Environmental Remediation Applications Research Articles

Synthesis of Metal-Organic Framework-Based ZIF-8@ZIF-67 Nanocomposites for Antibiotic Decomposition and Antibacterial Activities.

Toxic antibiotic effluents and antibiotic-resistant bacteria constitute a threat to global health. So, scientists are investigating high-performance materials for antibiotic decomposition and antibacterial activities. In this novel research work, we have successfully designed ZIF-8@ZIF-67 nanocomposites via sol-gel and solvothermal approaches. The ZIF-8@ZIF-67 nanocomposite is characterized by various techniques that exhibit superior surface area enhancement, charge separation, and high light absorption performance. Yet, ZIF-8 has high adsorption rates and active sites, while ZIF-67 has larger pore volume and efficient adsorption and reaction capabilities, demonstrating that the ZIF-8@ZIF-67 nanocomposite outperforms pristine ZIF-8 and ZIF-67. Compared with pristine ZIF-8 and ZIF-67, the most active 6ZIF-67@ZIF-8 nanocomposite showed higher decomposition efficacy for ciprofloxacin (65%), levofloxacin (54%), and ofloxacin (48%). Scavenger experiments confirmed that •OH, •O2-, and h+ are the most active species for the decomposition of ciprofloxacin (CIP), levofloxacin (LF), and ofloxacin (OFX), respectively. In addition, the 6ZIF-67/ZIF-8 nanocomposite suggested its potential applications in Escherichia coli for growth inhibition zone, antibacterial activity, and decreased viability. Moreover, the stability test and decomposition pathway of CIP, LF, and OFX were also proposed. Finally, our study aims to enhance the efficiency and stability of ZIF-8@ZIF-67 nanocomposite and potentially enable its applications in antibiotic decomposition, antibacterial activities, and environmental remediation.

Gamma irradiation-assisted synthesis of ultrafine AgNPs incorporated in MIL-100(Fe) for efficient catalytic reduction of dye

In this study, we report on the synthesis and characterization of ultrafine silver nanoparticles (AgNPs) incorporated in MIL-100(Fe) metal-organic frameworks (Ag@MIL-100(Fe)) for the efficient catalytic reduction of dyes in water treatment applications. The Ag@MIL-100(Fe)were synthesized using a one-step and effective technique and characterized using various techniques, including X-ray diffraction, transmission electron microscopy, and ultraviolet visible spectroscopy. The results showed that the AgNPs were highly stable and had an average size of ∼3 nm, with excellent distribution within the MIL-100(Fe) framework. The catalytic performance of the hybrid materials was evaluated using the reduction of methyl orange dye as a model reaction, and the results showed that the Ag@MIL-100(Fe) had a high catalytic activity. The enhanced catalytic activity of the nanoparticles is attributed to the synergistic effect between the AgNPs and the MIL-100(Fe) framework, which provides a highly stable and porous matrix for the efficient reduction of dyes. The results of this study demonstrate the potential of Ag@MIL-100(Fe) as a promising material for water treatment and environmental remediation applications.

Superhydrophobic coating composed of rosin acid and TiO2 with antimicrobial properties and excellent mechanical durability for oil/water separation

Developing multifunctional materials with green, lasting, and simple preparation processes is a hot topic and challenge in solving the problem of oil spill contamination. A multifunctionalized superhydrophobic coating was generated via cross-linking 3-(Trimethoxysilyl) propyl acrylate with Polyethyleneimine in a multifunctional covalent manner and modifying the cotton fabric surface with silylated modified rosin acid (RA-Si) as well as TiO2 nanoparticles. The coated samples had remarkable superhydrophobicity with self-cleaning as well as stain resistance. With bactericidal rates of 97.73 % and 98.36 %, respectively, the coated samples effectively inhibited the formation of biofilms and showed high antimicrobial performance for both Staphylococcus aureus and Escherichia coli. Meanwhile, the coated samples showed outstanding oil absorption and separation of the oil-water mixture. Both water-in-oil and oil-in-water stable emulsions would be effectively separated out of the coated samples after demulsifying. Additionally, the water droplet contact angle of the coated samples was maintained at approximately 150.0° after mechanical and chemical testing. It was noteworthy that the coated samples still exhibited satisfactory separation for stabilizing oil/water emulsions after mechanical wear and chemical corrosion treatment, indicating their excellent mechanical durability. The prepared multifunctional RA-TiO2 superhydrophobic coating has promising applications in oil-containing wastewater treatment and environmental remediation.

