Enhancing oxygen reduction reaction performance through eco-friendly chitosan gel-assisted molten salt strategy: Small NiCo alloy nanoparticles decorated with high-loading single Fe-NX

We developed an effective and eco-friendly strategy using chitosan gel-molten salt to achieve high loading (2.23 At. %) of single Fe-NX as assistive active sites. These sites were combined with small NiCo alloy NPs distributed on porous carbon aerogels to boost the ORR performance. The FeSAs-NiCo alloy@N-C sphere exhibits exceptional mass activity and specific activity of 3.705 A.mg-1 and 8.79 mA.cm-2(ECSA), respectively, at 0.85 V versus RHE. It has a superior onset potential of 1.08 V versus RHE, surpassing that of its nanoparticle Fe counterpart and NiCo alloy@N-C sphere. The significant improvement in ORR performance of the FeSAs-NiCo alloy@N-C sphere could be attributed to the positive effects of increased lattice strain due to the single atoms of Fe-NX hybridized with small NiCo alloy NPs. The chitosan gel-assisted molten salt strategy and assistive active sites of Fe-NX hybridized with NiCo alloy NPs regulate the electronic properties of the FeSAs-NiCo alloy@N-C sphere, both geometrically via lattice strain mismatch and electronically through shifting of the d-band center. This could influence the binding energies for oxygen and/or oxygen reduction intermediate adsorption/desorption. The additional improvement in the ORR performance of the FeSAs-NiCo alloy@N-C sphere also benefits from having a lower electrochemical activation energy.

Health risk assessment of workers exposed to lead dust in informal e-waste recycling workshops

Informal recycling of electronic waste (e-waste) has attracted significant attention due to its economic benefits and rapid growth rate in many parts of the world. Unfortunately, unsafe conditions of recycling workshops possess chronic exposure to workers and lead to elevated blood lead concentrations (BLCs). Upon measuring the lead concentration in the dust of recycling workshops and the e-wastes in southwestern region of Iran, the related health risks were assessed in 30 exposed workers and 30 non-exposed habitants cases based on the determination of BLC. The average BLCs in exposed workers and non-exposed habitants cases were 24 μg/dL and 7 μg/dL, respectively. The geo-accumulation index (Igeo) revealed heavy contamination of dust in informal e-waste recycling workshops (IERWs) (5023 μg/kg) and significantly lower levels in unexposed areas (49 μg/kg). Health risk assessment indicated that lead exposure from IERWs appears to be a potential threat to workers and indirectly to their families.

Ciprofloxacin degradation by catalytic activation of monopersulfate using Mn-Fe oxides: performance and mineralization

In this work, Mn₂O₃/Fe₂O₃ (MFO) was synthesized and used to activate monopersulfate (MPS) for the degradation of ciprofloxacin (CIP). The effect of several parameters was studied on CIP degradation. Under the optimum conditions (pH = 6.3 (natural pH), MFO = 300 mg/L and MPS = 2 mM), around 92% of CIP was decomposed. Nitrite, phosphate and bicarbonate ions had a strong inhibitory effect on the MFO/MPS process while the effect of chloride and nitrate ions was neutral. The catalytic activity of MFO was also studied by other chemical oxidants such as peroxydisulfate, periodate, hydrogen peroxide, percarbonate and peracetic acid. Scavenging tests showed that the role of sulfate radicals is more than hydroxyl radicals. MFO exhibited high catalytic activity in four recycling with insignificant leaching of Mn and Fe. During CIP oxidation, 45.5% carbon mineralization occurred and antibacterial activity of treated CIP solution was reduced. Finally, MFO/MPS was applied on actual wastewater (hospital effluent) and the results showed that MFO/MPS can be considered as a practical method for the treatment of contaminated water with emerging pollutants.

