Alkaline hydrolysis of Tetra Pak waste: a green process for hydrogen production and a cement hydration catalyst

This study introduces a clean, low-impact recycling method for Tetra Pak waste (TPW), demonstrating how green chemistry principles can transform complex post-consumer materials into valuable resources. The multilayer composition of TPW, primarily aluminum and polyethylene, poses significant challenges for conventional recycling due to its resistant structure. To overcome this, we developed a sustainable aqueous alkaline hydrolysis process that efficiently separated these layers under mild conditions, eliminating the need for toxic solvents or high energy consumption. A key advantage is the simultaneous generation of green hydrogen gas, a clean, renewable energy carrier produced by the reaction between aluminum and sodium hydroxide. Alongside hydrogen production, the process yields a porous, lettuce-like sodium aluminate byproduct. Rather than disposing of this solid, we repurpose it as an environmentally friendly additive in cement systems. When incorporated into Portland cement, it significantly accelerates the hydration process, dramatically reducing the initial setting time from 285 minutes to just 87 minutes. This catalytic effect was verified using Differential Scanning Calorimetry (DSC) and temperature evolution analysis. By addressing multiple environmental challenges, waste valorization, renewable energy generation, and enhanced construction materials, this integrated approach exemplifies green chemistry and circular economy principles. It provides a scalable, eco-friendly solution for sustainable industrial development and responsible resource management.