# Characterization and Use of Char Produced from Pyrolysis of Post-Consumer Mixed Plastic Waste
###### Abstract  
In this work, the pyrolysis of post-consumer mixed plastic waste (polypropylene (PP), polystyrene (PS) and polyethylene film (PE)) is carried out. The solid product of the pyrolysis is characterized and tested for its use as adsorbent of lead present in aqueous media. The pyrolysis temperature has a great influence on the solid product yield, decreasing when the temperature increases. The highest yield to solid product obtained is from the pyrolysis of film at lower temperature (450 \({}^{\circ}\)C), reaching almost 14%. The results of product solid characterization reveal that the carbon, hydrogen and nitrogen content decreases with increasing pyrolysis temperature. Furthermore, both the ash and the volatile content are related to the pyrolysis temperature. The ash content is higher when the pyrolysis temperature is higher, while when the temperature increases, a solid product with lower volatile content is obtained. In respect to specific surface area, a higher pyrolysis temperature improves the properties of the solid product as an adsorbent. The adsorption capacity increases as  
cables. In addition, some researchers have also used catalysts in the pyrolysis process of plastic materials and show that the amount of char obtained can remain constant or increase slightly [3; 4; 6]. The use or application of the solid product obtained (char) by pyrolysis of plastic waste depends in high extent on the composition of the material to be pyrolyzed, since the characteristics and properties of the char will depend on this, as indicated above. The most common use encountered for this product is as an adsorbent material based on its properties such as surface area or porosity. Nevertheless, the list of char potential applications is extended also to less traditional materials, e.g., char-based sensors [14; 15] and supercapacitors [16; 17]. In some cases, this char is treated to improve these surface properties and increase its adsorbent capacity. [PERSON] et al. [18] investigated with a mixture of pine forest biomass, used tires and a mixture of plastics composed of 56% of PE, 27% of PP and 17% of PS to simulate the composition of the plastic fraction from municipal solid waste in Portugal. The char produced from the pyrolysis of this material is subjected to a sequential Soxhlet extraction process with hexane and acetone to recovery various organic compounds of different groups that are retained in the solid. The solid resulting is dried at 80 \({}^{\circ}\)C for 24 h in a vacuum oven. At the end of the process, a solid composed of macropores enriched in oxygen functional groups is obtained. This solid is used to measure its efficiency based on its adsorption of lead present in an aqueous medium. The results achieve by these authors showed that the pyrolysis of mixtures with a higher content of biomass waste and used tires gives rise to solid products with better adsorption yields. [PERSON] et al. [10] also studied the efficiency of char from pyrolysis of polyvinyl chloride (PVC), polyethylene terephthalalate (PET) and PE waste in the adsorption of arsenic. These researchers showed that the mixture of plastic waste is a decisive factor in the properties of the resulting carbonaceous residue, with the PVC and PE mixtures obtaining the best results because they have the most surface areas, reaching adsorption percentages of 99.4%. They also found that the char prepared at higher temperatures (550 \({}^{\circ}\)C) showed greater adsorption capacity than those prepared at lower temperatures. [PERSON] et al. [10] concluded that the use of carbonaceous waste from pyrolysis of plastic waste can be considered as a novel and sustainable solution based on the application as a large-scale arsenic adsorbent and treatment for plastic waste. [PERSON] et al. [19] performed a fast pyrolysis of high-density polyethylene (HDPE) plastic waste and the solid product obtained is crushed and extruded to form briquettes. These briquettes are used based on fuel.