Kinetic and Equilibrium Studies of Modified Chabazite Particles to Remove Ammonium for Both Freshwater and Seawater Fish

Fresh and seawater fishing are the most popular outdoor recreational activities in Florida and throughout the U.S.  Bait and fresh caught fish need to be stored in tanks for at least 24 hours as the rule of some fish tournaments. Conventionally, tanks are aerated to maintain up to 99.5% saturation of dissolved oxygen to provide enough oxygen to fish to breathe. However, the ammonia excreted by fish is also poisonous to them over time. The aim of this project is to develop a commercial product that is user-friendly, sustainable, affordable, and able to extend the life of bait and fresh caught fish by removing ammonia safely.  Chabazite particles have been selected as an ammonium adsorption medium in this study. The chabazite particles were treated for both freshwater and seawater applications. The chabazite was characterized by powder X-ray diffraction (XRD) to compare the crystalline structure between natural, treated, and ammonium saturated particles. Meanwhile, the chemical composition of chabazite before and after treatments was determined. We found that the ammonium exchange capacities of treated chabazite is 0.77 meq/g and 0.34 meq/g for freshwater and seawater, respectively. Adsorption kinetics and equilibrium data for the removal of ammonia were examined by fitting the data to various models by both linear and non-linear regressions. Kinetic studies indicated that the ammonium adsorption process was met a pseudo-second-order reaction in both freshwater and seawater conditions. In addition, the equilibrium studies found that non-linear regression of Langmuir isotherm has the best fit. At the end, the use of treated chabazite particles were effective to extend the life expectance of stored fish.