Environmental Remediation Applications Research Articles

Recent advancements and prospects in carbon-based nanomaterials derived from biomass for environmental remediation applications

The conversion of waste biomass into a value-added carbonaceous nanomaterial highlights the appealing power of biomass valorization. The advantages of using sustainable and cheap biomass precursors exhibit the tremendous opportunity for boosting energy production and their application in environmental remediation processes. This review emphasis the development and production of carbon-based nanomaterials derived from biomass, which possess favourable characteristics such as biocompatibility and photoluminescence. The advantages and limitations of various nanomaterials synthesised from different precursors were also discussed with insights into their physicochemical properties. The surface morphology of the porous nanomaterials is also explored along with their characteristic properties like regenerative nature, non-toxicity, ecofriendly nature, unique surface area, etc. The incorporation of various functional groups confers superiority of these materials, resulting in unique and advanced functional properties. Further, the use of these biomass derived nanomaterials was also explored in different applications like adsorption, photocatalysis and sensing of hazardous pollutants, etc. The challenges and outcomes obtained from different carbon-based nanomaterials are briefly outlined and discussed in this review.

Nanoarchitectonics of lignin-sepiolite bionanocomposite foams for application in environmental remediation

Innovative bionanocomposite foams based on precipitated Kraft lignin (Lig) and Kraft black liquor (BL) loaded with sepiolite (Sep) were prepared. BL/Sep bionanocomposites were synthesized by emulsion templating and Lig/Sep bionanocomposites were prepared by freeze-drying, resulting in stable and rigid foams. BL/Sep bionanocomposites displayed a closed cell structure, a specific area between 19 and 35 m2/g and macropores of varying sizes. The porosity in this technique is achieved by the mechanical agitation of the emulsion. On the other hand, freeze-dried Lig/Sep bionanocomposites showed open cell morphology with surface areas ranging from 1 to 4 m2/g and uniform macropores due to the ice-templating process. The presence of sepiolite in both types of bionanocomposite foams improved their stiffness, with Young's moduli ranging from 0.21 to 9.6 MPa. The capacity of the foams to adsorb metals, drugs and dyes was evaluated and it was found that the synthesized bionanocomposite foams exhibiting similar adsorption capacities as that reported for lignin. Sepiolite significantly improved the adsorption of Cu(II), Cd(II), acetaminophen (ACT), and methylene blue (MB) in BL/Sep bionanocomposites. Meanwhile, the Lig/Sep bionanocomposites demonstrated superior adsorption capacities for the Cr(VI) anion and aromatic ring compounds, including ACT and MB. In this respect, these lignin-sepiolite foams can be considered as promising materials for the removal of pollutants in aqueous solution.

Terminalia bellirica (Gaertn.) Roxb. extract-mediated green synthesis of magnesium oxide nanoparticles for multifunctional applications

Green synthesis has emerged as a pivotal facet of nanotechnology, garnering significant attention for its inherent safety and eco-friendly attributes. This study presents a novel approach utilizing phytochemicals derived from Terminalia bellirica (Gaertn.) Roxb. fruit extract for the environmentally benign synthesis of magnesium oxide (MgO) nanoparticles. The resultant MgO nanoparticles were comprehensively characterized using UV–visible spectroscopy, X-ray Diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Energy dispersive X-ray (EDX), and High-Resolution-Transmission Electron Microscope (HR-TEM). The synthesized MgO nanoparticles exhibited remarkable stability, evidenced by zeta potential of −8.84 mV and an average size of 73.41 nm. In an eco-physiological context, the application of MgO nanoparticles at a concentration of 5 mg/100 ml significantly enhanced shoot length (7.94±0.70 cm), root length (8.44±0.53 cm), moisture content (97.16±0.83%), and chlorophyll expression (18.34±0.99 mg/g fresh weight (FW)) in Trigonella foenum-graecum seedlings. Furthermore, the MgO nanoparticles demonstrated biocompatibility with soil bacteria and exhibited potent photocatalytic activity, achieving a 42% degradation efficiency of the organic dye methyl orange under UV irradiation for 60 minutes. In the realm of biomedical applications, MgO nanoparticles displayed dose-dependent cytotoxicity against human breast cancer cells (MCF-7), with an IC50 value of 37.39±0.05 µg/ml. Remarkably, MgO nanoparticles were also harnessed for their memcapacitive properties, showcasing excellent non-volatile memory characteristics, including endurance for 15,000 cycles and retention for 4000 seconds. In summary, this study underscores the multifunctional prowess of MgO nanoparticles synthesized through Terminalia bellirica fruit extract, spanning applications in plant physiology, environmental remediation, cancer therapeutics, and nanoelectronics. The environmentally conscious synthesis approach and diverse functionalities presented herein position these nanoparticles as future promising candidates for sustainable and versatile technological advancements.

