Study On Phosphate Removal From Aqueous Solutions By MAL Modified Zeolite Composite Adsorbent

In recent years,the water body presents different degree of eutrophication with the fast-paced urbanization in our country.As a major pollution indicator,the total phosphorus has a close relationship with the eutrophication phenomenon.It is significant to improve the eutrophication phenomenon by managing phosphorus containing water especially low phosphorus wastewater effectively.A composite adsorbent was synthetized by fixing Mg-Al-La tri-metal on artificial zeolite(MALZ)with a certain percentage,which was applied to phosphorus removal.The static experiment of MALZ has been carried out,and the optimized adsorption conditions were obtained by response surface methodology(RSM).Besides,the dynamic experiment and granular research was also studied.Several important parameters,such as adsorbent dosage,initial phosphate concentration,initial pH and coexisting ions were investigated in the static experiment.The results showed that the equilibrium phosphorus concentration is below the limit of detection(0.01mg/L)under the condition that the initial phosphate concentration and adsorbent dosage was 10.0mg/L and 1.25g/L,respectively.The results are comparable with the raw MAL.Adsorption kinetics and isothermal adsorption studies showed that the pseudo second-order model and the Freundlich isotherm fitted the experimental data quite well.By using response surface methodology(RSM),the optimized adsorption conditions were obtained as follows: the initial phosphorus concentration was 10.0 mg/L,the solid-liquid ratio was 0.200 g/L,pH value was 5.79 and the temperature was 35?.The equilibrium adsorption capacity was verified to be 15.80mg/g under the same conditions.And there was no obvious metal dissolution when the initial pH range from 5.0 to 10.0 in the stability experiment,which shows that the MALZ composite adsorbent has good stability.Furthermore,the effects of bed quality,flow rate and temperature on the phosphorus removal were studied in the column adsorption experiment.The dynamic adsorption process was simulated by several mathematic models,such as Bohart–Adams model,Wolborska model,Thomas model and Yoon-Nelson model,the results turned out that Thomas model and Yoon-Nelson model fit well compared with the other two.In the study of the granulation of MALZ,it was found that under certain conditions,the phosphorus removal rate gradually increased with the increase of granulated adsorbent dosage.