Hydrophobic Modification of the α‐Hemihydrate Phosphogypsum (α‐HH) Surface by Myristic Acid

Phosphogypsum is widely used as a filler. However, gypsum fillers exhibit poor water resistance, compromising the performance of subsequent products. To address this issue, we modified α‐hemihydrate phosphogypsum (α‐HH) with myristic acid (ΜΑ), a low surface energy material used to prepare super hydrophobic (SHP) surfaces. The MA concentration, temperature, and modification time were optimized using a Box‐Behnken experimental design method. The surface properties, microstructure, and thermal stability of the modified powders were characterized using contact angle measurements, X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, Raman spectrum, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM‐EDS), and thermal gravimetry‐differential scanning calorimetry (TG‐DSC). Additionally, we discussed the hydrophobic modification mechanism of the modified α‐HH. The modified α‐HH/MA prepared with 11.0×10−4 mol L−1 MA at 60 °C for 60 min exhibited high hydrophobicity. During modification, MA bound to the calcium ions on the surface of α‐HH to form calcium myristate, thereby forming a hydrophobic film. The thermal stability of α‐HH was improved by MA modification. The modified powder maintained high hydrophobicity even at 250 °C. The alpha form of hemihydrate phosphogypsum (α‐HH) is modified using myristic acid (MA). The surface properties, microstructure, and thermal stability of α‐HH/MA are characterized using various analytical methods, including water contact angle measurements, X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR) spectroscopy, Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDS), and thermal gravimetry‐differential scanning calorimetry (TG‐DSC). A mechanism is proposed to explain the hydrophobicity of α‐HH/MA.α‐hemihydrate phosphogypsumHydratesHydrophobic effectmyristic acidprocess optimization