Next-generation biochar adsorbents from waste biomass: functionalization strategies and real-world water treatment applications

Abstract

Biochar has emerged as a sustainable and cost-effective adsorbent for the removal of emerging contaminants from wastewater. This review critically explores recent advances in the design and application of engineered biochars derived from diverse waste biomasses, focusing on the link between structural modifications and pollutant-specific removal mechanisms. Functionalization strategies including physical and chemical activation, heteroatom doping, surface grafting, and hybrid composite formation are systematically analyzed for their impact on adsorption efficiency and selectivity toward dyes, heavy metals, pharmaceuticals, and per- and polyfluoroalkyl substances. Particular attention is paid to performance in column systems, regeneration potential, and behaviour in complex real-world matrices, which remain underexplored in current literature. The diversity of adsorption mechanisms such as electrostatic interactions, π–π stacking, hydrogen bonding, ion exchange, and surface complexation is discussed in relation to surface chemistry and pollutant type. Despite promising results, critical challenges persist, including biochar heterogeneity, lack of standard production protocols, potential leaching of dopants, and limitations in large-scale implementation. This review highlights the need for unified assessment frameworks, life cycle analyses, and integration strategies aligned with circular economy principles. By bridging the gap between laboratory innovation and field-scale application, this work provides a comprehensive roadmap for researchers, engineers, and stakeholders seeking to deploy next-generation biochar-based sorbents in sustainable water treatment systems.

Graphical abstract

Keywords

Biochar / Waste biomass valorization / Surface functionalization / Adsorption mechanisms / Emerging contaminants / Water treatment

Highlight

	● Waste biomass valorized into engineered biochar for water pollutant removal.
	● Surface functionalization enhances selectivity and adsorption efficiency.
	● Pollutant-specific mechanisms mapped for dyes, metals, drugs, and PFAS.
	● Real effluent tests reveal gaps in scalability and long-term stability.
	● Integration with hybrid systems boosts treatment performance and reuse.

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