Optimization of value-added products using response surface methodology from the HDPE waste plastic by thermal cracking

Abstract

The current research aims at the thermal degradation of waste plastic in the presence of bentonite solid catalyst to produce value added products such as fuel oil, gas and charcoal. The thermal cracking of High-Density Polyethylene plastic produces the liquid fuel with conversion around 84.46 % with the characteristics: heating value 35.5 MJ/Kg, density 0.749 g/cc, viscosity 1.43cSt, a boiling point 200 °C and flash point 16 °C. The response surface methodology using the central composite design (CCD) method have been investigated to evaluate the effect of independent variables such as heating rate, temperature, time of operation on the production of value-added products. The optimal operating values for temperature, heating rate and batch time are 473.74 K, 24.9 °C/min and 159.90 min respectively. At the optimal operating conditions, the value-added products produced are fuel oil 91.16 %, gaseous products 8 % and solids 2 %. The experimental results were best fitted with quadratic polynomial model with the appreciable regression coefficient using the response surface method of analysis.