Multifunctional metal-organic frameworks in oil spills and associated organic pollutant remediation

Facile fabrication and application of highly efficient reduced graphene oxide (rGO)-wrapped 3D foam for the removal of organic and inorganic water pollutants

The pace of water contamination is increasing daily due to expanding industrialisation. Finding a feasible solution for effectively remediating various organic and inorganic pollutants from large water bodies remains challenging. However, a nano-engineered advanced hybrid material could provide a practical solution for the efficient removal of such pollutants. This work has reported the development of a highly efficient and reusable absorbent comprising a porous polyurethane (PU) and reduced graphene oxide (rGO) nanosheets (rGOPU) for the removal of different organic oils (industrial oil, engine oil and mustard oil), dyes (MB, MO, RB, EY and MV) and heavy metals (Pb(II), Cr(VI), Cd(II), Co(II) and As(V)). The structure, morphology and properties of the rGOPU hybrid absorbents were analysed by using Raman spectroscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunner-Emitte-Teller (BET) analysis. The rGOPU possessed both superhydrophobicity and superoleophilicity with water and oil contact angles of about 164° and 0°, respectively. The prepared rGOPU has demonstrated an excellent oil-water separation ability (up to 99%), heavy metals removal efficiency (more than 75%), toxic dye adsorption (more than 55%), excellent recyclability (> 500 times for oils), extraordinary mechanical stability (90% compressible for > 1000 cycles) and high recoverability. This work presents the first demonstration of rGOPU's multifunctional absorbent capacity in large-scale wastewater treatment for effectively removing a wide variety of organic and inorganic contaminants.

Recent perspective of antibiotics remediation: A review of the principles, mechanisms, and chemistry controlling remediation from aqueous media

Antibiotic pollution is an ever-growing concern that affects the growth of plants and the well-being of animals and humans. Research on antibiotics remediation from aqueous media has grown over the years and previous reviews have highlighted recent advances in antibiotics remediation technologies, perspectives on antibiotics ecotoxicity, and the development of antibiotic-resistant genes. Nevertheless, the relationship between antibiotics solution chemistry, remediation technology, and the interactions between antibiotics and adsorbents at the molecular level is still elusive. Thus, this review summarizes recent literature on antibiotics remediation from aqueous media and the adsorption perspective. The review discusses the principles, mechanisms, and solution chemistry of antibiotics and how they affect remediation and the type of adsorbents used for antibiotic adsorption processes. The literature analysis revealed that: (i) Although antibiotics extraction and detection techniques have evolved from single-substrate-oriented to multi-substrates-oriented detection technologies, antibiotics pollution remains a great danger to the environment due to its trace level; (ii) Some of the most effective antibiotic remediation technologies are still at the laboratory scale. Thus, upscaling these technologies to field level will require funding, which brings in more constraints and doubts patterning to whether the technology will achieve the same performance as in the laboratory; and (iii) Adsorption technologies remain the most affordable for antibiotic remediation. However, the recent trends show more focus on developing high-end adsorbents which are expensive and sometimes less efficient compared to existing adsorbents. Thus, more research needs to focus on developing cheaper and less complex adsorbents from readily available raw materials. This review will be beneficial to stakeholders, researchers, and public health professionals for the efficient management of antibiotics for a refined decision.

Eco-friendly adsorbents based on abietic acid, boswellic acid, and chitosan/magnetite for removing waste oil from the surface of the water

Petroleum oil leakage and industrial oily waste on the water surface are sustainable pollutions. The removal process by eco-friendly adsorbents is a critical challenge. It also requires sustainable treatment. The natural hydrophobic material such as abietic acid, boswellic acid, and chitosan was added to magnetite nanoparticles with different concentrations of 10, 15, and 20% on its surface. The magnetite acquires partially hydrophobic properties. The prepared natural adsorbents were analyzed by employing wide-angle X-ray diffraction (WAXD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), particle size and zeta potential, and contact angle measurements. Chitosan adsorbs at the outer surface of magnetite nanoparticles while boswellic and abietic absorb in bulk. All prepared adsorbents are effective in adsorbing waste oil from the water surface. The contact angle of MB20 (magnetite/20 percent boswellic) is greater than that of MA20 and MC20 (magnetite/20% abietic or chitosan, respectively), indicating that it has more hydrophobic characteristics. The oil removal efficiency and adsorption capacity of MB20 are the highest values 57.6%, and 24 g/g, respectively. All eco-friendly adsorbents are nontoxic with low-cost production and are used many times.

