Polímeros: Ciência e Tecnologia
Polímeros: Ciência e Tecnologia
Original Article

Separation of plastic mixtures by sink-float combined with froth flotation

Fernando Pita

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The aim of this research was to separate a mixture of six post-consumer plastics (PS, PMMA, PVC-D, PVC-M, PET-D and PET-S) by combination of sink-float separation and froth flotation.. In sink-float method two mediums of separation were used: sodium chloride water solution and ammonium nitrate water solution. Sink-float method allowed complete separation of the less dense plastic (PS) from intermediate density plastics (PMMA and PVC-D) and from high density plastics (PET-S, PET-D and PVC-M); also allowed good separation of intermediate density plastics (PMMA and PVC-D) from high density plastics (PVC-M, PET-D and PET-S) with an efficiency close to 100%. Separation of PVC-M from PET-D and PET-S by sink-float method led to fair results allowing a separation efficiency of about 60%. Since PMMA and PVC-D have similar density, their separation was achieved by froth flotation, using sodium lignosulfonate as selective wetting agent of PVC-D, with a separation efficiency of 85%.




density separation, plastic, mixture, particle size


1 Kaza, S., Yao, L. C., Bhada-Tata, P., & Van Woerden, F. (2018). What a waste 2.0: a global snapshot of solid waste management to 2050. Washington, DC: World Bank. Urban Development Series. http://dx.doi.org/10.1596/978-1-4648-1329-0.

2 Plastics Europe. (2021). Plastics - the facts 2021 - an analysis of European plastics production, demand and waste data. Brussels: Plastics Europe/European Association of Plastics Recycling and Recovery Organisations. Retrieved in 2023, April 4, from https://plasticseurope.org/wp-content/uploads/2021/12/Plastics-the-Facts-2021-web-final.pdf

3 Al-Salem, S. M., Lettieri, P., & Baeyens, J. (2009). Recycling and recovery routes of plastic solid waste (PSW): a review. Waste Management, 29(10), 2625-2643. http://dx.doi.org/10.1016/j.wasman.2009.06.004. PMid:19577459.

4 Organisation for Economic Co-operation and Development - OECD. (2022). Global plastics outlook: economic drivers, environmental impacts and policy options. Paris: OECD Publishing. https://doi.org/10.1787/de747aef-en.

5 Yenial, Ü., Burat, F., Yüce, A. E., Güney, A., & Kangal, M. O. (2013). Separation of PET and PVC by flotation technique without using alkaline treatment. Mineral Processing and Extractive Metallurgy Review, 34(6), 412-421. http://dx.doi.org/10.1080/08827508.2012.702705.

6 Gundupalli, S. P., Hait, S., & Thakur, A. (2017). A review on automated sorting of source-separated municipal solid waste for recycling. Waste Management, 60, 56-74. http://dx.doi.org/10.1016/j.wasman.2016.09.015. PMid:27663707.

7 Zheng, Y., Bai, J., Xu, J., Li, X., & Zhang, Y. (2018). A discrimination model in waste plastics sorting using NIR hyperspectral imaging system. Waste Management, 72, 87-98. http://dx.doi.org/10.1016/j.wasman.2017.10.015. PMid:29129466.

8 Masoumi, H., Safavi, S. M., & Khani, Z. (2012). Identification and classification of plastic resins using near infrared reflectance spectroscopy. International Journal of Mechanical and Mechatronics Engineering, 6(5), 213-220. Retrieved in 2023, April 4, from https://publications.waset.org/11237/pdf

9 Li, J., Wu, G., & Xu, Z. (2015). Tribo-charging properties of waste plastic granules in process of tribo-electrostatic separation. Waste Management, 35, 36-41. http://dx.doi.org/10.1016/j.wasman.2014.10.001. PMid:25453321.

10 Fraunholcz, N. (2004). Separation of waste plastics by froth flotation - a review, part I. Minerals Engineering, 17(2), 261-268. http://dx.doi.org/10.1016/j.mineng.2003.10.028.

11 Burat, F., Güney, A., & Kangal, M. O. (2009). Selective separation of virgin and post-consumer polymers (PET and PVC) by flotation method. Waste Management, 29(6), 1807-1813. http://dx.doi.org/10.1016/j.wasman.2008.12.018. PMid:19155169.

12 Carvalho, T., Durão, F., & Ferreira, C. (2010). Separation of packaging plastics by froth flotation in a continuous pilot plant. Waste Management, 30(11), 2209-2215. http://dx.doi.org/10.1016/j.wasman.2010.05.023. PMid:20576423.

13 Wang, C.-Q., Wang, H., Fu, J.-G., & Liu, Y.-N. (2015). Flotation separation of waste plastics for recycling - a review. Waste Management, 41, 28-38. http://dx.doi.org/10.1016/j.wasman.2015.03.027. PMid:25869841.

14 Pita, F., & Castilho, A. (2017). Separation of plastics by froth flotation. The role of size, shape and density of the particles. Waste Management, 60, 91-99. http://dx.doi.org/10.1016/j.wasman.2016.07.041. PMid:27478025.

