Pet And Pvc Separation By Froth Flotation

PET and PVC Separation by Froth Flotation Abbasi, M., and Salari Rad, M.M. Amirkabir University of technology [email protected] ABSTRACT The global production of plastic has grown exponentially over recent years. Because disposal of post consumer plastics is increasingly being constrained by legislation and escalating costs, there is considerable demand for alternatives to disposal or landfilling (1). As a result, the environmental effects due to plastic waste have become a challenging task. Complete recycling of waste mixed plastics represents a goal that has yet to be achieved by the recycling industry. The barrier to economic reuse of mixed plastic wastes, due to incompatibilities of the properties of different polymers, is separation into pure components (2). Physical separation techniques, such as gravity and electrostatic processes have been proposed to separate mixed plastic wastes into individual components, each of them with an ultimate limit of capabilities (3). For instance, the density of PVC and PET ranges from 1.32 to 1.37 g/cm3 and 1.33 to 1.37 g/cm3, respectively. Because of slight differences in densities, it is too difficult to separate mixed PVC and PET by conventional gravity separation processes. Selective flotation separation of the PET/PVC mixture is impossible without changing the surface properties of one of these polymers. Both polymers exhibit almost the same degree of hydrophobicity. In this research Tanic acid was employed as a wetting agent for selective depression of PET during flotation. The selection of reagent and its dosage was based on the contact angle measurement (θ) of PVC and PET at different conditions. Using a full factorial design procedure, the effects of depressant dosage (i.e., Tanic acid), temperature, and pH were optimized. The results indicate that at the optimum conditions, separation of PET and PVC by grade and recovery of more than 99% can be achieved. REFERENCES: [1] Huiting Shent; R.J. Pugh; and E. Forssberg, 1999,” A review of plastics waste recycling and the flotation of plastics”, Resources, Conservation and Recycling 25. [2] Gjergj Dodbiba. Et al., 2008, “The recycling of plastic wastes from discarded TV sets: comparing energy recovery with mechanical recycling in the context of life cycle assessment”, J. of Cleaner Production 16, pages 458-470. [3] Masami Tsunekawa et all, 2005, “Jig separation of plastics from scrapped copy machines”, Int. J. Miner. Process. 76 [4] Pavlína Basaˇrová et al, 2005, “The influence of flotation agent concentration on the wettability and flotability of polystyrene”, J. of Colloid and Interface Science 286, pages 333–338 [5]Huiting Shen, E. Forssberg , R.J. Pugh, 2002, “Selective flotation separation of plastics by chemical conditioning with methyl cellulose”, J. of Resources, Conservation and Recycling(35).