Novel N-functionalized tourmaline/pomelo peel biochar composite: preparation, characteristics, and mechanisms in adsorbing Pb2+

Pb contamination is a serious environmental concern, posing significant threats to ecosystems and human health. Biochar-based functional materials have attracted considerable attention owing to their great potential for practical application. In this study, a novel N-functionalized tourmaline-biochar composite (TNBC) from pomelo peels with co-modifications using urea and tourmaline was developed. The immobilization of Pb in solution and soil by TNBC was investigated, and influencing factors and mechanisms were also analyzed. The experimental maximum adsorption capacity of Pb 2+ on TNBC was 600.60 mg/g. Analysis of morphologies and surface functional groups revealed that precipitation regulated Pb 2+ adsorption on TNBC, followed by cation exchange, complexation, and metal-π interaction. The effect of co-existing cations in the solution on adsorption was marginal. Correlation analysis disclosed that enriched plenty of minerals and N-functional groups on TNBC surface were the main reasons for improving Pb 2+ adsorption on TNBC compared with pristine biochar. Moreover, TNBC exhibited potential for soil remediation and could be an alternative amendment for Pb contamination. The TNBC increased the pH, electroconductivity, and residual Pb content of the polluted soil; therefore, it can ameliorate the effects of Pb contamination in the soil. This study provides an alternative viewpoint on developing functionalized biochar composites for soil remediation. • N-functionalized tourmaline/pomelo peel biochar composite (TNBC) was synthesized. • Co-modifying before pyrolysis improved the properties of biochar composites. • The experimental maximum adsorption capacity of Pb 2+ by TNBC was 600.60 mg/g. • Pb 2+ adsorption on TNBC was correlated with enhanced cation ions and N-groups. • Correlation analysis clarifies the critical properties of biochar in Pb 2+ adsorption.