Adsorption of antibiotics and iopromide onto single-walled and multi-walled carbon nanotubes
Introduction
There is an increasing concern on the impact of pharmaceuticals on drinking water supplies, which are usually not easily biodegradable and pose a risk of their deleterious effects to human beings and ecosystems [1], [2], [3], [4]. Among the various pharmaceuticals, antibiotics have raised issues of antibiotic resistant bacteria and genes in the aquatic environment [5], [6], [7], [8], [9]. Besides antibiotics, there is also a concern on X-ray contrast medium, which has been detected in wastewater effluents, surface water, and drinking water at concentrations ranging from 0.5 to 15 μg L−1 [4], [10], [11], [12]. Wastewater treatment plants (WWTPs), which receive waste from hospitals or radiological clinics, have particularly shown high concentrations. Removal of pharmaceuticals and the contrast medium in water is immense important to meet the urgent need to clean water. Effective and sustainable water treatment technologies are critically required to meet the global demand of purified water.
Since the discovery of carbon nanotubes (CNTs) in 1991, engineered CNTs have shown great potential in many medical and environmental remediation applications [13], [14]. CNTs contain cylindrical graphite sheets, which have very high van der Waals index [15]. The benzenoid rings of graphite sheets have sp2-hybridized carbon atoms with high polarizability. These properties of CNTs make them superhydrophobic materials that may also strongly interact with aromatic pollutants through π–π coupling/stacking [16], [17]. Examples include nitroaromatics and amino- and hydroxyl-substituted aromatic compounds [18], [19].
Studies on adsorption of pharmaceuticals onto CNTs are forthcoming [20], [21], [22], [23], [24]. The focus of the present study is on the removal of selected pharmaceuticals and a contrast medium through their adsorption onto CNTs, which have different structural and surface properties. The antibiotics under study were lincomycine (LCN) and sulfamethoxazole (SMX), which have amide and sulfonamide moieties, respectively (Table 1). The contrast medium was iopromide (IPR) that has also amide moieties (Table 1). These pollutants have been detected in water and wastewaters [4]. The tested CNTs for sorption experiments were single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs). The experiments with powdered activated carbon (PAC) were also performed for the comparative purpose. Sorption studies on SMX using CNTs have been carried out [20], but no similar studies with LCN and IPR are known in literature. The objectives were (i) to investigate the sorption behavior of the selected pharmaceuticals onto CNTs, (ii) to understand the influence of particle size and surface area of engineered carbon materials on the interaction between the studied molecules and CNTs, and (iii) to evaluate the potential of CNTs for enhanced removal of micropollutants.
Section snippets
Standards and reagents
SWCNTs (purity > 95%, length 1–5 μm, and outer diameter 1.5 nm) and MWCNTs (purity > 95%, length 1–5 μm, and outer diameter 15 ± 5 nm) were purchased from Nano Lab (Newton, MA, USA) and were used without further purification. Based upon the information provided by the manufacturer, both CNTs have a hollow structure and were produced by a conventional chemical vapor deposition (CVD) method. Coconut-based PAC was obtained from Dongyang Carbon Co., Korea (Cheonan, Korea). Prior to use, the PAC was ground to
Characteristics of adsorbents
The structural properties of carbon materials used in the study are given in Table 2. Both CNTs have similar lengths, but differ in outer diameter and BET surface areas (Table 2). The BET surface area of SWCNT is approximately four times higher than that of MWCNT. Comparatively, the BET surface area of PAC is the highest; a slightly more than that of SWCNT. The size of PAC used in this study is 60–140 mesh (100–250 μm).
Adsorption of LCN
Initially, adsorption kinetics using LCN was performed on all three
Conclusions
CNTs and PAC could effectively adsorb the three pollutants. The adsorption of LCN by different material was almost complete within 100 h and the adsorption kinetics had two phases, rapid step was followed by a relatively slow step. Among the different materials, SWCNT has higher potential to adsorb LCN, SMX, and IPR than MWCNT and PAC. The surface area of the material significantly controlled the adsorption of the pollutants, but other factors including the moieties on the pollutants may also
Acknowledgments
This work was supported by the R&D program of MOTIE/KEIT (R&D program No. 10037331, Development of Core Water Treatment Technologies based on Intelligent BT-NT-IT Fusion Platform). Dr. Huang is partially supported by the Korea Institute of Toxicology, Korea (Project No. KK-1403-02, Environmental Risk Assessment of Manufactured Nanomaterials). Finally, authors wish to thank anonymous reviewers for their comments, which improved the paper greatly.
References (27)
- et al.
Ecotoxicological aspects related to the presence of pharmaceuticals in the aquatic environment
J. Hazard. Mater.
(2010) - et al.
EU-wide monitoring survey on emerging polar organic contaminants in wastewater treatment plant effluents
Water Res.
(2013) - et al.
Impact of wastewater treatment processes on antimicrobial resistance genes and their co-occurrence with virulence genes in Escherichia coli
Water Res.
(2014) - et al.
Urban wastewater treatment plants as hotspots for the release of antibiotics in the environment: a review
Water Res.
(2013) - et al.
Evaluating the efficiency of advanced wastewater treatment: target analysis of organic contaminants and (geno-)toxicity assessment tell a different story
Water Res.
(2014) - et al.
Monitoring of iodinated X-ray contrast media in surface water
Chemosphere
(2006) - et al.
Electrochemical treatment of iopromide under conditions of reverse osmosis concentrates – elucidation of the degradation pathway
Water Res.
(2014) - et al.
Functionalization of carbon nanotube by carboxyl group under radial deformation
Chem. Phys.
(2014) - et al.
Influence of nitrogen source on NDMA formation during chlorination of diuron
Water Res.
(2009) - et al.
Regenerable granular carbon nanotubes/alumina hybrid adsorbents for diclofenac sodium and carbamazepine removal from aqueous solution
Water Res.
(2013)
Determination of the solid-water distribution coefficient (Kd) for pharmaceuticals, estrogens, and musk fragrances in digested sludge
Water Res.
Global water pollution and human health
Annu. Rev. Environ. Resour.
Pharmaceutical residues in environmental waters and wastewater: current state of knowledge and future research
Anal. Bioanal. Chem.
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