Catalytic hydrolysis of cellobiose using different acid-functionalised Fe₃O₄ magnetic nanoparticles

The present study demonstrated the preparation of three different acid-functionalised magnetic nanoparticles (MNPs) and evaluation for their catalytic efficacy in hydrolysis of cellobiose. Initially, iron oxide (Fe₃O₄)MNPs were synthesised, which further modified by applying silica coating (Fe₃O₄-MNPs@Si) and functionalised with alkylsulfonic acid (Fe₃O₄-MNPs@Si@AS), butylcarboxylic acid (Fe₃O₄-MNPs@Si@BCOOH) and sulphonic acid (Fe₃O₄-MNPs@Si@SO₃H) groups. The Fourier transform infrared analysis confirmed the presence of above-mentioned acid functional groups on MNPs. Similarly, X-ray diffraction pattern and energy dispersive X-ray spectroscopy analysis confirmed the crystalline nature and elemental composition of MNPs, respectively. TEM micrographs showed the synthesis of spherical and polydispersed nanoparticles having diameter size in the range of 20-80 nm. Cellobiose hydrolysis was used as a model reaction to evaluate the catalytic efficacy of acid-functionalised nanoparticles. A maximum 74.8% cellobiose conversion was reported in case of Fe₃O₄-MNPs@Si@SO₃H in first cycle of hydrolysis. Moreover, thus used acid-functionalised MNPs were magnetically separated and reused. In second cycle of hydrolysis, Fe₃O₄-MNPs@Si@SO₃H showed 49.8% cellobiose conversion followed by Fe₃O₄-MNPs@Si@AS (45%) and Fe₃O₄-MNPs@Si@BCOOH (18.3%). However, similar pattern was reported in case of third cycle of hydrolysis. The proposed approach is considered as rapid and convenient. Moreover, reuse of acid-functionalised MNPs makes the process economically viable.