Electric field applications enhance the electron transfer capacity of dissolved organic matter in sludge compost

The concentration of radioisotopes (Potassium-40, Polonium-210, Radium-226, and Thorium-230) in fillet tissue carp fishes: A systematic review and probabilistic exposure assessment

Chemical contamination of seafood has become a global health concern. Carp fish is one of the most widely consumed globally, and several studies have been conducted on the contamination of carp fish with radioisotopes. In the current study, a meta-analysis and probabilistic exposure assessment regarding the Potassium-40 (40K), Polonium-210 (210Po), Radium-226 (226Ra), and Thorium-230 (230Th) in the fillet tissue of carp fish were performed. In this regard, Scopus and PubMed were screened to retrieve the associated citations with on the concentration of radioisotopes in the fillet tissue of carp fish until October 2021. The rank order of radioisotopes in fillet tissue carp fish was 40K (103.49 Bq kg-1) > 210Po (9.39 Bq kg-1) > 226Ra (0.62 Bq kg-1) > 230Th (0.39 Bq kg-1). The highest effective dose due to 210Po ingestion was observed in Spain (male; 4.44E-05 Sv y-1, female; 2.67E-06 Sv y-1); 40K (female, 5.07E-07 Sv y-1); 226Ra (male, 9.93E-09 Sv y-1). The mean of effective dose (ED) in the male and females in India due to ingestion of 230Th as result of carp fish consumption was (1.70E-06 Sv y-1) and (7.01E-08 Sv y-1), respectively. The probabilistic exposure assessment by the Monte Carlo simulation method revealed that consumers of fillet tissue carp fish content of radioisotopes are at a safe range (0.001 Sv y-1).

Coupled improvements on hydrodynamics and water quality by flowing water in towns with lakes

With the worsening environmental problems in the plain river network, flowing water has become important because of its obvious improvement effect. In order to solve water quality and water mobility problems of the river network in Shengze Town, this paper establishes four flowing water scenarios and compares the associated improvements in water quality and hydrodynamics of the river network with the use of coupled hydrodynamic and water quality models. It is identified as the best scenario to dispatch 20 m³/s of water from the Xiegang River downstream of the Qingxi River and 20 m³/s of water from Lake Xiangjiadang to Lake Beiyandang. Results of this scenario show a significant improvement in the water mobility of the river network in the southern area of the Qingxi River, with the flow rate increasing by 38.23%. The water quality in Lake Beiyandang has upgraded from Class V to Class IV (based on the Chinese water quality standards), and the water quality downstream of the Qingxi River has improved a lot. Findings in this work could provide references for the development of flowing water scenarios in similar watersheds.

Application of new chitosan 2,4-dihydroxyacetophenone Schiff base @SrFe12O19 nanocomposite for remove of Pb(II) ion from aqueous solution

A new chitosan 2,4-dihydroxyacetophenone Schiff base @SrFe₁₂O₁₉ (Cs-SB@SrFe₁₂O₁₉) nanocomposite was successfully prepared by one-pot reaction and fully characterized for its functional groups, morphology, elemental analysis and thermal behavior by FT-IR, XRD, VSM, DSC, TGA, zeta potential, FE-SEM and EDS techniques. The VSM result showed that Cs-SB@SrFe₁₂O₁₉ has M_s of 11.81 emu/g and H_c of 5488 Oe, known as hard magnetic material. Finally, the as-prepared sample utilized as a new sorbent for the removal of Pb(II) ions from aqueous solution by using batch adsorption experiments. The adsorption of Pb(II) was carried out at different pH, contact time and initial dose of Cs-SB@SrFe₁₂O₁₉. The maximum adsorption capacity was found to be 132 mg/g (99 %) at pH 5 and the contact time of 120 min. Finally, the kinetic studies reveals that the adsorption process of Cs-SB@SrFe₁₂O₁₉ followed by the pseudo second order kinetics model. Also, the sample showed excellent recyclable efficiency up to 5 cycles.

Ti3C2Tx MXene@MOF decorated polyvinylidene fluoride membrane for the remediation of heavy metals ions and desalination

