Study On Pyrolysis Of Photocured Waste From Photopolymerized 3D Printing

Photopolymerization-based 3D printing is the earliest developed and the largest consumption of 3D printing technology.It has garnered significant attention in both industrial applications and academic research worldwide due to its mature technology and highest printing precision.Due to the limitations of photopolymerization-based 3D printing process and raw materials,photocured waste(PCW)from photopolymerized 3D printing is inevitably generated.As a new type of organic solid waste,PCW is being generated at an immeasurable rate,with unpredictable environmental consequences.Based on the special molding method,there are residues of new aromatic organic pollutants —— photo-initiator in the chemical components of PCW,and the phenyl fragments formed in the process of printing,which has potential harm to organisms and the environment.There is currently a lack of targeted recovery and disposal methods,and environmental hazards exist without knowing their characteristics.Currently,pyrolysis technology has been proved to be a relatively suitable and promising disposal method for thermosetting plastics,which can reduce the generation of harmful pollutants,reduce the carbon footprint,and produce high-value chemicals such as pyrolysis oil and pyrolysis gas.However,the structure,basic characteristics,and thermochemical properties of PCW are not known both domestically and internationally,and the pyrolysis characteristics and product distribution are yet to be mastered.For this new type of organic solid waste,to explore the above characteristics is the key step of clean disposal and utilization.According to the above research background,firstly,based on available research results,the latest research progress of sources,disposal technologies,and environmental impact of PCW were summarized and analyzed.The ultimate components and chemical structure of PCW were obtained through ultimate analysis,proximate analysis,and Fourier infrared spectroscopy(FTIR)analysis.The pyrolysis characteristic curves and parameters were obtained through thermogravimetric(TG)analysis and pyrolysis kinetics analysis.Volatile products were identified through Py-GC-MS.Slow pyrolysis and fast pyrolysis were carried out in a tubular furnace to obtain the distribution of pyrolysis products and component of pyrolysis oil.The interaction between different influencing factors were determined through the response surface method.In addition,a series of experiments of UV-oxidation coupling catalytic pyrolysis were conducted.The main research results of this study are as follow:(1)The result showed that the PCW was a covalent crosslinked thermosetting plastic that was difficult to recycle or biodegrade.Photo-initiator residues and phenyl fragments had potential harm to organisms and the environment.The environmental risks may be caused without knowing its characteristics.(2)According to the results of ultimate analysis and proximate analysis,PCW was found to be suitable for disposal via pyrolysis.Compared with traditional plastics,PCW had higher oxygen content.FTIR analysis identified the presence of functional groups of photo-initiator in the chemical structure of PCW.(3)The results of TG and Py-GC-MS showed that TG curves of PCW had three weight loss peaks,with main volatile products being esters and aromatic compounds.In addition,there were photo-initiator in the pyrolysis process.(4)Slow pyrolysis showed the highest yield and lowest oxygen ultimate content of pyrolysis oil at 500℃,15 ℃/min,and 30 min.Fast pyrolysis showed the highest yield of pyrolysis oil at 600℃.Due to the existence of esters and other oxygen-containing compounds in the products,the calorific value of pyrolysis oil was low,so the quality of pyrolysis oil needed to be improved.In addition,the release of photo-initiator was found in both slow pyrolysis and fast pyrolysis processes.(5)The results showed that UV-oxidation coupling catalytic pyrolysis could significantly reduce the content of photo-initiator,improve the yield of aromatics hydrocarbons in pyrolysis oil,and the two could promote each other,which can effectively realize the clean disposal and utilization of PCW.