What are the density-based separation process for marine plastic recycling? 

Density-based separation processes are pivotal in recycling marine plastics, addressing the challenge of separating microplastics from marine and freshwater sediments. A common method involves using heavy salt solutions like zinc chloride and sodium iodide for density separation, extracting microplastics efficiently from sediments. The Munich Plastic Sediment Separator (MPSS) represents an advancement in this area, enabling the reliable separation of plastic particles from sediment samples across different ecologically relevant size classes. This method uses a ZnCl2-solution as the separation fluid, achieving high recovery rates for microplastic particles. Innovations in separation technology also include the development of devices that allow for the rapid, simple, and efficient extraction of microplastics from various sediment types. One such device, inspired by the Utermohl chamber, has demonstrated recovery rates of 94-98% for microplastics under 1,000 µm, proving effective across different sizes, polymer types, and sediment types. Moreover, the application of near-critical fluids, such as CO2 and SF6, in density-based separators has been explored for separating thermoplastics from each other and from contaminants. This approach has shown promise in achieving high purity levels of separated homopolymers, facilitating the recycling process. Liquid-fluidized bed classification (LFBC) is another technique under investigation for separating complex waste plastic mixtures, including those found in marine environments. This process, which can operate in both upflow and downflow modes using water as the fluidization medium, has demonstrated potential in segregating binary and ternary plastic particle mixtures. Lastly, the sinking-flotation technique has been applied on a pilot scale to separate virgin polymers and post-consumer plastic waste from municipal solid waste, which includes marine plastics. This technique utilizes different densification mediums, such as tap water, ethanol solutions, and sodium chloride, to achieve separation based on polymer density. Collectively, these density-based separation processes offer promising avenues for the efficient recycling of marine plastics, addressing both ecological impacts and resource recovery challenges.

Separation of virgin plastic polymers and post-consumer mixed plastic waste by sinking-flotation technique

Density-based separation process for marine plastic recycling involves sinking-flotation technique using different mediums like tap water, ethanol, and sodium chloride to separate polymers based on their densities.

Plastic particle separation via liquid‐fluidized bed classification

Density-based separation processes for marine plastic recycling include liquid-fluidized bed classification (LFBC), which can separate plastic particles based on their density using water as the fluidization medium.

Tribo-Electrostatic Separation Analysis of a Beneficial Solution in the Recycling of Mixed Poly(Ethylene Terephthalate) and High-Density Polyethylene

Not addressed in the paper.

Optimization of the high-pressure, near-critical liquid-based microsortation of recyclable post-consumer plastics

Density-based separation processes utilizing high-pressure, near-critical liquids were used for microsortation of post-consumer plastics, achieving high purity levels economically in the recycling process.

A model recycling process for low density polyethylene

Not addressed in the paper.

A comprehensive review of separation technologies for waste plastics in urban mine

Density-based separation processes like froth flotation and density separation are effective for liberating and separating waste plastics from various contaminants in urban mine recycling, as outlined in the paper.

A novel, highly efficient method for the separation and quantification of plastic particles in sediments of aquatic environments

The Munich Plastic Sediment Separator (MPSS) utilizes a ZnCl2 solution for density-based separation, achieving high recovery rates for large and small microplastic particles in aquatic sediments.

A new small device made of glass for separating microplastics from marine and freshwater sediments.

Density-based separation for marine plastic recycling involves using a small glass device without a valve, inspired by an Utermohl chamber, for efficient extraction of microplastics from sediments.

Density-based separation of thermoplastics found in the post-consumer waste stream

Density-based separation using CO2 and SF6 separates thermoplastics like HDPE/LDPE/PP and PVC/PET from post-consumer waste, achieving purity levels of 77%-100% for improved recycling.

Optimization of the recovery of plastics for recycling by density media separation cyclones

Density media separation cyclones are efficient for marine plastic recycling. They optimize recovery by separating plastics based on differences in densities, enhancing recycling capacities for various particle sizes.