Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study

Abstract

ABSTRACT:We investigated a new adsorbent system, Reactive Red 120 attached poly(2-hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA-EDMA)] beads, for the removal of Ni 2ϩ ions from aqueous solutions. Poly-(HEMA-EDMA) beads were prepared by the modified suspension copolymerization of 2-hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150 -250 m), having a swelling ratio of 55% and carrying 25.5 mol of Reactive Red 120/g of polymer, were used in the removal of Ni 2ϩ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA-EDMA) beads for Ni 2ϩ ions was investigated in aqueous media containing different amounts of Ni 2ϩ ions (5-35 mg/L) and having different pH values (2.0 -7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni 2ϩ ions onto the Reactive Red 120 attached poly(HEMA-EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni 2ϩ ions onto poly(HEMA-EDMA) beads was negligible (0.1 mg/g). The desorption of Ni 2ϩ ions was studied with 0.1M HNO 3 . High desorption ratios (Ͼ90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k 20°C ϭ 0.565 mg/g min 0.5 , k 30°C ϭ 0.560 mg/g min 0.5 , and k 40°C ϭ 0.385 mg/g min 0.5 . Adsorption-desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo-first-order kinetic model was used to describe the kinetic data.

Reactive red 120 and NI(II) derived poly(2‐hydroxyethyl methacrylate) nanoparticles for urease adsorption

“…This capacity level may have been due to the presence of functional chelating groups on the dye‐attached nanoparticles. The specificity of the metal‐chelating ligand (i.e., RR120 molecules) may also contribute to this high adsorption capacity …”

Adsorption of Cr(VI) ions onto poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole)

“…To investigate the mechanism of adsorption, the pseudofirst‐order model, pseudosecond‐order model, and intraparticle diffusion model were used for testing dynamic experimental data 23, 30–32. The pseudofirst‐order model of Lagergren is given as follows: …”

Preparation and characterization of nanostructured and high transparent hydrogel films with pH sensitivity and application

“…1 To date, these gels have been largely used in biomedical applications 4,5 and as separation or adsorption matrices for various metal ions. 6,7 However, many of their potential applications are hindered by their limited water uptake, 8 low mechanical strength, and slow response rate. 9,10 To improve the water swelling property of PHEMA hydrogels, various monomers which are more hydrophilic than HEMA are introduced such as vinylpyrolidone 11 and ethylene glycol methacrylate.…”

“…Poly(2‐hydroxyethyl methacrylate) (PHEMA) was the first hydrogel for biomedical applications in 1960s 1. To date, these gels have been largely used in biomedical applications4, 5 and as separation or adsorption matrices for various metal ions 6, 7. However, many of their potential applications are hindered by their limited water uptake,8 low mechanical strength, and slow response rate 9, 10.…”