Kinetics Study of Hydrothermal Degradation of PET Waste into Useful Products

Kinetics of hydrothermal degradation of colorless polyethylene terephthalate (PET) waste was studied at two temperatures (300 °C and 350 °C) and reaction times from 1 to 240 min. PET waste was decomposed in subcritical water (SubCW) by hydrolysis to terephthalic acid (TPA) and ethylene glycol (EG) as the main products. This was followed by further degradation of TPA to benzoic acid by decarboxylation and degradation of EG to acetaldehyde by a dehydration reaction. Furthermore, by-products such as isophthalic acid (IPA) and 1,4-dioxane were also detected in the reaction mixture. Taking into account these most represented products, a simplified kinetic model describing the degradation of PET has been developed, considering irreversible consecutive reactions that take place as parallel in reaction mixture. The reaction rate constants (k1-k6) for the individual reactions were calculated and it was observed that all reactions follow first-order kinetics.

Two Stages Thermal and Catalytic Cracking of Polyethylene Terephthalate to Fuel Production

PET (polyethylene terephthalate) is made up of polymerized repeating units of the ethylene terephthalate monomer (C10H8O4). PET is a recyclable plastic with the number 1 as its identification code. PET, which has a molecular weight of 192 gm/mole and contains 62.5 percent carbon, 33.3 percent oxygen, and 4.2 percent hydrogen, is utilized as synthetic fiber, polyester, plastic packaging, and soft drink containers all over the world. The main purpose of this study is to convert PET waste into liquid hydrocarbon fuel. Because PET use has risen significantly over the world, and the bulk of garbage is thrown into the soil rather than recycled, posing an environmental risk. During the heat breakdown phase, PET decomposes. It creates very strong and solid non-biodegradable terephthalic acid and benzoic acid complexes. To obtain liquid hydrocarbon fuel from PET, at 250-300℃, calcium hydroxide Ca(OH)2 is used as a catalyst in this study.

Aminolytic Depolymerisation of Polyethylene Terephthalate Wastes using Sn doped ZnO Nanoparticles

Poly(ethylene terephthalate) (PET) is one of the most consumed polymers because of its excellent thermal and mechanical properties. By increasing in PET production and since the disposal of PET waste has growing to be a major global environmental issue each year. Chemical recycling is a most successful method to achieve circular economy in the PET utilizing industries. Current research work aims to complete depolymerization of waste PET from soft drink bottles by the aminolysis method to produce bis (2-hydroxy ethylene) terephthalamide (BHETA) in the presence of Sn doped ZnO. To evaluate catalytic activity, pure and Sn2+ doped ZnO nanoparticles prepared using different Sn2+ molar ratios at 0.5, 1.0 and 2.0 mol% and calcined at 500 0C for 1h. The synthesized catalysts characterised using FT-IR, XRD, and UV-vis spectroscopy. The surface morphology and percentage doping obtained from SEM and SEM-EDS, respectively. We have observed a reduction in optical band gap and crystallite size of ZnO due to tin doping. Aminolytic depolymerization of PET waste using ethanolamine promoted by Sn doped ZnO effectively under conventional thermal method. Increase in the yield of the BHETA observed with respect to increasing doping percentage of Sn and 1-2 mol% Sn doped ZnO nanoparticles afforded over 90% of BHETA. Structure and purity of BHETA, depolymerised product characterized by FT-IR, 1HNMR, 13C NMR, and MS.

Fusion of Chitin-Binding Domain From Chitinolyticbacter meiyuanensis SYBC-H1 to the Leaf-Branch Compost Cutinase for Enhanced PET Hydrolysis

Polyethylene terephthalate (PET) is a mass-produced petroleum-based non-biodegradable plastic that contributes to the global plastic pollution. Recently, biocatalytic degradation has emerged as a viable recycling approach for PET waste, especially with thermophilic polyester hydrolases such as a cutinase (LCC) isolated from a leaf-branch compost metagenome and its variants. To improve the enzymatic PET hydrolysis performance, we fused a chitin-binding domain (ChBD) from Chitinolyticbacter meiyuanensis SYBC-H1 to the C-terminus of the previously reported LCCICCG variant, demonstrating higher adsorption to PET substrates and, as a result, improved degradation performance by up to 19.6% compared to with its precursor enzyme without the binding module. For compare hydrolysis with different binding module, the catalytic activity of LCCICCG-ChBD, LCCICCG-CBM, LCCICCG-PBM and LCCICCG-HFB4 were further investigated with PET substrates of various crystallinity and it showed measurable activity on high crystalline PET with 40% crystallinity. These results indicated that fusing a polymer-binding module to LCCICCG is a promising method stimulating the enzymatic hydrolysis of PET.

