Malaysian Journal of Analytical Sciences, Vol 28 No 3 (2024): 611 - 631

A REVIEW ON CONVERSION OF MICROPLASTICS INTO VALUE-ADDED PRODUCTS: CHALLENGES AND PERSPECTIVES

(Ulasan Tentang Penukaran Mikroplastik Kepada Produk Nilai Tambah: Cabaran dan Perspektif)

Nurul Mohd Ridzuan Afifah¹, Jennifer Janani Sathiaseelan¹, Seng Hon Kee¹, Tan Suet May Amelia¹, Wei Yien Lua², Nazli Aziz⁴, Wan Mohd Afiq Wan Mohd Khalik^1,5, Sevakumaran Vigneswari³, and Kesaven Bhubalan^1,3,5*

¹Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

²Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

³Institute of Climate Adaptation and Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

⁴Faculty of Business, Economics, and Social Development, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

⁵Microplastic Research Interest Group, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

*Correspondance: kesaven@umt.edu.my

Received: 30 December 2023; Accepted: 31 March 2024; Published: 29 June 2024

Abstract

Microplastics have emerged as a pressing environmental concern, exerting profound impacts on ecosystems, water bodies, terrestrial landscapes, and human food sources. In light of the global plastic waste crisis, innovative strategies are being explored to manage and recycle plastic waste, with an emphasis on microplastics. Research endeavours aimed at transforming waste microplastics into valuable resources align seamlessly with circular economy principles. Microplastics can be collected using surface water sampling, air sampling, sediment sampling, soil sampling, shoreline sampling, as well as wastewater and effluent sampling. Microplastics can be chemically and physically characterised for composition selection and then converted using biological, chemical, and mechanical approaches. Biological conversion involves microbial activity and enzyme utilisation, chemical conversion involves chemically breaking down polymers into smaller molecules that can be used as feedstock for valuable materials, while mechanical conversion applies physical force to reduce polymer size. Both conventional and biodegradable plastics can undergo biological, chemical, and mechanical recycling to an extent to maintain their value and prevent the waste of non-renewable resources. However, there are challenges to overcome in the conversion of microplastics, including cost-effectiveness, scalability, environmental friendliness, and regulatory considerations. Appropriate macroplastic management and life cycle assessment analyses are still crucial for transitioning to a sustainable and circular economy.

Keywords: microplastics, conversion techniques, value-added products

Abstrak

Mikroplastik telah muncul sebagai kebimbangan alam sekitar yang mendesak, memberikan impak yang mendalam terhadap ekosistem, badan air, landskap terestrial, dan sumber makanan manusia. Dalam konteks krisis sisa plastik global, strategi inovatif sedang dikaji untuk mengurus dan mengitar semula sisa plastik, dengan penekanan pada mikroplastik. Usaha penyelidikan yang bertujuan untuk mengubah mikroplastik sisa menjadi sumber daya bernilai selari dengan prinsip ekonomi bulat. Mikroplastik boleh dikumpulkan melalui pengambilan sampel air permukaan, pengambilan sampel udara, pengambilan sampel sedimen, pengambilan sampel tanah, pengambilan sampel garis pantai, serta pengambilan sampel air sisa dan air buangan. Mikroplastik boleh dicirikan secara kimia dan fizikal untuk pemilihan komposisi, dan kemudian diubah menggunakan pendekatan biologi, kimia, dan mekanikal. Penukaran biologi melibatkan aktiviti mikrob dan penggunaan enzim, penukaran kimia melibatkan pemecahan kimia polimer menjadi molekul yang lebih kecil yang boleh digunakan sebagai bahan mentah untuk bahan bernilai, manakala penukaran mekanikal menggunakan daya fizikal untuk mengurangkan saiz polimer. Plastik konvensional dan plastik terbiodegradasi boleh mengalami kitar semula biologi, kimia, dan mekanikal untuk mengekalkan nilai mereka dan mengelakkan pembaziran sumber tidak boleh diperbaharui. Walau bagaimanapun, terdapat cabaran yang perlu diatasi dalam penukaran mikroplastik, termasuk kos-efektif, skalabiliti, kemesraan alam sekitar, dan pertimbangan peraturan. Pengurusan makroplastik yang sesuai dan analisis penilaian kitar hidup masih penting untuk bergerak ke arah ekonomi lestari dan bulat.

Kata kunci: mikroplastik, teknik penukaran, produk bernilai tambah

References

1. Gad, A. K., Toner, K., Benfield, M. C., and Midway, S. R. (2023). Microplastics in mainstem Mississippi River fishes. Frontiers in Environmental Science, 10: 1065583.

2. Harb, C., Pokhrel, N., and Foroutan, H. (2023). Quantification of the emission of atmospheric microplastics and nanoplastics via sea spray. Environmental Science and Technology Letters, 10(6): 513-519.

3. He, D., Bristow, K., Filipović, V., Lv, J., and He, H. (2020). Microplastics in terrestrial ecosystems: A scientometric analysis. Sustainability, 12(20): 8739.

4. Lee, H., Kunz, A., Shim, W. J., and Walther, B. A. (2019). Microplastic contamination of table salts from Taiwan, including a global review. Scientific Reports, 9(1): 10145.

