Journal of Environmental Health Science and Engineering最新文献

The present study evaluated the performance of multiwalled carbon nanotube (MWCNT)@MgAl-layered double hydroxide (LDH) nanoparticles loaded on poly-2 aminothiazole (PAT)/chitosan (CS) matrix (CPML) to remove Cd²⁺ ions from aqueous solution. The removal efficiency of modified CS/PAT with MWCNT@MgAl-LDHs was increased significantly compared to pure CS/PAT. The influence of heavy metal ion concentration, pH, temperature, adsorbent dosage, and contact time on the adsorption was examined. The optimum conditions for the adsorption of Cd²⁺ ions were 25 ⁰C with the adsorbent dosage of 0.06 g and initial concentration for adsorption of the Cd²⁺ 100 mg/L at pH = 8. The maximum adsorption capacity was measured to be 1106.19 mg/g. The values of thermodynamic parameters namely Gibbs free energy (ΔG°), entropy change (ΔS°), and enthalpy change (ΔH°) indicated the feasibility, spontaneity and the endothermic nature of the adsorption process, respectively. The pseudo-second-order kinetics and the Langmuir model were selected as the best models for the adsorption process. Also, CPML nanocomposite (NC) was successfully tested for p-nitrophenol (p-NP) reduction in the presence of NaBH₄. The reaction was nearly completed in 6 min. The fabricated CPML-NC could be reused for three consecutive cycles.

Society's support upon chemicals over the last few decades has led to their increased production, application and discharge into the environment. Wastewater treatment plants (WWTPs) contain a multitude of these chemicals such us; pharmaceutical compounds (PCs). Often, their biodegradability by activated sludge microorganisms is significant for their elimination during wastewater treatment. In this paper the focus is laid on two PCs carbamazepine (CBZ) and diclofenac (DCF) and their main transformation products (TPs). Laboratory degradation tests with these two pharmaceuticals using activated sludge as inoculum under aerobic conditions were performed and microbial metabolites were analyzed by liquid chromatography-mass spectrometry (LC/MS-MS). In two different Mixed liquid Suspended Solids (MLSS) concentrations the biodegradability by activated sludge of CBZ and DCF were evaluated. Also, this article proposes a decision support system to optimize the prediction process of this type of pharmacological compounds. A study and analysis of the techniques of Support Vector Machine, Random Forest, Decision Trees and Multilayer Perceptron Network is carried out to select the most reliable and accurate predictor for the decision system. There are not significant differences in the removal of DCF with 30 mg MLSS/L and 60 mg MLSS/L. DCF was better removed than CBZ in all experiments studied. The TP detected in the samples were mainly 4-OH-DCF for DCF and 10, 11 EPOXICBZ for CBZ. The results show that the best models are obtained with Random Forest and Multilayer Perceptron Network techniques, with a model fit of more than 95% for both carbamazepine and diclofenac metabolites. Obtaining a root means square errors of 0.80 µg/L for the metabolite 4-OH-DCF for DCF with the technique Random Forest and a root means square errors of 1.13 µg/L for the metabolite 10, 11 EPOXICBZ for CBZ with the Multilayer Perceptron Network technique.

The escalating cadmium influx from industrial activities and anthropogenic sources has raised serious environmental concerns due to its toxic effects on ecosystems and human health. This review delves into the intricate mechanisms underlying microbial resistance to cadmium, shedding light on the multifaceted interplay between microorganisms and this hazardous heavy metal. Cadmium overexposure elicits severe health repercussions, including renal carcinoma, mucous membrane degradation, bone density loss, and kidney stone formation in humans. Moreover, its deleterious impact extends to animal and plant metabolism. While physico-chemical methods like reverse osmosis and ion exchange are employed to mitigate cadmium contamination, their costliness and incomplete efficacy necessitate alternative strategies. Microbes, particularly bacteria and fungi, exhibit remarkable resilience to elevated cadmium concentrations through intricate resistance mechanisms. This paper elucidates the ingenious strategies employed by these microorganisms to combat cadmium stress, encompassing metal ion sequestration, efflux pumps, and enzymatic detoxification pathways. Bioremediation emerges as a promising avenue for tackling cadmium pollution, leveraging microorganisms' ability to transform toxic cadmium forms into less hazardous derivatives. Unlike conventional methods, bioremediation offers a cost-effective, environmentally benign, and efficient approach. This review amalgamates the current understanding of microbial cadmium resistance mechanisms, highlighting their potential for sustainable remediation strategies. By unraveling the intricate interactions between microorganisms and cadmium, this study contributes to advancing our knowledge of bioremediation approaches, thereby paving the way for safer and more effective cadmium mitigation practices.

