Ammonium ion adsorption from aqueous solutions by using modified activated carbon derived from rice straw

Abstract

Many of the health problems of organisms have been attributed to the excessive release of ammonia and nitrogen-containing compounds into the environment. The study was conducted to identify the potential use of oxidized activated carbon (OAC) to remove ammonium ions from aqueous solutions on modified activated carbon in batch system adsorption. BET, SEM, and FTIR analyses were used to characterize the obtained adsorbent. The effects of adsorbent dose, initial concentration of ammonium ions, pH, temperature and contact time on removal efficiency were evaluated. Additionally, kinetic, thermodynamic and isotherm models were investigated to understand the mechanism of adsorption of ammonium ions on OAC. The results showed that 97% of ammonium was removed by modified activated carbon. The adsorption of ammonium ions on OAC increases with increasing adsorbent dose, pH, and contact time. Moreover, it decreased with an increasing initial concentration of ammonium ions. The equilibrium ammonium ion adsorption data for OAC were better fitted with the Langmuir model (r2= 0.999), and a maximum adsorption capacity of 41.50 mg g-1 was achieved. The ammonium ion absorbance kinetics were best described by a pseudo-second-order model (r2=0.999). The prepared adsorbent maintained its efficiency for up to 10 adsorption/desorption cycles. Due to its high adsorption capability and good stability, modified activated carbon powder can be utilized as a worthy adsorbent in water and wastewater treatment.