School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
Waste Manag. 2016 May;51:13-18. doi: 10.1016/j.wasman.2016.02.037. Epub 2016 Mar 7.
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.
一种有前景的方法，氨改性，被开发用于聚碳酸酯（PC）和聚苯乙烯（PS）废塑料的浮选分离。氨改性对 PS 的浮选行为影响不大，但对 PC 的浮选行为影响显著。当改性时间为 13 分钟时，漂浮产物中 PC 的回收率从 100%下降到 3.17%，然后在更长的改性时间后上升到 100%。通过接触角、傅里叶变换红外（FT-IR）和 X 射线光电子能谱（XPS）测量研究了氨改性的机理。PC 的接触角表明，漂浮产物中 PC 回收率的下降归因于表面润湿性的增加。FT-IR 和 XPS 谱表明，氨改性导致 PC 表面发生化学反应。研究了氨改性 PC 和 PS 的浮选行为，包括浮选时间、起泡剂浓度和颗粒大小。根据单一塑料的浮选行为进行了 PC 和 PS 废塑料的浮选分离。对不同粒径的 PC 和 PS 混合物进行了有效分离，表明该技术对塑料粒径具有优异的适用性。PS 和 PC 的纯度分别达到 99.53%和 98.21%，PS 和 PC 的回收率均大于 92.06%。提出了一种可靠、廉价、有效的 PC 和 PS 废塑料分离工艺。
