Engineered algal biochar for contaminant remediation and electrochemical applications

Biochar, a pyrogenic black carbon is derived by pyrolysis of carbon-rich biomass in an oxygen-limited environ- ment. The physico-chemical characteristics of biochar strongly impact the multifunctional role of biochar e.g., carbon sequestration and enhancement of soil fertility, biosorption or environmental remediation, fuel cells, supercapacitors, and biocatalyst. Owing to the poor performance of pristine biochar, engineered biochars have emerged, that are derived from physical, chemical, and biological modifications of pristine biochar to im- prove its surface properties and thus adsorption capacity. In the past two decades, researchers have been focus- sing more on low-cost biomass. Algal biomass is one such source that has shown significant prospective for biochar fabrication. The present review summarizes various applications of biochar, mechanisms associated with metal removal by biochar, various modification procedures for developing engineered biochars, algal bio- char production methods as well as characterization of algal biochar. The review is intended to evaluate recent advancements and research in engineered algal biochar with a primary focus on contaminant remediation and the development of bioelectrochemical systems using algal biochar. This review opens new vistas and adds inno- vative ideas for future research utilizing engineered algal biochar, towards renewable, sustainable, and low-cost production of biosorbents for remediation of contaminated aqueous environments.