Microalgae offer the potential to generate a range of high-value products, and after the extraction of value-added compounds, the residual biomass can be upcycled to truly turn “waste” into wealth within a zero-waste biorefinery framework. In this study, residual Phaeodactylum tricornutum biomass obtained after lipid extraction was utilized to produce biochar via pyrolysis at three different temperatures. The physicochemical properties show that the biochar obtained from 550 °C exhibits a higher amount of inorganic nutrients (K, Mg, Na, Ca, P, Fe), a porous and disordered structure, a moderately higher specific surface area, and active functional groups. When applied as a contaminant adsorbent, the biochar shows significant Pb removal efficiency with a maximum adsorption capacity of 476.19 mg/g. A kinetic and adsorption isotherm study revealed that the adsorption is well-defined by the pseudo-second-order model and the Langmuir adsorption isotherm model, respectively.
Mondal et al. (Thu,) studied this question.