Nowadays, the evolution of two-dimensional materials like transition metal carbides (MXene) prepares a novel path to surpass the "trade-off" between the membrane permeation and rejection rates. Based on water swelling and oxidation vulnerability, MXene membranes showed vivid defects such as inadequate stability, detrimental adsorption, and haphazardly stacked nanosheets. Here, we prepared Ti3C2Tx MXene@metal-organic frameworks nanosheets from aminated metal-organic framework-101 (NH2-MIL-101(Al)) via the in-situ growth method and incorporated them into the thin-film polymer to acquire desirable MXene nanosheets with tailor-made structures. The earned modified thin-film nanocomposite membrane showed high salt rejection for Na2SO4 (98.6 ± 0.5%), MgSO4 (96.9 ± 0.7%), MgCl2 (84.5 ± 0.8%), and NaCl (82.5 ± 0.8%), and also showed an improved permeation rate by three times (17.1 ± 0.2 L m-2. h-1. bar-1). Concurrently, the rejection rate of five different types of heavy metal ions (Ni2+, Cd2+, Mn2+, Cu2+, and Zn2+) was tested and denoted more than a 95.2 ± 0.5% rejection rate for all of them, notably high for Mn2+ (97.6 ± 0.4%). After modification, the flux recovery rate was as high as 95.3 ± 0.4%, denoting more than 30% improvement; besides, anti-compactness features enhanced by nearly 34 ± 0.7%. The long-term water permeation kept 91.5 ± 0.9% of its initial rate indicating almost 40 ± 0.8% enhancement. In addition, the rejection performance of Na2SO4 for the optimized membrane was more than 97% even after two weeks.

Biogenic synthesis of reduced graphene oxide decorated with silver nanoparticles (rGO/Ag NPs) using table olive (olea europaea) for efficient and rapid catalytic reduction of organic pollutants

In this work, graphene oxide (GO) sheets were prepared via a facile electrochemical exfoliation of graphite in acidic medium and subsequent oxidation with potassium permanganate. The GO sheets were employed for preparation of reduced GO adorned with nanosized silver (rGO/Ag NPs) using green reduction of GO and Ag(I) via olive fruit extract as a reducing and immobilizing agent. The crystal phase, morphology, and nanostructure of the prepared catalyst were characterized by XRD, SEM, EDX, UV-Vis and Raman spectroscopy techniques. The as-prepared rGO/Ag NPs showed superior catalytic performance towards the complete reduction (up to 99%) of 4-nitrophenol (4-NPH) to 4-aminophenol (4-APH) and rhodamine B (RhB) to Leuco RhB within 180 s using NaBH₄ at ambient condition. The rate constant (k) values were found to be 0.021 and 0.022 s^-1 for 4-NPH and RhB reduction, respectively. In addition, the regenerated catalyst could be reused after seven cycles without losing any apparent catalytic efficiency. Accounting for the excellent catalytic capability, chemical stability and environment-friendly synthesis protocol, the rGO/Ag NPs has great potential working as a heterogeneous catalyst in the transforming harmful organic contaminants into less harmful or harmless compounds.

Efficient Catalytic Combustion of Cyclohexane over PdAg/Fe2O3 Catalysts under Low-Temperature Conditions: Establishing the Degradation Mechanism Using PTR-TOF-MS and in Situ DRIFTS

Cyclohexane, a typical volatile organic compound (VOC), poses high risks to the environment and humans. Herein, synthesized PdAg/Fe₂O₃ catalysts exhibited exceptional catalytic performance for cyclohexane combustion at lower temperatures (50% mineralization temperature (T₅₀) of 199 °C, 90% mineralization temperature (T₉₀) of 315 °C) than Pd/Fe₂O₃ (T₅₀ of 262 °C, T₉₀ of 335 °C) and Fe₂O₃ (T₅₀ of 305 °C, T₉₀ of 360 °C). In addition, PdAg/Fe₂O₃ displayed enhanced stability by alloying Ag with Pd. The redox and acidity of the PdAg/Fe₂O₃ were studied by XPS, H₂-TPR, and NH₃-TPD. In situ diffuse reflectance infrared Fourier transform spectroscopy and proton-transfer-reaction time-of-flight mass spectrometry were applied to identify the intermediates formed on the catalyst surface and in the tail gas during oxidation, respectively. Results suggested that loading PdAg onto Fe₂O₃ significantly enhanced the adsorption and activation of oxygen and cyclohexane, oxidative dehydrogenation of cyclohexane to benzene, and catalytic cracking of cyclohexane to olefins at low temperatures. This in-depth study will benefit the design and application of efficient catalysts for the effective combustion of VOCs at low temperatures.

Application of sulfur-coated magnetic carbon nanotubes for extraction of some polycyclic aromatic hydrocarbons from water resources

In the present work, novel sulfur-coated magnetic carbon nanotubes (MCNTs-S) material was fabricated by S coating on the MCNTs using a simple heating procedure. TGA, EDX, XRD, TEM, and VSM were employed to characterize the as-prepared composite. Using HPLC-UV system, the produced superparamagnetic sorbent was employed for the extraction and measurement of trace levels of five polycyclic aromatic hydrocarbons (PAHs) in environmental waters. The synergistic effect of the sulfur layer and CNTs substrate is primarily responsible for the remarkable extraction efficiency of the MCNTs-S sorbent towards PAHs. The experimental factors including MCNTs-S dosage, sorption time, elution solvent, ionic strength and solution pH were explored and optimized. Considering that the ionic strength and pH do not have any impact on the PAHs extraction, as a result, there is no need the unnecessary adjustment of the water samples. The linear dynamic ranges and detection limits under optimal conditions were in the range of 0.05-0.11 ng mL^-1 and 0.2-150 ng mL^-1, respectively. The analysis of PAHs in the real samples (sea water and river water) using this approach was successfully assessed with appropriate recovery values (94.6%-99.0%).

