Probing mechanisms of zeolites removing ammonium

• Main Authors: Yi-Chun Lin, 林怡君
• Other Authors: Huei-Fen Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/13706072765935075808

碩士 === 國立臺灣海洋大學 === 應用地球科學研究所 === 97 === The purpose of this study can be used in aquaculture, when NH3 concentrations in water higher than 0.05 ~ 0.2 mg/l can cause acute death of fish, so to reduce the use of zeolite NH4+ concentration in the water to a safe start of the scope of this study. Second, previous studies of selective adsorption in zeolite, the zeolite only to explore the reaction between the ion balance, is not its role in ion exchange and adsorption of the controlled factors to explore further. In this study, the starting aqueous solution of ammonium concentration of 20 mg/l, 50 mg/l and 100 mg/l, to 500 ml of ammonium ion in aqueous solution with 5 g of zeolite powder in addition to ammonium reaction. The zeolites we using in this experiment include Mordenite, Chabazite, Erionite and Clinoptilolite; the synthetic zeolites are Merlinoite and zeolite P. Using of ICP-AES and spectrophotometer measure degree of Na+, K+, Ca2+ and NH4+ concentration of the end to explain the behavior of mechanisms in addition to ammonium, and by EPMA instrument that the boiling the chemical composition of stone. In addition to the mechanism of zeolite into ammonium ion exchange and physical adsorption, in the 20 mg/l based on ion exchange, with an increase in the concentration of ion exchange to lower the percentage, and the role of physical adsorption is a gradual increase in the percentage, the effect only affect the high and low concentrations of ammonium in addition to the role of zeolite. This experiment in the 28 ~ 32℃ and pH 6 ~ 9 of the conditions, the concentration of all the zeolite can be reduced to 28 mg/l below, applicable to 25 ~ 30℃ (pH 7.0) of 37.670 ~ 26.306 mg/l conditions under. In 20 mg/l initial concentration in the reaction Chabazite, Erionite and zeolite P can be lower than the NH4+ 1.32 mg/l below the pH value can be applied to the environment as much as 8.3; the initial concentration of 50 mg/l, the Chabazite concentration may be reduced to only 4.812 mg/l, up to pH value of 7.8 environmental use, still does not apply to other zeolite pH value of 7.8 or above; 100 mg/l initial concentration of the reaction, all the zeolite can only be applied to pH value of 7.0 the following environment. In addition to removing ammonium in the mechanism of zeolite, ion exchange capacity of zeolite (NH4+ion) and cation zeolite in the total number of positive correlation; and physical adsorption (NH4+ads) and zeolite cation of the total number of negative correlation . Cation means that a few more of the ion-exchange properties of zeolite, the better, but its relatively poor performance of physical adsorption. From the Si/Al ratio found in the proportion of ion exchange with the Si /Al increase and decrease in physical adsorption and the ratio with the Si/Al ratio increased. Both the role of a reverse change, particularly at low concentrations of 20 mg/l most obvious change. 50 mg/l is still done by ion exchange, 100 mg/l of physical adsorption greatly increased. The use of Langmuir Isotherm adsorption isotherm equation to understand the volume of zeolite monolayer adsorption, that the Merlinoite and Mordenite-2 with the greatest saturation of the monolayer adsorption capacity, up to per gram of zeolite adsorbed NH4+ 18.315 mg and 17.212 mg, other zeolite saturated monolayer adsorption capacity of the small area in the K value, Erionite the highest possible value of K for NH4+ has strong absorption force.