Study On The Preparation And Characteristics Of Ammonium Ion-exchange Material

Too much nitrogen compounds leading algal blooms and sharp drop in dissolved oxygen, water quality is severely degraded. With the development of sewage treatment technology, there have been a variety of ways to remove ammonia, but there are pros and cons or limitations of each method. Ion-exchange is a new method prevalently used to remove ammonia in recent years, which attracts more and more attention because of its unique advantages. It is not only a hotspot but the focus in recent scientific researches about how to find efficient and low-cost materials of the medium of exchange.The raw material used in this study is kaolin from Longyan in Fujian, and we make high-performance ion-exchange materials used in removing ammonia in sewage through its modification. We put forward a new modification process in order to solve the problems existing in previous experiments. The calcination temperature raised to 750℃, we use immersion alkali lye modified to reduce the amount of alkali and use orthogonal experimental method to determine the best conditions for the modification as follows: lye concentration is 5 mol/L, modified temperature is 100℃, and modified time is 4 h. Compared with the previous experiments, the capacity of ammonium ion exchange is greatly increased. This paper also does characterization tests about surface area, porosity, strength of the modified kaolin. The results showed that after forming and modification process, the surface area and porosity of the particle has been greatly improved. From an environmental scanning electron microscope photograph we can clearly see the hole structure. Universal machine experiment proved that the particles have sufficient strength to meet the demands of following experiments.On the basis of modification and molding experiments, the characteristics of ion-exchange removing ammonia is researched in this paper mainly from two aspects of thermodynamics and dynamics. The thermodynamics results show that the balance is favorable balance and the selectivity of NH₄⁺ is enhanced as the reaction temperature increasing. From the experimental data, we calculate the thermodynamic parameters.â–³G is negative, which means the ion-exchange process is a spontaneous reaction.â–³H is positive; we can say the process is endothermic reaction.â–³S is positive standing for entropy increasing. Dynamic results show that the increase of temperature can effectively reduce the time to reach balance, but the increase of concentration can only enhance its instantaneous exchange capacity but not change the balancing time. The spread of particles controls the whole ion-exchange process. We calculate dynamics parameters from the experimental data: the apparent activation energy of the reaction is 27.12KJ / mol and the reaction order is 1.2342.