Polyurea membrane for water cleaning: Kinetic and equilibrium modeling of dyes adsorption

Abstract

The present treatment of water from aqueous solutions, reported from our research work, uses polyurea (PU) as a novel adsorbent. Specifically, the adsorption efficacy of PU was tested in dyes with different characteristics (Congo red (CR) and methylene blue (MB)). The PU membrane was obtained by a sol-gel chemistry reaction of polyetheramine with polyisocyanate resulting in the formation of urea groups, confirmed through FTIR analysis. The polymeric membrane exhibited a high homogeneity, making it a viable purifying technology for wastewater. The high swelling capacity of the membrane played a crucial role in the CR dye diffusion/adsorption. Notably, PU membranes showed excellent adsorption to CR anionic dye, resulting in a removal efficiency over 85%. However, MB dye adsorption was less favorable, suggesting a high affinity with anionic species. Our analysis revealed that the adsorption of CR dye onto PU membranes follows the pseudo-second order kinetic and Langmuir isotherm models. Moreover, the intra-particle diffusion model demonstrated that the swelling of PU facilitates the adsorption/diffusion process, thereby accelerating the mass transfer of the CR dye onto the membrane. Overall, our findings suggest that PU membranes derived from commercially available reagents are highly promising for the decontamination of dye wastewater.