Enhancing microplastics removal from soils using wheat straw and cow dung-derived biochars.

Microplastics have attracted extensive public attention due to their harmful effects on environments and organisms, especially for small-size microplastics. Herein, six kinds of biochar were produced by wheat straw and cow dung at 500, 600 and 700 °C respectively for the removal of 1 μm polystyrene microplastics from soils. The removal efficiencies of microplastics exceeded 86% for all biochars. With increasing pyrolysis temperature, the removal performance of wheat straw biochars for microplastics gradually improved, while the removal efficiency of cow dung biochars decreased. Biochars effectively trapped microplastics within their channels, oxygen-containing functional groups (CO 3 2− and COO−) on the surface of biochars facilitated the adsorption of microplastics. After seven cycles of biochars recycling, the removal performance of microplastics remained above 85%, the removal process was primarily governed by the adsorption sites rather than the porous structure of biochars. This article provided eco-friendly and recyclable biochar materials for microplastics removal and technical support for addressing soil microplastics pollution. [Display omitted] • The highest removal efficiency of MPs by cow dung biochar reaches 92.4% at pH 9. • The removal efficiency of MPs remains above 85% after 7 cycles of biochar recycling. • Biochars show great stability and hold promising practical prospects for MPs removal. [ABSTRACT FROM AUTHOR]