A new composite of nano zero-valent iron encapsulated in carbon dots for oxidative removal of bio-refractory antibiotics from water

Abstract

In this paper, a novel Gum Tragacanth-based carbon dots-nano zero-valent iron composite was prepared via cost-effective and green one-step hydrothermal method. A new composite was applied for its potential as a novel heterogeneous Fenton-like catalyst in order to remove bio-refractory antibiotics from aqueous solution. The morphological, structural, electrochemical and physicochemical properties of the new composite were evaluated using TEM, SEM, DLS, Cyclic voltammetry, XRD and FTIR techniques. Development of nano-scale metallic iron particles encapsulated in carbon dot films with an average size of ∼237 nm was observed. Using experimental design and response surface methodology, at optimum process conditions ([H2O2] of 20 mM, time of 60 min and amount of catalyst of 765 mg/l), a superior catalytic performance of the composites were confirmed by removing rate of amoxicillin and ciprofloxacin equal to 90% and 51%, respectively. From the mechanism study using FTIR analysis, it can be concluded that composite reacts with H2O2 and due to oxidation, different iron oxides are produced indicating nano zero-valen iron particles is reduced and convert H2O2 to OH• radicals. The encapsulation of nano zero-valent iron in biopolymer based carbon dots can enhance air/water stability and prolong the reactivity of nano zero-valent iron with H2O2. Results indicate that carbon dots-nano zero-valent iron composite-mediated heterogeneous Fenton oxidation technology is an effective strategy for pollutant abatement.