Improving the thermal energy storage capability of diatom-based biomass/polyethylene glycol composites phase change materials by artificial culture methods

We report a novel shape-stabilized phase change materials (SSPCMs) made from polyethylene glycol (PEG) and diatom-based biomass. The diatom materials were prepared by artificial culture and simple acid pickling and sintering. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD) and polarizing microscopy (POM) were used to characterize the prepared materials, such as their chemical composition, morphology, crystallization performance and so on. The results indicated that no chemical reaction occurred between PEG and diatom-based biomass during the preparation process, but the crystalline regions of PEG were decreased. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and thermal cycling tests showed that the SSPCMs with sintered diatom frustules as the supporting material have a good phase change performance and thermal stability in the PEG solid-liquid phase transition region. The maximum latent heat values in the melting and crystallization processes are around 121.54 J/g and 127.20 J/g respectively, and the relative enthalpy efficiency reaches up to ~98.1%. At the same time, the prepared SSPCMs have reliable heat storage and temperature-regulated performance. Our study demonstrates the great potential and significance for the practical application of artificially cultured diatom-based biomass in phase change materials for waste heat recovery and temperature regulation.