基于电晕修饰促进聚乙烯与聚氯乙烯的浮选分离

Promoting Flotation Separation of Polyethylene and Polyvinyl Chloride based on Corona Modification

根据泡沫浮选结合前置表面改性可实现不同废塑料的高效分离的特点,针对传统前置改性方式存在吸附脱稳、催化时间长及温度高等限制,提出了一种相对绿色环保、高效的前置电晕放电改性技术,结合泡沫浮选优化分离高密度聚乙烯(PE-HD)及聚氯乙烯(PVC)混合塑料。通过接触角、扫描电子显微镜、傅里叶变换红外光谱仪进行表征分析并相互印证,结合表征结果进一步对电晕放电过程的机理进行探讨。研究结果表明,电晕放电可以增大PE-HD/PVC的可浮性差异,使得自由基在两者分子链中选择性引入。其最优电晕改性工艺参数为电晕功率300 W,接触曝光时间8000 ms。当PVC∶PE-HD进料质量比为3∶7时,PE-HD和PVC的回收率分别为96.36%,93.06%,纯度分别为97.01%,91.63%。

According to the characteristics that foam flotation combined with pre surface modification can achieve efficient separation of different waste plastics,in view of the limitations of traditional pre modification methods,such as adsorption destabilization,long catalytic time and high temperature,a relatively green and efficient pre modified corona discharge technology was proposed.The high density polyethylene(PE-HD)and polyvinyl chloride(PVC)mixed plastics were optimized by combining the foam flotation and the corona modification technology.The contact angle,scanning electron microscope and Fourier transform infrared spectrometer were used to characterize and confirm each other.Combined with the characterization results,the mechanism of corona discharge process was further discussed.The results show that corona discharge can increase the floatability difference of PE-HD/PVC,so that free radicals can be selectively introduced into their molecular chains.The optimal corona modification process parameters are corona power 300 W and contact exposure time 8000 ms.When the feeding mass ratio of PVC∶PE-HD is 3∶7,the recoveries of PE-HD and PVC are 96.36%and 93.06%respectively,the purity are 97.01%and 91.63%respectively.