Removal of Heavy Metals by Poly(Vinyl Pyrrolidone)/Laponite Nanocomposite Hydrogels

Abstract

Laponite cross-linked poly(vinyl pyrrolidone) (PVP) hydrogels were fabricated by in situ polymerization of vinyl pyrrolidone (NVP). Macroporous PVP/Laponite nanocomposite hydrogels were obtained by freeze drying of hydrogels, which exhibited faster adsorption kinetics than ambient-dried ones. We also investigated the influence of laponite content, initial ion concentration and pH of the solution on the adsorption capacity of PVP/Laponite hydrogels. Moreover, the PVP/Lapnoite hydrogels can further be fabricated into powder hydrogel samples, which can be used as a potential candidate of adsorbent for removal of heavy metals in water.

A Short Review on Recent Advances of Hydrogel-Based Adsorbents for Heavy Metal Ions

“…Controlled hydrolysis of polyacrylamide resulted in polyacrylamide-polyacrylic acid hydrogel used for the recovery and separation of Cu(II) and Cd(II) ions [86]. Laponite/polyvinyl pyrrolidone hydrogel removed Cu(II) ion efficiently [87].…”

Poly(N-vinylpyrrolidone)–Laponite XLG Nanocomposite Hydrogels: Characterization, Properties and Comparison with Divinyl Monomer-Crosslinked Hydrogels

“…Since then, numerous NC hydrogels have been prepared, mostly from acrylamide-type monomers, such as N-isopropylacrylamide [ 24 , 26 , 27 , 28 ], acrylamide [ 29 , 30 , 31 ], N,N-dimethylacrylamide [ 29 , 31 , 32 , 33 ], N,N-diethylacrylamide [ 34 ], N-acryloyl glycinamide [ 35 ], 4-acryloylmorpholine [ 36 ] and their copolymers with monomers such as 2-methoxy-ethyl acrylate [ 37 ], sodium methacrylate [ 38 , 39 , 40 ] and acrylate [ 41 ], 2-(dimethylamino)ethyl methacrylate [ 42 ] and isocyanoethyl methacrylate-glutamine [ 43 ]. NC hydrogels from non-acrylamide monomers have been reported in only very few cases: N-vinylpyrrolidone [ 44 , 45 ], 2-dimethylaminoethyl methacrylate [ 46 ] and 2-(2-methoxyethoxy)ethyl methacrylate–oligo(ethylene glycol) methacrylate copolymer [ 47 ]. Both Laponite XLG/RD [ 24 , 31 , 33 , 38 , 40 ] and Laponite XLS/RDS [ 27 , 29 , 30 , 31 , 42 ] were used as crosslinking agents, while the polymerization was initiated most often by the potassium peroxodisulfate-N,N,N′,N′-tetramethylethylenediamine redox initiating system [ 24 , 26 , 28 , 29 , 30 , 31 , 32 , 33 ] and in a much lower extent by 2,2′-azobis(isobutyronitrile) [ 33 ,…”

“…NC hydrogels from non-acrylamide monomers have been reported in only very few cases: N-vinylpyrrolidone [ 44 , 45 ], 2-dimethylaminoethyl methacrylate [ 46 ] and 2-(2-methoxyethoxy)ethyl methacrylate–oligo(ethylene glycol) methacrylate copolymer [ 47 ]. Both Laponite XLG/RD [ 24 , 31 , 33 , 38 , 40 ] and Laponite XLS/RDS [ 27 , 29 , 30 , 31 , 42 ] were used as crosslinking agents, while the polymerization was initiated most often by the potassium peroxodisulfate-N,N,N′,N′-tetramethylethylenediamine redox initiating system [ 24 , 26 , 28 , 29 , 30 , 31 , 32 , 33 ] and in a much lower extent by 2,2′-azobis(isobutyronitrile) [ 33 , 44 ] and photoinitiators [ 27 , 35 , 36 ].…”

“…Its hydrogel derivatives have been obtained either by NVP polymerization in the presence or absence of a divinyl comonomer or by crosslinking the preformed PNVP through irradiating its aqueous solutions with high energy or UV rays, usually in the presence of another polymer to enhance the mechanical properties of the hydrogel product [ 13 , 50 , 51 , 53 , 54 ]. Due to the remarkable properties of the constituent polymer, PNVP hydrogels display many (potential) applications such as wound management [ 4 ], disintegrants and dissolution agents in pharmaceutical tablets [ 55 ], drug [ 56 ] and protein [ 57 ] delivery systems, water purification [ 44 , 58 ], etc.…”

“…Surface and ground water pollution is an important issue of the present days, and from this point of view, (nano)composite hydrogels represent a valuable treatment solution for the contaminated waters [ 18 , 19 ]. This should be especially true when both the polymer and the filler display complexing/adsorption ability for various chemicals acting as water pollutants, such as in the case of poly(N-vinylpyrrolidone) NC hydrogels [ 44 ]. The present work aims at investigating, for the first time, the synthesis and properties of the hydrogels obtained by the aqueous solution free radical polymerization of NVP in the presence of Laponite XLG as a crosslinker, in comparison with the corresponding hydrogels prepared by using two conventional crosslinking divinyl monomers: tri(ethylene glycol) divinyl ether (DVE) and N,N′-methylenebisacrylamide (MBA).…”