Adsorption kinetics of phosphate onto sediments from the upper reaches of the Yellow River

The adsorption kinetics and its influencing factors,and adsorption mechanism of phosphate(P) onto 10 different sediments from the Upper reaches of the Yellow River were investigated.The results showed that the adsorption abilities of different sediments to P were different,but the change of P adsorption amount with time had the same trend.Adsorption rates were all faster within 0~8 h and then gradually getting slow within 8~48 h,and the adsorption tended to the dynamic equilibrium at 48 h.P adsorption amounts on different sediments increased with the increase of initial P concentration and decreased with the increase of sediment content,and P adsorption amounts were affected by pH value of waters and were bigger in the pH ranges of 6.0~9.0.At different initial P concentrations,P adsorption kinetics onto different sediments all followed second-order adsorption kinetic model and Weber-Morris diffusion equation which second-order adsorption rate constants and diffusion rate constants obtained by were in ranges of 10.85~229.29 g·mg-1·h-1 and 0.7×10-3 ~5.2×10-3 mg?g-1?h-1/2),respectively.The adsorption equilibrium process of sediments to phosphorus was controlled by the intra-particle diffusion.