Reduced graphene oxide/TiO2/NiFe2O4 nanocomposite as a stable photocatalyst and strong antibacterial agent

In this study, we prepared reduced graphene oxide (rGO)/titanium dioxide (TiO2)/nickel ferrite (NiFe2O4) nanocomposites with different mass ratios of rGO, TiO2, and NiFe2O4 by a simple hydrothermal method. These nanocomposites were found to exhibit enhanced visible light harvesting, reduced electron–hole recombination, and improved magnetic properties compared to rGO, TiO2, and NiFe2O4. The study evaluated the photocatalytic and antibacterial activity of the nanocomposites, with particular emphasis on the GTN211 (with a mass ratio of 2:1:1 for rGO:TiO2:NiFe2O4) nanocomposite. The results showed that the GTN211 nanocomposite exhibited the best photocatalytic performance under both UV and visible light irradiation, achieving 95 and 89% degradation of Methylene Blue dye in 15 min, respectively. The study also investigated the photodegradation mechanism using various scavengers and found that holes were the main active species in the process. In addition to photocatalytic activity, the GTN211 nanocomposite also showed good antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria, with the minimum inhibitory concentration of 1 mg mL−1 for both bacteria and a minimum bactericidal concentration of 0.8 and 1 mg mL−1, respectively. Hence, the GTN211 nanocomposite has potential as a material for environmental remediation and biomedical applications. The combination of photocatalytic and antibacterial activity makes this material a promising candidate for a wide range of applications.

Multifunctional characteristics of biosynthesized CoFe2O4@Ag nanocomposite by photocatalytic, antibacterial and cytotoxic applications

Carissa carandas, a traditional medicinal herb with a high concentration of antioxidant phytochemicals, has been used for thousands of years in the Ayurveda, Unani, and homoeopathic schools of medicine. By employing Carissa carandas bark extract as a reducing and capping agent in green biosynthesis, we extend this conventional application to produce CoFe2O4 and CoFe2O4@Ag nanocomposite. A variety of techniques have been used to characterize the synthesised nanocomposite, including UV–Vis, FTIR, XRD, FESEM, EDX, and BET. The CoFe2O4 and CoFe2O4@Ag nanocomposite demonstrated promising antibacterial action against human bacterial pathogens like B. subtilis and S. aureus as gram positive and P. aeruginosa and E. coli as gram negative with inhibition zones of 24.3 ± 0.57, 17.4 ± 0.75 and 20.5 ± 0.5, 19.8 ± 1.6 mm respectively, and the obtained results were superior to the nanocomposite without silver. Moreover, in-vitro cytotoxicity effects of biosynthesized CoFe2O4 and CoFe2O4@Ag were performed on the human breast cancer cell MCF-7. It was found that the MCF-7 cells' 50% inhibitory concentration (IC50) was 60 μg/mL. Additionally, biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite was used to demonstrate the photocatalytic eradication of Rhodamine Blue (RhB). Due to the addition of Ag, which increases surface area, conductivity, and increased charge carrier separation, the CoFe2O4@Ag nanocomposite exhibits a high percentage of photocatalytic degradation of ⁓ 98% within 35 min under UV light irradiation. The photocatalytic performance of as-synthesised nanocomposite was evaluated using dye degradation-adsorption in both natural light and dark condition. Under dark conditions, it was found that 2 mg mL−1 CoFe2O4@Ag in RhB aqueous solution (5 ppm) causes dye adsorption in 30 min with an effectiveness of 72%. Consequently, it is anticipated that the CoFe2O4@Ag nanocomposite will be a promising photocatalyst and possibly a noble material for environmental remediation applications.