5. Thornton Hampton, L. M., Brander, S. M., Coffin, S., Cole, M., Hermabessiere, L., Koelmans, A. A., and Rochman, C. M. (2022). Characterizing microplastic hazards: which concentration metrics and particle characteristics are most informative for understanding toxicity in aquatic organisms?. Microplastics and Nanoplastics, 2(1): 20.

6. Kallenbach, E. M., Eriksen, T. E., Hurley, R. R., Jacobsen, D., Singdahl-Larsen, C., and Friberg, N. (2022). Plastic recycling plant as a point source of microplastics to sediment and macroinvertebrates in a remote stream. Microplastics and Nanoplastics, 2(1): 26.

7. Li, J., Gao, F., Zhang, D., Cao, W., and Zhao, C. (2022). Zonal distribution characteristics of microplastics in the Southern Indian Ocean and the influence of Ocean current. Journal of Marine Science and Engineering, 10(2): 290.

8. Hernandez, L. M., Yousefi, N., and Tufenkji, N. (2017). Are there nanoplastics in your personal care products?. Environmental Science & Technology Letters, 4(7): 280-285.

9. McCormick, A. R., Hoellein, T. J., London, M. G., Hittie, J., Scott, J. W., and Kelly, J. J. (2016). Microplastic in surface waters of urban rivers: concentration, sources, and associated bacterial assemblages. Ecosphere, 7(11): e01556.

10. Kang, T., Kim, D., and Oh, J. H. (2021). Ingestion of microplastics by free-living marine nematodes, especially Enoplolaimus spp., in Mallipo Beach, South Korea. Plankton and Benthos Research, 16(2): 109-117.

11. Koelmans, A. A. (2015). Modeling the role of microplastics in bioaccumulation of organic chemicals to marine aquatic organisms. A critical review. Marine Anthropogenic Litter, pp. 309-324.

12. Moyo, S. (2022). An enigma: A meta-analysis reveals the effect of ubiquitous microplastics on different taxa in aquatic systems. Frontiers in Environmental Science, 10: 999349.

13. Rades, M., Schubert, P., Wilke, T., and Reichert, J. (2022). Reef-building corals do not develop adaptive mechanisms to better cope with microplastics. Frontiers in Marine Science, 9: 863187.

14. Li, W., Zhao, W., Zhu, H., Li, Z. J., and Wang, W. (2023). State of the art in the photochemical degradation of (micro) plastics: from fundamental principles to catalysts and applications. Journal of Materials Chemistry A, 11(6): 2503-2527.

15. European Environment Agency. (2022). Microplastics from textiles: Towards a circular economy for textiles in Europe. Retrieved on 23 August 2023 from https://www.eea.europa.eu/publications/microplastics-from-textiles-towards-a

16. Galgani, L., Beiras, R., Galgani, F., Panti, C., and Borja, A. (2019). Impacts of marine litter. Frontiers in Marine Science, 6: 208.

17. Pacheco-Lopez, A., Lechtenberg, F., Somoza-Tornos, A., Graells, M., and Espuna, A. (2021). Economic and environmental assessment of plastic waste pyrolysis products and biofuels as substitutes for fossil-based fuels. Frontiers in Energy Research, 9: 676233.

18. Payne, J., McKeown, P., and Jones, M. D. (2019). A circular economy approach to plastic waste. Polymer Degradation and Stability, 165: 170-181.

19. Nabgan, W., Nabgan, B., Tuan Abdullah, T. A., Ikram, M., Jadhav, A. H., Jalil, A. A., and Ali, M. W. (2022). Highly active biphasic anatase-rutile Ni-Pd/TNPs nanocatalyst for the reforming and cracking reactions of microplastic waste dissolved in phenol. ACS omega, 7(4): 3324-3340.

20. Vaccaro, P. A., Galvín, A. P., Ayuso, J., Lozano-Lunar, A., and López-Uceda, A. (2021). Pollutant potential of reinforced concrete made with recycled plastic fibres from food packaging waste. Applied Sciences, 11(17): 8102.

21. Dionela, T., Evangelista, A., Lansang, C. M., and Sato, M. V. U. (2022). Sustainable marketing: Studying the effects of environmental consciousness and involvement degree on purchasing behavior of consumers. Journal of Business and Management Studies, 4(1): 213-221.

22. Anand, U., Dey, S., Bontempi, E., Ducoli, S., Vethaak, A. D., Dey, A., and Federici, S. (2023). Biotechnological methods to remove microplastics: a review. Environmental Chemistry Letters, 21(3): 1787-1810.

23. Wu, H., Mehrabi, H., Naveed, N., and Karagiannidis, P. (2022). Impact of strategic control and supply chain management on recycled plastic additive manufacturing. Journal of Cleaner Production, 364: 132511.

24. Hale, R. C., Seeley, M. E., King, A. E., and Yu, L. H. (2022). Analytical chemistry of plastic debris: sampling, methods, and instrumentation. Microplastic in the Environment: Pattern and Process, pp. 17-67.

25. Hung, C., Klasios, N., Zhu, X., Sedlak, M., Sutton, R., and Rochman, C. M. (2021). Methods matter: methods for sampling microplastic and other anthropogenic particles and their implications for monitoring and ecological risk assessment. Integrated Environmental Assessment and Management, 17(1): 282-291.

