A sustainable synthesis, characterization of modified waste onion peels and its exploration in various applications

Abstract

The modification of waste to a bio-based material that is economical, environmentally sustainable, and extremely effective is crucial for organic conversions. For bio waste, that doesn’t decompose easily and have bad impact on environment such as onion peels, a suitable method is introduced which focuses on utilizing onion peels, a commonly discarded agricultural waste, as a valuable resource for antibacterial studies and bio sensing of heavy metals. A comparative study to analyse these properties were done using onion peel extract and saponified onion peels. The saponified material was obtained by treating onion peels (Allium cepa) with sodium hydroxide in the presence of calcium carbonate. The popularity of saponification reaction and saponified material is rising because of their special qualities and uses as disinfectants, surfactants, antifungal agents, in drugs for target based delivery etc. The saponified onion peels was analyzed by FTIR (Fourier transform infrared spectroscopy), and XRD (X-ray diffraction), EDX (energy-dispersive X-ray), SEM (scanning electron microscopy). Furthermore, against Bacillus subtilis (Gram positive), antibacterial activity of onion extract and saponified onion peels were studied. In comparative study onion peel extract shows better inhibition zone then saponified onion peels. Bio sensing of heavy metals were done by using these materials, onion peel extract shows visual colour change with Nickel chloride (NiCl2), Cobalt chloride (CoCl2), Potassium bromide (KBr), Manganese sulphate (MnSO4), Mercury chloride (HgCl2) and Copper sulphate (CuSO4) metal salts.

Keywords

• waste onion peels
• saponification
• green synthesis
• antibacterial action