On-Site Application of Solar-Activated Membrane (Cr-Mn-Doped TiO2@Graphene Oxide) for the Rapid Degradation of Toxic Textile Effluents

Solar-activated water treatment has become an emerging research field due to its eco-friendly nature and the economic feasibility of green photocatalysis. Herein, we synthesized promising, cost-effective, and ultralong-semiconductor TiO₂ nanowires (NW), with the aim to degrade toxic azo dyes. The band gap of TiO₂ NW was tuned through transition metals, i.e., chromium (Cr) and manganese (Mn), and narrowed by conjugation with high surface area graphene oxide (GO) sheets. Cr-Mn-doped TiO₂ NWs were chemically grafted onto GO nanosheets and polymerized with sodium alginate to form a mesh network with an excellent band gap (2.6 eV), making it most suitable to act as a solar photocatalytic membrane. Cr-Mn-doped TiO₂ NW @GO aerogels possess high purity and crystallinity confirmed by Energy Dispersive X-ray spectroscopy and X-ray diffraction pattern. A Cr-Mn-doped TiO₂ NW @GO aerogels membrane was tested for the photodegradation of Acid Black 1 (AB 1) dye. The synthesized photocatalytic membrane in the solar photocatalytic reactor at conditions optimized by response surface methodology (statistical model) and upon exposure to solar radiation (within 180 min) degraded 100% (1.44 kg/m³/day) AB 1dye into simpler hydrocarbons, confirmed by the disappearance of dye color and Fourier transform infrared spectroscopy. An 80% reduction in water quality parameters defines Cr-Mn-doped TiO₂ NW @GO aerogels as a potential photocatalytic membrane to degrade highly toxic pollutants.

Synthesis characterization of Zn-based MOF and their application in degradation of water contaminants

Metal-organic frameworks (MOFs) are currently popular porous materials with research and application value in various fields such as medicine and engineering. Aiming at the application of MOFs in photocatalysis, this paper mainly reviews the main synthesis methods of ZnMOFs and the latest research progress of Zn MOF-based photocatalysts to degrade organic pollutants in water, such as organic dyes. This nanomaterial is being used to treat wastewater and has proven to be very efficient because of its exceptionally large surface area and porous nature. The results show that Zn-MOFs are capable of high degradation of the above pollutants and over 90% of degradation was observed in publications. In addition, the reusability percentage was examined and studies showed that the Zn-MOF nanostructure has very good stability and can continue to degrade a high percentage of pollutants after several cycles. This review focuses on Zn-MOFs and their composites. First, the methods of synthesis and characterization of these compounds are given. Finally, the application of these composites in the process of photocatalytic degradation of dye pollutants such as methylene blue, methyl orange, crystal violet, rhodamine B, etc. is explained.

A Cu(ii) complex supported on Fe3O4@SiO2 as a magnetic heterogeneous catalyst for the reduction of environmental pollutants

Today, the presence of pollutants in the environment has become one of the serious problems and concerns of human beings. To eliminate these pollutants, researchers have made many efforts. One of the most important of these efforts is the reduction of such contaminants in the presence of effective catalysts. Two of the most important and widespread types of these pollutants are nitro compounds and organic dyes. In this paper, we report the synthesis of an efficient and reusable magnetic catalyst using Fe₃O₄@SiO₂ core–shell nanoparticles (NPs), N-(4-bromophenyl)-N′-benzoylthiourea, and copper(ii). Specifically, the Cu(ii)-N-(4-bromophenyl)-N′-benzoylthiourea complex supported on Fe₃O₄-core magnetic NPs (CM)/SiO₂-shell (SS) (CM@SS-BBTU-Cu(ii)) has been prepared. CM@SS-BBTU-Cu(ii) was characterized by FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), TEM (transmission electron microscopy), HRTEM (high resolution transmission electron microscopy), FFT (fast Fourier transform), VSM (vibrating sample magnetometry), TG-DTA (thermogravimetry-differential thermal analysis), STEM (scanning transmission electron microscopy), EDS (energy-dispersive X-ray spectroscopy), and elemental mapping. The synthesized CM@SS-BBTU-Cu(ii) was applied for the reduction of 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) in the presence of NaBH₄ (sodium borohydride) at room temperature. CM@SS-BBTU-Cu(ii) can be recycled and reused 5 times. Our results displayed that the performance of the catalyst was not significantly reduced by recycling.

Nitro-aromatic-pollutants are hazardous to people and the environment. In this work, the catalytic potential of CM@SS-BBTU-Cu(ii) has been investigated for reduction of nitro group in aqueous media by NaBH₄.