Preparation Of Calcium Alginate Aerogel And Its Adsorption On Heavy Metal Ions

With the rapid development of industrial economy,the water environment has suffered a lot of heavy metal ion pollution,heavy metal ion pollution is one of the serious environmental problems facing the world.The methods of treating heavy metal ions in water are mainly divided into chemical,physical and biological methods.The above methods have their own advantages and disadvantages.Adsorption method has many advantages,such as simple operation,short treatment time and heavy metal ion recovery.In this paper,sodium alginate and calcium ions were used to form gel.Through the adsorption experiments,the effects of p H value,temperature and contact time of the calcium alginate aerogel heavy metal ion adsorption capacity,the adsorption isotherm and adsorption kinetics study;using HCl as desorption agent on desorption regeneration ability;through infrared spectroscopy(FTIR),X ray photoelectron spectroscopy(XPS)has been studied the amount of calcium release and adsorption mechanism.The experimental results show that when pH is less than 3,the adsorption capacity decreases obviously and the adsorption reaches equilibrium in 180 min.The adsorption process accords with Langmuir isotherm model.The maximum adsorption capacity of Pb2+ and Cu2+ is 383.1mg/g and 101.9mg/g,respectively.The HCl desorption gas gel can be reused more than 10 times by Ca(OH)2,and the adsorption process is in accordance with the pseudo two order kinetics model.The mechanism of adsorption of heavy metal ions bycalcium alginate aerogel is ion exchange and electrostatic interaction.The calcium alginate aerogel was prepared by chemical crosslinking of ethylenediamine and sodium alginate,and then cross-linking with calcium ions.Through the adsorption experiments,the effects of pH value,temperature and contact time of modified calcium alginate aerogel heavy metal ion adsorption capacity,the adsorption isotherm and adsorption kinetics study;using HCl as desorption agent on desorption regeneration ability;by X ray photoelectron spectroscopy(XPS)measurements were used to study the adsorption mechanism and quantity calcium release.The experimental results show that when pH is less than 3,the adsorption capacity decreases obviously and the adsorption reaches equilibrium in 300 min.The adsorption process accords with Langmuir isotherm model.The maximum adsorption capacity of Pb2+ and Cu2+ is 215.3mg/g and 86.64mg/g,respectively.The gas desorption of HCl can be used directly for more than 5 times,and the adsorption process accords with the pseudo two order kinetics model.The mechanism of adsorption of heavy metal ions by ethylenediamine modified calcium alginate aerogel is ion exchange,electrostatic interaction and coordination.