Metal oxide‐loaded biochar for heavy metal removal from water on synthesis, mechanisms, and future perspectives
Heavy metal water pollution poses severe health risks to humans. Heavy metal contamination from natural and anthropogenic sources poses a serious threat to the environment. Various techniques including adsorption, ion exchange, precipitation, chemical reduction, and ultrafiltration have been employed to remove heavy metal ions from wastewater. Adsorption is frequently preferred due to its simple operation and good controllability. Metal oxide‐loaded biochar has unique properties and is a highly attractive adsorbent due to its low cost and good sustainability. In this review, the preparation methods and classification of metal oxide‐loaded biochar are first thoroughly described. The characterization approaches, including instrumental analysis and chemical analysis, are further introduced in detail. Adsorption kinetics, isotherms, and thermodynamics are discussed to elucidate the removal processes and mechanisms. Particular emphasis is placed on the mechanisms of physisorption and chemisorption. Furthermore, this review evaluates the application potential of metal oxide‐loaded biochar and analyzes key future research challenges in this field.