Journal of Environmental Health Science and Engineering最新文献

Water contamination by multiple pollutants is a serious environmental issue originating from the many diverse sources of pollution. It has worsened with the appearance of new contaminants, named emerging micropollutants, such as drug residues which are considered a potential threat to human health and/or ecosystems. These require prior treatment before release into the environment. Simultaneous adsorption and photocatalysis as well as solid-liquid separation are promising technologies for water treatment. In order to obtain low cost photoactive nanocomposites, porous and magnetic Fe₃O₄-hydroxyapatite (wFeHAp) nanocomposites were prepared by soft chemistry from the dissociation of natural phosphate into Ca²⁺ and H₃PO₄ precursors, further neutralized by ammonia in the presence of preformed Fe₃O₄ particles. The magnetic nanocomposites were characterized and examined as effective antibacterial agents. Fe₃O₄ association with apatite modifies the surface properties of the wFeHAp nanocomposite materials, yielding efficient antimicrobial activity for S. aureus, B. subtilis, E. coli and K. pneumoniae strains. The photocatalytic removal of ciprofloxacin (CPF) and oxytetracyclin (OXT) antibiotics in water was also evaluated. The wFeHAp nanocomposites adsorbed and degraded the selected antibiotics successfully. Toxicity evaluation of the treated water after photodegradation using the four strains demonstrates the absence of toxic by-products at the end of the reaction. Therefore, Fe₃O₄@HAp nanoparticles are valuable for antimicrobial and photocatalysis applications.

Abstract

Herein, the selectivity/simultaneously adsorption associated with Congo Red (CR) and Methylene Blue (MB) has been efficiently undertaken via amorphous perlite. Under optimum conditions of 38 min, 96 mg/L and 312°K for the contact time, the dye concentration, and the temperature, respectively, the optimization study using central composite design (CCD) matrix gave rise to high adsorption yields of 82.22 and 96.65% for CR and MB, respectively. Importantly, kinetic and isotherm studies attested that the batch adsorption occurs as intra-diffusional mass transport onto porous material. The obtained thermodynamic parameters are indicative of an endothermic/spontaneous physisorption process. Whereas SEM–EDS characterization revealed the superficial adsorption process of both CR and MB onto perlite. In addition, the FTIR analysis suggests that the adsorption process disrupted the short-range compounds order of perlite samples, revealing the marked crystallinity decrease of the adsorbent after adsorption. Finally, application of these optimum conditions tests on real industrial wastewater show that the adsorption was simultaneous at neutral pH and at 312°K, whereas CR and MB can be selectively adsorbed at pH 4 and 9, respectively.

Graphical abstract

The grafting of biopolymer gum ghatti (GG) over the PNIPAM and PAA was done and loaded with graphene oxide (GO). Aim of this work is carried out combine adsorption of sodium diclofenac (SD) and metformin (MF) by the prepared hydrogels under influence of various parameters. The adsorbent GG-g-P(NIPAM-co-PAA)/GO(3 mg) chosen for adsorption activity as it displayed highest swelling capacity. The effect of amount of both adsorbents GG-g-P(NIPAM-co-PAA and GG-g-P(NIPAM-co-PAA)/GO(3 mg) showed that highest adsorption capacity found at 40 mg of adsorbents for both drugs at conditions: 100 mg/L concentration, 30 °C, 24 h and pH 6 and subsequently became stable. Both the drugs were removed in greater amount at 25 mg/L concentration, 24 h of contact time, 30 °C, 40 mg amount of both adsorbents and pH 6. Effect of time revealed that as time elevated from 2 h to 12 (100 mg/L concentration,, 30 °C, 40 mg amount of both adsorbents and pH 6) led to increase adsorption efficiency and after that increase time did not much impact on adsorption activity. Adsorption activity of hydrogels declined with increase of temperature (100 mg/L concentration, 12 h, 40 mg amount of both adsorbents and pH 6). The acidic conditions favored adsorption of SD while MF adsorbed under the weak acidic(100 mg/L concentration, 30 °C, 12 h, 40 mg amount of both adsorbents). However, basic conditions did not much influence on adsorption of MF but effected on adsorption activity of SD. Adsorption isotherm and kinetic model suggested that adsorption is homogenous and chemical in nature. The maximum adsorption capacity (q_m) found to be 289.01 and 154.55 mg/g for SD and MF respectively.