Synergistic effects of β-NaFeO2 ferrite nanoparticles for photocatalytic degradation, antibacterial, and antioxidant applications.

Here, synthesis and thorough characterization of β-NaFeO2 nanoparticles utilizing a co-precipitation technique is presented. XRD analysis confirmed a hexagonal-phase structure of β-NaFeO2. SEM revealed well-dispersed spherical nanoparticles with an average diameter of 45 nm. The FTIR spectrum analysis revealed weak adsorption bands at 1054 cm-1 suggested metal-metal bond stretching (Fe-Na). UV-Visible spectroscopy indicates a 4.4 eV optical band gap. Colloidal stability of β-NaFeO2 was evidenced via Zeta potential (-28.5 mV) and Dynamic Light Scattering (DLS) measurements. BET analysis reveals a substantial 343.27 m2 g-1 surface area with mesoporous characteristics. Antioxidant analysis indicates efficacy comparable to standard antioxidants, while concentration-dependent antibacterial effects suggest enhanced efficacy against Gram-positive bacteria, particularly Streptococcus. The Photocatalytic activity of β-NaFeO2 showed significant pollutant degradation (>90% efficiency), with increased degradation rates at higher nanoparticle concentrations, indicating potential for environmental remediation applications.

Rational Design of TaON/Potassium Poly(Heptazine Imide) Heterostructure for Multifunctional Environmental Remediation

AbstractTantalum oxynitride (TaON) has recently attracted much attention due to its excellent performance as a semiconductor. However, its shortage in separation of photogenerated charges hinders the wide application, which, fortunately, can be made up by forming heterojunctions with other photocatalysts. In this study, the rational design of an inorganic‐organic TaON/potassium poly (heptazine imide) (KPHI) heterojunction is reported to separate the photo charges on the two sides of this dyadic structure. The incorporation of 20 wt.% TaON into KPHI resulted not only in H2 generation but also in a wider set of environmental remediation applications under visible light, including Cr(VI) reduction and degradation of otherwise resilient antibiotics. 20TaON/KPHI effectively reduced 17.5 ppm Cr(VI) solution in 35 min under low‐power blue light irradiation with a rate constant which is ≈6 and 30 times higher than that of pristine KPHI and TaON, respectively. Moreover, the composite demonstrated a 2‐ and 40‐fold increase in H2 evolution rate in comparison to pure KPHI and TaON, respectively. This remarkable enhancement in photocatalytic activity is ascribed to the efficient electron‐hole separation and formation of an effective Z‐scheme heterojunction. This work offers a new paradigm for designing efficient photocatalytic systems for environmental applications under low‐power LED and natural sunlight.

Green synthesis of silver deposited on copper ferrite nanoparticles for the photodegradation of dye and antibiotics

