Abstract:
To separate waste plastic mixture by applying gravity method and selective flotation. The experiments were divided into 2 parts. Part 1 concerned about sink-float method. The solution used in this part was tap water, dense medium solution and light medium solution. Part 2 involved in selective floatation. Factors studied in this part were (a) wetting agent (CaLS, PVA, CMCCa) (b) presence of nonionic surfactant (Poly(oxyethylene)(20)-sorbitane monooleate, Tween 89), presence of cationaic surfactant (Hexadecyltrimethyl ammonium bromide, CTAB), presence of anionic surfactant (Sodium dodecyl sulphate, SDS) (c) concentration and type of electrolyte (d) concentration of frother (e) pH (f) air flow rate and (g) condition time. Surface tension and contact angle measurements were also performed in order to interpret the obtained results. From Part 1, waste plastics can be separated into 2 groups by water. Group 1 included PP and HDPE. Group 2 accompanied with PET POM PC PVC PS and ABS. To separate PP from HDPE, isopropyl alcohol at concentration of 40 %v/v was used. To separate plastic in group 2 into subgroup, NaNo(subscript 3) was introduced. The plastic subgroups were then separated individually by selective floatation. To separate PS from ABS, it was introduced to use CaLS400 mg/l and CTAB 2.67*10 [supperscript -5] ppm at pH 6.8 and air flow rate of 140 SCCM. To separate PET from POM, it was introduced to use PVA 50 mg/l, CTAB 3.33*10[supperscript -5] ppm and MgSO[subscript 4] 0.01 %w/v at pH 6.8 and air flow rate of 238 SCCM. The recovery and purity of separated PS/ABS and PET/POM were more than 90%.