Graphical abstract

In this study, the removal efficiency of endosulfan as a persistent organic pollutant and formation of its metabolites were investigated using Ag/TiO₂/Fe₃O₄ photocatalyst under visible and UV-A light. Light intensity, catalyst amount, initial endosulfan concentration, initial pH and time were determined as controllable factors for Taguchi experimental design. The highest removal efficiencies of endosulfan were achieved as 86.14% and 85.46% for visible and UV–A light sources, respectively. According to the greatest best criterion, the level at which the highest S/N ratio was obtained for each parameter was accepted as the optimum value. As a result of the validation experiments, 94.2% and 91.9% efficiency were obtained for visible and UV-A light, respectively. The metabolite formations of endosulfan (endosulfan sulfate, ether, and lactone) remained below 7% in all experiments on a concentration basis. In the reuse experiments of the magnetically recovered photocatalyst, high removal efficiency of around 80% was obtained after four cycles. The removal efficiencies were found to be 86.7% and 84.8%, for real samples taken from the drinking water treatment plant inlet and the spring water network injected with endosulfan under optimal photocatalysis experimental conditions, respectively. It has been shown that nitrate and sulfate anions, which are in significant concentrations in raw water samples, have very little effects on endosulfan removal. The overall results showed that the Ag/TiO₂/Fe₃O₄ photocatalyst was produced successfully, the catalyst was highly effective in the mineralization of endosulfan in synthetic and real water samples under UV and visible light, and effective yields could be obtained even with reuse.

This study investigated photocatalytic degradation of pharmaceutical compound using CuO or PdO–TiO₂ membrane. The synthesized membranes were characterized by some techniques including X-ray powder diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The structural properties confirmed that the photocatalytic membranes were successfully prepared on ceramic supports. The PdO-TiO₂ and CuO-TiO₂ membranes were employed as photocatalytic membranes to degrade metronidazole (MNZ) and diphenhydramine (DPH) in aqueous solutions, respectively. Some parameters affecting the photocatalytic reaction such as pH, initial concentration, and light source were also investigated. The maximum degradation for both pharmaceutical compounds was obtained at basic pH (pH = 10), low initial concentration (C₀ = 10 ppm) under UV irradiation. At high transmembrane pressure (ΔP = 3 bar), the flow rate across the membrane increased up 0.0078 and 0.0082 cc/s.cm² for CuO-TiO₂ and PdO-TiO₂ photocatalytic membrane respectively while not affected on degradation efficiency (DE). At the same condition operation (C₀ = 10 ppm, pH = 10, ΔP = 2 bar under UV irradiation), the MNZ and DPH degradation of the PdO-TiO₂ membrane was 94 and 95% respectively that relatively higher than the CuO-TiO₂ membrane. It is probably due to the lower energy band gap of PdO-TiO₂ (2.5 eV) than CuO-TiO₂ (2.7 eV). The membrane stability tests confirmed the high performance of the prepared membranes.

