Polímeros: Ciência e Tecnologia
https://revistapolimeros.org.br/article/doi/10.1590/0104-1428.03320
Polímeros: Ciência e Tecnologia
Original Article

Separation of PET from other plastics by flotation combined with alkaline pretreatment

Fernando Pita; Ana Castilho

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Abstract

Plastics are naturally hydrophobic, so the selective flotation of plastic mixtures is impossible without changing their surface properties. The objective of this research is flotation separation of PET from PS, PMMA and PVC combined with sodium hydroxide pretreatment. NaOH pretreatment had a strong effect on PET’s floatability, medium effect on PMMA and PVC and limited effect on PS. The reduction of PET floatability is ascribed to a sharp decline of contact angle. The optimal pretreatment conditions were: 10% NaOH concentration, 70 °C (PET/PMMA and PET/PVC) to 80 °C (PET/PS) and plastic treatment times in the alkaline solution of 20 min (PET/PMMA and PET/PVC) to 30 min (PET/PS). Flotation separations were achieved efficiently and the best results were obtained for the PET/PS mixture, with a floated PS grade of 98% and a sunk PET grade of 100%. PET and PS was separated effectively, implying that sodium hydroxide treatment possesses superior applicability.

Keywords

alkaline treatment, flotation, particle size, plastic

References

1 PlasticsEurope. (2019). Plastics - the Facts 2019. An analysis of European plastics production, demand and waste data. Brussels, Belgium. Retrieved in 2020, January 5, from https://www.plasticseurope.org/en/resources/publications/1804-plastics-facts-2019

2 Geyer, R., Jambeck, J. R., & Law, K. L. (2017). Production, use, and fate of all plastics ever made. Science Advances, 3(7), e1700782. http://dx.doi.org/10.1126/sciadv.1700782. PMid:28776036.

3 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.

4 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.

5 Guney, A., Poyraz, M. I., Kangal, O., & Burat, F. (2013). Investigation of thermal treatment on selective separation of post consumer plastics prior to froth flotation. Waste Management, 33(9), 1795-1799. http://dx.doi.org/10.1016/j.wasman.2013.05.006. PMid:23747135.

6 Shen, H., Pugh, R. J., & Forssberg, E. (2002). Floatability, selectivity and flotation separation of plastics by using a surfactant. Colloids and Surfaces. A, Physicochemical and Engineering Aspects, 196(1), 63-70. http://dx.doi.org/10.1016/S0927-7757(01)00706-3.

7 Basarová, P., Bartovská, L., Korínek, K., & Horn, D. (2005). The influence of flotation agent concentration on the wettability and flotability of polystyrene. Journal of Colloid and Interface Science, 286(1), 333-338. http://dx.doi.org/10.1016/j.jcis.2005.01.016. PMid:15848435.

8 Takoungsakdakun, T., & Pongstabodee, S. (2007). Separation of mixed post-consumer PET-POM-PVC plastic waste using selective flotation. Separation and Purification Technology, 54(2), 248-252. http://dx.doi.org/10.1016/j.seppur.2006.09.011.

9 Abbasi, A., Salarirad, M. M., & Ghasemi, I. (2010). Selective separation of PVC from PET/PVC mixture using floatation by tannic acid depressant. Iranian Polymer Journal, 19(7), 483-489.

10 Yenial, U., Kangal, O., & Güney, A. (2013). Selective flotation of PVC using gelatin and lignin alkali. Waste Management & Research, 31(6), 613-617. http://dx.doi.org/10.1177/0734242X13476748. PMid:23439876.

11 Yenial, U., 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.

12 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.

13 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.

14 Drelich, J., Payne, T., Kim, J. H., Miller, J. D., Kobler, R., & Christiansen, S. (1998). Selective froth flotation of PVC from PVC/PET mixtures for the plastics recycling industry. Polymer Engineering and Science, 38(9), 1378-1386. http://dx.doi.org/10.1002/pen.10308.

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

16 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.

