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.

Water treatment is one of the most research-challenging areas, and continuously requires the development of efficient sustainable materials for catalytic total mineralization of organic compounds. Herein, Moringa oleifera biomass was converted to "black gold" biochar loaded with ZnO nanoparticles (MOFB@ZnO) by slow pyrolysis, at 500 °C under an inert atmosphere, (MOFB@ZnO). This composite catalyst was used for the total degradation of Congo Red, a model organic pollutant. SEM confirmed the uniform distribution of ZnO nanoparticles, while XPS and XRD indicated the presence of ZnO, primarily in the wurtzite crystalline structure. Optimization was conducted using the central composite design (CCD) method and STATISTICA 12.0 software. The composite catalyst was applied in the electrochemical degradation of Congo Red dye, using a platinum anode and a carbon felt cathode to generate H2O2 from O2 reduction. The ZnO-decorated Moringa oleifera biochar catalyst permitted to achieve of 98% removal of total organic carbon in less than 6h. It is 10-fold more efficient than pristine biochar and can be recycled up to 4 times without any significant loss. The process is highly efficient producing sustainable low-cost catalysts for water purification from organics, and contributes to sustainable chemical processes therefore addressing SDGs 6, 9, and 13.