The development of antibiotic-resistant bacteria due to the existence and fate of Pharmaceutically Active Compounds (PHAC) used to treat bacterial diseases in humans as well as veterinary medicine to prevent disease in animals such as poultry, cattle, swine, and fish during animal food production and as growth promoters like antibiotics entering the environment turned out to be a problem when not removed in a normal wastewater treatment plant as it has increased effects on the disturbance of the natural bacterial ecosystem, presence of it in the effluent of sewage treatment plants as well as to surface and groundwater, and concerns for human health. Fate and transport of particles is an important matter that describe their physical form and behavior in different media with primary concern of determining the transport speed and combined effects of the chemicals in their discharge environments. In order to predict the fate and transport in the environment, one important parameter that indicates how individual molecules and ions move through a medium under a concentration gradient at a certain pressure and temperature is the diffusion coefficient. In relation to the previously published work on diffusion coefficient of various livestock antibiotics at infinite dilution, the present work extended the calculation to determine the self-diffusion coefficient of constituent ions from the studied antibiotics using the Nernst-Einstein Equation. Other parameters such as activation energy, pre-exponential factor, and hydrodynamic radius needed in describing the infinite dilution diffusion behavior were also calculated using Arrhenius-type equation and Stokes-Einstein Equation, respectively. The results may provide an adequate understanding of the mobility and behavior of these constituent ions from these livestock antibiotics when present in environmental water system, which may be of help for future studies for the removal of these antibiotics which can lead to the microbial resistance bacteria.

Abstract. The fate of antibiotics entering the environment raised concerns on the possible effect of antimicrobial resistance bacteria. Prediction of the fate and transport of these particles are needed to be determined, significantly the diffusion coefficient of antibiotic in water at infinite dilution. A systematic determination of diffusion coefficient of antibiotic in water at infinite dilution of five different kinds of livestock antibiotics namely: Amtyl, Ciprotyl, Doxylak Forte, Trisullak, and Vetracin Gold in the 293.15 to 313.15 K temperature range are reported through the use of the method involving the electrolytic conductivity measurements. A continuous stirred tank reactor is utilized to measure the electrolytic conductivities of the considered systems. These conductivities are correlated by using the Nernst-Haskell equation to determine the infinite dilution diffusion coefficient. Determined diffusion coefficients are based on the assumption that in dilute solution, these antibiotics behave as strong electrolyte from which H + cation dissociate from the antibiotic's anion.

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