Urea Effect on Cellulose Phosphorylation and Sustainable Valorization of Recycled Washing Filtrates

Phosphorylated cellulose is a versatile material with a wide range of applications. However, traditional cellulose phosphorylation processes require toxic organic solvents. Safe and urea-based processes are adopted as promising alternatives, which still generate substantial waste, leading to high production costs and environmental concerns. Recycling the residual urea from aqueous wastes can reduce the phosphorylation cost. This work, investigated the recyclability of urea from washing filtrates, aiming to develop a cost-effective phosphorylation approach. Different urea amounts were tested to evaluate the urea effect on cellulose phosphorylation. Results indicated enhanced phosphorylation and flame-retardant ability with higher urea amounts. Cellulose phosphorylation using first and second washing filtrates was inspected to substitute urea. This study revealed the potential use of filtrates from two consecutive washings as a substitute for pure urea, which holds great potential for industrial applications, as it can be easily implemented on a larger scale for broader use.

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