Title : Sustainable reduction of heavy metal uptake in contaminated soil using walnut shell as a biosorbent
Abstract:
Environmental pollution caused by toxic heavy metals has become a major global concern due to its negative impacts on ecosystems, agricultural production, and human health. Heavy metals can accumulate in agricultural soils and enter the food chain through plant uptake, posing serious risks to food safety. Therefore, the development of sustainable and environmentally friendly remediation methods is essential. This study evaluated the effectiveness of walnut shell as a natural biosorbent for reducing the uptake of heavy metals by coriander (Coriandrum sativul L.) cultivated in contaminated soil. Ground walnut shells, both untreated and treated with different concentrations of phosphoric acid, were incorporated into the soil. Harvested coriander samples were prepared according to AOAC standards, and heavy metal concentrations were determined using atomic absorption spectrometry.
The results demonstrated that walnut shell significantly reduced the accumulation of heavy metals in coriander. The highest efficiency was achieved when walnut shell was treated with 2% phosphoric acid and applied to the soil at a concentration of 2% (w/w). Under these conditions, lead (Pb) showed the greatest reduction, reaching up to 85% compared with the contaminated control. The biosorbent began its activity immediately after application to the soil and continued to function effectively without causing adverse environmental effects. The findings suggest that walnut shell is an inexpensive, sustainable, and environmentally friendly biosorbent that can be used to reduce heavy metal contamination in agricultural systems and improve food safety.
Keywords: Walnut shell; Biosorption; Heavy metals; Lead (Pb); Cadmium (Cd); Nickel (Ni); Contaminated soil; Coriander; Food safety; Sustainable agriculture; Environmental remediation.