Wastewater remediation is a prominent concern that should be addressed, as it is a critical problem that damages natural resources and has a negative impact on living organisms. In this study, the synthesis of copper ferrite and silver doped-copper ferrite nanoparticles named CuFe2O4 and AgXCuFe2O4 using Monsonia burkeana (M. burkeana) as a fuel and their photocatalytic performance against the textile pollutant, Methylene blue (MB) and the pharmaceutical pollutant, sulfisoxazole (SSX) was reported. The physical, optical, spectroscopic, and surface analyses of the as-prepared nanoparticles were characterized using various techniques. XRD confirmed the crystalline structure of Ag-CuFe2O4 and the incorporation of silver on the surface of the nanoferrites. FTIR analysis indicated the formation of a single-phase spinel crystalline structure with two sub-lattices (Td and Oh). UV–Vis absorption spectra of silver-substituted copper ferrite revealed that the band gap energy (Eg) decreased with increasing crystallite size. Upon testing their degradation efficiency, at pH 12, the highest degradation of 99 % after 60 min for the 7 % AgCuFe2O4 was reported, and the rate of the reaction was found to be 0.09769 min−1. The 7 % Ag-CuFe2O4 catalyst could be reused more than 4 times with a minimal loss in photostability and the e− and •O2- were the primary species responsible for MB degradation. The photocatalyst 7 %Ag-CuFe2O4, showed a 60 % decomposition for the antibiotic after 120 min of UV-radiation. The 7 % Ag-CuFe2O4 photocatalyst displayed superior magnetic recovery capability under the action of the external magnetic field. These developments in this study offer wide promising applications in water environmental remediation.

A novel annulated dinuclear dizinc phthalocyanine cross-linked h-BN polyamides for efficient photocatalytic levofloxacin removal from real pharmaceutical wastewater

The alignment of the strong visible-light harvesting phthalocyanine and its metal derivatives onto wide-gap semiconductors has been recognized as a bright approach to fabricate highly effective photocatalysts for energy conversation and environmental restoration. However, the practical application of phthalocyanine-sensitized photocatalysts depends on their incorporation mode between phthalocyanine and basic materials. In this work, a novel high-effective dinuclear zinc (II) phthalocyanine-sensitized photocatalyst is fabricated via covalent immobilization of (Bis(82,112,152-tri-(6-oxyl-2-carboxyl)-naphthaoxytribenzo)[g,l,q]-5,10,15,20-tetraazaporphrinno[b,e]benzene) dizinc (II), (ZnTcPc)2 onto the amino functionalized hexagonal boron nitride (–NH2-h-BN) nanosheets for the first time by a facile condensation strategy. The optimized 9%(ZnTcPc)2/h-BN polymer displays remarkably improved photocatalytic activity in levofloxacin degradation from different aqueous solutions with long-term stability under visible-light illumination. Its decomposition rates reach 81.4%, 71.7% and 90.8% in deionized water, tap water and real pharmaceutical wastewater, respectively. It is approximately 7 times than that of bare h-BN nanosheets in deionized water. The detailed experimental data indicate that the critical role of for improving visible-light harvesting and photoinduced electron transfer capability of h-BN acted by the strongly chemical bond constructed between (ZnTcPc)2 and –NH2-h-BN. The improved photocatalytic mechanism for levofloxacin removal over 9%(ZnTcPc)2/h-BN polymer is proposed according to the results of ESR, UV–vis and fluorescence measurements. Therefore, this unique combination approach affords a carefully designed molecular photocatalyst with great potential application in environmental remediation.

Enhanced Generation of Reactive Oxygen Species via Piezoelectrics based on p-n Heterojunctions with Built-In Electric Field.

Tuning the charge transfer processes through a built-in electric field is an effective way to accelerate the dynamics of electro- and photocatalytic reactions. However, the coupling of the built-in electric field of p-n heterojunctions and the microstrain-induced polarization on the impact of piezocatalysis has not been fully explored. Herein, we demonstrate the role of the built-in electric field of p-type BiOI/n-type BiVO4 heterojunctions in enhancing their piezocatalytic behaviors. The highly crystalline p-n heterojunction is synthesized by using a coprecipitation method under ambient aqueous conditions. Under ultrasonic irradiation in water exposed to air, the p-n heterojunctions exhibit significantly higher production rates of reactive species (·OH, ·O2-, and 1O2) as compared to isolated BiVO4 and BiOI. Also, the piezocatalytic rate of H2O2 production with the BiOI/BiVO4 heterojunction reaches 480 μmol g-1 h-1, which is 1.6- and 12-fold higher than those of BiVO4 and BiOI, respectively. Furthermore, the p-n heterojunction maintains a highly stable H2O2 production rate under ultrasonic irradiation for up to 5 h. The results from the experiments and equation-driven simulations of the strain and piezoelectric potential distributions indicate that the piezocatalytic reactivity of the p-n heterojunction resulted from the polarization intensity induced by periodic ultrasound, which is enhanced by the built-in electric field of the p-n heterojunctions. This study provides new insights into the design of piezocatalysts and opens up new prospects for applications in medicine, environmental remediation, and sonochemical sensors.