26. Hamilton, B. M., Jantunen, L., Bergmann, M., Vorkamp, K., Aherne, J., Magnusson, K., ... and Peeken, I. (2022). Microplastics in the atmosphere and cryosphere in the circumpolar North: a case for multicompartment monitoring. Arctic Science, 8(4): 1116-1126.

27. Khalik, W. M. A. W. M., Ibrahim, Y. S., Anuar, S. T., Govindasamy, S., and Baharuddin, N. F. (2018). Microplastics analysis in Malaysian marine waters: A field study of Kuala Nerus and Kuantan. Marine Pollution Bulletin, 135: 451-457.

28. Radford, F., Horton, A., Hudson, M., Shaw, P., and Williams, I. (2023). Agricultural soils and microplastics: Are biosolids the problem?. Frontiers in Soil Science, 2: 941837.

29. Taha, Z. D., Amin, R. M., Anuar, S. T., Nasser, A. A. A., and Sohaimi, E. S. (2021). Microplastics in seawater and zooplankton: A case study from Terengganu estuary and offshore waters, Malaysia. Science of the Total Environment, 786: 147466.

30. Lots, F. A., Behrens, P., Vijver, M. G., Horton, A. A., and Bosker, T. (2017). A large-scale investigation of microplastic contamination: abundance and characteristics of microplastics in European beach sediment. Marine Pollution Bulletin, 123(1-2): 219-226.

31. McNeish, R. E., Kim, L. H., Barrett, H. A., Mason, S. A., Kelly, J. J., and Hoellein, T. J. (2018). Microplastic in riverine fish is connected to species traits. Scientific Reports, 8(1): 11639.

32. Talvitie, J., Mikola, A., Koistinen, A., and Setälä, O. (2017). Solutions to microplastic pollution–removal of microplastics from wastewater effluent with advanced wastewater treatment technologies. Water Research, 123: 401-407.

33. Laglbauer, B. J., Franco-Santos, R. M., Andreu-Cazenave, M., Brunelli, L., Papadatou, M., Palatinus, A., ... and Deprez, T. (2014). Macrodebris and microplastics from beaches in Slovenia. Marine Pollution Bulletin, 89(1-2): 356-366.

34. Zhou, C., and Wang, Y. (2020). Recent progress in the conversion of biomass wastes into functional materials for value-added applications. Science and Technology of Advanced Materials, 21(1): 787-804.

35. Lamichhane, G., Acharya, A., Marahatha, R., Modi, B., Paudel, R., Adhikari, A., ... and Parajuli, N. (2023). Microplastics in environment: global concern, challenges, and controlling measures. International Journal of Environmental Science and Technology, 20(4): 4673-4694.

36. Adhikari, S., Kelkar, V., Kumar, R., and Halden, R. U. (2022). Methods and challenges in the detection of microplastics and nanoplastics: a mini‐review. Polymer International, 71(5): 543-551.

37. Sun, Y., Duan, C., Cao, N., Ding, C., Huang, Y., and Wang, J. (2022). Biodegradable and conventional microplastics exhibit distinct microbiome, functionality, and metabolome changes in soil. Journal of Hazardous Materials, 424: 127282.

38. Thakur, S., Chaudhary, J., Sharma, B., Verma, A., Tamulevicius, S., and Thakur, V. K. (2018). Sustainability of bioplastics: Opportunities and challenges. Current Opinion in Green and Sustainable Chemistry, 13: 68-75.

39. Wang, C., Yu, J., Lu, Y., Hua, D., Wang, X., and Zou, X. (2021). Biodegradable microplastics (BMPs): a new cause for concern?. Environmental Science and Pollution Research, 28: 66511-66518.

40. Weinstein, J. E., Dekle, J. L., Leads, R. R., and Hunter, R. A. (2020). Degradation of bio-based and biodegradable plastics in a salt marsh habitat: another potential source of microplastics in coastal waters. Marine Pollution Bulletin, 160: 111518.

41. Fuller, S., and Gautam, A. (2016). A procedure for measuring microplastics using pressurized fluid extraction. Environmental Science and Technology, 50(11): 5774-5780.

42. Maxwell S, H., Melinda K, F., and Matthew, G. (2020). Counterstaining to separate nile red-stained microplastic particles from terrestrial invertebrate biomass. Environmental Science and Technology, 54(9): 5580-5588.

43. Jin, M., Liu, J., Yu, J., Zhou, Q., Wu, W., Fu, L., ... and Karimi-Maleh, H. (2022). Current development and future challenges in microplastic detection techniques: A bibliometrics-based analysis and review. Science Progress, 105(4): 00368504221132151.

44. Shim, W. J., Hong, S. H., and Eo, S. E. (2017). Identification methods in microplastic analysis: a review. Analytical Methods, 9(9): 1384-1391.

45. Friedrich, K., Möllnitz, S., Holzschuster, S., Pomberger, R., Vollprecht, D., and Sarc, R. (2019). Benchmark analysis for plastic recyclates in Austrian waste management. Detritus, 9(9): 105-112.

46. Schyns, Z. O., and Shaver, M. P. (2021). Mechanical recycling of packaging plastics: A review. Macromolecular Rapid Communications, 42(3): 2000415.

47. Hassan, T., Srivastwa, A. K., Sarkar, S., and Majumdar, G. (2022, February). Characterization of plastics and polymers: A comprehensive study. In IOP Conference Series: Materials Science and Engineering. IOP Publishing: p. 012033.

