No 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.

Clay/mercaptosuccinic acid hybrids were prepared through radical thiol-ene coupling between methacrylate-silanized clay and mercaptosuccinic acid. The clay surface was modified by 3-trimethoxysilylpropylmethacrylate, then mercaptosuccinic acid was clicked by ultraviolet (UV)-triggered thiol-ene addition reaction at 365 nm. Pristine and modified clays were characterized by X-ray diffraction (XRD), attenuated total reflection (ATR) and XPS. The clay/mercaptosuccinic acid material was employed as an adsorbent for the removal of Pb(II) from aqueous solutions. Kinetic studies indicated that the adsorption of Pb(II) followed the pseudo-first-order equation while the Langmuir model fitted the adsorption isotherm. The maximum adsorption was found to be 74.7 mg/g for an equilibrium time of~80 min. UV-triggered thiol-ene reaction is demonstrated to be an easy and elegant pathway for designing reactive and functional clay for environmental and other applications.

No abstract

No abstract