Today, the excessive and increasing use of phenoxy family herbicides such as 2-methyl-4-chlorophenoxyacetic acid (MCPA) and (2,4- dichlorophenoxy) acetic acid (2,4-DCPA) for reasons such as indestructibility and pollution of groundwater resources is one of the most important environmental problems. Pesticide adsorbents like layered double hydroxides (LDHs) are commonly utilized due to their straightforward synthesis, substantial specific surface area resulting from their layered structure, and the potential for surface modification. These natural minerals serve as effective options for adsorption. In this study, a co-precipitation approach was used to create an MgAl-LDH@Fe₃O₄ magnetic adsorbent for the simultaneous removal of MCPA and 2,4-DCPA herbicides from aqueous solution. Using different techniques such as TGA, XRD, FESEM, EDS and zeta potential, we investigated the properties of the prepared adsorbent. The partial least squares method measures the concentration of each herbicide in their mixture. The optimization of MCPA and 2,4-DCPA simultaneous adsorption by LDH was achieved through Doehlert experimental design and the response surface method. The optimal conditions for absorption were determined to be an adsorbent dose of 40.20 mg L^-1, a pH of 6.8, and an initial concentration of 28.35 mg L^-1. In this work, the equilibrium, kinetic, and thermodynamic absorption data of the absorption process were studied, and the obtained results were well described by the Freundlich model, and the pseudo-second-order model, respectively, and showed the spontaneity of the absorption process in this research. The highest absorption capacities of MCPA and 2.4-DCPA herbicides on the prepared adsorbent were 134.50 and 131.30 mg g^-1, respectively.

Graphical abstract

Heavy metals exist in the ecosystem both naturally and due to anthropogenic activities and as recalcitrant pollutants; they are non-biodegradable and cause acute and chronic diseases to human beings and many lifeforms. A statistical experimental approach was applied in this current study to optimize the detoxification of mercury [Hg(II)] from mono-component biosorption system by a novel hybrid granular activated carbon (biosorbent) prepared from maize plant residues. The analysis of variance by the application of central composite design shows that all the studied independent factors greatly influence Hg(II) removal efficiency and uptake capacity. The optimum experimental condition of 30 min contact time, 0.5 g/L biosorbent dosage, and 15 mg/L initial Hg(II) concentration were achieved after seeking 20 optimization solutions at 0.903 desirability. The optimum percentage removal and uptake capacity of Hg(II) at the optimal experimental setup was 96.7% and 10.8 mg/g, respectively. To confirm the quadratic models developed for the prediction of the responses as a function of the independent factors, confirmatory laboratory experiments were performed at the optimum condition. The results show that at the established best experimental condition, the optimum Hg(II) removal efficiency of 98.3% and uptake capacity of 11.2 mg/g were attained, which were within the prediction intervals indicating the suitability of the quadratic models in predicting future cases. The TEM and XRD analyses show that the Hg(II) ions were adsorbed by the biosorbent successfully and this suggests the potential and applicability of this novel biosorbent in treating water contaminants, especially heavy metals.

Spent caustic is a used industrial caustic whose chemical content puts it in the special waste category. The disposal of this waste and the production of value-added products from it has attracted the attention of researchers not only to solve environmental problems but also to take advantage of its byproducts. This research has experimentally proved the transferred thermal plasma technology as a practical method feasible for the disposal of spent caustic. In this study, the applied voltage, electrical current, and feed rate are variable parameters, and others are kept constant. GC analysis showed H₂ as the main product, which is environmentally beneficial. The percentage of hydrogen production of approximately 74% is a promising result, considering the difficulty of achieving such a high percentage of hydrogen.

Background

Today, antibiotics are widely used for treatment and feed additives to enhance livestock growth. Antibiotic residues may be found in food of animal origin for various reasons, including ignoring the withdrawal period after treatment, overuse for animals, and contamination of feed with treated animals in animal products. Among animal products, dairy products have a special place in the human diet, and antibiotic residues in them have caused a great deal of concern among consumers.

Objective

This systematic review and meta-analysis aimed to evaluate and compare studies conducted in Iran on antibiotic residues in dairy products during 2000–2022.

Methods

In this review, 52 eligible studies were collected by searching the Scientific Information Database (SID), Magiran, Google Scholar, Science-Direct, Scopus, and PubMed using the English or Persian keywords such as an antibiotic or antimicrobial residue, Beta-lactam residue, Tetracycline residue, Sulfonamide residue, Chloramphenicol residue, Aminoglycosides residue, Macrolide residue, Quinolones residue, Milk, Raw milk, Pasteurized milk, UHT milk, Powder milk, Cheese, Yogurt, Butter, Cream, Doogh, Kashk, Ice cream, and Iran.

Results

According to the reviewed studies, the total prevalence of antibiotic residues in dairy products was 29% (95% CI: 15–43%). Among the seven evaluated antibiotic groups, most studies have been conducted on tetracycline, beta-lactam, and sulfonamide groups, with 16, 10, and 7 respectively, and the highest level of contamination with 663 ± 1540 μg/l is related to tetracycline. Most studies on antibiotic dairy product residues in Iran with 12, 11, and 8 studies are associated with East Azarbaijan province, then Tehran and Khorasan Razavi respectively, and no study has been conducted in 11 provinces of the country. According to the studies, Gilan, Qazvin and Razavi Khorasan provinces had the highest amount of antibiotic residue in milk with an average value of 56.415 ± 33.354, 45.955 ± 4.179 and 45.928 ± 33.027, respectively. Most of the methods used in the studies to measure antibiotic residues in milk were the Copan test kit and the HPLC method, which were used in 19 and 14 studies, respectively.

