Melamine/MIL-101(Fe)-derived magnetic carbon nanotube-decorated nitrogen-doped carbon materials as sorbent for rapid removal of organic dyes from environmental water sample

Single-Walled (Magnetic) Carbon Nanotubes in a Pectin Matrix in the Design of an Allantoin Delivery System

Single-walled carbon nanotubes (SWCNTs) outperform other materials due to their high conductivity, large specific surface area, and chemical resistance. They have numerous biomedical applications, including the magnetization of the SWCNT (mSWCNT). The drug loading and release properties of see-through pectin hydrogels doped with SWCNTs and mSWCNTs were evaluated in this study. The active molecule in the hydrogel structure is allantoin, and calcium chloride serves as a cross-linker. In addition to mixing, absorption, and swelling techniques, drug loading into carbon nanotubes was also been studied. To characterize the films, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, surface contact angle measurements, and opacity analysis were carried out. Apart from these, a rheological analysis was also carried out to examine the flow properties of the hydrogels. The study was also expanded to include N-(9-fluorenyl methoxycarbonyl)glycine-coated SWCNTs and mSWCNTs as additives to evaluate the efficiency of the drug-loading approach. Although the CNT additive was used at a 1:1000 weight ratio, it had a significant impact on the hydrogel properties. This effect, which was first observed in the thermal properties, was confirmed in rheological analyses by increasing solution viscosity. Additionally, rheological analysis and drug release profiles show that the type of additive causes a change in the matrix structure. According to TGA findings, even though SWCNTs and mSWCNTs were not coated more than 5%, the coating had a significant effect on drug release control. In addition to all findings, cell viability tests revealed that hydrogels with various additives could be used for visual wound monitoring, hyperthermia treatment, and allantoin release in wound treatment applications.

Complex treatment of oily polluted waters by modified melamine foams: from colloidal emulsions to a free oil removal

This study deals with the efficient, low-cost, and scalable treatment of oily polluted waters including colloidal emulsions, oil-in-water mixtures, and free oil removal using melamine foams (MFs) modified by ferric chloride (FeCl3). Modified foams have superhydrophobic character due to the coordination of Fe3+ with free electron pairs on nitrogen and oxygen atoms within the melamine structure. The water contact angles (WCA) were 146° ± 2°, 148° ± 4°, 153° ± 2°, and 150° ± 4° for foams modified by the solutions with concentrations of 0.001 M, 0.005 M, 0.01 M, and 0.02 M, respectively. This modification enables the efficient treatment of various oil/water systems, including oil/water colloidal emulsions (99 vol% of the droplets have dimensions below 500 nm), oil-in-water mixtures up to 40 weight % of the oil component, and "free" oil removal as it was demonstrated in this study for the first time. The emulsions containing 100 ppm diesel oil (DO) were separated with 91.4% efficiency, and the mixtures containing 20 and 40 weight % DO were separated with 99.9% efficiency. Modified foams also quickly remove free DO from the water surface, absorbing 95 g/g DO, whereas water sorption was negligible. The separation of colloidal oil in water emulsions represents the key finding of this study as it indicates the applicability of the treated MFs for the treatment of emulsified industrial wastewater. The demulsification mechanism is based on multiple diffusion processes running at different time scales, including diffusion of the emulsion into the foam and diffusion of oil droplets within the foam, combined with parallel adsorption of oil droplets onto the solid skeleton of the foam. A multiplied usage of these foams for all these niche operations was also proven. The application of our current study with previous studies on modified MFs and polyurethane for water oil separation utilization is summarized in Table S1 ESI.

Enhancing Freshwater Production via Customizable and Highly Efficient Solar-Driven Seawater Desalination

Solar-powered water generation is an appealing strategy for cost-effective and energy-sustainable seawater purification/desalination, where rational material selection and device design is crucial. Nevertheless, prevailing carbon-based photothermal materials in such systems still suffer from mediocre steam-to-water efficiency, failing to satisfy an adequate freshwater supply. Herein, we demonstrate a biomimetic corrugated evaporator (CE) affording carbon nanotube (CNT) encapsulated Fe nanocluster-decoration in the pursuit of high-efficiency seawater purification. The thus-customized CE demonstrates a maximum evaporation rate of 4.2 kg m-2 h-1 with a refraction angle of 60° and a water-lifting height of 5.5 cm, outperforming most state-of-the-art carbon-based counterparts. By employing a tailored architectural design and optimized condensing volume, the steam-to-water efficiency increases from 65.8 to 88.2% as the volume enlarges from 0.8 to 5.3 L, further harvesting a peak value of 91% under negative pressure. Light intensity simulation and experimental mechanistic investigation disclose the dual property-performance relationships between evaporator microstructure and evaporation rate, as well as between condensing device volume and steam-to-water efficiency. The universality of the theoretical guidance of this work will offer insight into the development of solar-driven evaporator construction toward simultaneous seawater desalination and clean water generation.

