Effect of ammonoxidation on lignite properties

Abstract

Oxidised lignite is a potential alternative source of N fertilizers. Ammonoxidation is the reaction of a given substrate with oxygen in aqueous ammonia. Lignite ammonoxidation is used for converting low-rank lignite into slowly nitrogen-releasing artificial humic matter. A lignite sample is compared before and after ammonoxidation in terms of geochemical and petrological properties, as well as the acid-base and physical hydrophobic sorptive behavior. The most obvious change caused by ammonoxidation is the decrease of attrinite, texto-ulminite and textinite in favor mainly of densinite and gelohuminite. In general, the ammonoxidative reactions promote the destruction of the structured humic macerals (texto-ulminite, textinite), and the formation of gels, which resulted in the cementation of the freely fine humic particles (attrinite). The pzc values are 3.4 and 4.3 for oxidised and nonoxidised lignite, respectively. After ammonoxidation the contents of carboxylic and free phenolic groups are found to be lower. The oxidised lignite shows a statistically lower sorptive capacity and affinity than the original sample due to a possible decrease in the hydrophobicity of the lignite.

Lignite‐derived humic substances modulate pepper and soil‐biota growth under water deficit stress

“…Few HS were derived from low bioactive material, such as brown coal (lignite), and applied as solid products in the field ( Canellas et al, ). By using the ammonoxidation procedure (reaction with oxygen in aqueous ammonia), lignite‐derived HS can result in a product with lower hydrophobicity and higher bioactivity ( Karapanagioti et al, ). However, this product has never been evaluated regarding to the effects on plant growth and soil environmental changes.…”

Genesis, evolution and economic significance of the northen and the eastern parts of Karapinar-Ayranci coal deposit

“…Agricultural activities also need soil amendment and fertilizers. Low-rank coals can be applied after treatment as fertilizer due to their humic substance and nutrient elements contents (Yıldırım and Özbayoğlu, 1997;Giannouli et al, 2009;Turgay et al, 2009;Karapanagioti et al, 2010 6.15). These concentrations are higher than toxicity limits for soil and plants (Kabata-Pendias and Pendias, 1989;Goodarzi and Swaine, 1994b;Giannouli et al, 2009).…”