From urea to urea cocrystals: a critical view of conventional and emerging nitrogenous fertilizer materials for improved environmental sustainability

Authors: EISA, MOHAMED - Lehigh University; BRONDI, MARIANA - Lehigh University; Williams, Clinton; Hejl, Reagan; BALTRUSAITIS, JONAS - Lehigh University

Submitted to: Sustainable Chemistry for the Environment
Publication Type: Review Article
Publication Acceptance Date: 1/8/2025
Publication Date: 1/11/2025
Citation: Eisa, M., Brondi, M., Williams, C.F., Hejl, R.W., Baltrusaitis, J. 2025. From urea to urea cocrystals: a critical view of conventional and emerging nitrogenous fertilizer materials for improved environmental sustainability. Sustainable Chemistry for the Environment. 9. Article 100209. https://doi.org/10.1016/j.scenv.2025.100209.
DOI: https://doi.org/10.1016/j.scenv.2025.100209

Interpretive Summary: Nitrogen is a nutrient essential for plant growth and sustainable population development. Large environmental nitrogen losses to the environment have occurred due to its application from low-stability sources, such as urea. Urea production consumes large amounts of energy and losses from application has severe impacts on soil, air, and surface water quality. Therefore, improved stability of nitrogen fertilizer materials is needed to decrease environmental losses, improve efficiency, and decrease energy consumption during production. This work aims to critically review the current and emerging methods to increase stability of urea fertilizers in order to deliver nitrogen to the environment sustainably. Results from this review suggest that future research needs to focus on urea stabilization methods that create partial bonds between the constituents beyond weak molecular interactions within urea molecular crystals but avail unsustainable feedstock or molecules that affect the soil biota. Developmental products should then be transformed into thriving technologies that provide high-value fertilizers be decreasing the energy needed to make ammonia, the precursor of urea.

Technical Abstract: Nitrogen (N) is a critical nutrient that is essential for plant growth and sustainable population development. Since the inception of modern fertilizer technology, N has been supplied to the environment via low-stability fertilizer materials which has resulted in very large losses of reactive nitrogen to the environment. These losses have severe impacts on soil, air and surface water locally and result in changes to the ecosystem biodiversity as well as climate globally. Synthesis of nitrogen fertilizer, such as urea, consumes 1% to 2% of global energy as well as significant amounts of natural gas. Hence it is necessary to improve the stability of fertilizerN in the environment to decrease their losses and increase N-use efficiency. This work provides a critical evaluation of the current and emerging methods to stabilize urea fertilizers to deliver nitrogen to the environment more sustainably. The emphasis in this reviewis placed on material chemistry development, such as recent emergence of urea cocrystals that possess reduced solubility and enhanced environmental stability. The materials analysis suggests that future research needs to focus on urea stabilization methods that create partial bonds between the constituents beyond weak molecular interaction. This requires avoiding unsustainable feedstock, such as formaldehyde, or exogenous stabilizing molecules that affect the soil biota, such as urease inhibitors. These developmental products then need to be transformed into thriving technologies to provide high-value fertilizers by decreasing the energy footprint needed to make ammonia, a precursor of urea.