Study on delacquer used beverage cans by vacuum pyrolysis for recycle

Area of Science:

• Materials Science and Engineering
• Environmental Science
• Chemical Engineering

Background:

• Conventional methods for removing paint from used beverage cans (UBCs) have significant economic and environmental drawbacks.
• There is a need for sustainable and efficient delacquering processes to facilitate UBC recycling and resource recovery.

Purpose of the Study:

• To investigate a novel delacquering technique combining vacuum pyrolysis and dilute sulfuric acid leaching for UBCs.
• To evaluate the effectiveness of the proposed method in paint removal and valuable material recovery.

Main Methods:

• Used beverage cans (UBCs) were subjected to vacuum pyrolysis at varying temperatures and holding times.
• Delacquered UBCs were then leached with dilute sulfuric acid (5% H2SO4).
• Residual materials were calcined to recover titanium dioxide (TiO2).

Main Results:

• Optimal delacquering (nearly 100% paint removal) was achieved at 650 °C, 20 min holding time, and <0.1 kPa residual gas pressure.
• Pyrolysis oil, rich in phenol and 2-methy-phenol, was produced.
• Titanium dioxide (TiO2) was successfully recovered from the leached residuals.

Conclusions:

• The combined vacuum pyrolysis and sulfuric acid leaching method provides an effective and environmentally sound approach for delacquering UBCs.
• This innovative technology avoids toxic byproducts associated with direct combustion and enables the recovery of valuable chemical feedstocks and TiO2.