48. Sola, A., Chong, W. J., Simunec, D. P., Li, Y., Trinchi, A., Kyratzis, I. L., and Wen, C. (2023). Open challenges in tensile testing of additively manufactured polymers: A literature survey and a case study in fused filament fabrication. Polymer Testing, 117: 107859.

49. Niranjan, A. (2023, July 27). ‘Era of global boiling has arrived’, says UN chief as July set to be hottest month on record. The Guardian. https://www.theguardian.com/science/2023/jul/27/scientists-july-world-hottest-month-record-climate-temperatures

50. Ng, H. M., Saidi, N. M., Omar, F. S., Ramesh, K., Ramesh, S., and Bashir, S. (2002). Thermogravimetric analysis of polymers. Encyclopedia of Polymer Science and Technology, 2002: 1-29.

51. McKeen, L. (2012). The effect of sterilization on plastics and elastomers. William Andrew Publishing.

52. Danielsen, S. P. O., Beech, H. K., Wang, S., El-Zaatari, B. M., Wang, X., Sapir, L., Ouchi, T., Wang, Z., Johnson, P. N., Hu, Y., Lundberg, D. J., Stoychev, G., Craig, S. L., Johnson, J. A., Kalow, J. A., Olsen, B. D., and Rubinstein, M. (2021). Molecular characterization of polymer networks. Chemical Reviews, 121(8), 5042-5092.

53. Li, W., Luo, Y., and Pan, X. (2020). Identification and characterization methods for microplastics basing on spatial imaging in micro-/nanoscales. Microplastics in terrestrial environments: Emerging Contaminants and Major Challenges, 2020 : 25-37.

54. Tirkey, A., and Upadhyay, L. S. B. (2021). Microplastics: An overview on separation, identification, and characterization of microplastics. Marine Pollution Bulletin, 170: 112604.

55. Girão, A. V. (2022). SEM/EDS and optical microscopy analysis of microplastics. In handbook of microplastics in the environment. Cham: Springer International Publishing: pp. 57-78.

56. Ding, J., Li, J., Sun, C., Jiang, F., Ju, P., Qu, L., Zheng, Y., and He, C. (2018). Detection of microplastics in local marine organisms using a multi-technology system. Analytical Methods, 11(1): 78-87.

57. Dehaut, A., Hermabessiere, L., and Duflos, G. (2019). Current frontiers and recommendations for the study of microplastics in seafood. TrAC Trends in Analytical Chemistry, 116: 346-359.

58. Fytianos, G., Ioannidou, E., Thysiadou, A., Mitropoulos, A. C., and Kyzas, G. Z. (2021). Microplastics in mediterranean coastal countries: A recent overview. Journal of Marine Science and Engineering, 9(1): 98.

59. Renner, G., Schmidt, T. C., and Schram, J. (2017). A new chemometric approach for automatic identification of microplastics from environmental compartments based on FT-IR spectroscopy. Analytical Chemistry, 89(22): 12045-12053.

60. Lasch, P., and Naumann, D. (2006). Spatial resolution in infrared microspectroscopic imaging of tissues. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1758(7): 814-829.

61. Miller, L. M., and Dumas, P. (2010). From structure to cellular mechanism with infrared microspectroscopy. Current Opinion in Structural Biology, 20(5): 649-656.

62. Fu, W., Min, J., Jiang, W., Li, Y., and Zhang, W. (2020). Separation, characterization and identification of microplastics and nanoplastics in the environment. Science of the Total Environment, 721: 137561.

63. Baruah, A., Sharma, A., Sharma, S., and Nagraik, R. (2022). An insight into different microplastic detection methods. International Journal of Environmental Science and Technology, 19(6): 5721-5730.

64. Blanco, M., and Villarroya, I. (2002). NIR spectroscopy: a rapid-response analytical tool. TrAC Trends in Analytical Chemistry, 21(4): 240-250.

65. Peez, N., Becker, J., Ehlers, S. M., Fritz, M., Fischer, C. B., Koop, J. H. E., Winkelmann, C., and Imhof, W. (2019). Quantitative analysis of PET microplastics in environmental model samples using quantitative ¹H-NMR spectroscopy: validation of an optimized and consistent sample clean-up method. Analytical and Bioanalytical Chemistry, 411(28): 7409-7418.

66. Peez, N., Janiska, M. C., and Imhof, W. (2019). The first application of quantitative ¹H NMR spectroscopy as a simple and fast method of identification and quantification of microplastic particles (PE, PET, and PS). Analytical and Bioanalytical Chemistry, 411(4): 823-833.

67. Huppertsberg, S., and Knepper, T. P. (2018). Instrumental analysis of microplastics—benefits and challenges. Analytical and Bioanalytical Chemistry, 410: 6343-6352.

68. Sridhar, A., Kannan, D., Kapoor, A., and Prabhakar, S. (2022). Extraction and detection methods of microplastics in food and marine systems: A critical review. Chemosphere, 286: 131653.

69. Fries, E., Dekiff, J. H., Willmeyer, J., Nuelle, M. T., Ebert, M., and Remy, D. (2013). Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy. Environmental Science: Processes & Impacts, 15(10): 1949-1956.

