In-situ Removal of Ammonia from Water of Live Transports of Fish

—In-situ removal of ammonia from water is an important issue in live transports of fish. It has been believed that the adsorption of ammonia by a suitable absorbent is an economic and possible method. In this study the zeolites (CVB 600 and CVB712) with low molar ratio of SiO 2 /Al 2 O 3 were used as adsorbents to remove ammonia to reduce the concentration of ammonia in water with live fish. The mechanism of the adsorption of ammonia on these zeolites was obtained through the deduction of the Fourier Transform Infrared Spectroscopy (FTIR) spectra. According to the analysis of these IR spectra, two possible adsorption mechanisms were deduced: (1) NH 4+ adsorption, which gave stretching vibration at 2836cm -1 and bending vibration 1460 cm -1 . (2) O 2 Al + H-NH 3 adsorption: the adsorption at 3256 cm -1 (NH asymmetry stretching vibration), 3060 cm -1 (NH symmetry stretching vibration), 1642 cm -1 (NH asymmetry bending vibration), 1098 cm -1 (NH symmetry bending vibration) gave the evdences of the existence of O 2 Al + H-NH 3 on these zeolites. The interaction of ammonium with O 2 Al + H is discussed in detail in this study. To reduce the cost of zeolites as absorbents, the regeneration of used absorbents was also studied. The original and used zeolites were heated at various temperatures to obtain their XRD spectra for further analysis. Experimental results showed that these zeolites used in our study (SiO 2 /Al2O 3 molar ratio=5 and 11.5) will collapse over 350 ℃ . It is suggested that temperature of the regeneration of these zeolites should be below 350 ℃ .