Synthesis of Novel Bio-based Urea-Urethane Aerogels In-Situ Impregnated with Catalytic Metallic Nanoparticles for the Removal of Methylene Blue and Congo Red from Wastewater

Abstract

To combat environmental pollution resulting from discharge of hazardous contaminants into water streams, novel porous biocompatible urea-urethane aerogels in situ impregnated with catalytic metallic nanoparticles were synthesized. FTIR confirmed the formation of highly structured 2D-bifurcated hydrogen bonding network among neighboring urea groups creating aerogels that are strong enough to withstand the pressures of supercritical drying. In-situ impregnation with the catalytic metallic nanoparticles ensured that the systems are efficient in adsorbing, degrading and removing a variety of hazardous contaminants from polluted water. BET measurements indicated an almost reversible Type II isotherm and confirmed the macroporosity of the samples with surface area of around 6 m² g⁻¹. And swelling capvity of up to 700% The equilibrium uptake capacity of each contaminant increased with increasing the initial concentration due to the increasing driving force and has reached more than 90%. Thermodynamics interpretation indicated exothermic spontaneous processes for all systems with R² values around 0.9. Almost all adsorption processes followed a Langmuirian type behavior. Kinetics profile revealed that the adsorption is best fitted by pseudo-second order model with an intra-particle diffusion model suggesting that both pore diffusion and contaminant uptake by the aerogels play pivotal role in controlling the kinetics of the adsorption process.