Lignocellulose Nanoparticles Extracted from Cattle Dung as Pickering Emulsifiers for Microencapsulating Phase Change Materials

Nanocelluloses have attracted much attention in both academic and industrial fields. However, nanocelluloses, including cellulose nanocrystals and cellulose nanofibers, are generally produced by a "top-down" strategy with tedious violent chemical reactions and energy-intensive mechanical treatments. Fabrication of nanocellulose via facile and green approaches with a low cost is always challenging and promising. The digestion of grass by ruminants resembles the extraction processing of nanocelluloses from plants. Herein, lignocellulose nanoparticles (LCNPs) were extracted from cattle dung via facile filtration and centrifugation separation methods, indicating that LCNPs occurred naturally in cattle dung and were formed during digestion of grass. LCNPs are mainly composed of lignin, cellulose, and hemicellulose and possess an average diameter of ∼50 nm, high surface charge of −36.2 mV, and outstanding water dispersity. LCNPs show excellent Pickering emulsifying ability just as classic nanocellulose due to their partial wettability with both oil and water phases. LCNP stabilized Pickering emulsions were then employed as templates to prepare phase change material (PCM) microcapsules with melamine-formaldehyde shells to prevent leakage of PCM. The obtained PCM microcapsules display good thermal stability, durability, high PCM core content of 88.9% and phase change enthalpy of 214.3 J g–1, and are promising for thermal energy storage and temperature regulation applications. This study provides a sustainable approach to extract nanocellulose as Pickering emulsifier and will facilitate the high-value-added utilization of cattle dung.