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Research article2022Peer reviewedOpen access

Microalgae biomass as a sustainable precursor to produce nitrogen-doped biochar for efficient removal of emerging pollutants from aqueous media

Gonzalez-Hourcade, Maria; dos Reis, Glaydson Simoes; Grimm, Alejandro; Dinh, Van Minh; Lima, Eder Claudio; Larsson, Sylvia H.; Gentili, Francesco G.

Abstract

Preparing sustainable and highly efficient biochars as adsorbents remains a challenge for organic pollutant management. Herein, a novel nitrogen-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using a wild mixture of microalgae as novel carbon precursor. Phosphoric acid (H3PO4) was employed as activation agent to generate pores in the carbon material. In addition, the effect of melamine (nitrogen source) was evaluated over the biochar properties by the N-doping process. The results showed that the biochar’s specific surface area (SSA) increased from 324 to 433 m2 g− 1 with the N-doping process. The N-doping process increased the percentage of micropores in the biochar structure. Chemical characterization of the biochars indicated that the N-doping process helped to increase the graphitization process of the biochar and the contents of oxygen and nitrogen groups on the carbon surface. The biochars were successfully tested to adsorb acetaminophen and treat two synthetic effluents, and the N-doped biochar presented the highest efficiency. The kinetics and equilibrium data were well represented by the General-order model and the Liu isotherm model, respectively. The maximum sorption capacities attained were 101.4 and 120.7 mg g− 1 for the non-doped and doped biochars, respectively. The acetaminophen adsorption mechanism suggests that the pore-filling was the dominant mechanism for acetaminophen uptake. The biochars could efficiently remove up to 74% of the contaminants in synthetic effluents.

Keywords

Microalgae precursor; Phosphoric acid activation; Nitrogen doping; Doped biochars; Acetaminophen adsorption; Pharmaceuticals effluents

Published in

Journal of Cleaner Production
2022, Volume: 348, article number: 131280