A Study On The Influence Factors Of Hydration Portland Cement Adsorption Phosphate And Adsorbent Regeneration

Currently, lack of water resources and serious pollution of water, were puzzling thecity’s economy development generally. Especially excessive nutrition salts such asnitrofens, phosphorus, were discharged into water body, causing water eutrophication,this produced more and more serious impact for water pollution and human lives.The hydrated Portland cement （HC） particles from Construction and Demolitionwastes, is containing many abundant metal oxide, such as calcium, aluminium, iron. Itis a potential adsorbent for phosphorus. This paper studied on influence of pH andcoexisting ions, desorption and regeneration, with HC as sorbent. Discussion onwhether or not HC particles is a new type, economic and effective phosphorusadsorbent, finally the optimum operating condition and regeneration method weredetermined.The results of this study are as follows:1There is a adsorption processes of ammonia nitrogen on HC, The adsorptionfunction of HC toward NH4+is slight. Because of the alkalinity release fom HC, most ofthe ammonia nitrogen were removal by blow-off.2while adsorption of phosphorus on HC particles in water, when pH-value waslower, HC particles’ adsorb capacity is better, HC particles is more fit in acidic wastewater.3Coexistent ions in the water have different influence on HC particles adsorption.Among them, Cl^-promoted the adsorption in the lower concentration, but ifconcentration reached at300mg/L, the effect was not obvious. SO₄^2-and NO-3have verysmall interfere on adsorbing of phosphorus on HC particles in solution. When HCO₃^-and PO₄^3-coexisting, had some negative effect, reducing the adsorption quantity on HC particles adsorption.4Then HC particles modified by Al₂（SO₄）₃、FeCl₃、Fe₂（SO₄）₃、MgCl₂, thatthey could improve the adsorption capacity of HC particles differently. The HCparticles modified by alumina and magnesium have higher adsorption capacity. Becauseof high cost of magnesium, modified HC particles with alumina is the best way toimprove adsorption capacity.5, In order to investigate the kinetics of the present adsorption tractions, the kineticdata have been analyzed by the pseudo-first order, pseudo-second order, Elovich kineticmodel equations, intra-particle and film diffusion kinetics, Boyd kinetic plot, The actualrate-controlling step is the intra-particle diffusion for the HC particles modified withalumina salt and ferric salt. The rates of adsorption are controlled by the film （boundrylayer） diffusion for the HC particles modified with magnesium salt.6when using HCl and NaOH to desorption the Saturated HC particles, HCl hasbetter result than NaOH, but if the contact time is too long to desorption rates increase,while the desorption rate at1h was80%, is the best.7. After regeneration for3times, the adsorption capacity of HC particles is still55.6%of the modified HC particles, is13.9mg/g, more than the fresh HC particles, it isgood for reuse and recycle.8The cost of desorption HC particles and the cost of regeneration HC particles, areboth lower than other adsorbent, HC particles is suitable for used as adsorbent.