Degradation of toxic textile effluent rhodamine-B dyes using oxygen doped graphitic carbon nitride nanosheets

A metal-free oxygen-doped graphitic carbon nitride (O-gCN) is prepared by thermal decomposition techniques using urea and oxalic acid (OA). The O-gCN physio-chemical properties are obtained by using different analytical analyses. The O-gCN is utilized as a photocatalyst and applied to degrade rhodamine-B toxic environmental dye. The higher photocatalytic ability of O-gCN is ascribed to the nanostructure with a porous nature. In addition, the porous nature of prepared O-gCN initiated more reactive sites for the degradation of target pollutants. The dopant oxygen atoms in the gCN tri-s-triazine units have extended enormous light absorption capability in the visible range. Radical scavenging experiments exhibited that the reactive radicals played a key role in the photocatalytic degradation of rhodamine B (RhB). The treated waters' toxic and non-toxic nature is observed using mung bean seed germination. Hence, this present study portrayed a simple, eco-friendly, and cost-effective technique to prepare O-gCN nanosheets for environmental remediation applications.

Synthesis of SmMnO3/Sm2O3 nanocomposites as efficient photocatalysts for organic dye degradation by sol gel pechini method

In this research, we present SmMnO3/Sm2O3 nanocomposites as a novel ferromagnetic photocatalyst, synthesized through a straightforward sol-gel Pechini method utilizing citric acid and oxalic acid as fuels. Achieving the desired morphology involved varying the fuel type and calcination temperature. Comprehensive physicochemical characterizations were conducted using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller BET. With a band gap of 2.1 eV in the visible range, the SmMnO3/Sm2O3 nanocomposites exhibit promising optical properties. The photocatalytic prowess of these nanocomposites was systematically assessed against Malachite Green and Acid Red, with optimization of key parameters such as light source, pollutant concentration, and catalyst dosage. Notably, the peak photocatalytic activity was observed for Malachite Green, achieving an impressive 96% degradation under visible light within 120 min. The elucidation of the photocatalytic mechanism employed scavengers, revealing the pivotal role of OH• in the photodegradation process. Recycling experiments demonstrated consistent and acceptable results over five cycles, affirming the recyclability and durability of the SmMnO3/Sm2O3 nanocomposites. This study introduces a novel ferromagnetic photocatalyst with notable photocatalytic efficiency, emphasizing its potential applications in environmental remediation. The novelty of this work lies in the introduction of a new nanocomposite for photocatalysis in visible light, achieving high efficiency within a short time frame of 120 min.

Facile fabrication of binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite with Z-scheme heterojunction for efficient photocatalytic H2 production and CO2 reduction under visible light

A binary g-C3N4/NH2-MIL-125(Ti) MOF nanocomposite was fabricated through a facile sonochemical-assisted thermal approach for enhanced photocatalytic H2 production and CO2 reduction under visible light. Compared to pure g-C3N4, the g-C3N4/MOF photocatalyst showed enhanced visible light absorption with promoted charge carrier separation which increased the H2 production rate and the CO2 reduction into CH4 and CO. This enhancement was attributed to the successfully constructed Z-scheme heterojunction in addition to the visible-active, large surface area and highly CO2 adsorbable NH2-MIL-125(Ti) MOF. The highest H2 production of 480 µmol g−1 was exhibited over the g-C3N4/NH2-MIL-125(Ti) nanocomposite with 20 wt% MOF. Similarly, the highest CO production rate of 338 µmol g−1 was achieved with 20 wt% MOF composite. However, for the CH4 product gas, it was observed that the highest production rate was attained with pure g-C3N4 which reveals the NH2-MIL-125(Ti) MOF selectivity towards CO production instead of CH4. Among all the investigated sacrificial agents for H2 production, methanol was the best. The performance of CO2 reduction process was found to be increasing with the pressure increase. Furthermore, the stability investigations revealed continuous productions of H2, CO and CH4 over the C3N4/MOF photocatalyst in multiple cyclic runswithout any significant photocatalyst deactivation. This study provides new ideas for the fabrication of cheap, efficient and easy-synthesized nanomaterials for energy production and environmental remediation applications.

