Determination of isotherm and kinetics of carbon-based material produced from waste tires for ammonium adsorption from aqueous media

Ammonium pollution in groundwater and surface water is a major concern in many parts of the world due to the damage it causes to the environment and human health. The ammonia and ammonium ions, which cause undesired odours and several diseases, are the most commonly encountered nitrogenous compounds in wastewaters. The presence of excess ammonium could affect the quality of groundwater and surface water. Therefore, it is necessary to remove ammonium from water. Various techniques such as ion exchange, membrane technology, adsorption, nitrification-denitrification process, chemical precipitation and electrochemical separation have been applied to remove NH4+ ions from water and waste water. Of these, adsorption is considered an effective, inexpensive and simple technique for the removal of NH4+-N from water bodies, especially at low concentrations of NH4+-N. In this study, it was aimed to remove NH4+-N from aqueous solutions with carbon-based material recovered from waste tires. The characteristics of the carbon based material were determined by, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The effects of parameters such as contact time (0-60 min.), pH (3-10), adsorbent dosage (0,5-3 g/L) and initial ammonium concentration (5-50 mg/L) were examined. The results show that ammonium ion removal by carbon based material occurs rapidly within the first ten minutes, pH has an effect on ammonium ion removal efficiency, and the ammonium ion removal efficiency of carbon based material decreases with increase in initial ammonium ion concentration. In optimum conditions, approximately 80% of NH4+-N was removed by carbon-based material. The adsorption kinetics of ammonium on carbon based material followed Pseudo-second order kinetic model (R2=0,9522-0,999) whereas adsorption isotherm data showed that Temkin isotherm model the best fit for the equilibrium data at 30°C. Furthermore, thermodynamic studies show that the adsorption is an endothermic physical process, occurs spontaneously naturally and increasing randomness at the solid-solution interface during adsorption. The FTIR spectrum showed that the KBM adsorbent adsorbs NH4+-N, while SEM analysis showed that NH4+-N clings to KBM. Findings from this study indicated that carbon-based material recovered from waste tires can be used as an alternative adsorbent for the removal of ammonium from aqueous solutions.