Two-step grafting of 2-hydroxyethyl methacrylate (HEMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) onto a polyethylene plate for enhancement of Cr(VI) ion adsorption

Abstract

Polyethylene (PE) plates grafted with a neutral monomer, 2-hydroxyethyl methacrylate (HEMA), and a cationic monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA), (PE-g-PHEMA)-g-PDMAEMA plates were prepared by the two-step photografting. The Cr(VI) ion adsorption behavior of the (PE-g-PHEMA)-g-PDMAEMA plates was investigated as a function of the amounts of grafted HEMA, amount of grafted DMAEMA, initial pH value, and temperature. The adsorption capacity of the DMAEMA-grafted PE (PE-g-PDMAEMA) and (PE-g-PHEMA)-g-PDMAEMA plates had the maximum value at the initial pH value of 3.0, independent of the temperature. The adsorption capacity of (PE-g-PHEMA)-g-PDMAEMA plates increased with the amount of grafted HEMA (G) in the first-step grafting. The increase in the water absorptivity of the grafted layers and thereby the increase in the degree of protonation of dimethylamino groups on grafted PDMAEMA chains were found to lead to the increase in the adsorption capacity. This adsorption capacity was higher than or comparable to those of other polymeric adsorbents for Cr(VI) ions. The Cr(VI) ion adsorption behavior on both PE-g-DMAEMA and (PE-g-PHEMA)-g-PDMAEMA plates obeyed the mechanism of the pseudo-second-order kinetic model and was well expressed by Langmuir isotherm. The high values of the Langmuir constant suggest that the adsorption of Cr(VI) ions occurs through an electrostatic interaction between protonated dimethylamino groups on grafted PDMAEMA chains and [Formula: see text]ions. Cr(VI) ions were successfully desorbed from PE-g-PDMAEMA and (PE-g-PHEMA)-g-PDMAEMA plates in eluents such as NaCl, NaCl containing NaOH, NHCl, NHCl containing NaOH, and NaOH.

Removal of Chromium(VI) by Chitosan Beads Modified with Sodium Dodecyl Sulfate (SDS)

“…In a natural aqueous environment, Cr(VI) may exist in the form of CrO complexes. It is well-known that Cr(III) is an essential material for organisms, whereas Cr(VI) is more toxic, carcinogenic, and mutagenic [8,9]. Thus, the development of a recovery method for this metal (particularly Cr(VI)) is significant from the standpoint of environmental protection.…”

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.…”

“…Then, 0.2–1.0 g of the NH-silica beads were immersed in 20 mL of a 20.0 mM HCl solution and the solutions were mildly stirred for at least 24 h under a nitrogen atmosphere. The HCl solutions were titrated with a 20.0 mM NaOH solution with bromothymol blue as an indicator [ 3 , 19 ]. The amount of effective amino groups, A NH , was calculated from the concentration difference in the HCl solution using Equation (1): where W NHSB is the weight of the NH-silica beads immersed.…”

Reusable Surface-Modified Bacterial Cellulose Based on Atom Transfer Radical Polymerization Technology with Excellent Catalytic Properties

“…Pure poly(HEMA) itself is a unique synthetic polymer used in biomedical fields, including enzyme immobilization [27], artificial cornea [28] and soft contact lens [29]. Hydroxyl (–OH) and acrylate groups on HEMA monomers are suitable sites for metal ions and harmful dyes to bind by chelation and ion-ion exchange [30]. Atom transfer radical polymerization (ATRP), one of the controlled/quasi-living radical polymerization techniques [31], has often been adopted for making linear polymer chains/brushes with controlled molecular lengths/weights since the propagation centers do not undergo chain termination and/or chain transfer during polymerization, and thus the molecular weights/lengths increase linearly with the conversion of monomers [32].…”