Abstract
In this research, multiwalled carbon nanotubes (MWCNTs) were firstly oxidized with HNO3/H2SO4 mixture and then functionalized with silane groups and were used for the removal of amoxicillin (AMX) as one of the most consumed antibiotics from the solution media. In addition, NH4Cl-induced activated carbon (NAC) was also prepared as another adsorbent. Then the adsorption process was investigated by using silanized oxidized MWCNTs (S-F-MWCNTs). Physicochemical characterization of MWCNTs, F‑MWCNTs and S-F-MWCNTs was investigated by FTIR, FESEM, EDS, BET/BJH, TGA, and CA techniques. Also, NAC was characterized by FTIR technique. The effect of the operational variables such as pH, adsorbent dosage, contact time, sorbate concentration and temperature on the removal efficiency of the S‑F-MWCNTs adsorbent was studied in details by batch procedure. The results showed that maximum adsorption efficiency can be achieved under the optimized conditions of pH 7.0, adsorbate concentration = 70.0 mg/L, contact time = 45.0 min, S-F-MWCNTs adsorbent dosage = 0.020 g, and temperature = 25.0°C. Isothermic studies have showed that the Redlich–Peterson equation with a correlation coefficient of 0.995 and the lowest error rate has the highest correlation with the experimental data. The adsorption kinetics results show that AMX adsorption process was well-described by pseudo-second-order kinetic model. Thermodynamic parameters of the adsorption process were also calculated revealing that the adsorption of AMX onto S‑F‑MWCNTs and NAC is an exothermic and spontaneous process. Based on the experimental results, S‑F‑MWCNTs were regarded as an acceptable adsorbent for the removal of AMX from aqueous solutions. The AMX adsorption data under the optimum conditions via S-F-MWCNTs and NAC adsorbents revealed that the adsorption efficiency is desirable and satisfactory.
Published Version
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