17 Caparanga, A. R., Basilia, B. A., Dagbay, K. B., & Salvacion, J. W. L. (2009). Factors affecting degradation of polyethylene terephthalate (PET) during pre-flotation conditioning. Waste Management, 29(9), 2425-2428. http://dx.doi.org/10.1016/j.wasman.2009.03.025. PMid:19394808.

18 Carvalho, M. 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.

19 Nagy, M., Škvarla, J., & Sisol, M. (2011). A possibility of using the flotation process to separate plastics. Annals of Faculty Engineering Hunedoara International Journal of Engineering, 9(3), 275-278.

20 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.

21 Wang, C. Q., Wang, H., Liu, Q., Fu, J. G., & Liu, Y. N. (2014). Separation of polycarbonate and acrylonitrile-butadiene-styrene waste plastics by froth flotation combined with ammonia pretreatment. Waste Management, 34(12), 2656-2661. http://dx.doi.org/10.1016/j.wasman.2014.09.002. PMid:25266156.

22 Güney, A., Özdilek, C., Kangal, O., & Burat, F. (2015). Flotation characterization of PET and PVC in the presence of different plasticizers. Separation and Purification Technology, 151, 47-56. http://dx.doi.org/10.1016/j.seppur.2015.07.027.

23 Wang, C. Q., Wang, H., & Liu, Y. N. (2015). Separation of polyethylene terephthalate from municipal waste plastics by froth flotation for recycling industry. Waste Management, 35, 42-47. http://dx.doi.org/10.1016/j.wasman.2014.09.025. PMid:25449606.

24 Guo, J., Li, X., Guo, Y., Ruan, J., Qiao, Q., Zhang, J., Bi, Y., & Li, F. (2016). Research on Flotation Technique of separating PET from plastic packaging wastes. Procedia Environmental Sciences, 31, 178-184. http://dx.doi.org/10.1016/j.proenv.2016.02.024.

25 Wang, C., Wang, H., Liu, Y., & Huang, L. (2016). Optimization of surface treatment for flotation separation of polyvinylchloride and polyethylene terephthalate waste plastics using responses surface methodology. Journal of Cleaner Production, 139, 866-872. http://dx.doi.org/10.1016/j.jclepro.2016.08.111.

26 Wang, C. Q., Wang, H., Gu, G. H., Lin, Q. Q., Zhang, L. L., Huang, L. L., & Zhao, J. Y. (2016). Ammonia modification for flotation separation of polycarbonate and polystyrene waste plastics. Waste Management, 51, 13-18. http://dx.doi.org/10.1016/j.wasman.2016.02.037. PMid:26965210.

27 Wang, J., Wang, H., Wang, C., Zhang, L., Wang, T., & Zheng, L. (2017). A novel process for separation of hazardous poly(vinyl chloride) from mixed plastic wastes by froth flotation. Waste Managemen, 69, 59-65. http://dx.doi.org/10.1016/j.wasman.2017.07.049. PMid:28801216.

28 Negari, M. S., Ostad Movahed, S., & Ahmadpour, A. (2018). Separation of polyvinylchloride (PVC), polystyrene (PS) and polyethylene terephthalate (PET) granules using various chemical agents by flotation technique. Separation and Purification Technology, 194, 368-376. http://dx.doi.org/10.1016/j.seppur.2017.11.062.

29 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.

30 Zhang, Y., Jiang, H., Wang, H., & Wang, C. (2020). Separation of hazardous polyvinyl chloride from waste plastics by flotation assisted with surface modification of ammonium persulfate: process and mechanism. Journal of Hazardous Materials, 389, 121918. http://dx.doi.org/10.1016/j.jhazmat.2019.121918. PMid:31879107.

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

32 Shen, H., Forssberg, E., & Pugh, R. J. (2001). Selective flotation separation of plastics by particle control. Resources, Conservation and Recycling, 33(1), 37-50. http://dx.doi.org/10.1016/S0921-3449(01)00056-8.

33 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.

34 Marques, G. A., & Tenório, J. A. S. (2000). Use of froth flotation to separate PVC/PET mixtures. Waste Management, 20(4), 265-269. http://dx.doi.org/10.1016/S0956-053X(99)00333-5.
 

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