Montmorillonite: Effect of p H on Its Adsorption of a Soil Humic Compound

The d 001 spacing of sodium montmorillonite increased from 9.87 to 17.50 angstroms after interaction of the compound with fulvic acid at p H 2.5. The magnitude of the spacing decreased with increase in p H between 2.5 and 6.0. At p H 2.5 40 milligrams of Namontmorillonite adsorbed 31 mg of fulvic acid; at p H 6.0, only 15.8 mg.