Analysis of the Delamination Process with Nitric Acid in Multilayer Composite Food Packaging

Abstract

Multilayer packaging, commonly referred to as composite materials, is widely utilized in food storage, distribution, and consumption. The employment of plastic packaging, which consists of multiple layers of polymers, ink, paper, and metal, has elicited concerns regarding its detrimental impact on the environment. This article presents an in-depth study of the delamination process of multilayer plastic waste (MLPW) recycling, which is deemed as an effective solution for MLPW recycling. This study aimed to examine the effects of temperature, concentration, width, and ultrasound on the separation of layers in multilayer packaging. The results demonstrated that ultrasound is the most influential factor with nitric acid concentration ranking as the second most significant factor. The findings also disclosed considerable disparities among the time frames, and the impacts of various factors, such as temperature and concentration, lay the groundwork for further investigation into this process. The study underscores the importance of temperature and nitric acid concentration, which can inform the design of future experiments and the development of more efficient methods for layer separation.

Progress in Solvent-Based Recycling of Polymers from Multilayer Packaging

“…Commonly used adhesives include acrylics and polyurethanes (PU). Acrylic is more specifically suitable for bonding PE and aluminium, while polyurethane is more versatile and more widely used [ 20 ]. A schematic diagram of multilayer packaging is shown in Figure 3 .…”

“…The access surface area is another important parameter affecting the delamination rate. In all experiments reported in the literature, the multilayer packaging samples were cut into strips or pieces (to increase reaction surface area) and thoroughly immersed in selected solvents [ 20 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

“…Acids (including inorganic acids and organic acids) are one of the most commonly used delamination solvents. In 2023, Šleiniūtė et al [ 20 ] studied the delamination of aluminium-containing multilayer packaging using nitric acid. The role of nitric acid was to dissolve the aluminium layer and break down the structure of PU adhesive.…”

Mechanical Properties of Polymers Recovered from Multilayer Food Packaging by Nitric Acid

“…Nitric acid can be used as a selective solvent to dissolve specific components of multilayer packaging, facilitating the separation of layers. Ultrasonic treatment is used to enhance the efficiency of the separation process by applying high-frequency sound waves that induce vibrations and mechanical forces, which aid in the disintegration and detachment of layers [35].…”

Thermochemical and Kinetic Analysis of Combustion of Plastic Wastes and Their Blends with Lignite

“…Such plastic waste has little potential for recycling. Similarly, multilayered plastic waste and other composite plastic materials also have limited recycling potential [6] unless delamination is carried out [7].…”