Microplastics with a size lower than 5 mm are a ubiquitous plastic polymer present in almost all marine environments. Today, microplastic contamination of the marine environment has been an issue of ...increasing scientific concern. Due to their small size they can be easily misused by a wide range of marine biota and accumulated mainly in the gut. However, the exact consequences of microplastics exposure in the aquatic organisms are largely unknown. This paper summarizes the recent literature on the following objectives: (1) the properties, types and sources of microplastics; (2) the routes of microplastics entrance into the marine environment; (3) ingestion of microplastics by marine biota and the probable toxicological mechanisms; (4) gut microbiota alternation as an inflammation mediator in marine animal. This review focuses on experimental studies indicate histopathological evidences of size and shape dependent microplastics induced inflammation in fish.
Photocatalysis, a green technique is widely applied in the fields of environmental remediation for the removal of many pollutant constituents. It is known that major problems related to the present ...photocatalytic system, which significantly limit their photocatalysis efficiency, are low-usage of visible light, fast recombination and also the low migration ability of the photo-generated electrons and holes. To solve the problem associated with conventional photocatalytic systems, recently hybrid photocatalysts containing carbon quantum dots (CQDs) have been proposed. The tunable photocatalytic characteristics of CQDs are widely mentioned. Moreover, the excellent photocatalytic activity of CQDs alone and in combination with photoactive species in the photo-degradation of organic pollutants was confirmed in the many reports. This work presents a comprehensive view of the application of CQDs to improve conventional photocatalytic systems in those studies which considered organic dyes as sample pollutants. In addition to providing detailed information regarding important roles of CQDs in photocatalytic activity enhancement, this review provides the comprehensive details about findings of the photocatalytic degradation of dyes using CQD-based photocatalysts and the best CQD-based composites photocatalysts are highlighted.
•Combination of CQDs/conventional photo-catalysis systems improved their performance.•Multifunctional roles of CQD in photo-catalysis ate extensively elucidated.•CQD-based photo-catalysis degradation of organic dyes is comprehensively reviewed.
•Bio-polymer based Carbon dots can activate hydrogen peroxide to produce hydroxyl radicals.•Carbon dots show desirable catalytic activity for degrading phenol.•Carbon dot catalyst exhibit good ...recyclability under the recycling tests.•Effects of several main parameters on degradation of phenol were evaluated.•Carbon dot/H2O2 is a new emerging technology for wastewater treatment.
The reactivity of bio-polymer based nano carbon dots (NCDs) was studied for catalyzing the decomposition of H2O2 to generate free hydroxyl radicals and consequently its applicability in the removal of phenol. To the best of our knowledge, for the first time, this work reports that bio-polymer based NCDs could activate H2O2 and yielding more than 99% phenol degradation within 20 min in the presence of 12 mmol H2O2. Herein, a simple hydrothermal carbonization route was employed for the synthesis of NCDs. The surface morphology, functional groups and crystallinity of the NCDs are studied. SEM images show the NCDs with spherical shape. The graphitic nature of the NCDs was evident from the XRD pattern. The presence of many surface functional groups is confirmed by FT-IR spectra. The influences of three independent operating parameters involving hydrogen peroxide concentration (4–12 mmol), reaction time (10–20 min) and catalyst amount (50–1000 ppm) on the phenol oxidation rate by two NCDs were examined using response surface methodology (RSM). Terephthalic acid (TA) dosimetry demonstrates that the as-prepared NCDs can produce hydroxyl radicals from H2O2, and hence catalyze the oxidation of phenol. Finally, the reusability of the NCDs catalysts was examined and the produced catalysts exhibit good recyclability.
Abstract
Microplastics (MPs) as an emerging pollutant can affect aquatic organisms through physical ingestion, chemical problems and possible creation of biological layers on their surfaces in the ...environment. One of the significant ways for MPs to enter the aquatic environment is through the effluent discharge of wastewater treatment plants (WWTPs). In this study, first, the concentration and characteristics of MPs in secondary wastewater effluent, and the influential variables related to the coagulation process, for MPs removal were identified using systematic reviews of previous studies. Then, the most proper MPs characterization and coagulation variables were chosen by experts’ opinions using a fuzzy Delphi method. Therefore, the experiment tested in conditions close to the full-scale wastewater treatments. Finally, in the laboratory removal of MPs by coagulation of polyamide (PA), polystyrene (PS), and polyethylene (PE), < 125 and 300–600 μm in size, was tested by a jar test applying Al
2
(SO
4
)
3
in doses of 5 to 100 mg/L plus 15 mg/L polyacrylamide as a coagulant aid. Using R and Excel software, the results were analyzed statistically. It was concluded that the maximum and minimum removal efficiency was 74.7 and 1.39% for small PA and large PE, respectively. Smaller MPs were found to have higher removal efficiency. The MPs type PA achieved greater removal efficiency than PS, while PE had the least removal efficiency.
