Ultrasound-assisted synthesis of mixed calcium magnesium oxide (CaMgO2) nanoflakes for photocatalytic degradation of methylene blue

Enhanced ultrasonic degradation of methylene blue using a catalyst-free dual-frequency treatment

Methylene blue is one of the most common pollutants found in wastewater, primarily due to its widespread use in the dye industry. Consequently, it is imperative to explore environmentally friendly and efficient methods for degrading this pollutant into non-toxic byproducts. While ultrasonic degradation methods in combination with additives or catalysts have proven effective, such additives or catalysts may inadvertently contribute to secondary pollution. Moreover, the preparation of these catalysts imposes an additional burden in terms of effort and cost. To address these issues, this paper introduces a catalyst-free dual-frequency ultrasound degradation approach for methylene blue. The sonochemical quality of the cavitation bubbles is improved using this technique because the bulk solution is populated with two types of bubbles, whose mean sizes are determined by the dual ultrasound frequencies. The findings demonstrate that, under identical acoustic power density conditions, dual-frequency ultrasound consistently outperforms single-frequency modes across all investigated parameters. Furthermore, the larger the difference between the dual frequencies used, the more effective the degradation of methylene blue. Finally, after just 20 min of sonication, a degradation efficiency of 91% was achieved with dual frequencies of 20 and 80 kHz at an acoustic power density of 209.63 ± 6.94 W/L. Consequently, this technique offers an environmentally friendly, catalyst-free, and highly effective method for degrading methylene blue.

Uptake of BF Dye from the Aqueous Phase by CaO-g-C3N4 Nanosorbent: Construction, Descriptions, and Recyclability

Removing organic dyes from contaminated wastewater resulting from industrial effluents with a cost-effective approach addresses a major global challenge. The adsorption technique onto carbon-based materials and metal oxide is one of the most effective dye removal procedures. The current work aimed to evaluate the application of calcium oxide-doped carbon nitride nanostructures (CaO-g-C3N4) to eliminate basic fuchsine dyes (BF) from wastewater. CaO-g-C3N4 nanosorbent were obtained via ultrasonication and characterized by scanning electron microscopy, X-ray diffraction, TEM, and BET. The TEM analysis reveals 2D nanosheet-like nanoparticle architectures with a high specific surface area (37.31 m2/g) for the as-fabricated CaO-g-C3N4 nanosorbent. The adsorption results demonstrated that the variation of the dye concentration impacted the elimination of BF by CaO-C3N4 while no effect of pH on the removal of BF was observed. Freundlich isotherm and Pseudo-First-order adsorption kinetics models best fitted BF adsorption onto CaO-g-C3N4. The highest adsorption capacity of CaO-g-C3N4 for BF was determined to be 813 mg. g−1. The adsorption mechanism of BF is related to the π-π stacking bridging and hydrogen bond, as demonstrated by the FTIR study. CaO-g-C3N4 nanostructures may be easily recovered from solution and were effectively employed for BF elimination in at least four continuous cycles. The fabricated CaO-g-C3N4 adsorbent display excellent BF adsorption capacity and can be used as a potential sorbent in wastewater purification.

Highly ordered CaO from cuttlefish bone calcination for the efficient adsorption of methylene blue from water

The aim of this study is to synthesize cheap and highly ordered CaO from cuttlefish bone (CFB) as a green alternative to conventional adsorbents such as activated carbon. This study focuses on the synthesis of highly ordered CaO via calcination of CFB, at two different temperatures (900 and 1000°C) and two holding times (0.5 and 1 h), as a potential green route for water remediation. The as-prepared highly ordered CaO was tested as an adsorbent using methylene blue (MB) as a model compound for dye contaminants in water. Different CaO adsorbent doses (0.05, 0.2, 0.4, and 0.6 g) were used, keeping the MB concentration fixed at 10 mg/L. The morphology and crystalline structure of the CFB before and after calcination was characterized via scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses, while the thermal behavior and surface functionalities were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy, respectively. Adsorption experiments using different doses of CaO synthesized at 900°C for 0.5 h showed an MB removal efficiency as high as 98% by weight using 0.4 g (adsorbent)/L(solution). Two different adsorption models, the Langmuir adsorption model and the Freundlich adsorption model, along with pseudo-first-order and pseudo-second-order kinetic models, were studied to correlate the adsorption data. The removal of MB via highly ordered CaO adsorption was better modeled by the Langmuir adsorption isotherm giving (R² =0.93), thus proving a monolayer adsorption mechanism following pseudo-second-order kinetics (R²= 0.98), confirming that chemisorption reaction occurs between the MB dye molecule and CaO.

