Temperature swing adsorption of heavy metals on novel phosphate-type adsorbents using thermosensitive gels and/or polymers

Abstract

A novel thermosensitive adsorbent was developed, which adsorbs and/or desorbs heavy metals through temperature swing process. The gel-type and polymer-type adsorbents, composed of N-isopropylacrylamide (NIPA) as a thermosensitive component and 2-methacryloyloxyethyl phosphate (MEP) as an interactive component, were prepared by free radical copolymerization. For each type of poly(NIPA-co-MEP), phase transitions and temperature dependences for the amount of Cu, a model metal ion, adsorbed was examined. The proposed mechanism associated with the temperature swing adsorption (TSA) of Cu to poly(NIPA-co-MEP) is as follows. In the case of the shrinking gel at higher temperatures, two MEP groups are positioned so as to interact with one Cu ion, while in the swelling gel at lower temperatures, Cu is desorbed from isolated MEP groups. In the case of copolymers, at temperatures lower than the lower critical solution temperature (LCST), two MEP groups interact with one Cu ion as well as those in shrunken gels, and at temperatures higher than the LCST, an aggregate of the copolymer, which is strongly hydrophobic, ejects free water along with Cu ion in the shrinking process. The temperature dependences for adsorption to the copolymer are opposite to gels, even in the gel with a low density of crosslinking points.

Synthesis and characterization of PNIPAM/PS core/shell particles

“…1 The unique properties of PNIPAM inspired researchers to combine PNIPAM with polystyrene (PS) in areas such as biomedical 2 and bioseparations, 3 drug delivery, 4 catalysts, 5 and pollution control. 6 However, it is interesting to note that almost all of the research reported in the literature focused on synthesizing a PNIPAM shell around a PS core (or similar other polymeric materials), [7][8][9][10] although there are several studies describing the synthesis of a PNIPAM-based core and a PS shell. 11,12 It is thermodynamically favorable to form a hydrophilic shell around a hydrophobic core.…”

Polymer in Agriculture: a Review

“…Several articles showed that others versatile functionalities are sulfonate groups and phosphoric groups. [68,69] . They were able to create thermosensitive resins with LCST able to bind Cu (II) ions; finally thiacrown polymers immobilized on polystyrenedivinylbenzene were employed for Hg (II) removal [70] .…”

Adsorption of Cu2+ ions with poly(N‐isopropylacrylamide‐co‐methacrylic acid) micro/nanoparticles

“…For example, the adsorption amount with PNIPAAm-VBEDA ranged from 0.001 to 0.012 mmol/gdrygel, 12 and that of PNIPAAm-MEP ranged from 0.015 to 0.035 mmol/g-drygel. 25 The magnificent increase of adsorption should ascribe to the nanoscale particle size. The PNIPAAm-MAA particle size ranged from 30 to 500 nm, which greatly increased the effective contact area of the MAA and Cu 21 ions.…”