Research On Preparation Of Diatomite-based Sorbents And Performance Of Phosphate Removal From Aqueous Solution

It would cause eutrophication with a series of nausea cycles in the water body when phosphorus-containing wastewater flows into the water body,like long algae,oxygen deficiency,death of aquatic animals and plants,odor of water and so on.It is a difficult and urgent environment problem to remove phosphate,restrict eutrophication,keep balance of water ecological environment.adsorption method is effective method to remove phosphorus at present which is simple,fast,less time to achieve balance and high capacity with a widely PH range,etc.The preparation of excellent adsorbent is the key for adsorption method.Diatomite is a high quality adsorbent carrier with high specific surface area,large pore channels,high acid resistance and alkali resistance.Diatomite/lanthanum(D-La)and diatomite / zinc(D-Zn O)both of sorbents were prepared by using diatomite as carrier for lanthanum and zinc on diatomite in this study.Both of adsorption materials were characterized and analysed,adsorption experiments were carried out to explore the influence factors and adsorption mechanism of adsorption process.The conclusions of this paper are as follows:(1)Preparation of D-La.The D-La adsorbents were prepared under different temperatures(200,300,400,500,600 and 700 ?)in the muffle furnace after ultrasonic mixing and drying of lanthanum nitrate,glycine and diatomite,and they were compared for adsorption performance.We concluded that the adsorbent is best when calcination temperature is 400?,and adsorbents were prepared with different mass ratios D/La(1/0.15,1/0.3,1/0.45,1/0.6)Under this temperature to determine the effect of lanthanum content and the best mass ratio was 1/0.45.The characterzation results suggested that the lanthanum compound is lanthanum carbonate which was uniformly loaded on the surface of diatomite and bond by Si-O-La.(2)Study on the adsorption properties of D-La on phosphorus.four kinds of interfering ions(SO42-,NO3-,Cl-,and HCO3-)have no significant effect on the adsorption of phosphate.D-La has a higher adsorption capacity for phosphorus in a widely p H range.the adsorption amount of D-La to phosphorus is above 50 mg P/g When p H is 2-6;the adsorption kineticcurve was fited to pseudo second-order kinetic model,and adsorption equilibrium was quickly reached.The adsorption is mainly chemisorption.the Langmuir model fits the adsorption isotherm better,and the saturated adsorption capacity is 80.9mg P/g.The regeneration performance of D-La adsorbent is not good.With the increasing of regeneration times,the regeneration efficiency decreased rapidly.(3)The preparation of D-Zn O.The D-Zn O was prepared by droping of sodium hydroxide solution,separating,washing and drying after mixture of zinc nitrate with diatomite.The results of material characterization indicated that zinc nitrate was converted into zinc oxide and loaded on the whole surface of diatomite uniformly without agglomeration,and zinc oxide did not bond with diatomite.(4)Study on the adsorption properties of D-Zn O on phosphorus.As the initial p H of the solution increased,the adsorption of D-Zn O on phosphorus dropped off gradually;the adsorption was rapid and equilibrium was reached after 4 hours adsorption.The adsorption kinetic of D-Zn O accorded with the pesudo second-order model,and Adsorption isothermal conformed to the Langmuir model,with saturated adsorption amount was as high as111.1mg P/g.The regeneration performance of D-Zn O adsorbent is not as good as other adsorbents.