15 Wang, H., Zhang, Y., & Wang, C. (2019). Surface modification and selective flotation of waste plastics for effective recycling - a review. Separation and Purification Technology, 226, 75-94. http://dx.doi.org/10.1016/j.seppur.2019.05.052.

16 Kannan, P., Lakshmanan, G., Shoaibi, A. A., & Srinivasakannan, C. (2017). Polymer recovery through selective dissolution of co-mingled post-consumer waste plastics. Progress in Rubber, Plastics and Recycling Technology, 33(2), 75-84. http://dx.doi.org/10.1177/147776061703300202.

17 Yuan, H., Fu, S., Tan, W., He, J., & Wu, K. (2015). Study on the hydrocyclonic separation of waste plastics with different density. Waste Management, 45, 108-111. http://dx.doi.org/10.1016/j.wasman.2015.01.037. PMid:25736578.

18 Pita, F., & Castilho, A. (2016). Influence of shape and size of the particles on jigging separation of plastics mixture. Waste Management, 48, 89-94. http://dx.doi.org/10.1016/j.wasman.2015.10.034. PMid:26560809.

19 Fu, S., Fang, Y., Yuan, H., Tan, W., & Dong, Y. (2017). Effect of the medium’s density on the hydrocyclonic separation of waste plastics with different densities. Waste Management, 67, 27-31. http://dx.doi.org/10.1016/j.wasman.2017.05.019. PMid:28527864.

20 Quelal, W. O. M., Velázquez-Martí, B., & Gisbert, A. F. (2022). Separation of virgin plastic polymers and post-consumer mixed plastic waste by sinking-flotation technique. Environmental Science and Pollution Research International, 29(1), 1364-1374. http://dx.doi.org/10.1007/s11356-021-15611-w. PMid:34350580.

21 Dodbiba, G., Sadaki, J., Okaya, K., Shibayama, A., & Fujita, T. (2005). The use of air tabling and triboelectric separation for separating a mixture of three plastics. Minerals Engineering, 18(15), 1350-1360. http://dx.doi.org/10.1016/j.mineng.2005.02.015.

22 Pongstabodee, S., Kunachitpimol, B., & Damronglerd, S. (2008). Combination of three-stage sink-float method and selective flotation technique for separation of mixed post-consumer plastic waste. Waste Management, 28(3), 475-483. http://dx.doi.org/10.1016/j.wasman.2007.03.005. PMid:17493796.

23 Hori, K., Tsunekawa, M., Ueda, M., Hiroyoshi, N., Ito, M., & Okada, H. (2009). Development of a new gravity separator for plastics a hybrid-jig. Materials Transactions, 50(12), 2844-2847. http://dx.doi.org/10.2320/matertrans.M-M2009825.

24 Zhao, S., Zhu, L., & Li, D. (2015). Characterization of small plastic debris on tourism beaches around the South China Sea. Regional Studies in Marine Science, 1, 55-62. http://dx.doi.org/10.1016/j.rsma.2015.04.001.

25 Masura, J., Baker, J., Foster, G., & Arthur, C. (2015). Laboratory methods for the analysis of microplastics in the marine environment: recommendations for quantifying synthetic particles in waters and sediments. Silver Spring: National Oceanic and Atmospheric Administration. Retrieved in 2023, April 4, from http://hdl.handle.net/11329/1076

26 Quinn, B., Murphy, F., & Ewins, C. (2017). Validation of density separation for the rapid recovery of microplastics from sediment. Analytical Methods, 9(9), 1491-1498. http://dx.doi.org/10.1039/C6AY02542K.

27 Schulz, N. F. (1970). Separation efficiency. Transactions of the Society for Mining, Metallurgy, and Exploration, Inc., 247, 81-87.

28 Kangal, M. O. (2010). Selective flotation technique for separation of PET and HDPE used in drinking water bottles. Mineral Processing and Extractive Metallurgy Review, 31(4), 214-223. http://dx.doi.org/10.1080/08827508.2010.483362.

29 Carvalho, M. T., Ferreira, C., Santos, L. R., & Paiva, M. C. (2012). Optimization of froth flotation procedure for poly (ethylene terephthalate) recycling industry. Polymer Engineering and Science, 52(1), 157-164. http://dx.doi.org/10.1002/pen.22058.

30 Saisinchai, S. (2014). Separation of PVC from PET/PVC mixtures using flotation by calcium lignosulfonate depressant. Engineering Journal, 18(1), 45-53. http://dx.doi.org/10.4186/ej.2014.18.1.45.

31 Wang, H., Wang, C.-Q., Fu, J.-G., & Gu, G.-H. (2014). Flotability and flotation separation of polymer materials modulated by wetting agents. Waste Management, 34(2), 309-315. http://dx.doi.org/10.1016/j.wasman.2013.11.007. PMid:24355830.

32 Pita, F., & Castilho, A. (2019). Plastics floatability: effect of saponin and sodium lignosulfonate as wetting agents. Polímeros: Ciência e Tecnologia, 29(3), e2019035. http://dx.doi.org/10.1590/0104-1428.01419.

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