Co-adsorption and Fenton-like oxidation in the efficient removal of methylene blue by MIL-88B@UiO-66 nanoflowers

Development of binary MOF-on-MOF heterostructures is a research hotspot in MOFs chemistry due to the advantages elicited by a closely connected interface, which may endow more abundant functionality and even broader applications in interface chemistry. A MOF-on-MOF heterostructure was constructed by in situ growth of MIL-88B on the outer surface of UiO-66. The resultant MIL-88B@UiO-66 produced had an interesting flower-like morphology composed of MIL-88B (petal) on tetrahedral UiO-66 (core). The MIL-88B@UiO-66 heterostructure showed adsorption and Fenton-like oxidation abilities, with distinctly improved structural stability in aqueous solution compared with that of single MIL-88B. Methylene blue (MB) was selected as the target molecule to evaluate the adsorption and Fenton-like oxidation activities. The efficiency of total removal of MB was studied systematically under various operating conditions and the influencing factors were optimized. The kinetics of adsorption and catalytic oxidation were simulated to explore the interactions between MB and MIL-88B@UiO-66. The mechanisms of enhanced adsorption and Fenton-like oxidation were suggested. The cyclic removal performance and structural stability of MIL-88B@UiO-66 were also determined.

Adsorption Studies on the Removal of Anionic and Cationic Dyes from Aqueous Solutions Using Discarded Masks and Lignin

The carbon materials derived from discarded masks and lignin are used as adsorbent to remove two types of reactive dyes present in textile wastewater: anionic and cationic. This paper introduces the results of batch experiments where Congo red (CR) and Malachite green (MG) are removed from wastewater onto the carbon material. The relationship between adsorption time, initial concentration, temperature and pH value of reactive dyes was investigated by batch experiments. It is discovered that pH 5.0-7.0 leads to the maximum effectiveness of CR and MG removal. The equilibrium adsorption capacities of CR and MG are found to be 232.02 and 352.11 mg/g, respectively. The adsorption processes of CR and MG are consistent with the Freundlich and Langmuir adsorption models, respectively. The thermodynamic processing of the adsorption data reveals the exothermic properties of the adsorption of both dyes. The results show that the dye uptake processes follow secondary kinetics. The primary adsorption mechanisms of MG and CR dyes on sulfonated discarded masks and alkaline lignin (DMAL) include pore filling, electrostatic attraction, π-π interactions and the synergistic interactions between the sulphate and the dyes. The synthesized DMAL with high adsorption efficiency is promising as an effective recyclable adsorbent for adsorbing dyes, especially MG dyes, from wastewater.

Cd2+ and Zn2+ Complexes with 2,4,6-Tri(2-pyridyl)-s-Triazine and Terephthalate for Rapid, High-Capacity Adsorption of Congo Red

Three crystal complexes were designed and synthesised through the solvothermal method, with Cu²⁺ , Zn²⁺ , and Cd²⁺ ions as the metal centres and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) and terephthalate (BDC^2- ) as the ligands. Their compositions were determined to be Cd(TPTZ)Cl₂ (Cd-MOF), {[Zn(TPTZ)(BDC)] ⋅ 3H₂ O}_n (Zn-MOF), and Cu₂ (PCA)₂ (BDC)(H₂ O)₂ (Cu-MOF) (PCA^- =2-pyridinium amide), respectively. Cd-MOF can adsorb 90 % of Congo red (CR) in 10 s at room temperature and atmospheric pressure, and CR removal was complete at 20 s over a wide pH range. The adsorption capacity for CR reached 1440 mg g^-1 in 5 min. Selective adsorption was demonstrated in mixed dyes. The adsorption kinetic data agree well with the pseudo-second-order kinetic model. The Temkin model was successfully used to evaluate the adsorption isotherms of CR on Cd-MOF at room temperature, suggesting that adsorption occurs through a hybrid of monolayer and multilayer mechanisms.

Synthesis of Metal–Organic Frameworks Quantum Dots Composites as Sensors for Endocrine-Disrupting Chemicals

Hazardous chemical compounds such as endocrine-disrupting chemicals (EDCs) are widespread and part of the materials we use daily. Among these compounds, bisphenol A (BPA) is the most common endocrine-disrupting chemical and is prevalent due to the chemical raw materials used to manufacture thermoplastic polymers, rigid foams, and industrial coatings. General exposure to endocrine-disrupting chemicals constitutes a serious health hazard, especially to reproductive systems, and can lead to transgenerational diseases in adults due to exposure to these chemicals over several years. Thus, it is necessary to develop sensors for early detection of endocrine-disrupting chemicals. In recent years, the use of metal–organic frameworks (MOFs) as sensors for EDCs has been explored due to their distinctive characteristics, such as wide surface area, outstanding chemical fastness, structural tuneability, gas storage, molecular separation, proton conductivity, and catalyst activity, among others which can be modified to sense hazardous environmental pollutants such as EDCs. In order to improve the versatility of MOFs as sensors, semiconductor quantum dots have been introduced into the MOF pores to form metal–organic frameworks/quantum dots composites. These composites possess a large optical absorption coefficient, low toxicity, direct bandgap, formidable sensing capacity, high resistance to change under light and tunable visual qualities by varying the size and compositions, which make them useful for applications as sensors for probing of dangerous and risky environmental contaminants such as EDCs and more. In this review, we explore various synthetic strategies of (MOFs), quantum dots (QDs), and metal–organic framework quantum dots composites (MOFs@QDs) as efficient compounds for the sensing of ecological pollutants, contaminants, and toxicants such as EDCs. We also summarize various compounds or materials used in the detection of BPA as well as the sensing ability and capability of MOFs, QDs, and MOFs@QDs composites that can be used as sensors for EDCs and BPA.