Available Low Cost Agro-Waste as an Efficient Medium to Eliminate Heavy Metal Contamination using Sustainable Approach Achieving Zero Residue Level

Abstract

Although bismuth is a low toxic metal compared to other heavy metals, but its continuous accumulation in living tissues is considered a serious issue for health and environment. The present investigation aims to test the adsorption technique for removing bismuth ions from polluted aqueous medium via pomegranate peels as low-cost medium in an adsorption unit of batch-type at various operating parameters. The obtained results showed that pomegranate peels have a remarkable efficiency in to recover Bi+3 ions from polluted water, reaching approximately 75% at 38 ppm initial bismuth concentration, agitation speed of 350 rpm, 2.4 h contact time, acidity function of 7, 5 g dose of pomegranate peel, and 20 °C temperature. Isothermal and kinetic studies indicated that the Langmuir and pseudo-second order models are the closest to describing the adsorption. Furthermore, the adsorption was spontaneous, physical, and of low entropy according to thermodynamic, while the adsorption capacity was 2.26 mg/g. In order to dispose of the residual waste in an environmentally safe manner, it was investigated to convert them into a rodenticide. The pomegranate peels loaded with bismuth ions showed a clear and effective effect against laboratory rats of Sprague Dawley type, and the lethal half dose (LD50) calculated was very close to what was mentioned in the literature.

Keywords

• adsorption
• pomegranate peel
• bismuth
• batch unit
• zrl