Novel interface engineering of LDH-based materials on Mg alloy for efficient photocatalytic systems considering the geometrical linearity of condensed phosphates

This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide (LDH) nanoflakes, exploring their application as a photocatalyst, and investigating the influence of condensed phosphates’ geometric linearity on their photocatalytic properties. Herein, the MgO film, obtained by plasma electrolysis of AZ31 Mg alloys, was modified by growing an LDH film, which was further functionalized using cyclic sodium hexametaphosphate (CP) and linear sodium tripolyphosphate (LP). CP acted as an enhancer for flake spacing within the LDH structure, while LP changed flake dispersion and orientation. Consequently, CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis, effectively degrading organic dyes like Methylene blue (MB), Congo red (CR), and Methyl orange (MO). The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules. Furthermore, the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH, leading to its superior photocatalytic performance compared to LP@LDH. Specifically, LP@LDH demonstrated notable degradation efficiencies of 93.02%, 92.89%, and 88.81% for MB, MO, and CR respectively, over a 40 min duration. The highest degradation efficiencies were observed in the case of the CP@LDH sample, reporting 99.99% for MB, 98.88% for CR, and 99.70% for MO. This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation, offering promising prospects for environmental remediation and water detoxification applications.

Impact of polypyrrole units (pyr*n; n=3, 5, 7, or 9) on the adsorption and excitation dynamics of enrofloxacin antibiotic interaction with hafnium-doped graphene/boron nitride (Hf@GP/BN) heterostructure: A theoretical perspective

This research work focuses on investigating on influence of pyrrole units (pyr) on the structural stability, reactivity, adsorption potential, bonding variation, and the visible-light interactions of enrofloxacin (xacin) antibiotic with hafnium-doped graphene/boron nitride (Hf@GP_BN) heterostructure within the framework of hybrid exchange-correlation functional and the Monte Carlo molecular simulations. The interaction of enrofloxacin (xacin) with the hybrid surface pyr*n_Hf@GP_BN (where n = 3, 5, 7, or 9) provided insights into the effects of changing the polypyrrole (pyr) chain length on the resulting interactions: xacin_pyr3_Hf@GP_BN, xacin_pyr5_Hf@GP_BN, and xacin_pyr7_Hf@GP_BN respectively to gain more efficient degradation capabilities and the influence of the increase polymer chain. The calculated energy gap decreases due to the increase in LUMO energy experienced upon the addition another of ring, nonetheless when the length of the polypyrrole was further adjusted to seven, the energy gap of the composite increased from 2.184 eV to 2.205 eV which is in the range of semi-conductor to support efficient electron excitation. Results of the molecular dynamic (MD) simulation reveal that while the potential energy of the system decreased for all pyr*n_Hf@GP_BN combinations, the magnitude of the potential energy reduction varied with different pyr chain lengths. Pyr3 exhibited the least reduction of 1310.899 ± 36.119 kcal/mol, followed by 1402.128 ± 38.678 for pyr5, 1511.129 ± 40.494 for pyr7, and 1616.720 ± 43.445 kcal/mol for pyr9, which displayed the most substantial reduction. Longer pyr chains (pyr7 and pyr9) seem to have stronger attractive interactions with enrofloxacin, leading to more significant energy reductions. This indicates that longer pyr chains are more effective in stabilizing the interactions between the antibiotic and the hybrid surface. While the UV-excitation analysis revealed that an increase in the polypyrrole chain length led to a decrease in the wavelength for both the adsorbent and the interactions, decreasing order of exciton binding energy is observed as: 0.602585, 0.606008, and 0.597378 for xacin_pyr3_Hf@GP_BN, xacin_pyr5_Hf@GP_BN, and axacin_pyr7_Hf@GP_BN respectively which is below the 1.9 eV benchmark of efficient materials for photodegradation. The findings could contribute to the broader field of photocatalysis, potentially informing the design of more effective photocatalytic materials. Therefore, research contributes to the development of more efficient methods for antibiotic degradation, with potential applications in environmental remediation.

