removal of silver and copper ions in batch and, in the case of silver ions, also in dynamic adsorption experiments. The maximum removal rate of 17 mg·g-1 for silver and 3.8 mg·g-1 for copper ions was obtained in the batch removal experiment. Streaming potential, pH measurements, and infrared spectroscopy (FTIR) were conducted to verify the anionic binding of TSC groups, while neutral binding modes were revealed by FTIR and batch removal experiments. Furthermore, the removal of silver ions was also successfully demonstrated in a flow setup operated at 4 bar of applied pressure. The streaming potential and energy-dispersive X-ray (EDX) spectroscopy conducted on the membranes after the flow tests confirmed the complexation by TSC-functional groups as the separation mechanism. Finally, partial desorption of the silver ions was successfully conducted in water to demonstrate the reusability of pTSC membranes.
AB - Membrane technology is one of the many strategies to remove transition-metal ions from aqueous streams because of its relatively lower costs and ease of operation. Typically, adsorbent materials are added into polymeric membranes to impart chelating/complexing properties, but this often results in a limited number of adsorption sites within the membrane. In this work, polythiosemicarbazone (pTSC) is proposed as a material to prepare polymeric membranes due to its metal-complexing ligands in the backbone, providing more adsorption sites. The polymer was easily processed into membranes via the nonsolvent-induced phase separation technique and exhibited asymmetric structures with adequate mechanical strength. The porosity of the membranes was controlled by increasing the polymer concentration in the casting solution, leading to ultrafiltration- and nanofiltration-type membranes with permeabilities ranging from 30 to 0.7 L·m-2·h-1·bar-1. The resulting pTSC membranes were applied for the removal of silver and copper ions in batch and, in the case of silver ions, also in dynamic adsorption experiments. The maximum removal rate of 17 mg·g-1 for silver and 3.8 mg·g-1 for copper ions was obtained in the batch removal experiment. Streaming potential, pH measurements, and infrared spectroscopy (FTIR) were conducted to verify the anionic binding of TSC groups, while neutral binding modes were revealed by FTIR and batch removal experiments. Furthermore, the removal of silver ions was also successfully demonstrated in a flow setup operated at 4 bar of applied pressure. The streaming potential and energy-dispersive X-ray (EDX) spectroscopy conducted on the membranes after the flow tests confirmed the complexation by TSC-functional groups as the separation mechanism. Finally, partial desorption of the silver ions was successfully conducted in water to demonstrate the reusability of pTSC membranes.
KW - adsorption
KW - chelating polymer
KW - membrane
KW - metal−polymer complex
KW - transition-metal ions
KW - ultrafiltration
KW - UT-Hybrid-D
UR - http://www.scopus.com/inward/record.url?scp=85170241601&partnerID=8YFLogxK
U2 - 10.1021/acsapm.3c01192
DO - 10.1021/acsapm.3c01192
M3 - Article
AN - SCOPUS:85170241601
SN - 2637-6105
VL - 5
SP - 7240
EP - 7251
JO - ACS Applied Polymer Materials
JF - ACS Applied Polymer Materials
IS - 9
ER -