Measurement of polycyclic aromatic hydrocarbons in edible oils and potential health risk to consumers using Monte Carlo simulation, southwest Iran

Persistent organic pollutants, such as polycyclic aromatic hydrocarbons, are hazardous trace contaminants frequently observed in food ingredients, such as edible oils. This study aimed to measure PAHs in forty brands of edible oils marketed in southwest Iran. Additionally, we characterized the daily intake of MOE and ILCR using Monte Carlo simulation. To analyze the content of PAHs, the liquid-liquid extraction method followed by GC-MS was utilized. The average concentration of PAHs was mostly lower than the maximum value for individual PAH (2 μg/Kg); however, the average concentration of fluorene (3.86 μg/Kg) and benzo(a)anthracene (3.13 μg/Kg) was more than the permitted level. The highest residual concentrations of PAHs were mostly observed in canola and corn oils. The daily intake of BaP and 4-PAH for 95% of consumers was 0.01 ng/kg BW/day and 0.04 ng/kg BW/day, respectively. Also, MOE was more than 10,000 for the percentiles of 5%, 50%, and 95%. The modeled ILCR showed that consumption of oil does not currently pose a cancer risk for Iranian consumers due to PAHs exposure. Concerning potential health risks, consumption of edible oils is safe; however, regular monitoring and assessment are required.

Monitoring of pesticides in surface water, pesticides removal efficiency in drinking water treatment plant and potential health risk to consumers using Monte Carlo simulation in Behbahan City, Iran

Excessive application of pesticides to control pests and weeds leads to contaminating bodies of water and health problems for consumers. The present study was designed to investigate the concentration of pesticides in raw water originated from the Marun River as well as the treated water of the drinking water treatment plant in Behbahan City. The efficiency of each treatment process was evaluated. Moreover, the health risks caused by detectable pesticides for consumers of treated water were assessed. The target pollutants were extracted using droplet liquid-liquid microextraction and detected by a gas chromatograph-mass spectrophotometer. The results showed relatively high mean concentrations of organophosphate pesticides ranging from 0.87 to 3.229 μg/L in the river water and low concentrations of organochlorine pesticides, except for 1,3-dichloropropene with the concentration of 3.58 μg/L. Alachlor had a rather high concentration (2.44 μg/L) in the river water. The concentration of pesticides in the drinking water had been reduced to an acceptable amount. The major part of pesticides removal occurred in coagulation-flocculation and rapid sand filtration units (87 %) due to the hydrophobic nature of pesticides and the use of GAC in the filtration unit. Based on the risk assessment estimates, the total hazard quotient (THQ) for all the pesticides was much less than one. The value of THQ was higher in younger individuals and children for all the given pesticides. The highest value of THQ in children was 0.2 which was attributed to aldrin. Similarly, the carcinogenic risk (CR) of aldrin for children and teenagers was in the unsafe range (more than 10^-4) while the CR for other target compounds in all the age groups was negligible (10^-4-10^-6 or less). The high concentration of pesticides in the river water might be concerning and therefore selling and using pesticides, especially the banned ones, should be more regulated.

Geochemical determination and pollution assessment of heavy metals in agricultural soils of south western of Iran

Soil contamination with heavy metals due to the application of fertilizers and biocides in agricultural activities is a potential threat for human health through the food chain. The present work was designed to study the spatial distribution of heavy metals, pollution level and possible reasons for their contamination in agricultural soils of Aghili plain, Khuzestan, Iran. The median concentrations of As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, Zn, and Hg were 2.90, 0.29, 8.10, 39.0, 17.75, 354.0, 0.97, 58.35, 5.90, 34.0, 42.0, and 0.01 mg/kg, respectively. The results revealed that average concentrations of all studied heavy metals with an exception of Co, Cu, and Ni, were lower than background values. Analysis of source identification showed that Zn, Pb, and Cu (P < 0.01, r > 0.9) and Co, Cr, Mn, Ni, and V (P < 0.01, r > 0.7) were mainly from anthropogenic. In addition, Cd probably was originated from agricultural activities (application of manure and phosphorous fertilizers). Enrichment factor values of all metals (except Ni), were in the range of non to moderate enrichment (EF < 5). According to the degree of contamination (C_d) and ecological risk factor (ERF), all stations were categorized as low to moderate contaminated sites (4.5 < C_d < 17), and biological communities in some locations may be at risk (ERF >65). Results indicate that application of fertilizers, herbicides and pesticides in agricultural soils has led to soil contamination and special management and educational plans are needed for public and farmers to prevent further adverse effects.

