Evaluation of Adsorption Behavior of Chromium (VI) on 2-(Dimethylamino)ethyl Methacrylate Grafted Polyethylene Meshes

Abstract

A novel polymeric adsorbent for hexavalent chromium (Cr(VI)) ions was developed by photografting 2-(dimethylamino)ethyl methacrylate (DMAEMA) to a polyethylene (PE) mesh substrate. The DMAEMA-grafted PE (PE-g-PDMAEMA) meshes obtained were quaternized with iodoalkanes of different alkyl chain lengths. The grafting of DMAEMA and subsequent quaternization of dimethylamino groups were characterized by the FT-IR measurements. The Cr(VI) ion adsorption capacity at pH 3.0 and 30°C had the maximum value at the grafted amount of 2.6 mmol/g and the adsorption behavior obeyed the mechanism of the pseudo-second order kinetic model and well expressed by Langmuir isotherm. This can suggest that the adsorption occurs through an electrostatic interaction between protonated dimethylamino groups and hydrochromate ions. Cr(VI) ions were successfully desorbed in eluents such as NaOH, NaCl, and NH4Cl. When the PEg -PDAMEMA meshes were quaternized with the iodoalkanes, the adsorption capacity increased and the maximum adsorption ratio was obtained for the PEg -PDMAEMA mesh quaternized with iodoheptane. This value was about 1.83 times higher than the original PEg -PDAMEMA mesh. The results obtained in this study emphasize that the PEg -PDMAEMA meshes and their quaternized products can be applied as an adsorbent for Cr(VI) ions.

Kinetic, Isotherm, and Equilibrium Investigation of Cr(VI) Ion Adsorption on Amine-Functionalized Porous Silica Beads

“…Here, the desorption of Cr(VI) ions from AEAPTES-silica beads with the amount of amino groups of 0.220 mmol/g was measured in 0.50 M NaCl, 0.10 M NH 4 Cl, and 0.50 mM NaOH. These eluents were used for the desorption of Cr(VI) ions in our previous papers [ 4 , 19 , 45 ]. The desorption behavior was summarized in Table 6 .…”

“…The desorption occurs mainly through the ion exchange of HCrO 4 − ions with Cl − ions on protonated dimethylamino groups, -NH + (CH 3 ) 2 , in NaCl and NH 4 Cl and through the deprotonation from -NH + (CH 3 ) 2 to -N(CH 3 ) 2 in NaOH as shown in ref. [ 4 ] Figure 13, and [ 19 , 45 ]. Of them, the use of 0.10 M NH 4 Cl and 0.50 mM NaOH was effective for the desorption of Cr(VI) ions because high desorption % values were obtained, and the desorption was faster.…”