Preparation of MgO nano-rods with strong catalytic activity via hydrated basic magnesium carbonates

MgO nano-rods of several microns in length and 50–100 nm in width were prepared by calcining nesquehonite phase, obtained by simple precipitation using (NH₄)₂CO₃ under ambient condition. The MgO nano-rod with reasonably high surface area (75–120 m² g⁻¹) exhibits strong activity in solvent-free base catalyzed Claisen-Schmidt condensation giving 99% conversion in 2 h and is easily recyclable with no significant change in catalytic activity. Presence of numerous basic sites of different strengths (surface hydroxyl groups, low coordinate O²⁻ sites) is attributed to the observed effect.     

Time-dependent growth of CaO nano flowers from egg shells exhibit improved adsorption and catalytic activity

Succulent shaped CaO 3D nano flowers have been synthesized by time growth morphological evaluation from bud-to-blossom using dumped egg shells. A comparative study between commercially available calcium oxide and synthesized CaO nano flowers for adsorptive removal of used engine oil and aldol condensation was conducted. The as-synthesized nano particles were characterized by hydrodynamic particle size analyser, surface area by (BET) Brunauer-Emmett-Teller, XRD (X-ray Diffraction) for crystal structural and SEM-EDX (Scanning Electron Microscopy - Energy Dispersive X-ray) and HR-TEM (High-Resolution-Transmission Electron Microscopy) for morphological examinations. The average size distribution calculated using W-H analysis (1.28–1.38 µm) and morphological studies (1.26–1.30 µm) were in good agreement. The CaO_nsf showed higher adsorption activity for spill oil remediation by dispersion-adsorption method with an extent of separation capacity upto 18 times its weight (18.31 gg⁻¹ of CaO_nsf) in comparison to CaO_cm (8.4 gg⁻¹). The as-synthesized nano flowers displayed excellent catalytic activity for aldol condensation between acetophenone and benzaldehyde. The nano flowers comprising of succulent petals, are formed from many irregular elongated nanospheres. Higher surface area availability leads to higher catalytic activity for production of chalcone with a yield of about 76.3%. This study paves a way for development of CaO based 3D nanostructures, possessing higher adsorption efficiency for oil and an efficient catalyst for base catalysed reactions.