Preparation Of Microporous Calcium Silicate And Its Studies On Removal Of Phosphor In Waste Water

MCS of high quality（microporous calcium silicate）had been prepared by dynamichydrothermal synthesis using SiO2and CaO as the starting powder materials under theconditions of temperature and pressure. The microstructure and shape of MCS were determinedby modern analytical methods of SEM and XRD. Meanwhile, the MCS was applied to dealwith simulated phosphorus-containing wastewater and sludge thickening tank supernatant. Theeffects of MCS dose, starting pH, temperature and contact time had been studied. Moreover, theadsorption isotherm equations and kinetic adsorption models were employed to characterize theexperimental data. The phosphorus removal mechanism of MCS was also explored byanalysing the matching parameters in this paper. The preparation and application results were asfollows: During the single factor experiment, it was showed that the optimum conditions weremole ratio of3:4, water-to-solid quality ratio of1:15, crystallization time of7h, crystallizationtemperature of463K and agitation speed of greater than300. In addition, it was proved thatMCS has the ability of releasing Ca2+and OH-in aqueous solution through the experiment.The result of comparative experiments showed that it is notable to remove the phosphorususing microporous calcium silicate without adscititious Ca2+. The removal ratio of99.89%was achieved for phosphorus at the following optimal conditions: time2.5h, dosage1.0mg/L,temperature25℃,rotate speed150r/min, pH7~9, which the influent density was49.98mg/L.Meanwhile, under the same conditions the best removal ratio of99.27%was obtained forsludge thickening tank supernatant and the concentration of phosphorus in effluent was lowerthan0.05mg/L.Furthermore, the result of orthogonal experiment showed that microporous calcium silicatecould be applied widely because of dependent of temperature. In the same case, the ability ofreleasing Ca2+and OH-of microporous calcium silicate was better than that of CaSiO3andCaCO3. Moreover the concentration of phosphorus in effluent kept lower than0.05mg/L whichis far below the1stlevel of national discharge standard.The adsorption data of microporous calcium silicate towards phosphorus from wastewaterwas very suitable to Langmuir equation. Besides, the adsorption heat calculated by Van derWaal equation was above zero indicating the endothermic mechanism. Pseudo second-orderequation can describe the kinetic adsorption data of porous calcium silicate. Microporous calcium silicate had good application prospect in applying to phosphoruswastewater treatment because of feasible treatment effect and inexpensive raw materials forpreparation.