Recent progress in magnetic polydopamine composites for pollutant removal in wastewater treatment

Various water pollution issues pose a significant threat to human water safety. Magnetic polydopamine composites (MPCs), which can be separated by magnetic fields after the adsorption process, exhibit outstanding adsorption capacity and heterogeneous catalytic properties, making them promising materials for water treatment applications. In particular, by modifying the polydopamine (PDA) coating, MPCs can acquire enhanced high reactivity, antibacterial properties, and biocompatibility. This also provides an attractive platform for further fabrication of hybrid materials with specific adsorption, catalytic, antibacterial, and water-oil separation capabilities. To systematically provide the background knowledge and recent research advances in MPCs, this paper presents a critical review of MPCs for water treatment in terms of both structure and mechanisms of effect in applications. Firstly, the impact of different PDA positions within the composite structure is investigated to summarize the optimization of properties contributed by PDA when acting as the shell, core, or bridge. The roles of various secondary modifications of magnetic materials by PDA in addressing water pollution problems are explored. It is anticipated that this work will be a stimulus for further research and development of magnetic composite materials with real-world application potential.

Smart Synthesis of Hollow Microporous Organic Capsules with a Polyaniline Modified Shell

In this work, novel hypercrosslinked polymer-based hollow microporous organic capsules with a polyaniline (PANI)-modified shell (PANI@S-HMOCs) are prepared by in-situ polymerization of aniline in the porous structure of the sulfonated hollow microporous organic capsules (S-HMOCs). PANI@S-HMOC1, PANI@S-HMOC2, and PANI@S-HMOC3 are made by adjusting S-HMOCs and aniline weight ratios of 4:1 and 3:1, and 2:1, respectively. The characterizations of PANI@S-HMOCs demonstrate that electrostatic interaction between aniline and sulfonic acid groups plays an important role in encapsulating PANI in the pores of the shell. The content of PANI showed an evident effect on the porosity of PANI@S-HMOCs, and an appropriate polyaniline loading amount may increase the surface area. PANI@S-HMOC1 and PANI@S-HMOC2 have higher BET surface areas (529 and 503 m² g^-1 ) than S-HMOCs (424 m² g^-1 ), but PANI@S-HMOC3 has lower BET surface area (380 m² g^-1 ). Based on the structural and textural features, PANI@S-HMOC2 shows good adsorption performance for Cr(VI) from aqueous media (156 mg g^-1 , pH = 2, and 27 mg g^-1 , pH = 7).

Excellent fluoride removal performance by electrospun La–Mn bimetal oxide nanofibers

A novel La–Mn bimetal oxide nanofiber adsorbent was fabricated by the combination of an electrospinning approach and heat treatment in a simple strategy to remove fluoride ions from water.

Adsorption and detoxification of pharmaceutical compounds from wastewater using nanomaterials: A review on mechanism, kinetics, valorization and circular economy

Antibiotics overuse, inappropriate conduct, and discharge have led to adverse effects on various ecosystems. The occurrence of antibiotics in surface and drinking water is a matter of global concern. It is responsible for multiple disorders, including disruption of endocrine hormones and high chronic toxicity. The hospitals, pharmaceutical industries, households, cattle farms, and aquaculture are the primary discharging sources of antibiotics into the environment. This review provides complete detail on applying different nanomaterials or nanoparticles for the efficient removal of antibiotics from the diverse ecosystem with a broader perspective. Efforts have been made to focus on the degradation pathways and mechanism of antibiotic degradation using nanomaterials. More light has been shed on applying nanostructures in photocatalysis, which would be an economical and efficient solution. The nanoscale material or nanoparticles have incredible potential for mineralizing pharmaceutical compounds in aqueous solutions at low cost, easy handling characteristics, and high efficacy. Furthermore, nanoparticles can absorb the pharmaceutical by-products and wastes at a minimum cost as they can be easily recycled. With the increasing number of research in this direction, the valorization of pharmaceutical wastes and by-products will continue to expand as we progress from old conventional approaches towards nanotechnology. The utilization of nanomaterials in pharmaceutical wastewater remediation is discussed with a major focus on valorization, energy generation, and minimization and its role in the circular economy creating sustainable development.