With the development of nanotechnology and its application in various sciences, scientists have investigated the use of nanoparticles as adsorbents to remove heavy metals from aqueous solutions all over the world. So far, the results of many of these studies have been published in reputable journals. Obviously, reviewing these articles and summarizing the results of these studies from different aspects will provide new perspectives for the development of this technology for heavy metals removal from water. So the current study was performed to review the results of the published studies between 1/January/1980 to 1/January/2022. The focus of the study is on the analysis of these studies and their classification. In addition, a more detailed investigation was carried out. Among the 5155 articles, 576 articles were included based on Cochrane protocols. Results show that most of the studies (90.8%) were conducted on a laboratory scale and used synthetic solutions. Most studies were performed for Pb, Cd and Cu, removal respectively. Compared to other countries, authors with affiliation from China and Iran have published more articles. The ranking of the use of various nanomaterials were: nanocomposites > metal oxide nanomaterials > metal-based nanomaterials > carbon-based nanomaterials > dendrimers, with the wide range of sizes from less than 10 nm to several hundreds of nanometers. The required amount of carbon-based nanoparticles to remove many heavy metals were lower than other nanoparticles. In most studies, pH ≤ 7 has been reported as optimal. Most studies have been followed pseudo second-order and pseudo first-order reactions and have been more agreement with Langmuir and Freundlich adsorption isotherms respectively. The results of studies show that the synthesis and optimization of new nanomaterials can be considered as a new and competitive technology. However, more studies are needed to investigate the removal of heavy metals in real samples and to overcome some challenges in the full-scale application.

Purpose

The aim of this study was to evaluate the effectiveness of nitrilotriacetic acid (NTA) on cadmium (Cd) fractions and microbial biomass in a calcareous soil spiked with Cd under cultivated (Zea mays L.) and uncultivated regime subject to soil leaching condition. Expanding investigations related to soil–plant interactions on metal-contaminated soils with insights on microbial activity and associated soil toxicity perspective provides novel perspectives on using metal-chelating agents for soil remediation.

Methods

The experimental factors were three levels of Cd contamination (0, 25, and 50 mg kg⁻¹ soil) and three levels of NTA (0, 15, and 30 mmol L⁻¹) in loamy soil under maize-cultured and non-cultured conditions. During the experiment, the adding NTA and leaching processes were performed three times.

Results

The results showed that the amount of leached Cd decreased in cultivated soil compared to uncultivated soil due to partial uptake of soluble Cd by plant roots and changes in Cd fractions in soil, so that Cd leached in Cd₅₀NTA₃₀ was 9.2 and 6.1 mg L⁻¹, respectively, in uncultivated and cultivated soils. Also, Cd leached in Cd₂₅NTA₃₀ was 5.7 and 3.1 mg L⁻¹ respectively, in uncultivated and cultivated soils. The best treatment in terms of chemical and microbial characteristics of the soil with the high percentage of Cd removed from the soil was Cd₂₅NTA₃₀ in cultivated soil. In Cd₂₅NTA₃₀ compared to Cd₂₅NTA₀ in cultivated soil, pH (0.25 unit), microbial biomass carbon (MBC, 65.0 mg kg⁻¹), and soil respiration (27.5 mg C-CO₂ kg⁻¹ 24 h⁻¹) decreased, while metabolic quotient (qCO₂, 0.05) and dissolved organic carbon (DOC, 20.0 mg L⁻¹) increased. Moreover, the changes of Cd fractions in Cd₂₅NTA₃₀ in cultivated soil compared to uncultivated soil were as follows; the exchangeable Cd (F₁, 0.27 mg kg⁻¹) and Fe/Mn-oxide-bounded Cd (F₄, 0.15 mg kg⁻¹) fractions increased, in contrast, carbonate-Cd (F₂, 2.67 mg kg⁻¹) and, organically bounded Cd (F₃, 0.06 mg kg⁻¹) fractions decreased. NTA had no significant effect on the residual fraction (F₅).

Conclusion

The use of NTA, especially in calcareous soils, where most of the Cd is bound to calcium carbonate, was able to successfully convert insoluble fractions of Cd into soluble forms and increase the removal efficiency of Cd in the phytoremediation method. NTA is a non-toxic chelating agent to improve the accumulation of Cd in maize.

Purpose

The Eastern Mediterranean Region (EMR) countries suffer from exposure to high levels of ambient air pollutants due to dust storms and have unique climatic as well as topographic and socio-economic conditions which lead to adverse health effects on humans. The purpose of the review was to evaluate the quantity and quality of published articles on air pollution and health-based studies in 22 EMR countries to determine if they can be applied to adopting air quality standards.