Biomedical engineered nanomaterials to alleviate tumor hypoxia for enhanced photodynamic therapy

Photodynamic therapy (PDT), as a highly selective, widely applicable, and non-invasive therapeutic modality that is an alternative to radiotherapy and chemotherapy, is extensively applied to cancer therapy. Practically, the efficiency of PDT is severely hindered by the existence of hypoxia in tumor tissue. Hypoxia is a typical hallmark of malignant solid tumors, which remains an essential impediment to many current treatments, thereby leading to poor clinical prognosis after therapy. To address this issue, studies have been focused on modulating tumor hypoxia to augment the therapeutic efficacy. Although nanomaterials to relieve tumor hypoxia for enhanced PDT have been demonstrated in many research articles, a systematical summary of the role of nanomaterials in alleviating tumor hypoxia is scarce. In this review, we introduced the mechanism of PDT, and the involved therapeutic modality of PDT for ablation of tumor cells was specifically summarized. Moreover, current advances in nanomaterials-mediated tumor oxygenation via oxygen-carrying or oxygen-generation tactics to alleviate tumor hypoxia are emphasized. Based on these considerable summaries and analyses, we proposed some feasible perspectives on nanoparticle-based tumor oxygenation to ameliorate the therapeutic outcomes, which may provide some detailed information in designing new oxygenation nanomaterials in this burgeneous field.

Green calcium-based photocatalyst derived from waste marble powder for environmental sustainability: A review on synthesis and application in photocatalysis

Calcium, with its excellent adsorptive property and higher permissible limits in the environment, emerges as an effective wastewater treatment earth metal. Most of the catalysts, photocatalysts, and adsorbents reported in the literature have heavy metal complex, which creates a leaching problem. Majorly, precursors used for the synthesis of heterogeneous catalysts for wastewater treatment are costly. Therefore, the use of such precursors would be not suitable and feasible approach from an economic point of view. This review work is focused on giving an overview of the utilisation of calcium-based catalysts (adsorbents and photocatalyst) for the removal/degradation of various types of dye water pollutants and summarises the reported effects of calcium as a base on the removal efficiency of dopants. In this article, an extensive literature survey is presented on the various photocatalysts developed and the different syntheses involved in their preparation. As the utilisation of marble powder is a green sustainable approach, the scope of various calcium-based photocatalysts and their application is presented. This article also aims for the elementary and inclusive determination of the effect of introducing calcium as a base for different catalysts and adsorbents.

Synthesis of recyclable GO/Cu3(BTC)2/Fe3O4 hybrid nanocomposites with enhanced photocatalytic degradation of aflatoxin B1

This study evaluated the photocatalytic performance of the activated carbon assisted GO/Cu₃(BTC)₂/Fe₃O₄ photocatalyst for aflatoxin B1 (AFB1) degradation under ultraviolet light. The nanocomposite was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The numerous factors influencing the degradation efficiency of AFB1 including catalyst dose, pH importance, and contact time were also probed. The elevated degradation performance of AFB1 by 99% was due to a larger surface area and improved GO/Cu₃(BTC)₂/Fe₃O₄ photocatalyst. The degradation process followed a pseudo-first-order kinetic model. Moreover, it is possible to quickly isolate the catalyst from the solution and retain successful operation. In the degradation of AFB1, the hole(h⁺) and the hydroxyl radicals(OH) were found to play a significant role. These studies showed that GO/Cu₃(BTC)₂/Fe₃O₄ has high capturing capacity and photoactivity synergy, thereby offering a quick effect, and green solution to AFB1 degradation.

Direct Polypropylene and Polyethylene Liquefaction in CO2 and N2 Atmospheres Using MgO Light and CaO as Catalysts

The polyolefin to lighter molecules reaction reduces the waste-plastic residues to produce fuels and valuable chemicals. Commercial MgO light and CaO were used as catalysts for the direct polyethylene and polypropylene liquefaction in N₂ or CO₂ atmospheres. The products were analyzed (ATR-FTIR, GC-FID/TCD, GC-FID, density, refractive index). The use of MgO light and CaO improved the conversion of propylene and ethylene to liquid products. In addition, low gaseous and solid products yields were obtained. A good production of organic liquids in the gasoline, diesel and kerosene boiling range was obtained. The use of CO₂, in some cases, led to a higher conversion into liquids compared with the reactions performed in the N₂ atmosphere. In addition, the use of the CO₂ atmosphere led to a higher content of products with a boiling range in the diesel and kerosene ranges.

Zn-MOF decorated bio activated carbon for photocatalytic degradation, oxygen evolution and reduction catalysis

An emerging global necessity for alternative resources combined with maximum catalytic efficiency, low cost, and eco-friendly composite remains a hotspot in the scientific society. Hereby, a novel protocol is approached to design a heterostructure of Zinc MOF decorated on the surface of 2D activated carbon (AC) through a simplistic approach. To begin with, analytical, morphological and spectroscopical studies were performed to identify the functional moieties, cruciate-flower like morphology and oxidative state of atoms present in the composite Zn-MOF @AC. The photocatalytic material aids in degrading both cationic and anionic dye in a UV (254 nm) irradiated environment at a rate of 86.4% and 77.5% within 90 mins. Subsequently, the hybrid materials are coated on the carbon substrate to evaluate the catalytic activity using oxygen evolution and reduction reaction process. The mechanical insight for the catalytic activity relies on the electronic transitions of atoms on the edges of the sheets ascribing to d-d energy levels between the interfacial electron movement. Our composite exhibits an overpotential of 0.7 V and a Tafel slope of 70 mV/dec for the oxygen reduction reaction. This study proposes an alternate approach for developing MOF decorated carbon-based composites for photocatalytic degradability and energy necessity.