The metabolic mechanisms of Cd-induced hormesis in photosynthetic microalgae, Chromochloris zofingiensis

Cadmium, an environmental pollutant, is highly toxic and resistant to degradation. It exhibits toxicity at elevated doses but triggers excitatory effects at low doses, a phenomenon referred to as hormesis. Microalgae, as primary producers in aquatic ecosystems, demonstrate hormesis induced by cadmium, though the specific mechanisms are not yet fully understood. Consequently, we examined the hormesis of cadmium in Chromochloris zofingiensis. A minimal Cd2+ concentration (0.05 mg L−1) prompted cell proliferation, whereas higher concentrations (2.50 mg L−1) inhibited growth. The group exposed to higher doses exhibited increased levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT). Contrastingly, the group exposed to low doses exhibited a moderate antioxidant response without significantly increasing ROS. This implies that increased levels of antioxidative components counteract excessive ROS, maintaining cellular redox balance and promoting growth under conditions of low Cd2+. Validation experiments have established that NADPH oxidase-derived ROS primarily coordinates the hormesis effect in microalgae. Comparative transcriptome analysis has proved the involvement of antioxidant systems and photosynthesis in regulating hormesis. Notably, Aurora A kinases consistently displayed varying expression levels across all Cd2+ treatments, and their role in microalgal hormesis was confirmed through validation with SNS-314 mesylate. This study unveils the intricate regulatory mechanisms of Cd-induced hormesis in C. zofingiensis, with implications for environmental remediation and industrial microalgae applications.

Synthesis of a hybrid phase FeCoWO4/g‐C3N4 heterojunction composite for enhanced photocatalytic degradation of MB under visible light

AbstractRecently, the environmental contamination caused by toxic dyes has posed a severe threat to human health. Semiconductor‐based photocatalysis is gaining a lot of attention due to its potential applications in environmental remediation. Herein, photocatalytic reactive FeCoWO4/g‐C3N4 nanocomposites were prepared through a facile route hydrothermal process. The bare FeCoWO4, g‐C3N4 and FeCoWO4/g‐C3N4 nanocomposites possess specific features, including reactive surface sites, improved efficiency of charge transfer, and accelerated separation of photogenerated electron‐hole pairs. As a result, the photocatalytic activity towards methylene blue dye (MB) degradation activity of FeCoWO4/g‐C3N4 nanocomposites is significantly improved. Thus, photocatalysts exhibited the highest degradation activities and could remove 91.5 % of MB dye within 120 minutes of visible light irradiation. The enhanced photocatalytic activity with excellent recyclability shows potential for the practical application of FeCoWO4/g‐C3N4 nanocomposites for wastewater treatment.

Efficient sunlight-assisted degradation of organic dyes using V2O3/g-C3N4 nanocomposite catalyst

