Bio‐based epoxy modified with nano‐SiO2 and organosilicon for controlled‐release urea

Nearly 100 million tons of spent mushroom substrates (SMS) are discarded annually in China, which causes a series of environmental pollutants. To improve the nitrogen (N) use efficiency of and to shift dependence away from petroleum‐based products, a novel bio‐based epoxy coated urea was successfully developed. The bio‐based epoxy coating was synthesized from the liquefied SMS and bisphenol‐A diglycidyl ether. Subsequently, both nano‐SiO2 and organosilicon were employed to modify the bio‐based epoxy and increase its hydrophobicity. Water absorption, ammonium adsorption, and water contact angles of the bio‐based epoxy coatings were investigated. The nutrient release behaviors of the bio‐based epoxy coated urea in water were also investigated and the modification mechanisms were explored by Fourier transform infrared, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy and thermogravimetric analysis. The results revealed that the hydrophobic ability of the nano‐SiO2 and organosilicon dual modified bio‐based epoxy coated urea coating was significantly enhanced and that its nutrient release longevity was increased to 56 days. Therefore, this work demonstrated that bio‐based epoxy coated urea with superior release characteristics exhibited great potential in modern agricultural applications.