Separation of hazardous polyvinyl chloride from waste plastics by flotation assisted with surface modification of ammonium persulfate: Process and mechanism
Separation of hazardous polyvinyl chloride from waste plastics by flotation assisted with surface modification of ammonium persulfate: Process and mechanism
复制标题
过硫酸铵表面改性辅助浮选从废塑料中分离有害聚氯乙烯：工艺与机理
DOI：
10.1016/j.jhazmat.2019.121918
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发表时间：
2020
影响因子：
13.6
通讯作者：
Wang Chongqing
中科院分区：
文献类型：
--
作者：
Zhang Yingshuang;Jiang Hongru;Wang Hui;Wang Chongqing
塑料分离是从复杂的塑料混合物中分离出单一组分，提高塑料回收利用率的有效方法。基于高级氧化工艺，采用过硫酸铵（NH 4）2S 2 O 8辅助表面改性选择性润湿塑料表面，实现了有害聚氯乙烯（PVC）与丙烯腈-丁二烯-苯乙烯（ABS）、聚苯乙烯（PS）、聚碳酸酯（PC）的四次浮选分离。通过接触角、X射线光电子能谱（XPS）、傅立叶变换红外光谱（FT-IR）和扫描电镜（SEM）等测试手段对改性机理进行了研究。PS、PC和ABS的可浮性由于在塑料表面引入羰基（O= C单键O）、羟基（− OH）和酰胺（O= C-NH 2）而降低，这是硫酸根（SO 4-）氧化以及腈基（C三键N）和丁二烯（C双键C）水解的结果。建立了ABS、PS和PC的反应方程，对表面改性机理进行了补充。PVC浮选分离的最佳条件为（NH 4）2S 2 O 8浓度0.2M、温度70° C、预处理时间30 min、pH 10、浮选时间4 min、松油醇用量20 mg/L、粒径3-4 mm。PVC的回收率和纯度分别达到100%和99.7±0.2%，有利于分离后废塑料的再利用。
Plastic separation becomes an effective method to improve the plastic recycling by concentrating a single component from complex plastic mixtures. Based on advanced oxidation process, surface modification assisted by ammonium persulfate ((NH 4) 2 S 2 O 8) was applied to selectively wet plastic surface, achieving the separation of hazardous polyvinyl chloride (PVC) from acrylonitrile butadiene styrene (ABS), polystyrene (PS), and polycarbonate (PC) in forth flotation. The mechanisms were investigated through contact angle, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), as well as scanning electron microscope (SEM). The floatability of PS, PC, and ABS reduces owing to the introduction of carbonyl (O= C single bondO), hydroxyl (− OH), and amide (O= C–NH 2) on plastic surfaces, which is the result of the oxidation by sulfate radical (S O 4∙-) and the hydrolysis of nitrile group (Ctriple bondN) and butadiene (Cdouble bondC). Then, available reaction equations of ABS, PS, and PC were established to supplement the mechanisms of surface modification. The optimal conditions for flotation separation of PVC are (NH 4) 2 S 2 O 8 concentration 0.2 M, temperature 70° C, pretreatment time 30 min, pH 10, flotation time 4 min, terpineol dosage 20 mg/L, and particle size 3–4 mm. The recovery and purity of PVC reach 100% and 99.7±0.2% respectively, favoring the reuse of separated waste plastic.