Magnetite Fe3O4 nanoparticles impregnated on Chlorella vulgaris microalgae: Its role in obtaining hydrogen from the sodium borohydride-hydrolysis

Recently, the single-celled green freshwater microalgae species “Chlorella vulgaris” has attracted the attention of researchers due to its different usage areas. In particular, research focuses on the technology of obtaining bio‑hydrogen with various techniques. This research involves, for the first time, the use of the microalga Chlorella vulgaris as a bio-supporting material for magnetite Fe₃O₄ nanoparticles (Fe₃O₄NPs@Chlorella vulgaris) and the production of hydrogen through catalytic hydrolysis of NaBH₄ (sodium borohydride, SB) in the presence of the resulting magnetite nanoparticles. Here, detailed kinetic studies were carried out during the SB-hydrolysis by taking magnetite Fe₃O₄NPs@Chlorella vulgaris and SB in varying amounts and at varying temperatures, and the activation energy and lifetime of magnetite Fe₃O₄NPs@Chlorella vulgaris was found to be 23.49 kJ mol⁻¹ and 93,280 mol H₂ (mol Fe₃O₄)⁻¹, respectively. No change in the chemical and physical structure of the biocatalyst was observed during the hydrolysis of SB, so only detailed characterization of microalgae and magnetite Fe₃O₄NPs@Chlorella vulgaris was performed, and the particle size of the catalyst was calculated as 10.19 ± 2.17 nm. The results showed that these Fe₃O₄NPs@Chlorella vulgaris, which can be easily separated magnetically and have high catalytic activity, are a “clean” and quite surprising catalyst in terms of hydrogen production.