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Antibiotics are pharmaceutical emerging contaminants (ECs) that contaminate the environment and jeopardize public health. More dangerously, the widespread consumption of antibiotics and their impact on water contamination foster the formation and evolution of antibiotic-resistant genes in microbes. Graphene Oxide (GO) is an emerging carbon material with a great potential to operate as an adsorbent to remove antibiotics from water due to its unique physical and chemical properties. Thus, this study briefly reviews topics related to antibiotic removal from water using GO-based materials. This research also summarizes the benefits of GO structural properties, adsorption mechanisms, and the affinity of the GO synthesis method to the quality of the GO produced.

Introduction: In this work, bimetallic nickel/iron nanoparticles (Ni/Fe0) were prepared to enhance rhenium (Re(VII)) immobilization from aqueous solutions, as the surrogate of technetium (Tc(VII)).Methods: Two synthesis approaches of Ni/Fe0, pre-, and post-nucleation, were investigated towards Re(VII) removal. Different characterization techniques were considered to elucidate the physicochemical features of the fresh and reacted materials, such as scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX), X-ray diffraction (XRD), and X-ray absorption near edge spectroscopy (XANES). The influence of several reaction parameters on Re(VII) removal was investigated, including Ni/Fe0 ratio, dosage, initial pH, temperature, and initial concentration.Results and discussion: Results showed a promising potential of Ni/Fe0, either pre- or post-nucleation synthesized, in Re(VII) removal, especially at the early stage of the reaction, where Ni/Fe0: 0.4 yielded almost full removal efficiency of initial 15.0 μM-Re(VII) within the first 10 min of reaction. Even at low Ni/Fe0 dosages, such as 0.25 and 0.5 g/L, reasonable removal efficiency was achieved after 2 h reaction time of ∼73% and ∼98%, respectively. Unlike acidic/neutral pH, alkaline conditions were not favorable for Re(VII) removal by Ni/Fe0 owing to the delayed aqueous corrosion of Fe0-core resulting in insufficiency of electrons available for Re(VII) reduction. The reductive abilities were confirmed by XANES, revealing Re(VII) reduction to Re(IV)/(III) by the released electrons from Fe0-core in both Fe0 and Ni/Fe0 materials. Pseudo-first- and second-order kinetic models were suitable to describe Re(VII) removal by Ni/Fe0, implying physical and/or chemical processes were involved. Zeta potential measurements depicted the point of zero charge (pHPZC) of Fe0 and Ni/Fe0 to be 8.24 and 7.63, respectively, suggesting the involvement of electrostatic sorption of ReO4− on the positively charged surface of Ni/Fe0. The occurrence of multi- and mono-layer sorption within Re(VII) removal process was implicated, following Freundlich and Sips isotherm models. The presence of Ni0/NiO on Fe0-surface resulted in providing an efficient electron-transfer medium that facilitated Re(VII) reduction, leading to impressive kinetic rates. Overall, our study provided valuable insights into the use of Ni/Fe0 for Re(VII) removal from water and offered guidance for future research in such an aspect towards the pilot-scale applications of Tc(VII) removal from nuclear wastewater.

The rapid evolution of antimicrobial resistant genes (AMRs) in water resources is well correlated to the persistent occurrence of ciprofloxacin in water. For the first time, encapsulated nanoscale zerovalent iron (nZVI) with a shell of magnesium hydroxide (Mg/Fe0) was used to adsorb ciprofloxacin from water. Optimization of the removal conditions exhibited that 5% was the optimum mass ratio between magnesium hydroxide and nZVI [Mg(OH)2/nZVI)] as more than 96% of 100 mg L−1 of ciprofloxacin was removed. In addition, 0.5 g L−1 of Mg/Fe0 showed an extraordinary performance in removing ciprofloxacin over a wide range of pH (3–11) with removal efficiencies exceeded 90%. Kinetic analysis displayed that the kinetic data was well described by both Pseudo first-order and second-order models. Also, the equilibrium data was well fitted by Freundlich isotherm model. In addition, thermodynamic analysis evidenced that the removal of ciprofloxacin by Mg/Fe0 was exothermic, and spontaneous. The experiments also revealed that physisorption and chemisorption were the responsible mechanisms for ciprofloxacin removal. The proposed treatment system remediated 10 litters of 100 mg L−1 of ciprofloxacin solution with 100% overall removal efficiency. This treatment system could be a promising and practical solution to decrease ciprofloxacin concentration in different water bodies.