High carbon utilization: 5-(Chloromethyl)furfural (CMF) production from rice by-products and transformation of CMF residues into Li-ion energy storage systems

Biomass-derived 5-(chloromethyl)furfural (CMF) recently has garnered increasing attention over 5-hydroxymethylfurfural (HMF) as a significant platform molecule for a wide spectrum of value-added chemical compounds. This is due to CMF being able to be produced in higher yields under mild conditions directly from raw biomass compared to HMF. In this study, CMF was first synthesised from rice by-products via HCl/chloroform biphasic system resulting in a crude oil product containing 58%, 56%, 94%, and 89% CMF purities from rice bran (RB), rice hull (RH), broken white rice (BWR), and immature brown rice (IBR), respectively. BWR and IBR that exhibit high CMF purity become prospective biomass sources for CMF applications. The main by-product of the CMF production was solid residue. The RH residue contained appreciable levels of silica and was subsequently utilized as electrode material for lithium-ion battery (LIB) and symmetric supercapacitors. When employed as anode materials in LIB, the dried solid residue achieved a specific capacity of 383.17 mAh g−1. Meanwhile, the carbonised KOH-activated solid residue ([email protected]), which was fabricated in a non-aqueous symmetric supercapacitor, delivered a high energy density of 273.81 Wh kg−1 at a power density of 127.12 W kg−1, while the device reached an energy density of 57.89 Wh kg−1 at a very high-power density of 12.7 kW kg−1. This study develops a sustainable method for utilising different rice waste samples in the synthesis of CMF and simultaneously, employing the solid by-product for energy storage applications. Importantly, this work demonstrates production of high purity CMF in high yields under mild conditions. Collectively, this work paves the way toward the development of high-value products from waste, and can be easily extended to other waste streams.