Dear Aynaz Biuky please read to the end of this answer to find some papers to help throw more light on your question, please do well to recommend my answer too.

Removing colors from HDPE (High-Density Polyethylene) plastics can be a challenging process, and the method you choose will depend on the specific application and the degree of discoloration. Here are some common techniques for removing colors from HDPE plastics:

Please note that the effectiveness of these methods may vary depending on the type of colorant, the degree of discoloration, and the specific HDPE material. It is crucial to test these methods on a small, inconspicuous sample first to avoid potential damage to the plastic.

As for research publications, while there are numerous studies on HDPE recycling and color removal, it's important to note that the removal of colors from HDPE plastics is often part of larger recycling and reprocessing efforts. Here are five research papers that discuss aspects of color removal and HDPE recycling:

These research papers offer insights into different aspects of color removal from HDPE plastics and the challenges associated with recycling and reprocessing.

Thank you Tobias Makuochukwu Onyia

Actually, articles with these titles were not found

Excellent researched answer Tobias.

Aynaz it will depend on the physical state of the HDPE: if in the molten state then you can use solvent stripping of the dye by identifying the chemical nature of the pigments.

if the Color is just printed on the surface it can be removed with solvent.

Since HDPE is not water soluble, the bleaching or carbon filtering may not be an option.

Thank you dear Emilio Malaguti