Abstract
Wastewater cleaning strategies based on the adsorption of materials are being increasingly considered, but the wide variety of organic pollutants at low concentrations still makes their removal a challenge. The hybrid material proposed here consists of a zwitterionic polyethylenimine polymer coating a magnetic core. Polyethylenimine is phosphonated at different percentages by a one-step process and used to coat maghemite nanoparticles. It selectively extracts high amounts of cationic and anionic contaminants over a wide range of pH values, depending on the adjustable number of phosphonate groups introduced on the polymer. After recovering the nanoparticles with a magnet, pollutants are quantitatively released by repeated washing with low amounts of pH-adjusted water. The material can be reused many times without noticeable loss of efficiency and is designed to resist high temperatures, oxidation and harsh conditions.
Highlights
During the last decades, an increased emphasis was placed on the issue of diffuse contamination of water
The particles were re-dispersed in 20 mL of wash water per milligram of NP-PEIP depending on the pollutant: maximum adsorption (MO) was washed with the acidic solution, methylene blue (MB) with the basic one
Magnetic material preparation and conditions of the studies. The novelty of this contribution consists in the use of PEI with phosphonic groups allowing a solid grafting of PEI on the maghemite nanoparticles, by the formation of strong covalent P–O–Fe bonds
Summary
An increased emphasis was placed on the issue of diffuse contamination of water. Extraction of methyl orange and methylene blue with NP-PEIP A particles stock solution was prepared by dispersing 5 mg of NP-PEIP powder in 50 mL of distilled water. In the case of the MO solution, the supernatants were adjusted to pH 14 by addition of sodium hydroxide before recording the absorption in order to avoid a distortion of the measurements (Figure S4 in Supporting Information File 1).
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