title: Ammonia modification for flotation separation of polycarbonate and polystyrene waste plastics.
abstract: A promising method, ammonia modification, was developed for flotation separation of polycarbonate (PC) and polystyrene (PS) waste plastics. Ammonia modification has little effect on flotation behavior of PS, while it changes significantly that of PC. The PC recovery in the floated product drops from 100% to 3.17% when modification time is 13min and then rises to 100% after longer modification. The mechanism of ammonia modification was studied by contact angle, and Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements. Contact angle of PC indicates the decline of PC recovery in the floated product is ascribed to an increase in surface wettability. FT-IR and XPS spectra suggest that ammonia modification causes chemical reactions occurred on PC surface. Flotation behavior of ammonia-modified PC and PS was investigated with respect to flotation time, frother concentration and particle sizes. Flotation separation of PC and PS waste plastics was conducted based on the flotation behavior of single plastic. PC and PS mixtures with different particle sizes are separated efficiently, implying that the technology possesses superior applicability to particle sizes of plastics. The purity of PS and PC is up to 99.53% and 98.21%, respectively, and the recovery of PS and PC is larger than 92.06%. A reliable, cheap and effective process is proposed for separation of PC and PS waste plastics.
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Chong-Qing
authors.initials: CQ
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China. Electronic address: huiwang1968@163.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Gu
authors.affiliation: School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Qing-Quan
authors.initials: QQ
authors.lastname: Lin
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Zhang
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Luo-Luo
authors.initials: LL
authors.lastname: Huang
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
authors.forename: Jun-Yao
authors.initials: JY
authors.lastname: Zhao
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D011076:Polycarboxylate Cement / Q000032:analysis / Q000737:chemistry*; D011137:Polystyrenes / Q000032:analysis / Q000737:chemistry*; D059027:Recycling / Q000379:methods*; D012037:Refuse Disposal; D062611:Solid Waste / Q000032:analysis; D018505:Waste Management / Q000379:methods*
chemical_list: D011076:Polycarboxylate Cement; D011137:Polystyrenes; D062611:Solid Waste; C005506:polycarbonate; D000641:Ammonia
keywords: Ammonia modification; Contact angle; Flotation; Recycling; Waste plastics