70. Akoueson, F., Chbib, C., Monchy, S., Paul-Pont, I., Doyen, P., Dehaut, A., and Duflos, G. (2021). Identification and quantification of plastic additives using pyrolysis-GC/MS: A review. Science of the Total Environment, 773: 145073.

71. La Nasa, J., Biale, G., Fabbri, D., and Modugno, F. (2020). A review on challenges and developments of analytical pyrolysis and other thermoanalytical techniques for the quali-quantitative determination of microplastics. Journal of Analytical and Applied Pyrolysis, 149: 104841.

72. Castelvetro, V., Corti, A., Biale, G., Ceccarini, A., Degano, I., La Nasa, J., Lomonaco, T., Manariti, A., Manco, E., Modugno, F., and Vinciguerra, V. (2021). New methodologies for the detection, identification, and quantification of microplastics and their environmental degradation by-products. Environmental Science and Pollution Research, 28(34): 46764-46780.

73. Giaganini, G., Cifelli, M., Biagini, D., Ghimenti, S., Corti, A., Castelvetro, V., Domenici, V., and Lomonaco, T. (2023). Multi-analytical approach to characterize the degradation of different types of microplastics: Identification and quantification of released organic compounds. Molecules, 28(3): 1382.

74. Adelugba, A., and Emenike, C. (2023). Comparative review of instrumental techniques and methods for the analysis of microplastics in agricultural matrices. Microplastics, 3(1): 1-21.

75. Ru, J., Huo, Y. and Yang, Y. (2020). Microbial degradation and valorization of plastic wastes. Front Microbiology, 2020: 442.

76. Thiyagarajan, S., Maaskant-Reilink, E., Ewing, T. A., Julsing, M. K., and van Haveren, J. (2022). Back-to-monomer recycling of polycondensation polymers: opportunities for chemicals and enzymes. RSC Advances, 12(2): 947-970.

77. Wierckx, N., Prieto, M. A., Pomposiello, P., de Lorenzo, V., O'Connor, K., and Blank, L. M. (2015). Plastic waste as a novel substrate for industrial biotechnology. Microbial Biotechnology, 8(6):900-903.

78. Mohanan, N., Montazer, Z., Sharma, P. K., and Levin, D. B. (2020). Microbial and enzymatic degradation of synthetic plastics. Frontiers in Microbiology, 11: 580709.

79. Papari, S., Bamdad, H., and Berruti, F. (2021). Pyrolytic conversion of plastic waste to value-added products and fuels: A review. Materials, 14(10): 2586.

80. Ragaert, K., Delva, L., and Van Geem, K. (2017). Mechanical and chemical recycling of solid plastic waste. Waste Management, 69 : 24-58.

81. Palve, A. M., Arukula, R., and Gupta, R. K. (2021). Bioconversion of biowastes for energy applications. Sustainable Bioconversion of Waste to Value Added Products, pp. 1-22.

82. Narancic, T., and O’Connor, K. E. (2017). Microbial biotechnology addressing the plastic waste disaster. Microbial Biotechnology, 10(5): 1232-1235.

83. Tamoor, M., Samak, N. A., Jia, Y., Mushtaq, M. U., Sher, H., Bibi, M. and Xing, J. (2021). Potential use of microbial enzymes for the conversion of plastic waste into value-added products: a viable solution. Frontier Microbiology, 12: 777727.

84. Yoshida, S., Hiraga, K., Takehana, T., Taniguchi, I., Yamaji, H., Maeda, Y., Toyohara, K., Miyamoto, K., Kimura, Y. and Oda, K. (2016). A bacterium that degrades and assimilates poly(ethylene terephthalate). Science, 351(6278): 1196-1199.

85. Palm, G. J., Reisky, L., Böttcher, D., Müller, H., Michels, E. A. P., Walczak, M. C., Berndt, L., Weiss, M. S., Bornscheuer, U. T. and Weber, G. (2019). Structure of the plastic-degrading Ideonella sakaiensis MHETase bound to a substrate. Nature Communication, 10 : 1717.

86. Johnston, B., Adamus, G., Ekere, A. I., Kowalczuk, M., Tchuenbou-Magaia, F., and Radecka, I. (2022). Bioconversion of plastic waste based on mass full carbon backbone polymeric materials to value-added polyhydroxyalkanoates (PHAs). Bioengineering, 9(9): 432.

87. Lee, H. M., Kim, H. R., Jeon, E., Yu, H. C., Lee, S., Li, J., and Kim, D. H. (2020). Evaluation of the biodegradation efficiency of four various types of plastics by Pseudomonas aeruginosa isolated from the gut extract of superworms. Microorganisms, 8(9): 1341.

88. Vimala, P. P., and Mathew, L. (2016). Biodegradation of polyethylene using Bacillus Subtilis. Procedia Technology, 24: 232-239.

89. Gan, Z., and Zhang, H. (2019). PMBD: A comprehensive plastics microbial biodegradation database. Database: The Journal of Biological Databases and Curation, 2019: 1-11.

90. Atanasova, N., Stoitsova, S., Paunova‐krasteva, T., and Kambourova, M. (2021). Plastic degradation by extremophilic bacteria. International Journal of Molecular Sciences, 12: 5610.

