Oyster shell facilitates the green production of nitrogen-doped porous biochar from macroalgae: a case study for removing atrazine from water

Abstract

Low-cost and green preparation of efficient sorbents is critical to the removal of organic contaminants during water treatment. In this study, the co-pyrolysis of macroalgae and oyster shell was designed to synthesize nitrogen-doped porous biochars for sorption removal of atrazine from water. Oyster shell played a significant role in opening pores in macroalgae-derived biochars, resulting in the surface area of the macroalgae (Enteromorpha prolifera and Ulva lactuca) and oyster shell co-pyrolyzed carbonaceous as high as 1501.80 m² g⁻¹ and 1067.18 m² g⁻¹, the pore volume reached 1.04 cm³ g⁻¹ and 0.93 cm³ g⁻¹, and O/C decreased to 0.09 and 0.08, respectively. The sorption capacity of atrazine to nitrogen-doped porous biochars (the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous) reached 312.06 mg g⁻¹ and 340.52 mg g⁻¹. Pore-filling, hydrogen bonding, π-π or p-π stacking and electrostatic interaction dominated the multilayer sorption process. Moreover, the nitrogen-doped porous biochars showed great performance in cyclic reusability, and the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous sorption capacity still reached 246.13 mg g⁻¹ and 255.97 mg g⁻¹, respectively. Thus, this study suggested that it is feasible and efficient to remove organic contaminants with the nitrogen-doped porous biochars co-pyrolyzed from macroalgae and oyster shell, providing a potential green resource utilization of aquatic wastes for environmental remediation.

Highlight

•	Nitrogen-doped porous biochars (NPBs) were derived from natural wastes.
•	Oyster shell enhanced the micropore and mesopore structures of NPBs.
•	Physical sorption dominated atrazine sorption onto the NPBs.

Funding

the National Key Research and Development Program of China(2020YFC1807003)

the Strategic Priority Research Program of the Sciences(XDA28010501)

the Youth Innovation Promotion Association, CAS(2021309)

National Natural Science Foundation of China(42277303)