Phosphate Adsorption Kinetics of Hangjin 2~# Clay Complex Adsorbent

Adsorption equilibrium and kinetic behavior of phosphate onto the Hangjin 2# Clay-improved polyaluminium sulphate complex adsorbent was investigated through a series of batch adsorption experiments.The adsorption kinetic models were explored and adsorption mechanism was discussed from kinetic point of view.Results show that the removal rate of phosphate may reach as high as 96%,when the adsorbent is used at a rate of 5 g·L-1 and the adsorption lasted for 60 min in wastewater with pH at 6.0,temperature at 25 ℃ and the initial mass concentration of phosphorus less than 16.72 mg·L-1.The pseudo-second-order equation is found to be fit to the adsorption kinetics and the adsorption rate controlled by internal diffusion within the first 10 minutes and then jointly by film diffusion and internal diffusion later on,with the former in dominancy.The higher the initial concentration of phosphate,the lower the apparent internal diffusion coefficient and the apparent mass transfer coefficient.The adsorbent can be recycled.When recycled absorbent is used(5 g·L-1) to treat wastewater containing 16.72 mg·L-1 phosphorus,its adsorption capacity decreased somewhat with the number of recycling increased,but its phosphate removal rate still stayed above 89%.