This research was conducted to study the adsorption of ammonium ions onto pumice as a natural and low-cost adsorbent. The physico-chemical properties of the pumice granular were characterized by ...X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Modeling and optimization of a NHâ⺠sorption process was accomplished by varying four independent parameters (pumice dosage, initial ammonium ion concentration, mixing rate and contact time) using a central composite design (CCD) under response surface methodology (RSM). The optimum conditions for maximum removal of NHâ⺠(70.3%) were found to be 100 g, 20 mg/l, 300 rpm and 180 min, for pumice dosage, initial NHâ⺠ion concentration, mixing rate and contact time. It was found that the NHâ⺠adsorption on the pumice granular was dependent on adsorbent dosage and initial ammonium ion concentration. NHâ⺠was increased due to decrease the initial concentration of NHâ and increase the contact time, mixing rate and amount of adsorbent.
There is an increasing concern about the health effects of exposure to a mixture of pollutants. This study aimed to evaluate the associations between serum levels of heavy/essential metals (Arsenic ...(As), Cadmium (Cd), Mercury (Hg), Lead (Pb), Nickel (Ni), Chromium (Cr), Copper (Cu), Iron (Fe), and Zinc (Zn)) and the risk of developing cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2D). Data were collected from 450 participants (150 with CVDs, 150 with T2D, and 150 healthy subjects) randomly selected from the Ravansar Non-Communicable Disease (RaNCD) cohort in Western Iran, covering the years 2018-2023. Trace element levels in the serum samples were assayed using ICP-MS. Logistic regression was performed to estimate the adjusted risk of exposure to single and multi-metals and CVD/T2D. Odds ratios were adjusted for age, sex, education, residential areas, hypertension, and BMI. The mixture effect of exposure to multi-metals and CVD/T2D was obtained using Quantile G-computation (QGC). In the logistic regression model, chromium, nickel, and zinc levels were associated with CVD, and significant trends were observed for these chemical quartiles (P < 0.001). Arsenic, chromium, and copper levels were also associated with T2D. The weight quartile sum (WQS) index was significantly associated with both CVD (OR 4.17, 95% CI 2.16-7.69) and T2D (OR 11.96, 95% CI 5.65-18.26). Cd, Pb, and Ni were the most heavily weighed chemicals in these models.The Cd had the highest weight among the metals in the CVD model (weighted at 0.78), followed by Hg weighted at 0.197. For T2D, the serum Pb (weighted at 0.32), Ni (weighted at 0.19), Cr (weighted at 0.17), and Cd (weighted at 0.14) were the most weighted in the G-computation model. The results showed the significant role of toxic and essential elements in CVDs and T2D risk. This association may be driven primarily by cadmium and mercury for CVDs and Pb, Ni, Cr, and Cd for T2D, respectively. Prospective studies with higher sample sizes are necessary to confirm or refute our preliminary results as well as to determine other important elements.
This study evaluates the ability of heterogeneous Fenton-like reaction (nano zero-valent iron (NZVI)/H2O2) in combination with weak magnetic field (WMF) under continuous oxygen supply by air bubbling ...for pollutant abatement (using ciprofloxacin as a model pollutant). The considered operating variables were initial pH, catalyst dosage, reaction time and different intensities of magnetic field. Results indicated that NZVI/H2O2/aeration/weak magnetic field could effectively decompose ciprofloxacin at neutral condition and higher removal rates are observed at higher pH and NZVI concentrations. Superimposing a weak magnetic field leads to 20% enhancement in ciprofloxacin removal by catalytic Fenton under aeration condition. Employing simultaneously magnetic field induction and aeration exhibit excellent capability to the NZVI oxidation and significantly increased the dissolution rate of iron. Based on Fourier transform infrared spectroscopy, transformation products of NZVI are Fe3O4 and FeO(OH). The faster mass transport due to Lorentz and field gradient force, more oxygen diffusion to the iron surface and promoted electrochemical reactions results in more OH° production. Generation of weak magnetic field by permanent magnets and using aeration for both mixing and in situ oxygen supply significantly enhanced the Fenton reaction performance. This combination technology doesn't need any energy input and costly chemicals hence can be used easily for wastewater treatment applications.
