Review on application of algae-based biochars in environmental remediation: Progress, challenge and perspectives

Algae-based biochar has great developmental potential in environmental remediation because of its cheap and extensive sources of raw materials. This paper reviewed the new research progress in environmental remediation of algae-based biochar at the whole gas-solid-liquid level, mainly including water treatment, gas pollutant removal and soil amendment. According to the different types of pollutants, the adsorption and separation performance of algae-based biochar was systematically summarized (i.e., organic pollutants from wastewater, inorganic pollutants from wastewater, pollutants from gas stream, greenhouse gases and soil amendment). Besides, the activation/modification methods of algae-based biochar were also reviewed systematically. Results show that most of existing algae-based biochars still have underdeveloped pore structure and poor surface active sites, resulting in low adsorption performance. Multiple synergistic activation/modification of algae-based biochar, design of carbon materials with multidimensional structures, co-doping of multiple elements and modification using clean free radical advanced oxidation technologies are considered to be promising methods for improving the performance of algae-based biochars. Besides, further research is needed on simultaneous adsorption of multi-pollutants, regeneration of adsorbents, secondary pollution problem of spent algae-based biochars, and other some issues that are related to carbon footprint, energy consumption, and potential release of contaminants during the algae-based biochar preparation process.