This study reports the synthesis of vanadium oxide (V2O3) and graphitic carbon nitride (g-C3N4) nanocomposite for simple sunlight-assisted degradation of Methylene Blue(MB) and Rhodamine B (RhB) dyes. Herein, the V2O3 and g-C3N4 are synthesized via hydrothermal and thermal decomposition techniques, respectively. X-ray diffraction (XRD) analysis confirms the formation of the rhombohedral and hexagonal structures of V2O3 and g-C3N4 in the nanocomposite, respectively, while scanning electron microscopy (SEM) reveals the sheet-like morphology of g-C3N4 and V2O3 nanoparticles. The optical band gap of the nanocomposite is estimated as 1.89 eV using a Tauc's plot generated from UV–Vis reflectance spectroscopy. The as-synthesized nanocomposite exhibits an excellent dye degradation efficacy displaying a 100 % degradation of RhB and 90 % degradation of MB dyes within 1 h of exposure to daylight. This performance is attributed to the synergistic effect of the V2O3/g-C3N4 nanocomposite wherein the composite benefits from the large surface area and high visible light adsorption of g-C3N4, combined with the active catalytic sites of the rhombohedral V2O3 structure, resulting in its high efficiency for photocatalytic dye degradation. Scavenger studies confirm the hydroxyl (.OH) radicals and oxygen (O2−.) radicals as the primary reactive species in the degradation process MB. Furthermore, the catalyst exhibited remarkable stability over three cycles of photocatalysis thus confirming its utility for real-time environmental remediation applications.

Highly Efficient Liquid-Phase Exfoliation of Layered Perovskite-like Titanates HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) into Nanosheets

Nanosheets of layered perovskite-like oxides attract researchers as building blocks for the creation of a wide range of demanded nanomaterials. However, Ruddlesden–Popper phases are difficult to separate into nanosheets quantitatively via the conventional liquid-phase exfoliation procedure in aqueous solutions of bulky organic bases. The present study has considered systematically a relatively novel and efficient approach to a high-yield preparation of concentrated suspensions of perovskite nanosheets. For this, the Ruddlesden–Popper titanates HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) have been intercalated by n-alkylamines with various chain lengths, exposed to sonication in aqueous tetrabutylammonium hydroxide (TBAOH) and centrifuged to separate the nanosheet-containing supernatant. The experiments included variations of a wide range of conditions, which allowed for the achievement of impressive nanosheet concentrations in suspensions up to 2.1 g/L and yields up to 95%. The latter were found to strongly depend on the length of intercalated n-alkylamines. Despite the less expanded interlayer space, the titanates modified with short-chain amines demonstrated a much higher completeness of liquid-phase exfoliation as compared to those with long-chain ones. It was also shown that the exfoliation efficiency depends more on the sample stirring time in the TBAOH solution than on the sonication duration. Analysis of the titanate nanosheets obtained by means of dynamic light scattering, electron and atomic force microscopy revealed their lateral sizes of 30–250 nm and thickness of 2–4 nm. The investigated exfoliation strategy appears to be convenient for the high-yield production of perovskite nanosheet-based materials for photocatalytic hydrogen production, environmental remediation and other applications.

3D Motion Manipulation for Micro- and Nanomachines: Progress and Future Directions.

In the past decade, micro- and nanomachines (MNMs) have made outstanding achievements in the fields of targeted drug delivery, tumor therapy, microsurgery, biological detection, and environmental monitoring and remediation. Researchers have made significant efforts to accelerate the rapid development of MNMs capable of moving through fluids by means of different energy sources (chemical reactions, ultrasound, light, electricity, magnetism, heat, or their combinations). However, the motion of MNMs is primarily investigated in confined two-dimensional (2D) horizontal setups. Furthermore, three-dimensional (3D) motion control remains challenging, especially for vertical movement and control, significantly limiting its potential applications in cargo transportation, environmental remediation, and biotherapy. Hence, an urgent need is to develop MNMs that can overcome self-gravity and controllably move in 3D spaces. This review delves into the latest progress made in MNMs with 3D motion capabilities under different manipulation approaches, discusses the underlying motion mechanisms, explores potential design concepts inspired by nature for controllable 3D motion in MNMs, and presents the available 3D observation and tracking systems.