•Ciprofloxacin removal was carried out by NZVI/H2O2/Aeration/MF.•Complete CIP removal was rapidly achieved at neutral pH condition.•FTIR shows Fe3O4 and FeOOH are the main NZVI corrosion products.•Magnetic field assisted Fenton performance was higher in aerobic than anaerobic condition.
Today, energy has become one of the most important concerns of developing countries. The use of non-renewable energy sources, as well as the production of pollution, has led to growing efforts to ...replace fossil fuels, which are the most important energy sources in the modern world. Hydrogen as a clean fuel has attracted a lot of attention in recent years. Various methods have been reported for the production and storage of hydrogen. According to their advantages and disadvantages, it can be said that electrochemical hydrogen storage method is superior to other methods in terms of cost, safety, and optimum condition. The electrochemical hydrogen storage is done in a variety of techniques, and in recent years, the chronopotentiometry method has become one of the most popular methods for scientists. In chronopotentiometry technique, several parameters such as the reference electrode, the counter electrode, the working electrode, electrolyte, and current density are important. In this review, we investigated the articles that have been done in this regard from 2000 to 2020. This review can help scientists to better understand the electrochemical hydrogen storage system.
•The effective parameters in electrochemical hydrogen storage are reviewed.•The operative aspects in chronopotentiometry method are clean-up.•The type of reference, auxiliary, substrate, electrolyte and current density are effective.•Several effective parameters that didn't investigated in 2000–2020 have been listed.
The present study aimed at synthesizing chromium doped zinc oxide nanoparticles (Cr:ZnO NPs) under mild hydrothermal conditions (temperature ~100 °C, p = autogenous and time ~12 hr). Chromium oxide ...and n-butylamine were used as dopant and surface modifier, respectively. The characteristics of the synthesized nanoparticles were determined through conducting specialized experiments including powder XRD, FTIR, SEM, EDX, and UV-VIS spectroscopy. Then, the Cr:ZnO NPs were immobilized on a sandblasted glass through thermal method. The photocatalytic degradation of aniline was conducted in a continuous reactor with a volume of 1.5 liters. Before and after photocatalytic degradation, the immobilized Cr:ZnO NPs were characterized for SEM and EDX to determine the degree of stability of immobilized nanoparticles as well as the influence of the current applied on them. The photodegradation operational parameters investigated were aniline initial concentration (150, 200, and 250 mg/L), pH (5, 7, 6, and 12), and reaction time (2, 4, and 6 hours) under sunlight illumination. The characterization results indicated high purity of the Cr:ZnO NPs and no change in morphology or composition even after the immobilization and photo-oxidation process. Finally, it was found that the optimum conditions for 93% removal of aniline under sunlight illumination was about 6 hours retention time at pH 9.
The purpose of this study was to determine common pesticides in raw milk from the industrial cattle houses of Kermanshah region of Iran. A novel, simple, inexpensive, reliable and environmentally ...friendly method based on continuous sample drop flow microextraction combined with high-performance liquid chromatography-ultraviolet detection was developed. In this technique, a few microliters of organic solvent is transferred to the bottom of a conical test tube and the aqueous solution in form of fine droplets passes through the organic solvent. At this stage, target analytes are extracted into the organic solvent. After extraction, 20 μL of organic solvent was injected into the analytical instrument. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, the calibration graphs are linear in the range of 1–800 µg/L and limits of detection are in the range of 0.3–1.0 µg/L. Repeatability (intra-day) and reproducibility (inter-day) of the method based on five replicate measurements of 100 µg/L of target pesticides were in the range of 2.7–4.1 and 4.3–7.2%, respectively. The enrichment factors and recoveries are in the range of 308–372 and 77–93%, respectively.
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