Lead (Pb) contamination in soil is a growing environmental concern, posing risks to ecosystems and human health. To tackle this issue, researchers have developed an innovative biochar composite made from pomelo peels, tourmaline, and urea. This nitrogen-functionalized tourmaline-biochar composite (TNBC) exhibits superior ability to adsorb lead ions (Pb²⁺), with an experimental maximum adsorption capacity of 600.60 mg/g. This makes it more effective than its predecessors, tourmaline-biochar (TBC) and nitrogen-functionalized biochar (NBC).

The TNBC’s enhanced performance stems from its enriched surface minerals and nitrogen groups, which improve its affinity for Pb²⁺. Key mechanisms driving Pb²⁺ adsorption include precipitation, cation exchange, and complexation with surface functional groups. Precipitation, responsible for 60% of adsorption, occurs when dissolved carbonates form stable lead compounds.

Beyond water treatment, TNBC has shown promise in soil remediation. It increases soil pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More and electrical conductivity, making Pb less bioavailable and converting it into more stable forms. These effects can help mitigate the environmental impact of lead contamination in agricultural areas.

This study highlights TNBC as a cost-effective, sustainable solution for Pb pollution. Future research could explore its application in multi-metal contaminated soils, ensuring a broader impact on environmental health and safety.