SOLUBILIZATION OF PHOSPHORUS BY HUMIC ACIDS FROM LIGNITE

Using humic acids from a Spanish lignite, we determined their solubilization on Spanish phosphorites at pH 5 and 7. Studying the influence of the HA concentration on solubilization shows that increased HA concentration decreases the P solubilization. The kinetic data indicated that the reaction takes place in the first 2 h, and it is a first-order reaction. The electrophoretic study shows that one P fraction moves together with the HA. Another P fraction remains joined to the HA and does not present electrophoretic mobility. The third P fraction migrates independently of the HA.