Detection and sorption of heavy metal ions in aqueous media using Zn-based luminescent metal-organic framework

In this study, we present the synthesis and comprehensive characterisation of a novel, luminescent Metal-Organic Framework (MOF) denoted as PUC7, derived from Zn(NO3)2·6H2O, 1,2-di(4-pyridyl)ethylene, and 2-amino-terephthalic acid through solvothermal method. The PUC7 was successfully characterised using many techniques, including single crystal X-ray diffraction, powder X-ray diffraction, FTIR spectroscopy, BET surface area analysis, FESEM imaging, XPS, UV–visible spectroscopy, and zeta potential measurements. Remarkably, PUC7 exhibited high luminescence properties and water stability. The luminescence properties were utilised for the detection of heavy metal ions. Consequently, PUC7 displayed exceptional selectivity and sensitivity towards W6+ and V5+, with impressively low detection limits of 0.17 μM and 0.22 μM, along with high quenching constant values of 2.5 × 105 M−1 and 1.1 × 105 M−1, respectively. Additionally, we explored PUC7′s proficiency in removing W6+ and V5+ ions from aqueous solution, revealing maximum adsorption efficiencies of 476.2 mg/g and 460.8 mg/g, respectively, fitting well with the Langmuir adsorption model and exhibiting second-order kinetics. Encouragingly, PUC7 demonstrated reusability for up to five cycles in removing W6+ and V5+ ions. Altogether, this research underscores the potential of PUC7 as a versatile and promising tool for efficiently detecting and removing W6+ and V5+ ions from water, with implications for environmental remediation and water purification applications.

Tetracycline adsorption/desorption by raw and activated Tunisian clays

Clay-based adsorbents have applications in environmental remediation, particularly in the removal of emerging pollutants such as antibiotics. Taking that into account, we studied the adsorption/desorption process of tetracycline (TC) using three raw and acid- or base-activated clays (AM, HJ1 and HJ2) collected, respectively, from Aleg (Mazzouna), El Haria (Jebess, Maknessy), and Chouabine (Jebess, Maknessy) formations, located in the Maknessy-Mazzouna basin, center-western of Tunisia. The main physicochemical properties of the clays were determined using standard procedures, where the studied clays presented a basic pH (8.39–9.08) and a high electrical conductivity (446–495 dS m−1). Their organic matter contents were also high (14–20%), as well as the values of the effective cation exchange capacity (80.65–97.45 cmolckg−1). In the exchange complex, the predominant cations were Na and Ca, in the case of clays HJ1 and AM, while Mg and Ca were dominant in the HJ2 clay. The sorption experimental setup consisted in performing batch tests, using 0.5 g of each clay sample, adding the selected TC concentrations, then carrying out quantification of the antibiotic by means of HPL-UV equipment. Raw clays showed high adsorption potential for TC (close to 100%) and very low desorption (generally less than 5%). This high adsorption capacity was also present in the clays after being activated with acid or base, allowing them to adsorb TC in a rather irreversible way for a wide range of pH (3.3–10) and electrical conductivity values (3.03–495 dS m−1). Adsorption experimental data were studied as regards their fitting to the Freundlich, Langmuir, Linear and Sips isotherms, being the Sips model the most appropriate to explain the adsorption of TC in these clays (natural or activated). These results could help to improve the overall knowledge on the application of new low-cost methods, using clay based adsorbents, to reduce risks due to emerging pollutants (and specifically TC) affecting the environment.

Exploration of risk analysis and elimination methods for a Cr(VI)-removal recombinant strain through a biosafety assessment in mice

