Preparation of ionic liquids functionalized nanodiamonds-based composites through the Michael addition reaction for efficient removal of environmental pollutants

Nanodiamonds (ND) is a novel type of carbon nanomaterials with small size, large specific surface areas, low cost and some other physicochemical properties. However, the environmental applications of ND are still rarely reported because of its low adsorption performance. In this work, we reported for the first time for the surface modification of ND with ionic liquids through a facile and effective Michael addition reaction. To synthesis of the ternary ND@IL composites, ND was first linked with APTES by a silanization reaction and then [C 16 VIm + ] [Br − ] was conjugated on the surface of amino groups functionalized ND via the Michael addition reaction. The ND@IL composites were applied as adsorbents for removal of Congo red (CR) from aqueous solution and displayed high removal efficiency (92.78%) at room temperature and neutral solution. Under certain adsorption conditions, the adsorption capacities of pristine ND and ND@IL towards CR is 61.1 and 226.4 mg g −1 , respectively. The pseudo-second-order model fitting the adsorption kinetic data is superior to pseudo-first-order model and Freundlich isotherm model describes the experimental data well. Further experiments showed that the removal process was pH dependence, exothermic and spontaneous. More importantly, ND@IL composites could be regenerated via adjustment of pH values and still maintain high adsorption capacity after five regeneration cycles. All of the above results demonstrated that these ionic liquids modified ND are promising adsorbents for highly efficient and quick removal of environmental pollutants from aqueous effluents.