Comparative Study Of Adsorption Of Phosphate On Several Types Of Mineral

In order to decrease the more and more serious eutrophication of reservoirs, this article studies the adsorption of phosphate in simulated water with concentrations from 5mg/L to 50mg/L by several typical types of mineral-iron hydroxides/oxides (goethite, hematite, synthesis goethite and amorphous ferric hydroxide) and attapulgite (attapulgite, hydrothermal attapulgite and dolomite- attapulgite) from the adsorption thermodynamics and adsorption kinetics.Freundlich adsorption istherm approximatively can be availabed to adsorption of phosphate on goethite and hematite, the linear relationship of Langmuir adsorption isotherm is better with adsorption of phosphate on synthesis goethite and amorphous ferric hydroxide. Theâ–³G of goethite and hematite are -15.08 - -14.94 and -14.55--13.24kJ/mol individually, these indicate adsorptions of phosphate on goethite and hematite are physical adsorption. Theâ–³G of synthesis goethite and amorphous ferric hydroxide are -28.44 --26.08 and -31.73 - -27.68kJ/mol individually, these indicate adsorptions of phosphate on synthesis goethite and amorphous ferric hydroxide are not only involve physical process, but also involve chemical adsorption. The whole process of adsorption of phosphate on goethite and hematite are more in line with the Bangham's kinetics equation. The diffusion of phosphate ions in the pore size is divided into four phases: rapid adsorption stage; gently stage; again, accelerated phase; flat stage again.The adsorptions of phosphate on attapulgite, hydrothermal attapulgite and dolomite-attapulgite are suitable to Freundlich adsorption istherm. Theâ–³G of attapulgite, hydrothermal attapulgite and dolomite-attapulgite are all negative, and the adsorption of phosphate is physical adsorption process. In the range of the researching concentrations, the adsorption kinetics data of phosphate on them can be used to meet the pseudo-second-order model. The content of dolomite has a certain impact on adsorption of phosphate on attapulgite, but little effect.