Peroxymonosulfate enhanced photocatalytic degradation of organic dye by metal-free TpTt-COF under visible light irradiation

Recently, the activation of persulfate (PDS) by non-metallic photocatalysts under visible light has attracted significant interest in applications in environmental remediation. This study presents a pioneering investigation into the combined application of the TpTt-COF and PMS for visible light degradation of organic dyes. Synthesized orange TpTt-COF monomers exhibit exceptional crystallinity, a 2D structure, and notable stability in harsh conditions. The broad visible light absorption around a wavelength of 708 nm. The TpTt-COF emerges as a promising candidate for photocatalytic dye degradation. The study addresses high charge recombination in the TpTt-COF, highlighting the crucial role of its electron donor and acceptor for the PMS activation. Comparative analyses against traditional photocatalytic materials, such as the metal-free carbon-based material g-C3N4 and transition metal-containing TiO2, demonstrate TpTt-COF's superior performance, generating diverse free radicals. In simulated experiments, the TpTt-COF's degradation rate surpasses PMS-combined g-C3N4 by 13.9 times. and 1.6 times higher than the TpTt-COF alone. Remarkably, the TpTt-COF maintains high activity under harsh environments. Investigations into the degradation mechanism and the TpTt-COF's reusability reveal its efficiency and stability. Under visible light, TpTt-COF facilitates efficient electron–hole separation. Combining the TpTt-COF with PMS produces various radicals, ensuring effective separation and a synergistic effect. Radical quenching experiments confirm the pivotal role of O2-· radicals, while ·OH and SO4-· radicals intensify the degradation. After five cycles, TpTt-COF maintains an impressive 83.2% degradation efficiency. This study introduces an efficient photocatalytic system mediated by PMS and valuable insights into governing mechanisms for organic pollutant degradation in water environments.

Photocatalytic Activity of BaAl2O4 for Water Purification.

Degradation of dyes under natural light sources is one of the most active research areas in basic science for greener technology. In this context, the photocatalytic activity of semiconductors has received massive attention in solving water treatment-related issues as these possess enormous potential for degrading organic impurities. Here, we report that barium aluminate (BaAl2O4, BAO), which has been extensively studied for photoluminescence applications, is found to be a highly potent candidate for photocatalytic activities. We have explored the degradation of dyes (meant for water purification) by using the photocatalytic properties of pure and Dy- and Yb-codoped BAO. Crystal structure, electron microscopy, and Raman analysis of the autocombustion-synthesized pure and codoped BAO samples revealed significant morphological changes such as increased particle size and stabilization of rod-like structures. UV-vis absorbance measurements confirm the presence of multiple bandgaps in the BAO samples, which is substantiated by X-ray absorption spectroscopy measurements. Photocatalytic degradation studies of methylene blue (MB) dye (with different catalyst concentrations, dopings, and MB dye concentrations) have been carried out by using BAO. The kinetics of the photocatalytic degradation measurements has been explained by the Boltzmann distribution function, and the fastest (in less than 40 min), with more than 99% degradation of MB impurity, is reported here for the first time in BAO compounds. Synthesized BAO samples show excellent cyclic stability, which is essential for their potential applications in environmental remediation. The trade-off between the enhancement of surface area and increased particle size is considered the key parameter for controlling the photocatalytic performance of the BAO catalyst after Dy and Yb codopings.

A self-floating graphite felt evaporator: Interface wetting control and its application in environmental remediation and desalination

At present, the shortage of drinking water caused by environmental pollution hinders social development. The advent of solar interface evaporation systems provides an effective solution for clean water production. However, the issue of residual pollutants has not been adequately addressed. In this paper, we introduce BiOBr into the floating layer, which not only increases the roughness to achieve superhydrophobic performance but also photodegrades soluble pollutants. Additionally, to overcome the poor water supply capacity of carbon felt, we propose the use of a sodium alginate hydrogel, which reduces the evaporation enthalpy to 1690 J/g and increases the steam flux to 1.99 kg m−2 h−1 under 1 sun irradiation. It is hoped that the design strategies presented in this paper will provide a reference for optimizing solar evaporation systems and enhancing environmental purification.

