There is a recognized need for plastic waste management and treatment. Plastic waste gasification is becoming an interesting thermochemical method for upcycling plastics waste. Plastic waste is converted into hydrogen-rich syngas with a high heating value in this method. This chapter set out to comprehensively develop air gasification modeling for plastic waste. In this chapter, equilibrium constant and Gibbs free energy minimization coupled with Lagrange undetermined multipliers techniques for air gasification modeling were developed and applied to the plastic waste. The research was based on two case studies. (1) Air gasification of plastic waste by equilibrium constant technique. (2) Air gasification of plastic waste by Gibbs free energy minimization coupled with Lagrange undetermined multipliers technique. All modeling cases were comprehensively described and validated compared to the experimental results reported. The results confirmed that the models predicted the syngas composition with desirable accuracy in all cases.
