Characterization of the coal derived humic acids from Mukah, Sarawak as soil conditioner

Abstract

Na Malásia encontram-se abundantes reservas de carvão em Sarawak e Sabah. A utilização dessas reservas, até agora, ocorre principalmente para produção de energia. O uso não-energético como condicionador de solo ainda é inexplorado. Assim, este estudo foca a caracterização de ácidos húmicos presentes no carvão de Mukah e a avaliação de suas propriedades como condicionador de solo. Os ácidos húmicos presentes em carvão regenerados foram também avaliados. Os resultados revelaram que diferentes extratores influenciam as propriedades dos ácidos húmicos. A extração com KOH 0,5 mol L -1 produziu carvões com baixo teor de cinzas e alto teor de grupos ácidos funcionais, que são importantes como condicionadores de solo. No entanto, o rendimento foi baixo. Amostras de carvão regenerado com ácidos nítricos aumentam o rendimento em 83,45% em média. A acidez dos grupos funcionais nitro-húmicos foi aumentada mantendo-se a quantidade de cinza em nível mínimo.In Malaysia, abundant coal resources were found in Sarawak and Sabah. The utilization of coal resources, to date, is emphasized on the energy productions. The non-energy utilization as soil conditioner is unexplored. Therefore, this study attempted to characterize the coal humic acids extracted from Mukah coal and to evaluate its properties as soil conditioner. The coal humic acids from the regenerated sample were also assessed. The results revealed that different extractants and concentrations influenced the properties of humic acids. The extraction with KOH at 0.5 mol L -1 produced humic acids with low ash content and high acidic functional groups, which are substantial as soil conditioner. However, the yield was low. Regeneration of coal sample with 10% nitric acids improved the yield to an average of 83.45%. The acidic functional groups of nitrohumic acids were improved with the ash content remained at a low level.

Chemistry of metal–humic complexes contained in Megalopolis lignite and potential application in modern organomineral fertilization

“…Lowrank coals are usually rich in humic substances (Fong et al, 2006); the minimum humic substances content in alkali-extracted solutions (at least 30 wt.% in all cases) was the basic criterion for selecting Megalopolis lignite samples (Table 1) to investigate their potential application in modern fertilizing.…”

Reducing Ammonia Loss from Urea by Mixing with Humic and Fulvic Acids Isolated from Coal

“…Measurement was continued until the loss declined to 1% of the N added in the urea [4,18,19] . After the incubation period, soil samples were taken at 0-1.5 and 1.5-3.0 cm depth followed by pH, were extracted from the soil by the method of Keeney and Nelson [20] . Exchangeable Ca 2+ , Mg 2+ and K + were extracted by the double acid method [15] and the extracts were analyzed as described previously.…”

Nitric Acid Oxidation for Improvement of a Chinese Lignite as Soil Conditioner

“…The impacts of these improvements were reflected in greater crop productivity. Coal resources with relatively high HA content and oxygen-containing functional groups are ideal soil conditioners for agricultural production (Fong et al 2006). …”

“…The oxidation products with HNO 3 have been used as a kind of soil conditioner in Japan, demonstrating conclusively that humic substances have significant impact on soil structure and plant growth (Sakai et al 1987). Fong et al (2006) used HNO 3 to oxidize a low-grade coal from Mukah, Sarawak of Malaysia, and found that regeneration of coal sample with 10% HNO 3 improved HA's yield from 20% to 85% of total mass of coal. However, the nutrient-retention capacity of natural and oxidized HAs by HNO 3 has seldom been mentioned in previous studies.…”