Biochar Production from Cardboard Feedstock

Biochar can be used to sequester carbon, as a low-carbon fuel, or for applications such as regenerable agriculture. Biochar research commonly focuses on agricultural and forestry waste products, municipal waste, and food waste, but research for cardboard as a feedstock is limited. Although cardboard can be recycled, the process is limited by diminishing material quality of 10% while other materials, such as paper or aluminum, have negligible material loss. Our research investigates a new feedstock, corrugated cardboard, as a possible biochar feedstock. Biochar from corrugated cardboard was produced in a pyrolysis furnace reactor as well as in a Thermogravimetric Analyzer (TGA). Our analysis of mass as a function of temperature determined that the pyrolysis process for our feedstock sample begins at 350°C. Pyrolysis was performed in an electronic furnace at temperatures between 350°C and 500C°C leading to char yields between 26% and 19%. At 500°C, char yield from the pyrolysis reactor was 19.6%, similar to char yields of 21.6% from the TGA. Of nine previously studied bio-waste feedstocks for char production, (walnut shells, pistachio shells, coconut shells, corncob, pumpkin seeds, sunflower seeds, sawdust, and coffee grounds), the cardboard yields were among the lowest when measured at a pyrolysis temperature of 500°C. The ash, or inorganic content, of the cardboard char was found to be 11.7% of the biochar, higher than that of previously studied feedstocks like nutshells (3.8-6.0 wt% ash in biochar) and lower than feedstocks like corncob and sawdust (23.3-26.5 wt% ash in biochar). This research shows that cardboard can be a potential feedstock for biochar and pyrolysis can be used as a waste management tool to produce value from previously recycled cardboard.