# Plant Design for the Conversion of Plastic Waste into Valuable Chemicals (Alkyl Aromatics)
## 1 Introduction
### Types of Plastic  
Plastics are marked with a triangle symbol, denoting a number from 1 to 7, representing the specific resin used in the product. However, not all plastics can be recycled due to their non-degradability, leading to accumulation and environmental issues. This section provides an overview of various types of plastics and their recycling capabilities.  
1. Polyethylene terephthalate (PET): Commonly found in beverage containers and packaging, PET is single-use due to leaching and contamination risks. It can be recycled into textile fibers and various products [4].
2. High-density polyethylene (HDPE): Used in water jugs, product bottles, and various durable items, HDPE exhibits excellent recyclability and is often reused for multiple purposes [5].
3. Polyvinyl chloride (PVC): PVC is a flexible plastic utilized in various applications, including food wrapping, construction materials, and tubing. It has limited recyclability and is considered environmentally hazardous. Also named \"poison plastic\", PVC contains multiple toxins that can be released throughout the course of a product's lifetime. Less than 1% of PVC is recycled, as objects made from it cannot be reused or recycled [6].
4. Low-density polyethylene (LDPE): LDPE is commonly found in plastic bags, shrink wraps, and other packaging materials. While it poses fewer risks, LDPE recycling is currently limited but emerging.
5. Polypropylene (PP): PP's heat resistance makes it suitable for a wide range of products, but its recycling rate remains low. It serves as a barrier against liquids, oils, and other corrosive substances so that cereal, for example, can stay fresher for longer. PP can be found in a wide variety of everyday items, including baby nappies, plastic bottle caps, cheese and yoghurt bottles, snack bags, straws, packaging tape, and rope. Although PP is one of the most widely used plastics, comprising at least 20% of the market share [7], the recycling rate remains very low due to its rigidity and inclusion in complex products [8]. Landscaping border stripping, battery casings, brooms, bins, and trays are products that can benefit from recycled PP.
6. Polystyrene (PS): Many different items can be made from PS because of its inexpensive price, light weight, and malleability. Egg cartons, polyurethane picnic utensils, foam packing, and \"peanuts\" used to stuff packages are just a few examples. Rigid cellulose insulation and laminate underlay sheets are two more common uses for PS. PS is easily broken down and dispersed throughout the natural environment because of its structural instability and light weight.
7. Polycarbonate (PC) and Lexan: PC is well known and is widely utilized because of its strength and durability. Sunglasses, sports goggles, and safety glasses are just a few of the many products that benefit from PC lenses. It can also be found in compact discs (CDs) and mobile phones. This resin's leaching causes the production of bisphenol A, a chemical that is suspected of being detrimental to the environment when heated to high degrees, and as a result, its use has been contentious in recent years. In addition, BPA does not break down in landfills, so it will persist in the environment for long periods and ultimately end up in water sources, where it can cause contamination.