Abstract
There is an urgent demand worldwide for the development of highly selective adsorbents and sensors of heavy metal ions and other organic pollutants. Within these environmental and public health frameworks, we are combining the salient features of clays and chelatant polymers to design selective metal ion adsorbents. Towards this end, the ion imprinting approach has been used to develop a novel nanohybrid material for the selective separation of Cu2+ ions in an aqueous solution. The Cu2+-imprinted polymer/montmorillonite (IIP/Mt) and non-imprinted polymer/montmorillonite (NIP/Mt) nanocomposites were prepared by a radical photopolymerization process in visible light. The ion imprinting step was indeed important as the recognition of copper ions by IIP/Mt was significantly superior to that of NIP/Mt, i.e., the reference nanocomposite synthesized in the same way but in the absence of Cu2+ ions. The adsorption process as batch study was investigated under the experimental condition affecting same parameters such as contact time, concentration of metal ions, and pH. The adsorption capacity of Cu2+ ions is maximized at pH 5. Removal of Cu2+ ion achieved equilibrium within 15 min; the results obtained were found to be fitted by the pseudo-second-order kinetics model. The equilibrium process was well described by the Langmuir isothermal model and the maximum adsorption capacity was found to be 23.6 mg/g. This is the first report on the design of imprinted polymer nanocomposites using Type II radical initiators under visible light in the presence of clay intercalated with hydrogen donor diazonium. The method is original, simple and efficient; it opens up new horizons in the general domain of clay/polymer nanocomposites.
Highlights
There is global concern about heavy metal pollution of the environment considering the high risk of these elements entering the food chain via natural and anthropogenic routes [1]
Montmorillonite was first cation exchanged with a diazonium compound bearing dimethyl amino groups to provide a macro-photoinitiator, and visible light radical photopolymerization was conducted in the presence of the modified clay, the monomers
To investigate the effect of pH, 4 mg imprinted polymer/montmorillonite (IIP/montmorillonite clay (Mt)) and non-imprinted polymer/montmorillonite (NIP/Mt) were added to 20 mL sample solutions containing 20 mg/L of Cu(II) ion at pH range 2.0–9.0, respectively, pH values were adjusted by 1 mol/L
Summary
There is global concern about heavy metal pollution of the environment considering the high risk of these elements entering the food chain via natural and anthropogenic routes [1]. The second important issue is to develop high-capacity adsorbents to remove or pre-concentrate heavy metals in order to have a complete picture of the pollution by metal ions from the surface physicochemical point of view. Towards this end, clays can be regarded as natural inorganic “sponges”. Montmorillonite was first cation exchanged with a diazonium compound bearing dimethyl amino groups to provide a macro-photoinitiator, and visible light radical photopolymerization was conducted in the presence of the modified clay, the monomers (4-vinylpyridine, (VP) methacrylic acid (MA), CQ, and the heavy metal ions. Thorough rinsing of the final product removed the metal ions and created artificial receptor sites for the selective recognition of copper
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