Synthesis and Characterization of LIX-84 Noncovalently Bound Silica Sorbents for Metal-Ion Recovery

Abstract

Mesoporous silica particles were modified with LIX-84 (2-hydroxy-5-nonylacetophenome oxime). LIX-84 was attached to the surface of silica via noncovalent forces. The effects of silica particle size, pore size, temperature, and pH on metal-ion-exchange properties were studied to characterize metal ion adsorption properties for chelating groups noncovalently bound to the surface of silica. The adsorbent had a capacity of 0.6 mmol of Cu 2+ /g of adsorbent at room temperature and a capacity of 1.1 mmol of Cu 2+ /g of adsorbent at 60 °C. Depending on the solution pH, the adsorbent had varying capacity for Cu 2+ , Ni 2+ , and Pb 2+ . The adsorbent was found to have good stability and gave high metal recovery when regenerated with 2 vol % nitric acid. An increased ion-exchange rate was achieved and was attributed to the use of larger pore size silica. The silica was found to contain from 5 to 7 wt % LIX-84.

Modified Superparamagnetic Nanocomposite Microparticles for Highly Selective HgII or CuII Separation and Recovery from Aqueous Solutions

“…The DRIFT spectrum of modified particles (Figure 7b) shows absorptions between 3200 and 3600 cm −1 (p-and m-hydroxyl groups), at 1400−1500 cm −1 (substituted benzene), and at 1600 cm −1 (C−N bond). 62 Magnetization drops to 16 emu/g, indicating a 47 wt % loading of the particles with LIX84 (probably including some residual kerosene). LIX84-modified composite microparticles are rather hydrophobic but disperse fairly well in water if vigorously shaken.…”

Preparation and Characterization of Immobilized Chelate Extractant in PVA Gel Beads for an Efficient Recovery of Copper(II) in Aqueous Solution

“…Therefore, the D e values in the SIRs are estimated to be in an order of magnitude of 10 -10 -10 -8 cm 2 /s, which are comparable with the reported values of 10 -12 -10 -9 cm 2 /s for the different dense gel phases. 23,30,31 In other words, the diameter of the PVA gel beads can be made much larger than that of the hydrophobic matrix type microcapsules to obtain a constant extraction efficiency for a fixed extraction time. Within an appropriate range of the gel bead size, the larger diameter is more advantageous for reducing the bed pressure drop, simplifying the preparation and handling of gel beads, enhancing the bead interfacial stability, etc.…”

“…Silica gel as a solid support for immobilization of chelating reagents with no organic solvent is employed because it has good mechanical strength and immobilization procedures are relatively simple. 23,24 With neither chelate extractant nor solvent used, poly(acrylic acid) gel beads having metal ion chelating properties are coated by a polyamide membrane for improved mechanical strength of the beads. [29][30][31] In addition, a thermosensitive geltype adsorbent composed of a thermosensitive polymer and an interactive polymer is presented for temperature swing adsorption.…”

“…A variety of researches and developments have been reported to overcome the problems with the conventional solvent extraction of heavy metals with chelate extractant. Each of them employs its own type of confinement or immobilization of solvent and/or chelate extractant using hollow fiber membrane, − liquid membrane, − ,, resin, − microcapsule, − or silica gel. , For example, confinement of chelate extractant in the double emulsion liquid membrane, i.e., w/o/w micelle, provides a great interfacial area for metal transport from the feed solution toward the stripping liquid with a very small volume of organic solvent. A nondispersive solvent extraction system consists of two hollow fiber membrane type contactors, one being for extracting and the other for stripping.…”

“…Other types of solid-phase extractions have been developed with different ligands or functional groups immobilized in an inert support or stationary polymer matrix with no solvent. Silica gel as a solid support for immobilization of chelating reagents with no organic solvent is employed because it has good mechanical strength and immobilization procedures are relatively simple. , With neither chelate extractant nor solvent used, poly(acrylic acid) gel beads having metal ion chelating properties are coated by a polyamide membrane for improved mechanical strength of the beads. − In addition, a thermosensitive gel-type adsorbent composed of a thermosensitive polymer and an interactive polymer is presented for temperature swing adsorption . The mechanisms in these solid phase extractions are not fully clarified.…”