Recovery of Plastics from WEEE through Green Sink-Float Treatment

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Growing demand for electronics generates substantial waste electrical and electronic equipment (WEEE).
• Efficient sorting of plastic polymers within WEEE is crucial for effective recycling.
• Traditional WEEE sorting methods face challenges in separating diverse plastic types.

Purpose of the Study:

• To assess the efficacy of green sink-float treatment for sorting common WEEE plastic polymers.
• To investigate the use of molasses solutions at varying densities for polymer separation.
• To evaluate the recovery rates of polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6), polystyrene (PS), and polyvinyl chloride (PVC) from WEEE.

Main Methods:

• Utilized sink-float treatment with water-molasses solutions of adjustable densities.
• Tested methodology on virgin polymers before application to real WEEE plastic samples.
• Characterized polymers using near-infrared spectroscopy (NIRS) and Fourier-transform infrared spectroscopy (FTIRS).
• Detected additives and flame retardants via sliding spark technology (SSS2) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX).

Main Results:

• Achieved 55.85% recovery of PP in tap water, with the remainder recovered using 90% molasses solution.
• Obtained 100% recovery for PS and 93.73% for ABS using 10% molasses solution.
• Reached 100% recovery for PVC and PA6 using a solution of 100% molasses.

Conclusions:

• Green sink-float treatment with molasses solutions is a viable and effective method for WEEE plastic sorting.
• Adjusting molasses concentration allows for tailored separation of different plastic polymers.
• This approach offers a sustainable pathway for enhancing WEEE recycling rates and resource recovery.