Chapter 24 - Attraction to adsorption: Preparation methods and performance of novel magnetic biochars for water and wastewater treatment

Abstract

Several studies approached the development of cheaper and effective materials in the last years, using many non-conventional low-cost adsorbents produced from biomasses that otherwise would just be waste. These adsorbents, referred to as biochars, have attracted much attention due to their high surface area and pore volumes, leading to a fast adsorption rate, requiring low time to attain the equilibrium. However, the separation of adsorbents from the aqueous medium is still a drawback in its application. Thus, magnetic particles’ addition to biochar can effectively increase the mechanisms responsible for adsorption while also facilitating its solid-liquid separation and recycling utilizing an external magnetic field. In this chapter, we present the main synthesis and preparation methods for producing magnetic biochars, such as pyrolysis, co-precipitation, and carbonization, in addition to hydrothermal, solvothermal, and sol-gel synthesis. Coating and functionalization techniques are also discussed. Moreover, the applications of these composites in the environmental remediation of inorganic and organic pollutants—such as metals, dyes, pharmaceuticals, and pesticides—are also presented and discussed in detail.