Removal of oil droplets from water using carbonized rice husk: enhancement by surface modification using polyethylenimine

Facile Fabrication of Marine Algae-Based Robust Superhydrophobic Sponges for Efficient Oil Removal from Water

Water pollution caused by oil spillages has aroused worldwide attention. Therefore, it is of great significance to develop low-cost, environmentally friendly materials to remove oil contaminants from water. Herein, a "green" superhydrophobic sponge made from marine algae was fabricated by one-step growth of silicone nanofilaments onto a AgNP-decorated alginate sponge via chemical vapor deposition of an azeotrope of (CH₃)₃SiCl and SiCl₄. The reaction of the azeotrope with the alginate sponge was termed "instant", as it took only a few minutes (5 min) at room temperature to achieve superhydrophobicity (152.0°). Such sponges resist high temperatures, UV irradiation, organic solvents, and mechanical abrasion without losing the superhydrophobicity. The sponges absorbed oil droplets within seconds (1.3-7.0 s) with 11.7-17.1 g/g of sorption capacities for oils of different viscous levels (0.56-1775.00 mPa·s). These sponges could retain 90% of the initial oil sorption capacities after 10 consecutive oil sorption/desorption cycles. Benefiting from the superhydrophobicity and superoleophilicity, the sponges also exhibited high efficiency in oil/water mixture separation. Once the oil/water mixture was injected into the sponge, oil drops were retained in inner pores while water was rejected and spouted from the surface. These excellent performances make the resultant sponge a competitive material for oil spill emergency remediation.

An investigation on the capability of magnetically separable Fe3O4/mordenite zeolite for refinery oily wastewater purification

Damage to the water resources and environment as a consequence of oil production and use of fossil fuels, has increased the need for applying various technologies and developing effective materials to remove contaminates from oily wastewaters resources. One of the challenges for an economic industrial wastewater treatment is separation and reusability of the developed purifying agents. Development of magnetic materials could potentially facilitate easier and more economic separation of purifying agents. Therefore, herein we have synthesised an efficient and easily recyclable Fe₃O₄/mordenite zeolite using a hydrothermal process to investigate its purification capability for wastewater from Kermanshah oil refinery. The synthesised Fe₃O₄/mordenite zeolite was characterised using XRD, FTIR, SEM, EDX, XRF and BET analysis. XRD result showed that the synthesised Fe₃O₄/mordenite zeolite comprised sodium aluminium silicate hydrate phase [01-072-7919, Na₈(Al₆Si₃₀O₇₂)(H₂O)_9.04] and cubic iron oxide phase [04-013-9808, Fe₃O₄]. Response Surface Method (RSM) combined with Central Composite Design (CCD) was used to identify the optimum operation parameters of the pollutant removal process. The effect of pH, contact time and Fe₃O₄/mordenite zeolite amount on the Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Nephelometric Turbidity Unit (NTU) were investigated. It was found that pH was the most significant factor influencing COD and BOD removal but the quantity of Fe₃O₄/mordenite zeolite was the most influential factor on the turbidity removal capacity. The optimum removal process conditions were identified to be pH of 7.81, contact time of 15.8 min and Fe₃O₄/mordenite zeolite amount of 0.52% w/w. The results show that the regenerated Fe₃O₄/mordenite zeolite can be reused for five consecutive cycles in purification of petroleum wastes.

The Preparation and Characterization of MnFe2O4-Decorated Expanded Graphite for Removal of Heavy Oils from Water

Recently, many methods have been developed to efficiently eliminate oil spills due to its long-term harmful effects on marine life and human health. Expanded graphite (EG) has been considered as an excellent platform to remove contaminated oil from aqueous solution through a facile adsorption route. As an innovative approach, the decoration of magnetic components, namely, MnFe₂O₄, into graphite layers was taken into account for facilitating phase separation under magnetic field which resulted into an easy collection of the used adsorbents in a large scale. The expanded graphite/manganese ferrite composites were prepared from Vietnamese graphite flakes via a two-stage process. Characterization was performed using Scanning Electron Microscope (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray Powder Diffraction (XRD), Vibrating Sample Magnetometer (VSM), Energy-Dispersive X-ray (EDS), and nitrogen adsorption/desorption analysis. The adsorption behavior of EG-MnFe₂O₄ for widespread used heavy oils, including diesel oil and crude oil, was investigated under the effects of adsorption conditions, i.e., contact time, loaded oil dosage, and salinity of mixing oil and water. The obtained results showed successful incorporation of MnFe₂O₄ into graphite sheets and no considerable change on the worm-like structure of EG. The results also showed that incorporated manganese ferrites enhanced the magnetism EG up to 16 emu/g, which made the recovery of used adsorbent conveniently. The EG-MnFe₂O₄ adsorbents exhibited the strong adsorption ability toward diesel oil (32.20 ± 0.46 g DO/g EG) and crude oil (33.07 ± 0.33 g CO/g EG). In brief, EG-MnFe₂O₄ material provides a potential and promising platform with high performance for oil spill removal.