91. Nguyen, S. T., McLoughlin, E. A., Cox, J. H., Fors, B. P., and Knowles, R. R. (2021). Depolymerization of hydroxylated polymers via light-driven C–C bond cleavage. Journal of the American Chemical Society, 143(31): 12268-12277.

92. Gao. R. and Sun, C. (2021). A marine bacterial community capable of degrading poly(ethylene terephthalate) and polyethylene. Journal of Hazardous Materials, 416: 125928.

93. Wu, Z., Shi, W., Valencak, T. G., Zhang, Y., Liu, G., and Ren, D. (2023). Biodegradation of conventional plastics: Candidate organisms and potential mechanisms. Science of The Total Environment, 2023: 163908.

94. Zhang, M. Q., Wang, M., Sun, B., Hu, C., Xiao, D., and Ma, D. (2022). Catalytic strategies for upvaluing plastic wastes. Chemistry, 8(11): 2912-2923.

95. Taniguchi, I., Yoshida, S., Hiraga, K., Miyamoto, K., Kimura, Y., and Oda, K. (2019). Biodegradation of PET: Current status and application aspects. ACS Catalysis, 9(5): 4089-4105.

96. Roberts, C., Edwards, S., Vague, M., León-Zayas, R., Scheffer, H., Chan, G., Swartz, N. A., and Mellies, J. L. (2020). Environmental consortium containing Pseudomonas and Bacillus species synergistically degrades polyethylene terephthalate plastic. mSphere, 5(6): e01151-20.

97. Qi, X., Ma, Y., Chang, H., Li, B., Ding, M., and Yuan, Y. (2021). Evaluation of PET degradation using artificial microbial consortia. Frontiers in Microbiology, 12 : 778828.

98. Wang, C., and El-Sepelgy, O. (2021). Reductive depolymerization of plastics catalyzed with transition metal complexes. Current Opinion in Green and Sustainable Chemistry, 32: 100547.

99. Knott, B. C., Erickson, E., Allen, M. D., Gado, J. E., Graham, R., Kearns, F. L., Pardo, I., Topuzlu, E., Anderson, J. J., Austin, H. P., Dominick, G., Johnson, C. W., Rorrer, N. A., Szostkiewicz, C. J., Copié, V., Payne, C. M., Lee Woodcock, H., Donohoe, B. S., Beckham, G. T., and McGeehan, J. E. (2020). Characterization and engineering of a two-enzyme system for plastics depolymerization. Proceedings of the National Academy of Sciences, pp. 1-20.

100. Alberti, C., and Enthaler, S. (2020). Depolymerization of end-of-life poly(lactide) to lactide via zinc-catalysis. Chemistry Select, 5(46): 14759-14763.

101. Mao, Y., Fan, S., Li, X., Shi, J., Wang, M., Niu, Z., and Chen, G. (2023). Trash to treasure: Electrocatalytic upcycling of polyethylene terephthalate (PET) microplastic to value-added products by Mn0.1Ni0.9Co2O4-δ RSFs spinel. Journal of Hazardous Materials, 457(2023): 131743.

102. Han, Z., Rong, L., Wu, J., Zhang, L., Wang, Z., and Ding, K. (2012). Catalytic hydrogenation of cyclic carbonates: A practical approach from CO₂ and epoxides to methanol and diols. Angewandte Chemie, 124(52): 13218-13222.

103. Klein, S., Dimzon, I. K., Eubeler, J., and Knepper, T. P. (2018). Analysis, occurrence, and degradation of microplastics in the aqueous environment. Freshwater Microplastics: Emerging Environmental Contaminants?, pp. 51-67.

104. Al-Azzawi, M. S., Kefer, S., Weißer, J., Reichel, J., Schwaller, C., Glas, K., ... and Drewes, J. E. (2020). Validation of sample preparation methods for microplastic analysis in wastewater matrices—reproducibility and standardization. Water, 12(9): 2445.

105. Mahari, W. A. W., Kee, S. H., Foong, S. Y., Amelia, T. S. M., Bhubalan, K., Man, M., Yang, Y. F., Ong, H. C., Vithanage, M., Lam, S. S., and Sonne, C. (2022). Generating alternative fuel and bioplastics from medical plastic waste and waste frying oil using microwave co-pyrolysis combined with microbial fermentation. Renewable and Sustainable Energy Reviews, 153: 111790.

106. Akgül, A., Palmeiro-Sanchez, T., Lange, H., Magalhaes, D., Moore, S., Paiva, A., Kazanç, F., and Trubetskaya, A. (2022). Characterization of tars from the recycling of PHA bioplastic and synthetic plastics using fast pyrolysis. Journal of Hazardous Materials, 439: 129696.

107. Nabgan, W., Nabgan, B., Tuan Abdullah, T. A., Ikram, M., Jadhav, A. H., Ali, M. W., and Jalil, A. A. (2022). Hydrogen and value-added liquid fuel generation from pyrolysis-catalytic steam reforming conditions of microplastics waste dissolved in phenol over bifunctional Ni-Pt supported on Ti-Al nanocatalysts. Catalysis Today, 400–401: 35-48.

108. Jung, J. M., Cho, S. H., Jung, S., Lin, K. Y. A., Chen, W. H., Tsang, Y. F., and Kwon, E. E. (2022). Disposal of plastic mulching film through CO2-assisted catalytic pyrolysis as a strategic means for microplastic mitigation. Journal of Hazardous Materials, 430: 128454.

