The removal of heavy metal ions from aqueous solutions by novel pH-sensitive hydrogels

A response surface modelling study for sorption of Cu2+, Ni2+, Zn2+ and Cd2+ using chemically modified poly(vinylpyrrolidone) and poly(vinylpyrrolidone-co-methylacrylate) hydrogels

“…Analytical grade 4,4 0 -dicyano-4,4 0 -azovaleric acid (Fluka), poly(ethylene glycol) (Merck) and 4-vinylbenzyl chloride (Sigma-Aldrich) were used as monomers for synthesizing the macroinimer (MIM) (Yildiz et al, 2010 …”

“…Varying amounts of VP and MA (Table 1) were mixed in the presence of same MIM (0.30 g) amount and then the obtained hydrogel samples were dried. The prepared PVP and P(VP-co-MA) hydrogels were then characterized accordingly using various techniques as reported by our previous study (Yildiz et al, 2010), and then used for further applications and optimization. The sorption properties of PVP and P(VP-co-MA) hydrogels for the different metal ions were then tested under non-competitive conditions by immersing the hydrogels in the different metal ions solutions.…”

“…The sorption capacity of P(VP-co-MA) hydrogel for the different metal ions was also investigated and the obtained plots represented in Figure 4 , Zn 2þ and Cd 2þ metal ions were significantly higher than that of the homopolymer hydrogel. This was due to the presence of additional oxygen atoms from methylacrylate which coordinated more metal ions thereby increasing the metal ion binding capacities (Milosavljevic et al, 2011 However, the higher sorption capacities of Cu 2þ metal ion obtained using PVP and P(VPco-MA) hydrogels was attributed to the Jahn-Teller effect which states 'For any non-linear molecule in an electronically degenerate state, distortion must occur to lower the symmetry, remove the degeneracy and lower the energy' (Justi et al, 2005;Yildiz et al, 2010). In addition, Cu 2þ is known as one of the easiest metal ions to form complexes with ligands containing nitrogen and oxygen atoms.…”

Poly(2-acrylamido-2-methyl-1-propane sulfonic acid-co-1-vinyl-2-pyrrolidone) Hydrogel and its use in the Removal of Cd(II), Pb(II) and Cu(II)

“…The removal of heavy metals has become a major problem since they do not have a biodegradable property naturally in the environment [1]. Hydrogels, hydrophilic, cross-linked and three-dimensional networks, have an excellent water absorbing capacity without being soluble [3][4][5]. These smart materials are widely used in the removal of heavy metal ions because of the presence of the functional groups (i.e.…”

Synthesis and application of polyethylene glycol/vinyltriethoxy silane (PEG/VTES) copolymers

“…It is widely used in the pharmaceutical industry, agriculture, food handling, biological and material science and chemical engineering fields (Kitagawa et al, 2010). In recent years, a PEG functional monomer has been used to prepare hydrogels of differing structures (Hazer, 1992;Yildiz et al, 2010;Lynn and Bryant, 2011;Diez, 2009;Stahl et al, 2010). For wastewater treatment, PEG has served as a carrier for the immobilization of activated sludge.…”