Comprehensive evaluation of adsorption and degradation of tetracycline and oxytetracycline by nanoscale zero-valent iron

Abstract

A B S T R A C TThe interaction of tetracycline (TC) and oxytetracycline (OTC) with nanoscale zero-valent iron (nZVI) was examined with a batch experimental series in order to determine the removal efficiency and transformation products. Experimental variables, such as solution pH, nZVI dosage, contact time, initial TCs concentration, and reaction temperature, were systematically studied. Adsorption kinetics showed that equilibrium was reached within 2 h according to the pseudo-second-order model. The adsorption behavior was pH-dependent and favored at pH 6 regardless of TC type considered due to electrostatic attraction between nZVI and TCs. The adsorption capacity of TC was more than that of OTC. The results of LC-MS-MS showed that main transformation product was 4-epi-tetracycline for TC and insignificant for OTC. On the other hand, desorption studies exhibited that nZVI adsorbed not only parent compounds but also transformation products. The results showed that the removal mechanism of TC and OTC by using nZVI surface was mainly the adsorption relatively than the degradation process.

An Overview on Usage of Nanoscale Zero Valent Iron for Pharmaceuticals Elimination

“…It was consistent with the results reported in a previous study [61] about the adsorption of TC onto nZVI. The highest removal was observed at about pH:5 resulted from the electrostatic attraction between nZVI and TC since nZVI was positively charged at pH<5.38 and negatively charged at pH>5.33 while the pHzpc of ZVI was found to be 5.38 [61].…”

“…The removal process of TC after treatment by Fe-MCM-41-A included two key stages, a rapid adsorption rate within the first 30 min followed by a slow removal process at 30-60 min. This behavior was also confirmed with the study of Chen et al [66] and Hanay and Türk [61].The rapid adsorption rate could be attributed to the large surface area, the appropriate pore size and volume of the adsorbent which can promote the internal mass transfer in adsorption process effectively. Adsorption mechanisms of TC onto Fe-MCM-41-A were also dependent on multiple interactions including hydrophobicity, ion exchange and surface complexes [67].…”

“…On the other hand, Halling-Sorenson et al [90] reported that several tetracycline transformation products were more toxic than their parent on both sludge and tetracycline-sensitive soil bacteria . However, their toxicity will be less significant in the aqueous matrix since sorption of these products on nZVI happened quickly during the reaction [61].…”

Removal of tetracyclines from aqueous solution by nanoscale Cu/Fe bimetallic particle

“…These values are higher than q m obtained for TC by graphene oxide (313.48 mg g −1 ) [45], illite (IMt-2) (32 mg g −1 ) [43]. Also, in the study investigating the adsorption on nZVI of TC and OTC, q m values at 30, 45, and 60˚C were found as 159, 208, and 233 mg g −1 for TC and 110, 145, and 149 mg g −1 for OTC [46]. However, the higher q m value for OTC was obtained by graphene oxide (212.314 mg g −1 ) [45].…”

The Use of Nanoparticles in Soil and Water Remediation Processes

“…The studies addressed mostly water body contamination, and some of them used some type of iron-based nanoparticles [72,[73][74][75], and another, 14C-phenanthrene and 14C-benzo-[a] pyrene [76].…”