Preparation of core–shell magnetic ion-imprinted polymer for selective extraction of Pb(II) from environmental samples

Abstract

a b s t r a c tA novel magnetic ion-imprinted polymer (Fe 3 O 4 @SiO 2 @IIP) was synthesized by using 3-(2-aminoethylamino)propyltrimethoxysilane (AAPTS) as the functional monomer, tetraethylorthosilicate (TEOS) as the cross-linker and Pb(II) as the template and evaluated for selective extraction of Pb(II) from environmental sample by magnetic solid phase extraction (M-SPE) procedure. The factors affecting separation and preconcentration of the target heavy metals involving pH, eluting solvent and sample volume were studied in detail. Under the optimized experimental conditions, the kinetics adsorption and adsorption capacity of the Fe 3 O 4 @SiO 2 @IIP toward Pb(II) were estimated. The results indicated that the adsorption mechanism is corresponding with the second-order adsorption process with correlation coefficient (r 2 = 0.990), and the maximum adsorption capacity is 19.61 mg g −1 . The relative selectivity factor (ˇ) values of Pb(II)/Cu(II), Pb(II)/Zn(II), Pb(II)/Cd(II) and Pb(II)/Hg(II) are 7. 41, 6.76, 3.75 and 6.39, respectively. The Fe 3 O 4 @SiO 2 @IIP was applied for extracting and detecting of Pb(II) in real environmental samples combined with atomic adsorption spectrometer successfully with high recoveries of 98.0%.

Silica-Coated Magnetic Nanocomposites for Pb2+ Removal from Aqueous Solution

“…The complexity derives from the non-uniformity of the adsorption process variables employed and the different measuring units for adsorption capacity or parameters that were used to express the results. Roughly, functionalization of the silica shell is significant when the initial metal concentration is as low as 0.01-0.2 mg/mL [13,47,48] or when small quantities of adsorbent (0.4-1 mg/mL) [11,12,[14][15][16] and reduced contact times (30 min) [12] should be used.…”

Organic-Inorganic Hybrid Polymers as Adsorbents for Removal of Heavy Metal Ions from Solutions: A Review

“…To study Sections 3.1–3.5, the characteristics of different kinds of organic-inorganic hybrid polymers were as follows: (1) Some functional groups of these adsorbents are –SH, –COOH, amines and –S–S–, –OH, –SO 3 − and ion exchange sites of hybrid polymer; (2) adsorption processes mostly obey the Langmuir isotherm that shows the adsorption is monolayer and there is a uniform distribution of sites on the surface of adsorbents; (3) the adsorption capacity of each certain organic functional group changes depending on its content [181,214], the used organic compound, inorganic support [166,195], crosslinking agent [212], aggregation of nanoparticles [253] and the used synthesis method [182,189]; (4) in some cases, organic compounds are used only for increasing thermal and mechanical stability of adsorbents and without adsorbing heavy metal ions [224]; (5) mesoprous compounds, due to their porous structures have a rather higher adsorption capacities compared to those of organically-functionalized layered, core-shell compounds and products of sol-gel method; (6) heavy metals as cations and oxyanions are adsorbed via electrostatic interactions and the increase in the hydrophobicity of functional groups of adsorbent (e.g., –N(C 2 H 5 ) 2 [156] or from –NH 2 to –NH(propyl) to –N(propyl) 2 [178]) decreases their adsorption capacity for metal cations and increases their q max values (e.g., from trimethylammonium to tri- n -butylammonium functional groups) for the adsorption of some hydrophobic oxyanions [183]; (7) In the most cases, for example [141–147,216,221,225,241,243,249,252], the used adsorbents are recovered by acid treatment and in the cases that acid dissolves the adsorbent [199], they have used another washing solutions; (8) some ions may react with metallic ions, e.g., Cl − with Hg 2+ [226], and inhibit their adsorption; (9) some ions, e.g., Cl − [183], SO 4 2− [196] or metallic cations [252], may react with functional groups of hybrid adsorbents and decrease their adsorption capacity for heavy metal ions; (10) steric hindrance on functional group decreases its adsorption capacity [151]; (11) in most cases, adsorption capacities of organic-inorganic hybrid polymers are bigger than those of their organic or inorganic constituents; (12) most of heavy metals were adsorbed in the pH range 4–7. With the increase in alkalinity of solution, heavy metal ions convert to metal hydroxides and this decreases their affinity for interaction with binding sites of adsorbents […”

“…Copyright 2012 Elsevier) and ( b ) template in Fe 3 O 4 @SiO 2 @IIP (Reprinted with permission from [252]. Copyright 2011 Elsevier).…”

Selective sorption behavior of metal(II) ion-imprinted polymethacrylate microspheres synthesized via precipitation polymerization method

“…Most of the current researches in the solid phase extraction are focused on the use of metal ion-imprinted polymers (MIIPs) owing to their cost effectiveness, high stability in different environments, and high selectivity compared to common separation techniques [22][23][24][25][26][27][28][29]. The ion-imprinted polymer particles are generally prepared by the solution, bulk, suspension polymerization, or surface imprinted technique [30][31][32][33].…”