Physicochemical Characterization and Stability of Biochar Obtained from 5 Species of Forest Biomass in Peru

Abstract

The maintenance of the extensive parks at National Agrarian La Molina University (UNALM) generates a large amount of forest biomass, with high treatment costs. For this reason, the pyrolysis of the forest biomass is an alternative for valorization, allowing proper management producing biochar. The aim of the research was to evaluate the stability of biochar at 300°C and 500°C from forest biomass of five predominant species at UNALM, Grevillea robusta, Schinus molle, Casuarina cunninghamiana, Ficus benjamina and Eucalyptus spp. To determine the stability of biochar produced, two methodologies were used (IBI and an adaptation of the López et al.(2010) method), for which organic, labile, oxidizable, recalcitrant carbon on biochar were determined. The results showed a decrease in biochar yield of 6.50% with an increasing pyrolysis temperature. Regarding physicochemical characteristics, the biochar produced was alkaline (pH above 8); besides, the pH and electrical conductivity increased with temperature, by 0.64 and 0.38 ds/m, respectively. However, in the case of nitrogen and ashes, the opposite occurred. It was concluded that all the biochar produced complied with the stability limits according to the applied methodologies, and BSM500 had the highest value of stability considering the applied methodologies. This may indicate that it could have the greatest sequestration of C once applied to the soil and also the reduction of emissions; for that reason, it would be important to carry out future research to estimate the potential for C sequestration in the long term.

Influence of Pyrolysis Temperature and Time on Biochar Properties and Its Potential for Climate Change Mitigation

“…The DBC feedstock contained a low ash composition (0.77%) compared with bamboo, which contained differences of 2.57% [46] and 8.69% in Ampel bamboo [72]. The difference in such chemical composition, even in bamboo feedstock, is caused by its structure, age, species, and part of the plant, affecting the composition of lignin, cellulose, hemicellulose, and other extractions [31,36,53].…”

“…The results showed that the DBC had a high VM content (85.16%), a low MC (3.83%), and a low ash content (0.77%). All wood biomass typically has an acidic pH because all wood species are naturally acidic, caused by free acids and acidic groups, especially acetic acid and acetyl groups [31,36,55]. Therefore, the DBC feedstock was strongly acidic, with a pH of 5.07.…”

“…It has been widely observed that biochar can be produced from many types of lignocellulosic biomasses, such as rice husk [27], wheat straw [28], shell and peel [29], herbaceous [30], tree branches and bark [31], paper sludge [32], and manure [33,34]. Recently, researchers have given considerable attention to wood-based feedstocks due to their abundant availability and favorable characteristics [25,35,36], especially wood wastes, which generate and drive a circular economy. Single-use or disposable bamboo chopsticks (DBCs) constitute a large proportion of urban waste worldwide because they are used for food consumption in Asian cultures.…”