Conversion of Waste Polyethylene Terephthalate (PET) Polymer into Activated Carbon and Its Feasibility to Produce Green Fuel

In this study, a novel idea was proposed to convert the polyethylene terephthalate (PET) waste drinking-water bottles into activated carbon (AC) to use for waste cooking oil (WCO) and palm fatty acid distillate (PFAD) feasibility to convert into esters. The acidic and basic char were prepared by using the waste PET bottles. The physiochemical properties were determined by employing various analytical techniques, such as field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET) and temperature-programmed desorption – ammonia/carbon dioxide (TPD-NH3/CO2). The prepared PET H3PO4 and PET KOH showed the higher surface area, thus illustrating that the surface of both materials has enough space for impregnation of foreign precursors. The TPD-NH3 and TPD-CO2 results depicted that PET H3PO4 is found to have higher acidity, i.e., 18.17 mmolg−1, due to the attachment of phosponyl groups to it during pretreatment, whereas, in the case of PET KOH, the basicity increases to 13.49 mmolg−1. The conversion results show that prepared materials can be used as a support for an acidic and basic catalyst for the conversion of WCO and PFAD into green fuel.

Mechanical Properties of Concrete with Recycled Plastic Waste

Plastics are a vast group of synthetic or semi-synthetic materials that are often made of polymers. Because of their plasticity, plastics can be molded, extruded, and pressed into solid objects of different sizes. Its extensive use is due to its flexibility, as well as a number of other properties such as light weight, durability, and low manufacturing costs. The high use of plastics has resulted in an increase in solid waste, with domestic waste accounting for a significant portion of it. Since this waste is not biodegradable and takes up a lot of space, it is considered a serious environmental problem. To overcome these adverse effects, recycling plastic waste and using it in concrete can be an effective way to protect the environment. In this study, an attempt was made to experimentally evaluate the mechanical properties of concrete with recycled PET plastic wastes. The effect of this type of plastic waste was investigated by adding it in three different lengths: 22 mm, 45 mm, and a combination of both lengths 22 + 45 mm. For each length of fiber, it was added in three percentages to concrete 0.1, 0.3 and 0.5 % of cement weight. Several experiments were carried out on concrete mixtures such as slump test, compressive test, splitting tensile test, flexural test, and ultrasound pulse velocity test. The findings showed that PET waste in the form of fibers could be incorporated into concrete and achieve adequate compressive strength. When the ultrasound test results were compared to the results of previous tests, it was discovered that normal concrete containing plastic waste in the form of fibers performed exceptionally well.

Polyethylene Terephthalate Waste Utilisation for Production of Low Thermal Conductivity Cement Sand Bricks

There is a tremendous increase in plastic waste that negatively impacts the environment due to various industrial activities. Furthermore, plastic waste has non-biodegradable properties that make it hard to reduce its accumulation around the globe. Hence, this study aims to investigate the possibility of incorporating Polyethylene terephthalate (PET) waste as a partial replacement material of sand to improve the thermal insulation properties of cement sand brick by looking at findings of low thermal conductivity value. The study uses a PET plastic bottle that has been cut into small flakes and grind using a granulator machine to produce PET waste granules whose size is not more than 5 mm, similar to the sand size. This waste was added to other raw materials, i.e., cement and sand. The percentages of PET waste vary from 2.5%, 5%, and 7.5% by weight. This study produced two types of samples, i.e., control brick and PET waste cement sand brick. All samples undergo laboratory works involving geotechnical gradation, physical, mechanical, and thermal conductivity testing. Based on the results obtained, the optimum proportion of PET waste replacement in cement sand bricks making is 5% by its having the lowest thermal conductivity value of 0.581 W/mK and meeting the standard requirements of 3.90 MPa > 3.45 MPa (ASTM C129-11 for compressive strength), and 2,146 kg/m3 > 2,000 kg/m3 (ASTM C129-11 for normal weight non-loadbearing brick). Thus, PET plastic bottle waste can be a potential partial sand replacement material in cement sand bricks. Its potential to enhance the thermal conductivity of existing cement sand brick reduces sand consumption, solves plastic waste problems, and promotes a better environmentally-friendly construction industry.