The relevant effect of marine salt and epiphytes on Posidonia oceanica waste pyrolysis: Removal of SO2/HCl emissions and promotion of O/HCOOH formation.

[Display omitted] • Washed and unwashed P. oceanica wastes were pyrolyzed using TG-MS. • Its natural detrital inorganic matter affects its pyrolysis substantially. • O release and HCOOH formation were probably promoted by AAEMs and Fe 2 O 3. • SO 2 /HCl release decreases, due to carbonates and alkali metal chloride presence. • Depending on the purpose, the interest of P. oceanica washing should be studied. Significant quantities of Posidonia oceanica deposit on some beaches and coastlines every year, which generates high costs associated with the disposal of this waste. Pyrolysis may be an adequate way for its valorization. However, it would imply to know how the process takes place and if the removal of its natural detrital inorganic matter (epiphytes, marine salt and sand) is necessary, which are the objectives of this research. Pyrolysis by thermogravimetry-mass spectrometry was carried out on both the washed and unwashed samples. During this waste pyrolysis, the following occurs: (i) the high alkali metal chloride content promotes fragmentation reactions of carbohydrates and O formation, which increases HCOOH intensities at temperatures between 250 and 360 °C; (ii) from 500 °C to 650 °C, Fe 2 O 3 and decomposition of carbonates seem to be involved in reactions that produce O release and steam and CO 2 reforming of hydrocarbons and oxygenated organic compounds with H 2 generation; (iii) from 650 °C to 750 °C, Fe 2 O 3 , high alkali metal content and carbonate decomposition generate char gasification, an increase in O release, SO 2 capture and HCOOH formation. In general, the abundance of inorganic matter (chlorides, carbonates, etc.) minimizes the release of various compounds during pyrolysis, including SO 2 and HCl, while increasing HCOOH production. Thus, this high content of inorganic matter may represent an advantage for its pyrolysis, producing value-added chemical products with a reduced environmental impact. Therefore, this study may be the starting point for defining the optimal pyrolysis conditions for this waste valorisation. [ABSTRACT FROM AUTHOR]