In this research, it was aimed to determine the adsorption, saturation reaching and desorption effects of ammonium, which is one of the parameters that should be kept in control for aquarium life, by clinoptilolite type zeolite which is a natural filtration material. In the aquarium water, Z1: 20 mg/l TAN and Z2: 40 mg/l TAN concentrations were determined to have adsorption up to Z1: 10 mg/l TAN and Z2: 24 mg/l TAN concentration at the end of the experiment period. After this phase, where zeolites had reached saturation, desorption system was created, and 2 groups were formed with 5-liter research aquariums and 3 repetitions. During the five-days test, water parameters were determined daily and at the same time of day (10.00). At the beginning of the experiment, mean values of 0.4 ± 0.00 mg / l TAN in Z1 and Z2 groups were determined at the end of the experiment as 1.55 ± 0.176 mg/l (15.5%) and 2.153 ± 0.27 mg/l (13.5%) TAN in Z1 and Z2 groups, respectively. When the data obtained in this study were evaluated, zeolite was determined to make desorption periodically in proportion with the amount of retained ammonium, when it reached the saturation. In intensive aquaculture systems or aquarium conditions, recondition of zeolite for necessary periods is recommended to be performed by considering these data.

The effect of temperature and pH on adsorption-desorption of fungicide hexaconazole was studied in two Malaysian soil types; namely clay loam and sandy loam. The adsorption-desorption experiment was conducted using the batch equilibration technique and the residues of hexaconazole were analysed using the GC-ECD. The results showed that the adsorption-desorption isotherms of hexaconazole can be described with Freundlich equation. The Freundlich sorption coefficient (Kd) values were positively correlated to the clay and organic matter content in the soils. Hexaconazole attained the equilibrium phase within 24 h in both soil types studied. The adsorption coefficient (Kd) values obtained for clay loam soil and sandy loam soil were 2.54 mL/g and 2.27 mL/g, respectively, indicating that hexaconazole was weakly sorbed onto the soils due to the low organic content of the soils. Regarding thermodynamic parameters, the Gibb’s free energy change (ΔG) analysis showed that hexaconazole adsorption onto soil was spontaneous and exothermic, plus it exhibited positive hysteresis. A strong correlation was observed between the adsorption of hexaconazole and pH of the soil solution. However, temperature was found to have no effect on the adsorption of hexaconazole onto the soils; for the range tested.