Adsorption of isonicotinic acid from aqueous solution using multi-walled carbon nanotubes/Fe3O4

Emerging nanomaterials incorporated in membranes for polyfluoroalkyl substances (PFAS) removal from water: A review

Water purification become more challenging day by day, due to novel anthropogenic pollutants such as per- and polyfluoroalkyl substances (PFAS) used in nonstick cookware, firefighting foams, packaging etc. PFAS has adverse effects on human health and ecosystem and their physicochemical properties and unique molecular structures make the conventional water treatment methods more challenging. Among the novel PFAS removal technologies, nanomaterials incorporated in membranes are regarded as promising membrane technology for the treatment of PFAS. This review explores the incorporation of nanomaterials in membranes for PFASs removal, examining both current applications and future prospects. Nanomaterials possessing excellent features when incorporated in membranes can enhance their properties and hence makes this technology a potential candidate for PFAS removal. In this critical review, the relationships between membrane performance and properties are studied. Challenges and limitations such as high production costs, stability of nanomaterials within membranes, non-uniform distribution of nanomaterials in membrane matrices, and potential toxicity associated with nanomaterials are identified. This analysis also underscores research gap, prompting further exploration and development such as large-scale production and commercialization of mixed matrix membrane systems, optimization of membrane fabrication techniques, and the exploration of additional 2D nanomaterials.

Application of magnetic carbon nanocomposite from agro-waste for the removal of pollutants from water and wastewater

Water pollution has significant impact on water usage, and various contaminants, such as organic and inorganic compounds, heavy metals, dyes, pharmaceuticals compounds, pathogens and radioactive compounds, are implicated. The quest for globalisation, structural developments and other related anthropogenic activities promote the release of contaminants that induce water pollution. Hence, treatment and remediation options that can remove pollutants from watercourses and wastewater have been developed. Applied nanotechnology using carbon nanocomposites has recently drawn attention because it has the advantages of low preparation cost, high surface area, pore volume and environmental stability. Magnetic carbon nanocomposites usually exhibit excellent performance in adsorbing contaminants from aqueous solutions, and thus expanding the use of nanotechnology in water treatment is of great importance. Therefore, this review explores the geographical outlook of water pollution, sources of water pollution and types of contaminants found in water and discusses the use of carbon nanocomposites as an emerging sustainable technology for water pollutant removal. The various properties of carbon-based composites influence the extent of pollutant adsorption during water treatment processes. Most carbon-based nanocomposites are generated from biomass produced by agro-waste materials. Magnetic activated carbon nanocomposites produced from walnut shells and rice husk waste can remove 78% of Cd(II) from contaminated aqueous systems. Magnetic nanocomposites from peanut shell, tea waste, curcumin nanoparticles, sunflower head waste, rice husk, hydrophyte biomass, palm waste and sugarcane bagasse facilitate hydrothermal carbonisation, chemical precipitation, co-precipitation, chemical activation, calcination and fast pyrolysis. These nanocomposites have benefitted wastewater treatment by increasing efficiency in removing pharmaceutical, dye and organic contaminants, such as promazine, ciprofloxacin, amoxicillin, rhodamine 6G, methyl blue, phenol and phenanthrene. Hence, this review discusses the relatively low costs, good biocompatibility, large surface-to-volume ratio, magnetic separation capability and reusability carbon materials and highlights the advantages of using magnetic carbon nanocomposites in the removal of contaminants from water or wastewater through adsorption mechanisms.

Design of nanomaterials for the removal of per- and poly-fluoroalkyl substances (PFAS) in water: Strategies, mechanisms, challenges, and opportunities

Due to their persistent and pervasive distribution and their adverse effects on human health, the removal of per- and polyfluoroalkyl substances (PFAS) from the environment has been the focus of current research. Recent studies have shown that engineered nanomaterials provide great opportunities for their removal by chemical, physical and electrochemical adsorption methods, or as photo- or electrocatalysts that promote their degradation. This review summarizes and discusses the performance of recently reported nanomaterials towards PFAS removal in water treatment applications. We discuss the performance, mechanisms, and PFAS removal conditions of a variety of nanomaterials, including carbon-based, non-metal, single-metal, and multi-metal nanomaterials. We show that nanotechnology provides significant opportunities for PFAS remediation and further nanomaterial development can provide solutions for the removal of PFAS from the environment. We also provide an overview of the current challenges.

Surface modified polythiophene/Al2O3 and polyaniline/Al2O3 nanocomposites using poly(vinyl alcohol) for the removal of heavy metal ions from water: kinetics, thermodynamic and isotherm studies

In this study, polythiophene/Al₂O₃ (PTh/Al₂O₃) and polyaniline/Al₂O₃ (PAn/Al₂O₃) nanocomposites in the presence of poly(vinyl alcohol) (PVA) as the surfactant were synthesized via in situ chemical oxidative polymerization method in aqueous medium. The synthesized nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Results indicated that the Al₂O₃ and poly(vinyl alcohol) influenced the properties of synthesized nanocomposites. The aim of this research was to investigate the sorption characteristics of polythiophene and polyaniline nanocomposites for the removal of heavy metal cations including Pb(II), Zn(II) and Cd(II) from aqueous solution. The factors that affected the adsorption equilibrium as well as the removal efficiency of the nanoadsorbents, i.e., contact time, metal ion concentration, pH and adsorption conditions were investigated in detail. From the kinetic results, it was concluded that the pseudo-second-order kinetic model was found to be the best at describing the adsorption process for Pb(II), Zn(II) and Cd(II) on PTh-PVA/Al₂O₃ and PAn-PVA/Al₂O₃. In addition, thermodynamic analysis suggests the endothermic and spontaneous nature of the present adsorption process with increased entropy on PTh-PVA/Al₂O₃ and PAn-PVA/Al₂O₃. The results suggest polythiophene, polyaniline and their nanocomposites have great potential to be used as efficient absorbent for the removal of heavy metal ions from water.

Nano Porous Carbon Derived from Citrus Pomace for the Separation and Purification of PMFs in Citrus Processing Wastes

The by-product of citrus juice processing is a huge source of bioactive compounds, especially polymethoxyflavones (PMFs) and fibers. In this study, a method for the separation and purification of PMFs from citrus pomace was established based on citrus nanoporous carbon (CNPC) enrichment. Different biomass porous carbons were synthesized, their adsorption/desorption characteristics were evaluated, and the CNPCs from the peel of Citrus tangerina Tanaka were found to be best for the enrichment of PMFs from the crude extracts of citrus pomace. Using this method, six PMF compounds including low-abundant PMFs in citrus fruits such as 5,6,7,4'-tetramethoxyflavone and 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone can be simultaneously obtained, and the purities of these compounds were all higher than 95%, with the highest purity of nobiletin reaching 99.96%. Therefore, CNPCs have a great potential for the separation and purification of PMFs in citrus processing wastes, potentially improving the added value of citrus wastes. We also provide a method reference for disposing of citrus pomace in the future.