Abstract
A facilitated transport of Pb(II) through polymer inclusion membrane (PIM) containing 1,8,15,22-tetra(1-heptyl)-calixresorcin[4]arene and its tetra- and octasubstituted derivatives containing phosphoryl, thiophosphoryl or ester groups as an ion carrier was investigated. The efficiency of Pb(II) removal from aqueous nitrate solutions was considered as a function of the composition of membrane (effect of polymer, plasticizer, and carrier), feed (effect of initial metal concentration and presence of other metal ions) and stripping phases, and temperature of the process conducting. Two kinetic models were applied for the transport description. The highest Pb(II) ions removal efficiency was obtained for the membrane with tetrathiophosphorylated heptyl-calixresorcin[4]arene as an ion carrier. The activation energy value, found from Eyring plot to be equal 38.7 ± 1.3 kJ/mol, suggests that the transport process is controllable both by diffusion and chemical reaction. The competitive transport of Pb(II) over Zn(II), Cd(II), and Cr(III) ions across PIMs under the optimal conditions was also performed. It was found that the Cr(III) ions’ presence in the feed phase disturb effective re-extraction of Pb(II) ions from membrane to stripping phase. Better stability of PIM-type than SLM-type membrane was found.
Highlights
Global economic development, which brings new technologies and materials improving the quality of human life, leads to adverse changes in the natural environment.Despite the fact that many countries implement adequate laws mandating reductions in the emission of pollutants to the environment, the presence of substances dangerous for organisms in the environment remains a valid problem
Liquid membranes are better than solvent-based extraction and solid membranes because they can be designed so that they are highly selective for a specific substance at a fairly low consumption of the extractant/carrier
Stripping phase (s), in the function of transport through polymer inclusion membrane (PIM), in order to determine the kinetics of membrane release of Pb(II) ions
Summary
Global economic development, which brings new technologies and materials improving the quality of human life, leads to adverse changes in the natural environment.Despite the fact that many countries implement adequate laws mandating reductions in the emission of pollutants to the environment, the presence of substances dangerous for organisms in the environment remains a valid problem. Extraction processes based on liquid membranes have attracted much attention as separation methods that could replace the currently used technologies for environmental water, process solution and industrial wastewater treatment [3]. Recent decades saw intensive research efforts focusing on polymer inclusion membranes (PIMs) in the aspect of their use for selective release of harmful substances from post-production waste flux, industrial wastewater or environmental waters. The literature data suggest that the membranes enable effective removal of a wide range of organic and inorganic substances, both neutral and ionic, including heavy metals, from synthetic and real solutions [4,5,6,7,8,9,10,11]
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