Sn(IV)porphyrin-Incorporated TiO2 Nanotubes for Visible Light-Active Photocatalysis.

In this study, two distinct photocatalysts, namely tin(IV)porphyrin-sensitized titanium dioxide nanotubes (SnP-TNTs) and titanium dioxide nanofibers (TNFs), were synthesized and characterized using various spectroscopic techniques. SnP-TNTs were formed through the hydrothermal reaction of NaOH with TiO2 (P-25) nanospheres in the presence of Sn(IV)porphyrin (SnP), resulting in a transformation into Sn(IV)porphyrin-imbedded nanotubes. In contrast, under similar reaction conditions but in the absence of SnP, TiO2 (P-25) nanospheres evolved into nanofibers (TNFs). Comparative analysis revealed that SnP-TNTs exhibited a remarkable enhancement in the visible light photodegradation of model pollutants compared to SnP, TiO2 (P-25), or TNFs. The superior photodegradation activity of SnP-TNTs was primarily attributed to synergistic effects between TiO2 (P-25) and SnP, leading to altered conformational frameworks, increased surface area, enhanced thermo-chemical stability, unique morphology, and outstanding visible light photodegradation of cationic methylene blue dye (MB dye). With a rapid removal rate of 95% within 100 min (rate constant = 0.0277 min-1), SnP-TNTs demonstrated excellent dye degradation capacity, high reusability, and low catalyst loading, positioning them as more efficient than conventional catalysts. This report introduces a novel direction for porphyrin-incorporated catalytic systems, holding significance for future applications in environmental remediation.

Trends on barrier characteristics improvement of emerging biopolymeric composite films using nanoparticles - A review

BackgroundBio-based films have wide applications in various areas, including medical, packaging, biosensor design, and environmental remediation. Unfortunately, their associated features restricted the application windows for these bio-based films. Barrier properties, such as H2O permeability, O2 permeability, and UV-barrier properties, are among the typical qualities important in designing packaging films because they safeguard food safety and extend shelf life. MethodsEnhancing the barrier qualities has been imperative in recent years owing to its significant impact on food preservation and the valorization of natural biopolymers. The most innovative method is adding metal and metal oxide nanoparticles to the biopolymer with carefully regulated loads and parameters. This review aims to examine the barrier performance as well as their enhancement methods using metal, metal-oxide, and the synergetic effects of nanoparticles. Significant findingsThe review concludes that incorporating metallic and metallic oxide NPs into films has improved their barrier quality. The current and future materials in the property improvement field include metallic and metallic oxide nanoparticles, such as Ag, ZnO, GO, and TiO2, as well as their binary effects. Improvements to the barrier characteristics of bio-based films address the environmental and socioeconomic problems brought on by using petro-based films.

Enhanced photocatalytic activities of LaCoO3 perovskite nanostructures for degrading cationic and anionic dyes

Sustainable and cost-effective technologies are crucial for addressing environmental pollution issues. Perovskite photocatalysts have gained increased attention as a potential solution which could be accounted to their tuneable structural characteristics, flexible bandgap, and superior catalytic properties. In this study, we synthesized Lanthanum Cobaltite (LaCoO3) perovskite nanostructures via co-precipitation for photocatalytic purposes. Morphological analysis revealed LaCoO3 nanoparticles with an average size of ∼33 nm whose crystalline characteristics were investigated as a function of annealing temperatures. We found that the pure and crystalline LaCoO3 phase formed after the post-annealing process at 600°C. Photocatalytic studies showed that the degradation potential of LaCoO3 was significantly improved when hydrogen peroxide (H2O2) was added as co-catalyst system. We achieved degradation efficiencies of up to 91% and 85% for MB and methyl orange (MO), respectively. LaCoO3/H2O2 exhibited excellent photocatalytic potential for degrading both anionic and cationic organic dyes for environmental remediation applications.

