Review: dissolved organic carbon content of biochar varying with the type of feedstock and the pyrolysis temperature

The present review aims at investigating the influence of the type of feedstock and the production temperature on the dissolved organic carbon (DOC) content of biochar (BC) from slow pyrolysis. To collect data from the literature, peer reviewed articles in English published in 2007–2016 were considered. The different types of BC were classified depending on the fractions of cellulose and lignin and the type of feedstock. A linear regression (R-squared = 0.5) of the mean values of DOC content (g/kg) of BC was calculated in the range of 350–800 °C with slope (–0.005) and intercept (4.1) significant at p <0.05. Irrespective of the type of feedstock, slow pyrolysis with temperatures above 500 °C would be a proper choice for limiting the mean DOC content of BC to values in the range of 0.28–1.01 g/kg.