109. National Energy Technology Laboratory (n.d.). Gasification introduction. Retrieved from https://netl.doe.gov/research/Coal/energy-systems/gasification/gasifipedia/intro-to-gasification. [Accessed on 23/8/2023].

110. Wang, Z., Liu, X., Burra, K. G., Li, J., Zhang, M., Lei, T., and Gupta, A. K. (2021). Towards enhanced catalytic reactivity in CO2-assisted gasification of polypropylene. Fuel, 284: 119076.

111. Moghadam, R. A., Yusup, S., Uemura, Y., Chin, B. L. F., Lam, H. L., and Al Shoaibi, A. (2014). Syngas production from palm kernel shell and polyethylene waste blend in fluidized bed catalytic steam co-gasification process. Energy, 75: 40-44.

112. Lin, Y., Kouznetsova, T. B., and Craig, S. L. (2020). Mechanically gated degradable polymers. Journal of the American Chemical Society, 142(5): 2105-2109.

113. Alauddin, M., Choudhury, I. A., El Baradie, M. A., and Hashmi, M. S. J. (1995). Plastics and their machining: A review. Journal of Materials Processing Technology, 54(1–4): 40-46.

114. Zhou, J., Hsu, T. G., and Wang, J. (2023). Mechanochemical degradation and recycling of synthetic polymers. In Angewandte Chemie - International Edition, 62(27): 768.

115. Damayanti, D., Saputri, D. R., Marpaung, D. S. S., Yusupandi, F., Sanjaya, A., Simbolon, Y. M., Asmarani, W., Ulfa, M., and Wu, H. S. (2022). Current prospects for plastic waste treatment. Polymers, 14(15): 3133.

116. Eitzen, L., Paul, S., Braun, U., Altmann, K., Jekel, M., and Ruhl, A. S. (2019). The challenge in preparing particle suspensions for aquatic microplastic research. Environmental Research, 168: 490-495.

117. Kefer, S., Miesbauer, O., and Langowski, H. C. (2021). Environmental microplastic particles vs. engineered plastic microparticles—a comparative review. Polymers, 13(17): 2881.

118. Ramos, A., Monteiro, E., and Rouboa, A. (2022). Biomass pre-treatment techniques for the production of biofuels using thermal conversion methods – A review. Energy Conversion and Management, 270: 116271.

119. Lievens, S., Vervoort, E., Poma, G., Covaci, A., and Van Der Borght, M. (2023). A production and fractionation protocol for polyvinyl chloride microplastics. Methods and Protocols, 6(1): 15.

120. Nykamp, G., Carstensen, U., and Müller, B. W. (2002). Jet milling - A new technique for microparticle preparation. International Journal of Pharmaceutics, 242(1-2): 79-86.

121. Boey, J. Y., Lee, C. K., and Tay, G. S. (2022). Factors affecting mechanical properties of reinforced bioplastics: A review. Polymers, 14(18): 3737.

122. Sikora, J. W. (2008). Increasing the efficiency of the extrusion process. Polymer Engineering & Science, 48(9): 1678-1682.

123. Ragaert, K., Delva, L., and Van Geem, K. (2017). Mechanical and chemical recycling of solid plastic waste. Waste Management, 69: 24-58.

124. Schyns, Z. O., and Shaver, M. P. (2021). Mechanical recycling of packaging plastics: A review. Macromolecular Rapid Communications, 42(3), 2000415.

125. La Mantia, F. P., and Vinci, M. (1994). Recycling poly(ethyleneterephthalate). Polymer Degradation and Stability, 45(1): 121-125.

126. Vogt, B. D., Stokes, K. K., and Kumar, S. K. (2021). Why is recycling of postconsumer plastics so challenging? ACS Applied Polymer Materials, 3(9): 4325-4346.

127. Pfohl, P., Roth, C., Meyer, L., Heinemeyer, U., Gruendling, T., Lang, C., ... and Jessl, S. (2021). Microplastic extraction protocols can impact the polymer structure. Microplastics and Nanoplastics, 1: 1-13.

128. Imteaz, M. A., Arulrajah, A., and Maghool, F. (2020). Environmental and geotechnical suitability of recycling waste materials from plasterboard manufacturing. Waste Management and Research, 38(4): 383-391.

129. Almohana, A. I., Abdulwahid, M. Y., Galobardes, I., Mushtaq, J., and Almojil, S. F. (2022). Producing sustainable concrete with plastic waste: A review. Environmental Challenges, 9: 100626.

130. Rosenboom, J. G., Langer, R. and Traverso, G. (2022). Bioplastics for a circular economy. Nature Review Materials, 7: 117-137.

131. Maurya, A., Bhattacharya, A., and Khare, S. K. (2020). Enzymatic remediation of polyethylene terephthalate (PET)–based polymers for effective management of plastic wastes: an overview. Frontiers in Bioengineering and Biotechnology, 8: 602325.

132. Williams, J. M., Nitzsche, M. P., Bromberg, L., Qu, Z., Moment, A. J., Hatton, T. A., and Park, A. H. A. (2023). Hybrid thermo-electrochemical conversion of plastic wastes commingled with marine biomass to value-added products using renewable energy. Energy and Environmental Science, 16(12): 5805-5821.