Methods

We designed a review based on a broad search of the literature in the Scopus, PubMed, and web of science (WOS) databases published from January 1, 2000, to January 2, 2022, using combinations of the following relevant terms: air pollution, health, and EMR countries. The generic eligibility criteria for this review were based on the population, exposure, comparator, outcome, and study design (PECOS) statement.

Results

The search results showed that following the PRISMA approach, of 2947 identified articles, 353 studies were included in this review. The analysis of the types of studies showed that about 70% of the studies conducted in EMR countries were Health Burden Estimation studies (31%), Ecological and time trend ecological studies (23%), and cross-sectional studies (16%). Also, researchers from Iran participated in the most published relevant studies in the region 255 (~ 63%) and just 10 published documents met all the PECOS criteria.

Conclusion

The lack of sufficient studies which can meet the PECOS appraising criteria and the lack of professionals in this field are some of the issues that make it impossible to use as potential documents in the WHO future studies and adopt air quality standards.

Treatment of wastewater and reuse of purified water in an industrial process can provide an alternative source of fresh water as well as reduce pollution load by discharging a lower quantity of wastewater. When adsorption is used for treatment, the regeneration of the used adsorbent may also account for a large portion of the operational cost and cause secondary pollution. This problem may be solved by cyclic repetition of adsorption/regeneration cycles using a column method. In this paper, a total of nine successive cycles of zinc capture and zeolite bed regeneration using a column method have been investigated. The derived form of the breakthrough curve was used for analysing mass transfer in the column. For that purpose, the Dose–response, the Thomas, the Bohart-Adams, the Yoon-Nelson and the Wolborska models were used for modelling the breakthrough curve by nonlinear regression analysis. Simulation results and mathematical similarities between the models were discussed. This is the first study that used derived form of Dose–response model to analyse the inflection points of the breakthrough curve and mass transfer during nine consecutive sorption-regeneration cycles of zinc ions on natural zeolite. Obtained peak shape rate profiles were analysed for all cycles. Optimal operation conditions were evaluated with respect to the inflection point, the model parameters, and the residence time.

This study aims to evaluate the performance of rotating aluminum electrodes in the electrocoagulation reactor for removing hexavalent chromium (Cr⁶⁺⁾ from synthetic tannery wastewater. Taguchi and Artificial Neural Network (ANN) based models were developed to obtain the optimum condition for maximum Cr⁶⁺ removal. The optimum working condition obtained by Taguchi approach for the maximum Cr⁶⁺ removal (94%) was: Initial Cr⁶⁺ concentration (Cr⁶⁺_i) = 15 mg/L; Current Density (CD) = 14.25 mA/cm²; Intial pH = 5; Rotational Speed of Electrode (RSE) = 70 rpm. In contrast, the optimal condition for maximum Cr⁶⁺ ions removal (98.83%) obtained from the BR-ANN model was: Cr⁶⁺_i = 15 mg/L; CD = 14.36 mA/cm²; pHi = 5.2; RSE = 73 rpm. Compared to the Taguchi model, the BR-ANN model outperformed in terms of providing higher Cr⁶⁺ removal (+ 4.83%); reduced energy demand (-0.035 KWh/gm Cr⁶⁺ remove); lower error function value (χ² = -7.9674 and RMSE = -3.5414); and highest R² value (0.9991). The data for the conditions 91,007 < Re < 227,517 and Sc = 102.834 were found to fit the equation for the initial Cr⁶⁺ concentration of 15 mg/l; Sh = 3.143Re^0.125 Sc^0.33. The Cr⁶⁺ removal kinetics was best described by Pseudo 2^nd Order model, as validated by high R² and lower error functions value. The SEM and XRF analysis confirmed that Cr⁶⁺ was adsorbed and precipitated along with metal hydroxide sludge. The rotating electrode led to lower SEEC (10.25 kWh/m³), as well as maximum Cr⁶⁺ removal (98.83%), compared to EC process with stationary electrodes.