Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate

Molybdenum (Mo) adsorption by acidic yellow-brown soil was investigated as a function of a pH (1-13) and the equilibrium of P solution (0, 3.1, and 31 mg L-1) concentration. Mo adsorption by acidic yellow-brown soil increased within the pH range from 1 to 4. Above pH 4, Mo adsorption decreases with an increase in pH. The maximum adsorption was found between pH 2 and 4. Competitive adsorption experiments showed that the equilibrium sorption data fitted into Langmuir and Freundlich isotherms. The sorption data of Mo on the acidic yellow-brown soil fitted well with the Langmuir isotherm model due to the higher R-2 value. A reduction in Mo adsorption by the acidic yellow-brown soil was noticed at higher addition levels of P (3.1 and 31 mg L-1). Therefore, P increasing the bioavail-ability of Mo and enhancing Mo uptake by plants might be related to the inhibition of Mo absorption by the acidic yellow-brown soil.