133. Tiwari, R., Azad, N., Dutta, D., Yadav, B. R., and Kumar, S. (2023). A critical review and future perspective of plastic waste recycling. Science of the Total Environment, 2023: 163433.

134. Geyer, R., Jambeck, J. R., and Law, K. L. (2017). Production, use, and fate of all plastics ever made. Science Advances, 3(7): e1700782.

135. Cole, M., Lindeque, P., Halsband, C., and Galloway, T. S. (2011). Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin, 62(12): 2588-2597.

136. González-Pleiter, M., Tamayo-Belda, M., Pulido-Reyes, G., Amariei, G., Leganés, F., Rosal, R., and Fernández-Piñas, F. (2019). Secondary nanoplastics released from a biodegradable microplastic severely impact freshwater environments. Environmental Science: Nano, 6(5): 1382-1392.

137. Ma, H., Pu, S., Liu, S., Bai, Y., Mandal, S., and Xing, B. (2020). Microplastics in aquatic environments: Toxicity to trigger ecological consequences. Environmental Pollution, 261: 114089.

138. Aragaw, T. A., and Mekonnen, B. A. (2021). Distribution and impact of microplastics in the aquatic systems: A review of ecotoxicological effects on biota. microplastic pollution. Sustainable Textiles: Production, Processing, Manufacturing & Chemistry. Springer Singapore: pp. 65-104.

139. Sequeira, I. F., Prata, J. C., da Costa, J. P., Duarte, A. C., and Rocha-Santos, T. (2020). Worldwide contamination of fish with microplastics: A brief global overview. Marine Pollution Bulletin, 160: 111681.

140. Kutralam-Muniasamy, G., Pérez-Guevara, F., Elizalde-Martínez, I., and Shruti, V. C. (2020). Review of current trends, advances and analytical challenges for microplastics contamination in Latin America. Environmental Pollution, 267: 115463.

141. Carrington, D. (2022, March 24). Microplastics found in human blood for first time. The Guardian. Retrieved from https://www.theguardian.com/environment/2022/mar/24/microplastics-found-in-human-blood-for-first-time. [Accessed on 22 August 2023]

142. Mitrano, D. M., and Wohlleben, W. (2020). Microplastic regulation should be more precise to incentivize both innovation and environmental safety. Nature Communications, 11(1): 5324.

143. Poonacha, S. (2023, May 8). Plastic action in rural india with the alliance to end plastic waste. Retrieved from https://repurpose.global/blog/post/partnership-highlights-mobilizing-plastic-action-in-rural-india-with-the-alliance-to-end-plastic-waste. [Accessed on 22August 2023]

144. Liu, J., Yang, Y., An, L., Liu, Q., and Ding, J. (2021). The value of China’s legislation on plastic pollution prevention in 2020. Bulletin of Environmental Contamination and Toxicology, 2021: 1-8.

145. Extended Producer Responsibility Act (EPRA). 2022. Retrieved from https://legacy.senate.gov.ph/republic_acts/ra%2011898.pdf. [Accessed on 22 August 2023]

146. Solid Waste and Public Cleansing Management Act 2007 (Act 672).

147. Department of Agriculture, Water and the Environment. (2021). National Plastics Plan 2021.

148. Department of Environment and Natural Resources. (2020). National solid waste management commission.

149. Ministry of Energy, Science, Technology, Environment and Climate Change. (2018). Malaysia’s roadmap towards zero single-use plastics 2018-2030: Towards a sustainable future.

150. Ministry of Environment and Water. (2021). Malaysia plastics sustainability roadmap 2021-2030: Catalysing sustainability and circularity towards a new plastics economy. Retrieved from https://ce.acsdsd.org/knowledge/the-malaysia-plastic-sustainability-roadmap-2021-2030-catalyzing-sustainability-and-circularity-towards-a-new-plastic-economy/. [Accessed on 22 August 2023]

151. GESAMP (2015). Sources, fate and effects of microplastics in the marine environment: a global assessment, London: International Maritime Organization.

152. Microbeads-Free Waters Act (2015)

153. OECD (2013 October 28). Policies for Bioplastics in the Context of a Bioeconomy, OECD Science, Technology and Industry Policy Papers, No. 10, OECD Publishing, Paris. Retrieved from http://dx.doi.org/10.1787/5k3xpf9rrw6d-en. [Accessed on 22 August 2023]

154. OECD (2020, June 4). Microbeads in cosmetics. The Oceans-Policy in practice.

155. OECD (2021). Policies to reduce microplastics pollution in water: Focus on textiles and tyres.

156. The Strait Times (2023, May 9). Malaysia to impose total ban on plastic bags by 2025. Retrieved from https://www.straitstimes.com/asia/se-asia/malaysia-to-impose-total-ban-on-plastic-bags-by-2025. [Accessed on 22 August 2023]

157. UNEP (2018). Legal limits on single-use plastics and microplastics: A global review of national laws and regulations. Retrieved from https://www.unep.org/resources/report/legal-limits-single-use-plastics-and-microplastics. [Accessed on 23 August 2023]

158. Xinhua (2020). China reveals plan to cut plastic use by 2025. China.org.cn. Retrieved from http://www.china.org.cn/china/2020-01/19/content_75629958.htm. [Accessed on 22 August 2023]