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Isoelectronic points (PI), pH values in water, quantity of carboxylic groups, phenolics, and total acidity values of the functionalized charcoals (CHox) obtained according to nitric acid concentration and reaction time of humic acid obtained from charcoal (AH CH ) and eucalyptus charcoal (CH)

Isoelectronic points (PI), pH values in water, quantity of carboxylic groups, phenolics, and total acidity values of the functionalized charcoals (CHox) obtained according to nitric acid concentration and reaction time of humic acid obtained from charcoal (AH CH ) and eucalyptus charcoal (CH)

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Functionalized charcoal (CHox) incorporated into urea is known for its ability to reduce NH3 volatilization and increase agronomic efficiency. However, it is important to optimize the functionalization process and to elucidate its relationship with the physicochemical properties of CHox for N supply. Thus, charcoal obtained from eucalyptus wood was...

Contexts in source publication

Context 1
... AH CH showed a higher O content than CHox, while the contents of C and N were higher for CHox. The pH of CH in water was 5.86, while that of AH CH was 3.56 and that of CHox ranged from 2.73 to 3.25 (Table 2). The isoelectric points indicate that the positive and negative charges in the compounds are balanced at a pH between 1.57 and 2.08, while for charcoal, the PI was 6.06, being higher than its pH in water ( Table 2). ...
Context 2
... pH of CH in water was 5.86, while that of AH CH was 3.56 and that of CHox ranged from 2.73 to 3.25 (Table 2). The isoelectric points indicate that the positive and negative charges in the compounds are balanced at a pH between 1.57 and 2.08, while for charcoal, the PI was 6.06, being higher than its pH in water ( Table 2). ...
Context 3
... pH of CHox was influenced only by the concentration of HNO 3 , as shown by the adjusted regression equation (Table 3). The isoelectric point, however, was neither significantly influenced by the concentration of HNO 3 nor by the reaction time, corresponding to a mean value of 1.68 (Table 2). ...
Context 4
... total acidity of AH CH was 11 times higher than that of CH, while the total acidity of CHox was between 5.7 and 12.9 times higher than that of CH (Table 2). For CHox, the carboxyl groups presented a total acidity of 59 to 74 %, while for AH CH , total acidity was 76 %, based on the data presented in table 2. The carboxyl group content of the CHox increased linearly with the concentration of HNO 3 , while the contents of phenolic groups increased in a quadratic manner (Table 3). ...

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