Recent advances in photocatalytic remediation of emerging organic pollutants using semiconducting metal oxides: an overview

Many untreated and partly treated wastewater from the home and commercial resources is being discharged into the aquatic environment these days, which contains numerous unknown and complex natural and inorganic compounds. These compounds tend to persist, initiating severe environmental problems, which affect human health. Conventionally, physicochemical treatment methods were adopted to remove such complex organic chemicals, but they suffer from critical limitations. Over time, photocatalysis, an advanced oxidation process, has gained its position for its efficient and fair performance against emerging organic pollutant decontamination. Typically, photocatalysis is a green technology to decompose organics under UV/visible light at ambient conditions. Semiconducting nanometal oxides have emerged as pioneering photocatalysts because of large active surface sites, flexible oxidation states, various morphologies, and easy preparation. The current review presents an overview of emerging organic pollutants and their effects, advanced oxidation processes, photocatalytic mechanism, types of photocatalysts, photocatalyst support materials, and methods for improving photodegradation efficiency on the degradation of complex emerging organic pollutants. In addition, the recent reports of metal-oxide-driven photocatalytic remediation of emerging organic pollutants are presented in brief. This review is anticipated to reach a broader scientific community to understand the first principles of photocatalysis and review the recent advancements in this field.

Detection, Contamination, Toxicity, and Prevention Methods of Ochratoxins: An Update Review

Ochratoxins (OTs) with nephrotoxic, immunosuppressive, teratogenic, and carcinogenic properties are thermostable fungal subordinate metabolites. OTs contamination can occur before or after harvesting, during the processing, packing, distribution, and storage of food. Mold development and mycotoxin contamination can occur in any crop or cereal that has not been stored properly for long periods of time and is subjected to high levels of humidity and temperature. Ochratoxin A (OTA) presents a significant health threat to creatures and individuals. There is also a concern of how human interaction with OTA will also express the remains of OTA from feedstuffs into animal-derived items. Numerous approaches have been studied for the reduction of the OTA content in agronomic products. These methods can be classified into two major classes: inhibition of OTA adulteration and decontamination or detoxification of food. A description of the various mycotoxins, the organism responsible for the development of mycotoxins, and their adverse effects are given. In the current paper, the incidence of OTA in various fodder and food materials is discussed, which is accompanied by a brief overview of the OTA mode of synthesis, physicochemical properties, toxic effects of various types of ochratoxins, and OTA decontamination adaptation methods. To our knowledge, we are the first to report on the structure of many naturally accessible OTAs and OTA metabolism. Finally, this paper seeks to be insightful and draw attention to dangerous OTA, which is too frequently neglected and overlooked in farm duplication from the list of discrepancy studies.

Synthesis of a copper (II) metal-organic framework for photocatalytic degradation of rhodamine B dye in water

The Cu(II) metal-organic frameworks (MOFs) based on 1,3,5-benzenetricarboxylic acid (Cu₃(BTC)₂) was synthesized by the hydrothermal method. The synthesized Cu₃(BTC)₂ exhibited pyramid-shaped morphology and showing an average specific area of 32.16 m² g^-1. The Cu₃(BTC)₂ photocatalysts were characterized using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy (FESEM-EDX), UV-Vis diffusive reflectance spectra, and Brunauer-Emmett-Teller (BET). The photocatalytic activity of Cu₃(BTC)₂ was examined on Rhodamine B (RhB) degradation under visible light irradiation. The outcomes displayed exceedingly enhanced photocatalytic activity under visible light. In addition, its recyclability was also confirmed for multiple cycles. The easiness of construction and high photocatalytic performance of Cu₃(BTC)₂ photocatalysts can be capable in environmental applications to treat water contamination.

Nanomaterials significance; contaminants degradation for environmental applications

Nanotechnology provides an innovative platform that is inexpensive, reasonable, having least chances of secondary contamination, economical, and an effective method to concurrently eradicate numerous impurities from contaminated wastewater. Presently, different researches have been conducted exhibiting versatile multifunctional nanoparticles (NPs) that concurrently confiscate several impurities existing in the water. Nanotechnology helps in eliminating impurities from water through the rapid, low-cost method. Pollutants such as 2,4-dichlorophenol (death-causing contaminant as it quickly gets absorbed via the skin), or industrial dyes including methyl violet (MV) or methyl orange (MO) causing water contamination were also concisely explained. In this mini-review, nanomaterials were critically investigated, and the practicability and effectiveness of the elimination of contaminations were debated. The analysis shows that a few of these processes can be commercialized in treating diverse toxins via multifunctional nanotechnology innovations. Hence, nanotechnology shows a promising and environmental friendly method to resolve the restrictions of current and conventional contaminated water treatment. We can progress the technology, without influencing and affecting the natural earth environment conditions.