Fabrication, functionalization and advanced applications of magnetic hollow materials in confined catalysis and environmental remediation

Magnetic hollow-structured functional hybrid materials with unique architectures and preeminent properties have always been an area of extensive research. They represent a subtle collaboration of hollow architecture, mesoporous nanostructure and magnetic character. Owing to the merits of a large void space, low density, high specific surface area, well-defined active sites and facile magnetic recovery, these materials present promising application projections in numerous fields, such as drug delivery, adsorption, storage, catalysis and many others. In this review, recent progress in the design, synthesis, functionalization and applications of magnetic hollow-meso/nanostructured materials are discussed. The first part of the review has been dedicated to the preparation and functionalization of the materials. The synthetic protocols have been broadly classified into template-assisted and template-free methods and major trends in their synthesis have been elaborated in detail. Furthermore, the benefits and drawbacks of each method are compared. The later part summarizes the application aspects of confined catalysis in organic transformations and environmental remediation such as degradation of organic pollutants, dyes and antibiotics and adsorption of heavy metal ions. Finally, an outlook of future directions in this research field is highlighted.

Designed Core-Shell Fe3O4@Polydopamine for Effectively Removing Uranium(VI) from Aqueous Solution

Adsorbents with the combination of magnetic separation and removal performance are expected for reducing the adverse impact of nuclear pollution. In this study, the core-shell Fe₃O₄@polydopamine (Fe₃O₄@PDA) was successfully synthesized and used for removal of uranium (U(VI)) ion from aqueous solution. The abundant N-containing groups derived from PDA exist as the chelate sites for U(VI) and contribute greatly for U(VI) removal. Experimental results show that Fe₃O₄@PDA (56.39 mg g^-1) exhibits greater sorption capacity for U(VI) removal compared with the pure Fe₃O₄ (9.17 mg g^-1). The sorption isotherm can be well fitted with Freundlich model and the sorption process is endothermic and spontaneous. The removal of U(VI) can be explained by the complexation of U(VI) with -NH-, -NH₂ and C-O in the surface of Fe₃O₄@PDA by X-ray photoelectron spectroscopy (XPS) analysis.

Ultra-high adsorption of tetracycline antibiotics on garlic skin-derived porous biomass carbon with high surface area

A porous carbon material with ultra-high specific surface area was prepared from waste garlic skin, and exhibited excellent adsorption properties to TCs in a water environment.

Removal of antibiotics from aqueous solutions by nanoparticles: a systematic review and meta-analysis

Antibiotics, as one of the emerging pollutants, are non-biodegradable compounds and long-term exposure to them may affect endocrine, hormonal, and genetic systems of human beings, representing a potential risk for both the environment and human health. The presence of antibiotics in surface waters and drinking water causes a global health concern. Many researches have stated that conventional methods used for wastewater treatment cannot fully remove antibiotic residues, and they may be detected in receiving waters. It is reported that nanoparticles could remove these compounds even at low concentration and under varied conditions of pH. The current study aimed to review the most relevant publications reporting the use of different nanoparticles to remove antibiotics from aqueous solutions. Moreover, meta-analysis was conducted on the results of some articles. Results of meta-analysis proved that different nanoparticles could remove antibiotics with an acceptable efficiency of 61%. Finally, this review revealed that nanoparticles are promising and efficient materials for degradation and removal of antibiotics from water and wastewater solutions. Furthermore, future perspectives of the new generation nanostructure adsorbents were discussed in this study.

Simple Urea Immersion Enhanced Removal of Tetracycline from Water by Polystyrene Microspheres

Antibiotics pose potential ecological risks in the water environment, necessitating their effective removal by reliable technologies. Adsorption is a conventional process to remove such chemicals from water without byproducts. However, finding cheap adsorbents with satisfactory performance is still a challenge. In this study, polystyrene microspheres (PSM) were enhanced to adsorb tetracycline by surface modification. Simple urea immersion was used to prepare urea-immersed PSM (UPSM), of which surface groups were characterized by instruments to confirm the effect of immersion. Tetracycline hydrochloride (TC) and doxycycline (DC) were used as typical adsorbates. The adsorptive isotherms were interpreted by Langmuir, Freundlich, and Tempkin models. After urea immersion, the maximum adsorption capacity of UPSM at 293 K and pH 6.8 increased about 30% and 60%, achieving 460 mg/g for TC and 430 mg/g for DC. The kinetic data were fitted by first-order and second-order kinetics and Weber–Morris models. The first-order rate constant for TC adsorption on UPSM was 0.41 /h, and for DC was 0.33 /h. The cyclic urea immersion enabled multilayer adsorption, which increased the adsorption capacities of TC on UPSM by two to three times. The adsorption mechanism was possibly determined by the molecular interaction including π–π forces, cation-π bonding, and hydrogen bonding. The simple surface modification was helpful in enhancing the removal of antibiotics from wastewater with similar structures.

Highly efficient Pb(ii) and Cu(ii) removal using hollow Fe3O4@PDA nanoparticles with excellent application capability and reusability

The easily synthesized Fe₃O₄@PDA material showed excellent performance for Pb(ii) and Cu(ii) elimination from wastewater, and its adsorption mechanism was revealed.