Application of electrostatic separation to the recycling of plastic wastes: separation of PVC, PET, and ABS.
Plastics are widely used in everyday life as a useful material, and thus their consumption is growing at a rate of about 5% per year in Korea. However, the constant generation of plastic wastes and their disposal generates environmental problems along with economic loss. In particular, mixed waste plastics are difficult to recycle because of their inferior characteristics. A laboratory-scale triboelectrostatic separator unit has been designed and assembled for this study. On the basis of the control of electrostatic charge, the separation of three kinds of mixed plastics, polyvinyl chloride (PVC), poly(ethylene terephthalate) (PET), and acrylonitrile-butadiene-styrene (ABS), in a range of similar gravities has been performed through a two-stage separation process. Polypropylene (PP) and high-impact polystyrene (HIPS) were found to be the most effective materials for a tribo-charger in the separation of PVC, PET, and ABS. The charge-to-mass ratio (nC/g) of plastics increased with increasing air velocity in the tribo charger. In the first stage, using the PP cyclone charger, the separation efficiency of particles considerably depended on the air velocity (10 m/s), the relative humidity (< 30%), the electrode potential (> 20 kV), and the splitter position (+2 cm from the center) in the triboelelctrostatic separator unit. At this time, a PVC grade of 99.40% and a recovery of 98.10% have successfully been achieved. In the second stage, using the HIPS cyclone charger, a PET grade of 97.80% and a recovery of 95.12% could be obtained under conditions of 10 m/s, over 25 kV, a central splitter position, and less than 40% relative humidity. In order to obtain 99.9% PVC grade and 99.3% PET grade, their recoveries should be sacrificed by 20.9% and 27%, respectively, with moving the splitter from the center to a (+)6 cm position.
Park
Chul-Hyun
CH
Hanyang University, Department of Geoenvironmental System Engineering, Seoul, Korea.
Jeon
Ho-Seok
HS
Yu
Hyo-Shin
HS
Han
Oh-Hyung
OH
Park
Jai-Koo
JK
D000180:Acrylic Resins; D002070:Butadienes; D003247:Conservation of Natural Resources; D006813:Humidity; D011093:Polyethylene Terephthalates; D011137:Polystyrenes; D011143:Polyvinyl Chloride; D055672:Static Electricity; D018505:Waste Management / Q000379:methods*; D014866:Waste Products
D000180:Acrylic Resins; D002070:Butadienes; D011093:Polyethylene Terephthalates; D011137:Polystyrenes; D014866:Waste Products; D011143:Polyvinyl Chloride; C024636:ABS resin