Functional Ion Membranes Supported Inside Microporous Polypropylene Membranes to Transport Chromium Ions: Determination of Mass Transport Coefficient

Abstract

Polypropylene (PP) membranes incorporating interpenetrating polymer networks of poly [(ar-vinylbenzyl) trimethylammonium chloride](P(ClVBTA)) and poly[sodium (styrenesulfonate)] P(SSNa) were modified via an "in-situ" radical polymerization synthesis inside the pores. The modified polypropylene membranes were characterized using SEM, ATR/FTIR, DRX, TGA, and Donnan dialysis for the transport of chromium ions. The modified membranes exhibited a percent modification between 2.5% and 4.0% in weight gain and a hydrophilic character with a water uptake capacity between 15% and 20%. The mass transport coefficient was determined using the non-linear fit of the experimental data to the exponential equation. Hexavalent chromium ions were efficiently transported by the modified membranes containing P(ClVBTA). At pH 3.0, the M4Cl.PEI (11.0×10 -6 m s -1 ), and at pH 9.0, the M3Cl (14.4×10 -6 m s -1 ) could transport hexavalent chromium ions efficiently using a 1 mol L -1 NaCl extraction agent. In the same way, the transport of trivalent chromium could be performed using membranes modified with P(SSNa). At pH 3.0 and 4.0×10 -2 mol L -1 trivalent chromium in the food chamber, the M9Na.PVA (16.3×10 -6 m s -1 ) performed efficient transport using 1×10 -3 mol L -1 HNO 3 as the extraction agent.Keywords: interpenetrating polymer network, membranes, Donnan dialysis, chromium, ion exchange, and polypropylene. INTRODUCTIONEnvironmental pollution of water, soil, and air is a serious problem when it includes oxyanions. Some oxyanion water-contaminating species employed in industry are chromate, arsenate, permanganate, hydrogen selenite, and selenate. A particular case is the derivatives of the chromium oxyanions. Chromium ions have two oxidation states in the water, for example, the trivalent chromium Cr(III) and hexavalent chromium Cr(VI).Cr(VI) produces the oxyanion (chromate) and the polyoxyanion (dichromate). These oxyanions are the more toxic ionic species and cause serious health problems such as cancer. The toxicity depends on the concentration and the exposure period 1,2 . Cr(VI) oxyanions are water-soluble across all pH ranges and accumulate well in biological systems (bioassimilable), and their speciation depends on the pH and concentration. If the pH is strongly acidic and the Cr(VI) ions are highly concentrated, the chromium ions exist as dichromate The most common methods developed to remove Cr(VI), and Cr(III) ions from polluted solutions are reduction and precipitation 9 , adsorption 10 , and ion exchange 11,12 . Membrane technologies allow for reverse osmosis, ultrafiltration, nanofiltration, dialysis, diffusion dialysis, Donnan dialysis, membrane electrolysis, and electrodialysis 4,12-14 (liquid, emulsified and supported) 13,15,16 . However, it is difficult to eliminate the oxyanions Cr(VI) and the Cr(III) ions selectively from the water. The improvement of the removal methods and the production of new functional polymer materials are very useful in the development of new technologies for removal, retention, an...

EFFICIENT REMOVAL OF Cr(VI) BY POLYELECTROLYTE-ASSISTED ULTRAFILTRATION AND SUBSEQUENT ELECTROCHEMICAL REDUCTION TO Cr(III)

“…28 The quantity retained was determined from the difference between the initial and final concentration. The pH was monitored by a pH meter (H. Jurgen and Co., Germany).…”

Donnan Dialysis Assisted by Interpenetrating Polymer Networks for Chromium Ion Transport in Aqueous Media

“…Similar results were obtained when the experimental data of the Cr(III) ions were fitted to a non-linear curve as the exponential mathematical model using the Leveberg-Marquardt algorithm. 42 Figure 6 shows the mathematical model fit by the Cr(III) ions at pH 2.0 in the feed phase, and the extraction phase at pH 1.0. Cr(III) can exist as CrOH 2+ and Cr(OH) 2 + at 0.04 mol/L.…”

Removal of Cr(vi) by Stabilized Solvent Impregnated Resin (Sir) Prepared by Using a Hydrophilic Polymer Adsorbent and Aliquat 336.

“…On the other hand, the materials employed in adsorption and ion exchange processes have generally low adsorption capacities and they show less selectivity towards metal ions than solvent extraction method. Chelating ion exchange resins are highly selective but they are expensive and elution of metal ions from these resins are difficult [5,6] .Water-soluble polymers (WSP) in conjunction with ultrafiltration membranes are also good alternatives but they require an expensive operation system such as ultrafiltration to remove huge quantity of metal ions [7][8][9][10][11] .…”