Abstract
Ciprofloxacin (CIP) is a commonly used antibiotic which is excreted in significant quantities and may likely be found in environments, especially wastewater. Thus, in the present study, we aimed to remove CIP from aqueous solutions using activated carbon supported with multivalent carbon nanotubes MWCNTs/AC. Herein, we prepared the MWCNTs/AC and the structural characterization of the adsorbent was performed using the BET, FTIR, and SEM methods. In order to obtain the optimal conditions of MWCNTs/AC activity, different experimental conditions including the pH, adsorbent dosage, contact time, initial CIP concentration, and temperature were examined. Afterward, to approach reality, the experiments were carried out under the optimal conditions using a sewage sample previously determined in terms of the BOD, COD, pH, EC, turbidity, and concentration of ciprofloxacin. Finally, the CIP levels were measured by HPLC. According to the results, the pH of 7, contact time of 30 min, adsorbent dosage of 20 mg/L, temperature of 40 °C, and initial CIP concentration of 20 mg/L were found to be the optimal conditions for MWCNTs/AC activity. In these conditions, the maximum removal efficiency of CIP from the synthetic and actual samples was 100% and 73%, respectively. Moreover, the adsorption behavior was in compliance with the pseudo-second-order, Freundlich isotherm kinetics. According to our findings, using MWCNTs/AC led to a considerable removal of CIP from the sewage samples. Thus, the use of this adsorbent is highly recommended in order to remove other antibiotics from water and wastewater.
Highlights
Antibiotics are partially metabolized in the body, and 30–90% of them remain active after excretion (Malakootian et al 2019c)
The morphological properties of multiwalled carbon nanotubes (MWCNTs)/activated carbon (AC) were studied by scanning electron microscopy (SEM) analysis
We showed that the CIP adsorption by MWCNTs/AC increased continuously with an increase in contact time until reaching equilibrium
Summary
Antibiotics are partially metabolized in the body, and 30–90% of them remain active after excretion (Malakootian et al 2019c). These compounds are found in different scales of nano- to micrograms per liter in various drinking water, groundwater, surface water, sewage, and wastewater sources (Javid et al 2019). Developing the adsorbents with easy preparation, high efficiency, and low cost is still a challenge and problem in the application of antibiotic adsorption. Among adsorbents, activated carbon (AC) is applied widely, due to having large surface area, high adsorption capacity, and versatile selectivity (Loqman et al 2017). The use of AC to adsorb and remove antibiotics from aqueous environments has been investigated so far (Al-Othman et al 2012; El-Shafey et al 2012; Li et al 2015), their separation after treatment remains the main defect of such powdered AC or nanosize adsorbents, which may result in the generation of secondary pollution
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