Conclusions

Studies have shown that the prevalence of antibiotic residue in dairy products in Iran is high, so applying an effective strategy and developing the necessary standards in this field to control milk quality is a public health necessity. The findings of this study show that further evaluation of fermented dairy products, especially non-fermented ones such as butter and cream, is needed to prevent adverse health reactions.

In-situ modification of cellulose fibers with titania nanoparticles (TiO₂ NPs) (TiO₂ NPs-cellulose) was carried out via the sol–gel process using titania sol and fibers of cellulose. Cellulose fibers were extracted from wheat straw, an agricultural waste material, whereas titania sol was prepared from titanium(IV) acetoximate, [Ti{ONC(CH₃)₂}₄]. The synthesized TiO₂ NPs-cellulose composite was characterized by FT-IR, SEM–EDX, and XRD analyses. The obtained results exposed that TiO₂ NPs were homogeneously dispersed over the surface of cellulose fibers. A study was conducted to compare the photocatalytic activities of TiO₂ NPs-cellulose composite and TiO₂ NPs towards the degradation of methylene blue and methyl orange dyes under sunlight, and it was observed that the photo-degradation of methylene blue (99.99%) and methyl orange (80.73%) within 160 min is higher in the presence of TiO₂ NPs-cellulose composite than TiO₂ NPs. The adsorption capabilities of TiO₂ NPs-cellulose composite towards Pb²⁺, Cd²⁺, and Cr³⁺ toxic metal ions were also examined, and it was found 44.73 mg. g⁻¹ (89.46%), 38.82 mg. g⁻¹ (77.65%), and 4.42 mg. g⁻¹ (8.85%), respectively. Removal of pollutants from textile industrial effluent were also investigated using TiO₂ NPs-cellulose composite under sun light. The results obtained were very promising which shows potential of TiO₂ NPs-cellulose composite as an efficient photocatalyst and absorbent for real time applications.

Graphical abstract

Purpose

The presence of toxic heavy metals (HMs) in agricultural crops ‎can be considered as a noteworthy threat for consumers. The aim of this study was to assess the content of HMs ‎(Pb, As, Cr, Cd, Co, Hg, and Ag) and their potential health risk in summer crops and vegetables (watermelon, cantaloupe, cucumber, melon, tomato, onion, ‎potato, raw and stewed vegetables) in Ilam province, Iran.

Methods

Totally, 31 crop samples were collected from local farms during the 2019 harvest ‎season and the elements ‎ content were evaluated using inductively coupled plasma-mass spectrometry (ICP-MS). The non-carcinogenic health risk of HMs to the adults and children was estimated by Monte Carlo simulation method and target hazard quotients (THQs).

Results

In general, the results showed that the concentration of Cr in the studied ‎agricultural crops was higher than other HMs. As well as, the carcinogenic risk (CR) obtained for adults and children were more than the acceptable range for As. Also, CR for As in raw vegetable was the most (‎8.19E-1) and violated the threshold risk limit. The total carcinogenic risk of HMs in children was higher than that in adults.

Conclusion

These results suggest that the agricultural crops were not safe for human consumption with potential risks associated. Due to the possible health effects of such products consumption, proper action should be taken to avoid chronic exposure, prevention of further pollution and consequent adverse health implications.

Amongst the various water pollutants, heavy metal ions require special attention because of their toxic nature and effects on humans and the environment. Preserving natural resources will have positive impacts on living conditions by reducing diseases and water treatment by nanotechnology is effective in solving this problem owing to the properties of nanomaterials. In this study, a goethite nanoparticle was prepared by hydrothermal method, while ZnO/goethite nanocomposite by co-precipitation was developed. The nanoparticles were characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transform Electron Microscopy (TEM), Thermogravimetric Differential Thermal Analysis (TGA-DTA), Dynamic Light Scattering (DLS), and Breunner-Emmet-Teller (BET) surface area analysis. The adsorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) ions systems on ZnO/goethite nanocomposite was investigated in a batch mode. The findings of the study showed that nanoparticles ZnO/goethite composite were mixed of spherical and rod-like shapes. The BET results revealed average particle sizes of 41.11 nm for nanoparticles for ZnO/goethite while TGA/DTA confirmed the stability of the adsorbents. The optimum adsorption capacities of the nanocomposite for Pb(II), Cd(II), and Ni(II) ions from the Pb-Cd-Ni ternary system were 415.5, 195.3, and 87.13 mg g⁻¹, respectively. The adsorption isotherm data fitted well with the Langmuir isotherm model. The study concluded that the nanoparticle adsorbents are efficient for the remediation of toxic pollutants and are, therefore, recommended for wastewater treatment.