Adsorption of Humic Substances on Synthetic Amorphous Aluminosilicates of Varying Si/Al Molar Ratio

Adsorption of purified humic and fulvic acids on different synthetic amorphous aluminosilicates (AAS) was studied as a function of pH and concentration. Adsorption of humic acid and fulvic acid was affected by pH and the adsorption increased with decreasing pH. The amount of HA and FA adsorbed decreased with increasing Si/Al molar ratio except in the sample with Si/Al molar ratio of 0.89 whose adsorption was slightly higher than the sample with Si/Al molar ratio of 0.79. The variation in adsorption among AAS of different Si/Al molar ratios was pronounced at higher pH. Adsorption of humic acid and fulvic acid, in general, showed L type adsorption curve.