Magnetic γ-Fe2O3/ZIF-7 Composite Particles and Their Application for Oily Water Treatment

Crude oil spills are about global challenges because of their destructive effects on aquatic life and the environment. The conventional technologies for cleaning crude oil spills need to study the selective separation of pollutants. The combination of magnetic materials and porous structures has been of considerable interest in separation studies. Here, γ-Fe₂O₃/ZIF-7 structures were prepared by growing a ZIF-7 layer onto supermagnetic γ-Fe₂O₃ nanoparticles with an average size of 18 ± 0.9 nm in situ without surface modification at low temperatures. The product composite particles were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, and N₂ adsorption/desorption isotherms. The analyses revealed a time growth-dependent ZIF-7 rod thickness with abundant nanocavities. The γ-Fe₂O₃/ZIF-7 surface area available for sorption (647 m²/g) is ∼12-fold higher than that of the γ-Fe₂O₃ nanoparticles. Moreover, the crystal structure of γ-Fe₂O₃ remained essentially unchanged following ZIF-7 coating, whereas the superparamagnetism declined depending on the coating time. The γ-Fe₂O₃/ZIF-7 particles were highly hydrophobic and selectively and rapidly (<5 min) sorbed crude oil and other hydrocarbon pollutants from water. As high as 6 g/g of the hydrocarbon was sorbed by the γ-Fe₂O₃/ZIF-7 particles immersed into the hydrocarbon. A coefficient of determination, R ₂ ², consistently >0.96 at all pollutant concentrations suggested a pseudo-second-order sorption kinetics. The thermal stability and 15 cycles of use and reuse confirmed a robust γ-Fe₂O₃/ZIF-7 sorbent.

Polyethylene over magnetite-multiwalled carbon nanotubes for kerosene removal from water

In this study, a nano-adsorbent was prepared for kerosene removal from water. Multiwalled carbon nanotubes (MWCNTs) were functionalized with concentrated HNO₃ (nitric acid). Subsequently, Fe₃O₄ (magnetite) nanoparticles were deposited on the MWCNTs to prepare a magnetite/MWCNTs (Fe-MWCNTs) nanocomposite. Then, polyethylene was added to the Fe-MWCNTs to fabricate a polyethylene/magnetite/MWCNTs (PE/Fe-MWCNTs) novel nanocomposite. The nano-adsorbent was characterized using BET, FTIR, Raman, XRD, TEM, and SEM. A kerosene-water model mixture was used for adsorption tests. Several parameters: adsorption time, adsorbent dose, solution pH, solution temperature, and kerosene concentration in the kerosene-water model mixture, were analyzed during adsorption experiments. After each batch experiment, kerosene concentration was determined using high-performance liquid chromatography (HPLC). Magnetic field was used to remove the adsorbent after each experiment. The kerosene adsorption capacity and removal efficiency of the PE/Fe-MWCNTs nanocomposite (3560 mg/g and 71.2 %, respectively) were higher than those of Fe-MWCNTs, ox-MWCNTs, and fresh MWCNTs (3154 mg/g and 63.1 %, 2204 mg/g and 44.0 %, and 2092 mg/g and 41.8 %, respectively). Kerosene adsorption followed a pseudo-second-order kinetic model (R² = 0.999) and the Langmuir isotherm model, suggesting that adsorption was uniform and homogenous process.

Highly connected framework materials from flexible tetra-isophthalate ligands

High connectivity octacarboxylate ligands containing non-coordinating diamine cores lead to a wide variety of new MOFs, many containing cage-like pores.

Fabrication of outstanding thermal-insulating, mechanical robust and superhydrophobic PP/CNT/sorbitol derivative nanocomposite foams for efficient oil/water separation

Water pollution caused by industrial oily wastewater, is world-widely concerned by both scientific and practical researches, owing to its catastrophic destruction to natural environment, which highlights the urgency of producing green and advanced separation materials. Herein, a novel approach was proposed to fabricate oil-absorbing and oil/water-separating microcellular polypropylene (PP)/carbon nanotubes (CNTs)/sorbitol nanocomposites using a simple, green, and facile microcellular foaming technology. Owning to the effectively modified crystallization via introducing CNTs/sorbitol derivatives, the ultralight and highly-reticulated PP microcellular foam was prepared with an open-cell content of 99.4% and an expansion ratio of 50, which facilitated the creation of nano-porous structures on cell walls. Hence, the as-prepared PP nanocomposite foam presented pronounced absorption capacity of 40 g/g for applied oils with recovery efficiency of 97.2%, superior thermal-insulating and mechanical performance. Furthermore, the as-achieved unique hierarchical porous structures of the PP/CNT/sorbitol foam contributed to the outstanding oil/water separation capability, separation efficiency of up-to 97.6%, ascribed to its superhydrophobicity, capillary penetration action, high porosity and open-cell content. Therefore, this work provided new insight into the feasibility of advantageous, high-efficiency, environmentally friendly, and profitable PP-based foams as oil absorbents, which, to the best of our knowledge, outperform conventional polymer absorbents in treatment of oily wastewater.

Fluorescence-Based Sensing of Pesticides Using Supramolecular Chemistry

The detection of pesticides in real-world environments is a high priority for a broad range of applications, including in areas of public health, environmental remediation, and agricultural sustainability. While many methods for pesticide detection currently exist, the use of supramolecular fluorescence-based methods has significant practical advantages. Herein, we will review the use of fluorescence-based pesticide detection methods, with a particular focus on supramolecular chemistry-based methods. Illustrative examples that show how such methods have achieved success in real-world environments are also included, as are areas highlighted for future research and development.