New crosslinked polyamides provide alternatives for water treatment.
20 January 2020
Global industrialisation ranks among the leading causes for rising levels of heavy metal in waterways. The high toxicity of arsenic, cadmium, chromium, lead and mercury mean they are of public concern. The elements enter the waterways through effluents from industries such as dying, printing, engineering, nuclear power operations and battery manufacturing.
A paper published in SCI’s journal Polymer International indicates that methods such as coagulation membrane filtration, oxidation, ion exchange, adsorption and precipitation are available for removing heavy metals and oil pollutants. However, few of these methods are used due to their cost, low efficiency and the fact that many are limited to just a few pollutants.
Adsorption has been reported as one to the most effective remediation strategies owing to its low cost and ease of operation. Many inorganic materials have been studied for metal ion uptake such as silica, silica gel, metal oxides, pumice stone and zeolite type minerals.
Crosslinked polymers are useful adsorbents with some designed to have more binding sites, along with environmental and thermal stability. Researchers have now looked at different crosslinked polyamides as potential adsorbents having more binding sites for toxic heavy metal ions which can be used in the remediation of water. Polyamides are a class of macromolecules with high temperature resistance. Crosslinking enhances the crystallinity, thermal stability and metal binding ability of the resin, due to definite patterns, chain alignment and entanglement.
The crosslinked polyamides provided efficient uptake of divalent cations and so proved to be useful for removing heavy metal from water. The structure of the new polyamides was confirmed using spectroscopic analysis.
Researchers found that the relative uptake of the cationic species indicated that the crosslinked polymers showed maximum affinity towards ferrous ions followed by lead, cadmium and copper. Ongoing work will look at the possibility for reuse of the resins.
Polymer International: DOI:10.1002/pi.5918
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