Advancements in Nanomaterial-Enhanced Biochar for Microplastic Remediation: A Comprehensive Review of Environmental Impact and Remediation Strategies

Abstract Microplastics (MPs) and nanoplastics (NPs) pollution represents a critical environmental crisis, yet conventional remediation techniques are frequently constrained by low removal efficiencies and high secondary-pollutant risks. This review critically evaluates nanomaterial-enhanced biochar as a superior, synergistic solution to these limitations. We identify the primary technical challenges in current remediation, specifically the kinetic barriers of sub-micron particle capture and the recovery of spent adsorbents from complex aquatic matrices. The key contribution of this work lies in detailing the transition from general adsorption to precision-engineered nano-interfaces, highlighting mechanisms such as π-π electron donor-acceptor interactions, Fe 3 O 4 -driven magnetic separation, and Reactive Oxygen Species (ROS)-mediated catalytic degradation. We further analyze hybrid innovations, including graphene oxide-functionalized biochar and enzyme-immobilized composites, which bridge the gap between physical entrapment and chemical mineralization. To facilitate the transition from laboratory-scale proof-of-concept to industrial restoration, we provide three main recommendations: (1) the adoption of standardized ecotoxicity assessments for spent nano-composites to prevent secondary contamination; (2) the development of AI-driven synthesis for polymer-specific biochar targeting; and (3) the integration of circular-economy frameworks to valorize agricultural waste into high-value remediation tools. By synthesizing recent advancements, this review provides a strategic roadmap for the scalable deployment of nano-biochar technologies in wastewater treatment and soil remediation.