Boosting tetracycline degradation of BaTiO3-based piezo-catalysts via modulating phase boundary and band structure

Piezoelectric catalysis, which converts mechanical energy into chemical activity, has important applications in environmental remediation. However, the piezo-catalytic activity of various piezoelectric materials is limited by the weak piezoelectricity as well as the mismatched band-gap, leading to inefficient electron-hole pair generation and difficult carrier migration. Here, a simple strategy combining phase boundary and energy band structure modulation was innovatively proposed to enhance the piezo-catalytic activity of BaTiO3 ferroelectric by Ce ions selecting different doping sites. Thanks to the coexistence of tetragonal (P4mm) and orthorhombic (Amm2) phases effectively flattened the Gibbs free-energy and thus enhanced the piezoelectric activity, as well as suitable energy bandwidth facilitating the carrier migration were realized in the B-sites doped Ba(Ti0.95Ce0.05)O3. The degradation rate constant k of tetracycline (TC) was high to 30.56 × 10-3 min−1, which was 2.03 times higher than that of pure BaTiO3 and superior to most representative lead-free perovskite piezoelectric materials. Theoretical calculations validated that the charge density and high O2 and OH– adsorption energy on the Ba(Ti0.95Ce0.05)O3 surface promoted more efficient •O2– and •OH radicals conversion and bettered response to piezo-catalytic reaction. This work is important to design high-performance piezo-catalysts by synergistic regulation of phase boundary and energy band structure in perovskite materials for long-term antibiotic tetracycline removal.

Biomineralization induced synthesis and self-assembly of photocatalyst-enzyme hybrid system for highly efficient environmental remediation

The photocatalyst-enzyme hybrid systems (PEHSs) provided a promising method for environmental remediation by simultaneously harnessing the power of solar-energy conversion and biocatalysis. However, the use of PEHSs for environmental remediation was restricted by a complicated synthesis and assembly process. This work explored a simple one-pot biomineralization approach to fabricate PEHS. It was found that the cytochrome enzyme could be directly self-assembled onto the biosynthesized CdS during biomineralization by Shewanella oneidensis MR-1. More strikingly, those attached cytochrome enzymes could efficiently receive the photoelectrons from the CdS and serve as the photoreduction center which formed a typical PEHS. Impressively, this bio-CdS-cytochrome PEHS exhibited an extremely high photocatalytic decolorization rate of 69.4 mg/g/min, which was the highest record ever reported for procion red H-E3B. This work provided a simple and facile approach for PEHSs fabrication, which would be promising for practical application in environmental remediation.

A customized 3D bio-macroporous cryogels for efficient and selective gold extraction

The swift and efficient extraction of gold from electronic wastes carries significant economic and environmental benefits. In the present work, chitosan and keratin were modified with vinyl pyrrolidone via grafting cryopolymerization used UV-irradiation for efficient Au(III) removal from actual electronic waste solution. The rapidly attaining adsorption equilibrium for Au(III) within just 4 h can be attributed to the biosorbent macroporous nature. Under ideal conditions (C0 = 1200 mg g−1, 308 K and pH 3), the Freundlich model exhibited superior fitting, showcasing the biosorbent's remarkable adsorption capacity for Au(III) at an impressive amount of 613.27 mg g−1. An Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES, Varian) was implemented to measure the adsorption of Au(III) and other coexisting ions. Additionally, the biosorbent displayed enhanced thermal stability and a prolonged shelf-life, indicating its potential for use in challenging environmental conditions. In addition to its stability, the material maintained its Au(III) adsorption efficiency after four consecutive usage cycles. In addition, it exhibited the capacity to specifically adsorb Au(III) from leaching solutions of electronic waste, resulting in a recovery rate of 89.2 %. The presence of amino (–NH2) and sulfide (-S-S-) functional groups on the biosorbent played a pivotal role in capturing Au(III) ions through electrostatic and chelation mechanisms. The presence of sulfide linkage and amino (–NH2) functionality, a major component of keratin is a pristine factor in this study, particularly well-suited for Au(III) extraction. The crosslinked biosorbent introduced random pores due to its random cooling process, enabling efficient diffusion and more significant Au(III) retention than traditional gels. In addition to its capacity for recovering precious metals from electronic waste, this biosorbent is a cost-effective solution with promising applications in environmental remediation and wastewater treatment.

