Investigation of physicochemical and biological properties of boron-doped biochar

Abstract

Boron doping of biochar leads to the formation of activated oxygen species and pores and defects in the carbon structure Therefore, boron-containing biochar was prepared by treating boric acid (H3BO3) solutions in diferent concentrations of hazelnut shells before pyrolysis. DSC results showed that treatment of biomass with solutions containing a low concentration (0.1 wt. %) of H3BO3 increased the degradation of cellulose and hemicellulose, but also increased char formation. However, treatment with solutions containing 2% and 5% H3BO3 increased biochar oxidation with the formation of boron oxide (B2O3). The FT-IR and XPS results showed the presence of B–B, B–O, and B–O–B in the H3BO3 treatment, which is due to the formation of B2O3. The examination of the proliferation of L929 mouse fbroblast cells in response to diferent concentrations of boron-containing biochars using the MTT assay revealed that biochar treated with 2% H3BO3 promoted cell growth (100.32±1.93). However, above this concentration, the formation of polycrystalline B2O3 species exhibited an inhibitory efect on cell proliferation (81.98±1.26) in the samples of H3BO3-doped biochar with 5% concentration. The results of the in vitro hemolysis tests for undoped biochar and high boron-containing (% 5) biochar sample showed mild hemolytic activity, with percentages of 2.46±0.02 and 3.08±0.04, respectively, according to the reported standards. Antimicrobial studies have shown that Candida albicans (a yeast, ATCC 10231) is more sensitive to H3BO3 than Staphylococcus aureus (Gram-positive bacteria, ATCC 29213). Boron-containing biochar can be used in a variety of applications, including biosensing, drug delivery, biological scafolds, and biological imaging, as well as an adsorbent in the removal of pollutants and a catalyst in oxidation and electrochemical reactions.