This study investigates the synthesis of amide-containing oligomers through the aminolysis of secondary polyethylene terephthalate (PET) with ethanolamine. Optimization of reaction conditions (temperature 130–190°C, duration 4–6 hours, molar ratio 1:3 to 1:7) allowed obtaining high yields (up to 85%) and products with low viscosity. The synthesized oligomers, in combination with HCl acid, were applied as inhibitors against mineral scale deposition in oil field environments, showing 70–80% inhibition efficiency against calcium carbonate and sulfate scales. Structural and molecular weight distribution (Mw ≈ 800–1200 Da) were confirmed by infrared spectroscopy (IR) and gel permeation chromatography (GPC). This approach not only addresses PET waste management but also provides an eco-friendly alternative for oilfield inhibitors, reducing environmental impact.

Recycled polyethylene terephthalate, ethanolamine aminolysis, amide oligomers, mineral scale inhibitors, oilfield chemistry, scale deposition.

Jixuan Han, Jian Zuo, George Zillante, Ruidong Chang, Linwei Du. A systematic review of PET circularity technologies and management strategies: Challenges and future directions. Resources, Conservation and Recycling Volume 219, 1 June 2025, 108280

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

Paszun, D., & Spychaj, T. (1997). Chemical recycling of poly(ethylene terephthalate). Industrial & Engineering Chemistry Research, 36(4), 1373-1383.

Awaja, F., & Pavel, D. (2005). Recycling of PET. European Polymer Journal, 41(7), 1453-1477.

Meyliyeva L.Q., Davlyatova Z.M., Kadirov X.I. Polietilentereftalat asosli chiqindilarni qayta ishlash va olingan mahsulotlarning qo‘llanilish yangi sohalari. Farg‘ona politexnika instituti ilmiy – texnika jurnali. , Farg‘ona – 2022 , Tom 26, №2. 146-151 b.

IMARC Group. (2024). PET bottle recycling market size, share, report 2025-2033. IMARC Group Reports.

Global Market Insights. (2024). PET bottles market size, share & forecast report, 2025-2034. Global Market Insights.

Bohre A, Jadhao PR, Tripathi K, Pant KK, Likozar B, Saha B. Chemical Recycling Processes of Waste Polyethylene Terephthalate Using Solid Catalysts. ChemSusChem. 2023 Jul 21;16(14)

Abedsoltan, A., et al. (2023). A focused review on recycling and hydrolysis techniques of polyethylene terephthalate. Polymer Engineering & Science, 63(10).

Popa, A., Vlase, T., & Doca, N. (2010). Thermal behavior of PET in the presence of ethanolamine. Journal of Thermal Analysis and Calorimetry, 100(2), 551-557.

Lex.uz. (2024, January 4). PF-5-сон 04.01.2024. Chiqindilarni boshqarish tizimini takomillashtirish va ularning ekologik vaziyatga salbiy ta’sirini kamaytirish bo‘yicha chora-tadbirlar to‘g‘risida.

Lex.uz. (2025, March 24). PF-56-son 24.03.2025. Chiqindilarni qayta ishlash sohasini yanada takomillashtirish hamda kompleks tizimlashtirish chora-tadbirlari to‘g‘risida.

MarketsandMarkets. (2024). Scale Inhibitors Market by Type (Phosphonates, Carboxylate/Polymers, Sulfonates, Others), Application (Power & Construction, Oil & Gas, Water & Pulp Treatment, Boiler, Paper & Pulp, Others), Region - Global Forecast to 2028.

L.M. Meyliyeva., V.Z. Nurmukhamedova., Sh.A. Niyozova., B.U. Zokirov., Sh.Sh. Khasanov., O.N. Ashirov., J.M. Abdurakhmanov., Sh.A. Mutalov. Investigation of the conditions of alcoholization of secondary polyethylene terephthalate with triethanolamine. European Chemical Bulletin. 2023, 12(4), 888-895 p.

A.T. Karimov., L.M. Meyliyeva., H.T. Tilovov., S.J. Kholikova., Kh.I. Kadyrov. Effective catalysts of the synthesis of quinoline and quinoline derivatives. European Chemical Bulletin. 2023, 12 (Regular Issue 6), 76-86 p.

L.M. Meyliyeva., Kh.I. Kadyrov. ML-IOMS-7 mineral tuzlar to‘planishiga qarshi ingibitorining ishlab chiqarish texnologiyasi va neft-gaz quduqlarida qo‘llanilishi. Central asian food engineering and technology. Xalqaro, elektron (online) jurnali volume 1, issue 2, september 2025 issn: 2181-385x. 69-76 b.

Aarti More., Ravindra A Kute, Shashank Mhaske. Chemical conversion of PET waste using ethanolamine to bis(2-hydroxyethyl) terephthalamide (BHETA) through aminolysis and a novel plasticizer for PVC January 2013Iranian Polymer Journal 23(1):59-67

Ling-na Zhang., Li-zhu Liu, Qun-feng Yue., Chun-cheng Zhu. From Aminolysis Product of PET Waste to Value-added Products of Polymer and Assistants. January 2014Polymers and Polymer Composites 22(1):13-16.

Fink, J. K. (2012). Petroleum engineer's guide to oil field chemicals and fluids. Gulf Professional Publishing.

Kelland, M. A. (2014). Production chemicals for the oil and gas industry. CRC Press.