Abstract
Residual antibiotics in water are often persistent organic pollutants. The purpose of this study was to prepare a cellulose nanocrystals/graphene oxide composite (CNCs-GO) with a three-dimensional structure for the removal of the antibiotic levofloxacin hydrochloride (Levo-HCl) in water by adsorption. The scanning electron microscope, Fourier transform infrared (FT-IR), energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and other characterization methods were used to study the physical structure and chemical properties of the CNCs-GO. The three-dimensional structure of the composite material rendered a high surface area and electrostatic attraction, resulting in increased adsorption capacity of the CNCs-GO for Levo-HCl. Based on the Box–Behnken design, the effects of different factors on the removal of Levo-HCl by the CNCs-GO were explored. The composite material exhibited good antibiotic adsorption capacity, with a removal percentage exceeding 80.1% at an optimal pH of 4, the adsorbent dosage of 1.0 g l−1, initial pollutant concentration of 10.0 mg l−1 and contact time of 4 h. The adsorption isotherm was well fitted by the Sips model, and kinetics studies demonstrated that the adsorption process conformed to a quasi-second-order kinetics model. Consequently, the as-synthesized CNCs-GO demonstrates good potential for the effective removal of antibiotics such as levofloxacin hydrochloride from aqueous media.
Highlights
Water-soluble antibiotics constitute a serious type of organic environmental pollutants as the early lack of guidance and regulatory measures related to antibiotics has led to their overuse and abuse [1]
The analogous scanning electron microscope (SEM) images for the CNCs-graphene oxide (GO) are presented in figure 1e,f
According to the optimization results from response surface graphs and practical operation, the optimal conditions for adsorption were determined as an initial pollutant concentration of 10.0 mg l−1, an initial pH of 4, an adsorbent dosage of 0.1 g l−1 and a 4 h contact time
Summary
Water-soluble antibiotics constitute a serious type of organic environmental pollutants as the early lack of guidance and regulatory measures related to antibiotics has led to their overuse and abuse [1]. A variety of methods have been explored to mitigate environmental antibiotic contamination, such as adsorption, catalytic degradation, biodegradation, photocatalytic degradation and advanced oxidation [1,6,7,8]. Among these methods, the widely used adsorption technique offers the advantages of easy operation, flexibility, low energy consumption, high removal rates, low secondary pollution and low adsorbent regeneration cost [9]. The inadequate adsorption efficiencies, poor adsorption capacities, unsatisfactory recyclability, secondary pollution problems and high costs of these adsorbent materials have greatly hampered their practical application. The development of new, high-efficiency, low-cost adsorbents for the removal of antibiotics from water is a pressing need
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