Large oil spills and oily wastewater discharges from ships and industrial activities can have serious impacts on the environment with potentially major economic impacts. Current oil remediation techniques are inefficient and may have deleterious environmental consequences. However, nanotechnology offers a new route to potentially remediate oil pollution. In this study, a cheap and facile hydrothermal method was developed to synthesize polyvinylpyrrolidone-coated magnetite nanoparticles to separate a reference MC252 oil from oil-water mixture under environmentally relevant conditions. Fluorescence and Proton nuclear magnetic resonance spectroscopy results showed near 100% oil removal from oil-water mixture in the ultrapure water under optimum condition. Based on gas chromatography-mass spectrometry data, approximately 100% of lower molecular mass alkanes (C9-C21) were removed within 10 min of magnetic separation and by increasing the separation time to 40 min, greater than 67% of C22-25 alkanes were removed. Moreover, nanoparticles removed near 100% oil from synthetic seawater solutions in the presence and absence of fulvic acid showing excellent oil removal capacity of the nanoparticles under different conditions. Results show that these nanoparticles can be utilized to remove oil over a short time with a high removal efficiency under environmentally relevant conditions.

Fluorescence spectra for oil–water mixtures before and after oil removal using PVP-coated magnetic nanoparticles under different environmentally relevant conditions.

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PVP–Fe3O4 NPs synthesized with no organic solvents, low toxicity reactants and low temperature/energy requirements could remove Cd, Cr, Ni, Pb efficiently in the different synthetic water media under environmentally relevant conditions.

A new nanomaterial composed of polyvinylpyrrolidone coated iron oxide was successfully used to remediate toxicity of oil-contaminated seawater.

Background: Car wash wastewater contains several contaminants such as organic matter, oil, grease, detergents and phosphates, all of which are harmful for the environment. In this study, the application of electrocoagulation (EC) to treat car wash wastewater has been studied, and the operating parameters optimized. The electro-Fenton (EF) for further contaminant removal was also investigated. Methods: In EC process, the effect of pH, current density, and the reaction time of the removal efficiency of chemical oxygen demand (COD), phosphate, and turbidity were investigated using the response surface methodology (RSM). The electrochemical cell consisted of four iron electrodes that were connected to a power supply using a monopolar arrangement. In the EF process, the effect of pH, reaction time, and hydrogen peroxide concentration on COD removal efficiency were probed. Results: The optimum pH, current density, and the reaction time for the EC process were 7.3, 4.2 mA cm-2 and 20.3 minutes, respectively. Under these conditions, the COD, phosphate, and turbidity removal percentages were 80.8%, 94.9% and 85.5%, respectively, and the specific energy consumption was 1.5 kWh m-3. For the EF process, the optimum pH, reaction time, current and hydrogen peroxide dosage were 3, 10 minutes, 2 A and 500 mg L-1 , respectively. The EF showed higher COD removal efficiency (85.6%) with a lower specific energy consumption (0.5 kWh m-3) and reaction time compared to the EC. Conclusion: This study shows that both EC and EF can effectively treat car wash wastewater with high removal efficiency within a short reaction time.

Oil spills can have dramatic impacts on the environment. The limitations of current oil remediation techniques have inspired researchers to study the application of nanotechnology for oil cleanup. Previously, we reported essentially 100% removal of a reference MC252 oil using polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles (NPs) from oil−water mixtures under a wide range of environmentally relevant conditions. Our previous results showed that in the synthetic water samples, the concentration of cations and natural organic macromolecules (NOM) can significantly affect the oil removal efficiency of NPs. Here, we studied the application of these NPs for oil removal from natural freshwater samples and compared the results with the synthetic water samples with the same concentrations of major ions and NOM. For both natural and synthetic samples, concentrations of NOM, calcium, and magnesium were positively correlated with oil removal (p-value <0.05). NPs show an average of 30% higher oil removal efficiency from natural samples compared to the synthetic samples. Using up to 50 ppm of NP, essentially 100% oil removal was observed under most conditions specially hardwater samples (initial 0.15 g L −1 oil concentration). Results show that these NPs are a facile and reliable technique for removing oil under realistic conditions.

PVP coatings on magnetic NPs are partially displaced in the presence of fulvic acid, which reduces crude oil adsorption onto the magnetite.