Investigation on the co-pyrolysis of bamboo sawdust and low-density polyethylene via online photoionization mass spectrometry and machine learning methods

The high oxygen content of biomass is the limitation for its widespread utilization, and the co-pyrolysis of biomass feedstock with plastics has gotten much attention by researchers in recent years. Herein, bamboo sawdust (BS) and low-density polyethylene (LDPE) are selected to investigate the synergistic effects during co -pyrolysis via photoionization mass spectrometry (PI-MS). Based on the statistical analysis, for enhancing the synergetic effects of co-pyrolysis, the suitable LDPE/BS ratio should be at least 1:1. During the co-pyrolysis, LDPE promotes the conversion of BS-derivatives to low molecular weight oxygenated compounds (e.g., furfurals and simple phenolic compounds), while the decomposition of LDPE could also be enhanced by BS pyrolysis products. The synergetic effect of LDPE and lignin is more notable than that of LDPE and cellulose or hemicellulose. Meanwhile, for overcoming the drawback of PI-MS analysis in obtaining quantitative information, the RF (Random Forest) and LSTM (Long Short-Term Memory) algorithms are successfully used to predict the TG curves of BS/LDPE mixtures via the temperature-evolved profiles of representative products. This work could provide a reliable tool for monitoring co-pyrolysis process at different LDPE/BS ratios and combine with machine learning, which is helpful to reduce the cost of industrial application by shortening the experimental cycle.

Automated summary

Researchers have paid much attention to the co-pyrolysis of biomass feedstock with plastics in order to overcome the limitation of high oxygen content in biomass for its widespread utilization. They investigated the synergistic effects during co-pyrolysis of bamboo sawdust (BS) and low-density polyethylene (LDPE) using photoionization mass spectrometry (PI-MS). Statistical analysis revealed that a suitable LDPE/BS ratio of at least 1:1 enhances the synergetic effects of co-pyrolysis. LDPE promotes the conversion of BS-derivatives to low molecular weight oxygenated compounds, while the decomposition of LDPE is enhanced by BS pyrolysis products. The synergetic effect between LDPE and lignin is more significant than that between LDPE and cellulose or hemicellulose. Moreover, the use of RF and LSTM algorithms successfully predicts the TG curves of BS/LDPE mixtures, overcoming the limitation of quantitative information from PI-MS analysis.