Preparation Of Vaterite-type Calcium Carbonate And Its Adsorption Behavior And Mechanism Of Phosphorus And Lead In Water

As a nutrient element,excessive discharge of phosphorus into the water environment will cause eutrophication of lakes and red tides in oceans,thus endangering the water environment such as lakes and oceans.In addition,the problem of heavy metal pollution of water bodies has also received more and more attention.For low concentrations of inorganic pollutants,adsorption is currently one of the most effective methods for removing or stabilizing phosphates and heavy metals.Calcium carbonate,as a cheap and readily available mineral adsorbent,has been widely studied for the removal of phosphate and heavy metals from water.biological calcium carbonate has a unique microstructure and abundant organic functional groups,and its performance is better than that of mineral calcium carbonate.In this study,sophorolipid was used to regulate microbial induced mineralization to generate calcium carbonate,and its morphology and crystal form were further characterized to observe and study its adsorption effect on phosphorus and lead in water,determine the most suitable adsorption conditions,and explore its adsorption.In order to provide a new idea and efficient method for the treatment of phosphorus and lead containing wastewater by calcium carbonate precipitation induced by microorganisms.1.In this study,microbial fermentation biosurfactant was used as a template agent,and the favorable conditions for microbial-induced mineralization to synthesize calcium carbonate were selected through its content control.The biosynthetic calcium carbonate was characterized by scanning electron microscopy(SEM),infrared spectroscopy(FT-IR)and X-ray diffractometer(XRD).The characterization results showed that the vaterite-type bio-calcium carbonate was successfully induced to mineralize by regulating microorganisms with microbial fermentation biosurfactants.2.The adsorption process and adsorption kinetics of phosphate/Pb(Ⅱ)in aqueous solution by vaterite-type bio-calcium carbonate were studied by static single factor experiments,and the adsorption mechanism was discussed.The results show that the surface of vaterite-type bio-calcium carbonate has obvious phosphate accumulation area after adsorption saturation,and the hydroxyl group of metal hydroxide plays an important role in the adsorption of phosphate.When the p H was 7.0 and the dosage was 2.0 g/L and the adsorption time was 240 min,the removal rate of phosphate reached the highest,which was 91.08%;the removal rate of Pb(Ⅱ)reached the highest when the p H was 5.0 and the dosage was 2.5 g/L and the adsorption time was 30 min,which was 90.58%.3.The adsorption kinetics of vaterite-type bio-calcium carbonate to phosphate/Pb(Ⅱ)conformed to the pseudo-second-order kinetic model,respectively;The adsorption isotherm fitting results show that the adsorption of phosphate/Pb(Ⅱ)by vaterite-type bio-calcium carbonate is more in line with the Langmuir equation,respectively,indicating that the adsorption of phosphate/Pb(Ⅱ)by vaterite-type bio-calcium carbonate is a monolayer adsorption process;Thermodynamic analysis showed that the adsorption of phosphate/Pb(Ⅱ)by vaterite-type bio-calcium carbonate was a spontaneous endothermic process,respectively.Therefore,this study expanded the range of phosphate/Pb(Ⅱ)adsorbent materials and provided a theoretical support for the removal of phosphate/Pb(Ⅱ)in aqueous solution.