Though recombinant strains are increasingly recognized for their potential in heavy metal remediation, few studies have evaluated their safety. Moreover, biosafety assessments of fecal-oral pathway exposure at country as well as global level have seldom analyzed the health risks of exposure to microorganisms from a microscopic perspective. The present study aimed to predict the long-term toxic effects of recombinant strains by conducting a subacute toxicity test on the chromium-removal recombinant strain 3458 and analyzing the gut microbiome. The available disinfection methods were also evaluated. The results showed that strain 3458 induced liver damage and affected renal function and lipid metabolism at 1.0 × 1011 CFU/mL, which may be induced by its carrier strain, pET-28a. Strain 3458 poses the risk of increasing the number of pathogenic bacteria under prolonged exposure. When 500 mg L−1 chlorine-containing disinfectant or 250 mg L−1 chlorine dioxide disinfectant was added for 30 min, the sterilization rate exceeded 99.9 %. These findings suggest that existing wastewater disinfection methods can effectively sterilize strain 3458, ensuring its application value. The present study can serve a reference for the biosafety evaluation of the recombinant strain through exposure to the digestive tract and its feasibility for application in environmental pollution remediation.

Photocatalytic and adsorption behavior of a new efficient LaxNiyMn3–(x+y)O4/SiO2 composite for environmental remediation application

Environmental remediation of organic contaminants has recently received significant attention, necessitating the development of energy-efficient, cost effective, and environment-friendly catalysts. In this study, novel dual-doped LaxNiyMn3–(x+y)O4 nanoparticles (NPs) and their composite with an adsorptive material (mesoporous silica) were synthesized using a low-cost, environment-friendly coprecipitation technique. The as-prepared LaxNiyMn3–(x+y)O4 NPs and their composite were studied via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier-transform infrared (FTIR) spectroscopy, and ultraviolet–visible spectroscopy. XRD analysis revealed that the LaxNiyMn3–(x+y)O4 NPs possessed a crystalline structure. FESEM showed that LaxNiyMn3–(x+y)O4 NPs were spherical with diameters ranging from 60 to 100 nm. The presence of metal–oxygen bonds in the LaxNiyMn3–(x+y)O4 NPs was confirmed by FTIR analysis. The LaxNiyMn3–(x+y)O4 NPs could degrade crystal violet (CV) dye under visible light with a percentage degradation of 82%, which increased to 92% with the addition of 0.5 mL of 6% H2O2 solution. Furthermore, to increase the adsorption ability of the LaxNiyMn3–(x+y)O4 NPs, a composite LaxNiyMn3–(x+y)O4/SiO2 was synthesized. Under dark conditions, the adsorption percentage of the LaxNiyMn3–(x+y)O4 NPs was 58%, whereas that of LaxNiyMn3–(x+y)O4/SiO2 reached 73%. The adsorption process was further explored using adsorption isotherms and reaction kinetic models. The central composite rotatable design of response surface methodology was used to statistically maximize the adsorption of CV by optimizing factors such as time (40 min), pH (8.68), and composite dose (12 mg). The prominent diffraction peak in the XRD pattern and the large surface area (532 m2/g) determined via Brunauer–Emmett–Teller analysis of the composite confirmed its unique porous characteristics, illustrating its high capacity for adsorbing pollutants inside the porous network. Studies on the degradation efficiency and adsorption–photocatalysis synergy suggest the substantial potential of the synthesized composite for application in environmental remediation.

Advancing energy and water solutions: Unleashing the potential of Nd2S3:Ni9S8 thin film for supercapacitors and sustainable water purification

AbstractThe research was done on the creation and use of bi‐metal sulfide thin film, Nd2S3:Ni9S8. 41 nm‐sized crystallites with 80% crystallinity were found in the material. The evaluated optical characteristics showed a 2.9 eV band gap energy. The presence of Nd3d, S2p, and Ni2p in the created material was confirmed by X‐ray photoelectron spectroscopy. Voltammetry tests were carried out to assess the electrochemical characteristics. With a value of 750 Fg−1, the findings obtained showed remarkable supercapacitive capability. Additionally, a thorough examination was done to learn more about the material's potential as a photocatalyst. Malachite green dye, fuberidazole, and phenol were used as environmental contaminants to test the thin films' photocatalytic degradation effectiveness. The highest degradation was found for fuberidazole with a rate constant of 2.46x10−2 min−1. The results demonstrated the versatility of thin films and their efficacy in degrading these pollutants, highlighting their potential for environmental remediation applications.