Law And Mechanism Of The Advanced Removal Ammonia And Nitrogen In Wastewater By Attapulgite

Attapulgite is a kind of clay mineral widely distributed in China.It has been used in many fields due to its many excellent properties and low price.Water pollution has become an important problem,especially the fresh water has been seriously threatened,ammonia and nitrogen as one of the water pollution substances,the quality of water decreased,not only harm the environment,but also further threatened the normal activities and survival of organisms.Traditional ammonia and nitrogen removal method for ammonia and nitrogen removal is not ideal,and the investment is high,long processing time.Attapulgite is a kind of mineral material with good adsorption performance,and in addition,it is rich reserves in our country.Using attapulgite to treat ammonia nitrogen is a good subject that can provide research,and it is a very advanced method.In this paper,the selection of modification conditions and the adsorption mechanism were discussed by studying the change of ammonia nitrogen removal ability of attapulgite and its modification before and after.The main research contents are as follows: the changes and comparison of physical and chemical properties of attapulgite before and after modification which analyzed by specific surface area test,XRD,FTIR,SEM and EDS instruments.Different modification methods and various modification conditions(single modification and composite modification)were selected to carry out ammonia nitrogen adsorption experiments,and the best modification method was selected.The adsorption isotherm equation and adsorption kinetics equation were fitted,therefore the mechanism of attapulgite for ammonia and nitrogen removal in simulated water samples was discussed.The main research results are as follows:For different modification treatment,the best choice is: thermal modified attapulgite is 500℃,the removal rate is 66%;Salt-modified attapulgite was 1.5mol/L Na Cl solution with a removal rate of 70.864%.Acid modified attapulgite was 1mol/L sulfuric acid solution with removal rate of 63.567%.Alkali modified attapulgite was Na OH solution of 1mol/L,which was the best in single modification with the removal rate of 79.783%.The treatment method of alkali-thermal composite modified attapulgite was Na Cl solution at 1.5mol/L concentration after heat treatment at 500℃,and the removal rate was 81.135%.The treatment method of salt-thermal composite modified attapulgite was Na OH solution with concentration of 1mol/L after heat treatment at 500℃,which showed that the composite modified attapulgite had the best ammonia nitrogen removal effect,with the removal rate of 83.567%.For attapulgite and attapulgite heated to 500℃,the adsorption kinetic equations were more closely fitted to the pseudo-first-order kinetic equations,mainly ion adsorption.In the fitting of adsorption isotherm,both of them more closely fit the adsorption isotherm equation of Langmuir and are more inclined to monolayer localization adsorption.The above two fitting equations are mainly used to explain chemical adsorption,so the adsorption method of attapulgite is mainly chemical adsorption.The experimental conclusions involved in this paper can provide a theoretical basis and basis for the modification of attapulgite and the removal of ammonia and nitrogen by clay minerals in the future.