Enhanced peroxymonosulfate activation by S-scheme AgI/Cu-BiVO4 heterojunction for efficient photocatalytic organics degradation and Microcystis aeruginosa inactivation: Performance, interfacial engineering and mechanism insight

Novel oxygen vacancies-enriched AgI/Cu-BiVO4 (ACBV) S-scheme heterojunction catalysts were constructed to boost photocatalytic organics degradation and M. aeruginosa inactivation with peroxymonosulfate (PMS) assistance. Specific interfacial charge transfer and abundant active centers were guided by introducing Cu doping and AgI coupling into BiVO4, with the catalytic activity and mechanism systematically investigated. The optimal 0.25-ACBV heterojunction exhibited 97.6% tetracycline (TC) degradation under PMS-assisted visible light and achieved effective inactivation of M. aeruginosa within 20 min (78.8%). The S-scheme heterostructure from Cu-BiVO4 to AgI and synergistic effects endowed the system with high-energy carrier transfer kinetics and strong oxygen reduction capability. Meanwhile, the redox cycling of Cu2+/Cu+ and surface oxygen defects served as electron acceptors to accelerate interfacial charge separation and as adsorption activation sites for PMS, promoting efficient mass transfer in the non-homogeneous system. This study inspires the design of high-performance S-scheme photocatalytic activators and expands their potential applications in environmental remediation.

Effects of Fe(II) and humic acid on U(VI) mobilization onto oxidized carbon nanofibers derived from the pyrolysis of bacterial cellulose

The effects of Fe(II) and humic acid on U(VI) immobilization onto oxidized carbon nanofibers (Ox-CNFs, pyrolysis of bacterial cellulose) were investigated by batch, spectroscopic and modeling techniques, with results suggesting that, Ox-CNFs exhibited fast adsorption rate (adsorption equilibrium within 3 h), high adsorption performance (maximum adsorption capacity of 208.4 mg/g), good recyclability (no notable change after five regenerations) in the presence of Fe(II) towards U(VI) from aqueous solutions (e.g., 40 % reduction and 10 % adsorption at pH 8.0), which was attributed to the various oxygen-containing functional groups, excellent chemical stability, large specific surface area and high redox effect. U(VI) adsorption increased with increasing pH from 2.0 to 5.0, then high-level plateau and remarkable decrease were observed at 5.0–6.0 and at pH > 6.0, respectively. According to FT-IR and XPS analysis, a negative correlation between U(VI) reduction and organic in the presence of Fe(II) implied that U(VI) reduction was driven by Fe(II) while inhibited by humic acid. The interaction mechanism of U(VI) on Ox-CNFs was demonstrated to be adsorption and ion exchange at low pH and reduction at high pH according to XPS and surface complexation modeling. These findings filled the knowledge gaps pertaining to the effect of Fe(II) on the transformation and fate of U(VI) in the actual environment. This carbon material with distinctive performance and unique topology offers a potential platform for actual application in environmental remediation.

Carbon Nanotubes as Adsorbents for Heavy Metals: Focus on Arsenic and Hydrargyrum Removal from Water

Water is the most common and indissoluble substance in the ecosystem. It is really sad that the development of cities, people, and industries has side effects on water resources, as they are getting worse. Heavy metals are mostly found in industries; their toxicity levels are a big challenge. The work details the latest methods employed in the removal of water contaminants with heavy metals, absorption being the technique used. Following the completeness of the literature review for various sorbents that are used to remove heavy metals from wastewater, this article details one of the possible sorbents that can play this role, using carbon nanotubes as a sorbent. Through the test, it has been demonstrated that CNTs have high efficiency, yet some shortcomings have also been shown. It should, additionally, be known that further improvement of desulfurizing agents to make them better at removing heavy metals is needed. This work demonstrates that, in comparison to IL's, which must be supplied by producers, DES's, as an alternative approach, are cheaper, more accessible to use, and much safer for the environment. In other words, the method of adsorption with functionalized CNTs + DESs proved to be the most suitable. The practical diagnostics and conclusions generated from this research should prove valuable to engineers and environmental scientists involved in carbon nanotube applications in environmental remediation.