Synergistic effects of co-pyrolysis of macroalgae and polyvinyl chloride on bio-oil/bio-char properties and transferring regularity of chlorine

The present study aimed to investigate synergistic effects on properties of bio-oil/bio-char and transferring regularity of chlorine during co-pyrolysis of macroalgae Enteromorpha clathrata (EN) mixed with different mass percentage of polyvinyl chloride (PVC) (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in a fixed bed reactor at 550 degrees C. The results showed that the experimental values of bio-oils were 0.43-2.57 wt% lower than the calculated values, while the bio-chars were 1.28-4.93 wt% higher. From the GC-MS analysis of bio-oils, the relative contents of oxygenated and nitrogenated compounds were reduced significantly while those of phenols, aromatic and aliphatic compounds were increased dramatically during co-pyrolysis of EN and PVC. Interaction during co-pyrolysis of EN and PVC decreased the H/C atomic ratio of bio-chars, enhancing the aromatic degree. In addition, the chlorine distribution in bio-chars increased whereas decreased in bio-oils and non-condensable gas with the addition content of PVC increasing. The results showed that a majority of chlorine from EN-PVC blends was trapped in bio-char products, which was favorable to the utilization of bio-oils and friendly to pyrolysis equipment and environment.