Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar

Dissolved black carbon (DBC) is becoming increasingly concerned by researchers due to its unique environmental behavior. However, understanding of the influencemechanism of biopolymer compositions of cellulose (CEL), hemicellulose (HEM) and lignin (LIG) on the formation and physiochemical characteristics of DBC from lignocellulose-based biochar is limited. This study therefore examined the formation of DBCs derived from the biopolymer compositions, corn straw (CS), corncob (CC), bamboo sawdust (BS) and pinewood sawdust (PS) under the heat treatment temperatures ( HTTs) of 300-500 degrees C. Zeta potential and hydrodynamic diameters (Dh) of DBCs produced under 300 degrees C were further investigated. DBC formation may be closely associated with the HTT-dependent heterogeneities of biopolymer compositions, in which significant effects of CEL and HEM charring on physiochemical properties of DBCs were identified under the HTT of 300 and 400 degrees C, while the formation of DBCs was closely related to LIG and its proportions in biomass under high HTT (>500 degrees C). On the rise of the HTT, the carbonaceous structures of biopolymer compositionswere reorganized and converted to graphitic structures in biochar accompanied by the large decomposition or carbonization of CEL and HEM, leading to the reduced carbon content, surface functional groups, aromaticity and molecular weight of DBCs, as well as the decrease of protein-like and relative increase of fulvic-like fluorescent substances in most DBCs. LIG in biomass may facilitate the migration of DBCs due to abundant surface negative charges and the formation of low Dh. This study offered newinsights into our understanding of influencingmechanisms of biopolymer compositions on the characteristic of DBCs under different HTTs. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the influence of different biopolymer compositions on the characteristics of DBCs and found that as the heat treatment temperature increased, the carbonaceous structures of biopolymer compositions were reorganized and converted to graphitic structures. Additionally, lignin may facilitate the migration of DBCs.