Taguchi optimization approach for metronidazole removal from aqueous solutions by using graphene oxide functionalized β-cyclodextrin/Ag nanocomposite

Metronidazole (MNZ) is a major threat to the ecosystems and human health, due to its toxicity and carcinogenic nature. The main aim of this study was to evaluate the efficiency of graphene oxide functionalized β-cyclodextrin/Ag nanocomposite (GO/β-CD/Ag) for MNZ removal from aqueous solution. The effect of operational parameters such as solution pH (2-5), adsorbent dosages (0.2-1 g/L), contact time (10-80 min), initial MNZ concentrations (0.25-10 mg/L) and ionic strength (0.001-0.1 mol/L) was studied using Taguchi experimental design. The maximum removal efficiency of 93.5% was observed for optimum conditions. The optimum values of contact time, the initial MNZ concentration, the ionic strength, the adsorbent dosage and solution pH were found to be 20 min, 0.25 ppm, 0.01 mol/L, 0.4 g/L and 2, respectively. Freundlich and Dubinin-Radushkevich isotherm models were best-fitted with experimental data. Pseudo-first order and type 1 pseudo-second order kinetic models showed the maximum correlation with the experimental data. Adsorption experiments with real samples indicated that the adsorptive removal of MNZ from a hospital wastewater was 72%. Desorption studies showed maximum recovery of GO/β-CD/Ag nanocomposite during three cycles. According to the obtained results, it can be concluded that the application of carbon adsorbents such as GO/β-CD/Ag can be considered an efficient method for final treatment of effluents containing antibiotics.

Enhanced photocatalytic degradation of tetracycline and real pharmaceutical wastewater using MWCNT/TiO2 nano-composite

Photocatalytic degradation of tetracycline using MWCNT/TiO₂nanocomposite was investigated under UVC irradiation. The effective operational parameters included pH, irradiation time, photocatalyst dosage, weight ratio of MWCNT to TiO₂ and tetracycline concentration and were studied consecutively. Complete removal of tetracycline concentrations of up to 10 mg/L was obtained at MWCNT to TiO₂ ratio of 1.5 (w/w%), pH 5, photocatalyst dosage of 0.2 g/L. Pseudo-first order kinetic model was best fitted with the experimental results (R²: 0.91-0.98 for different tetracycline concentrations). Based on TOC analysis, mineralization was 37% in the same reaction conditions for initial tetracycline concentration of 10 mg/L and reached to 83% after 300 min. In the case of real pharmaceutical wastewater, the COD concentration of 2267 mg/L decreased to 342 mg/L after 240 min in the same operational conditions.

Enhanced coagulation-photocatalytic treatment of Acid red 73 dye and real textile wastewater using UVA/synthesized MgO nanoparticles

Sequencing coagulation - photocatalytic degradation using UVA/MgO nanoparticles process was investigated for Acid red 73dye removal and then treatment of a real textile wastewater. Effective operational parameters including pH and coagulant and photocatalyst dosage were studied in synthetic wastewater and then the process was applied for real wastewater. Both coagulation and photocatalytic processes were pH dependent. At coagulant dosage of 200 mg/L and initial pH of 6, the dye concentration decreased from 200 to 31 mg/L. Complete removal of AR73 was observed with MgO nanoparticles of 0.8 g/L, initial pH of 5 and reaction time of 60 min. Langmuir-Hinshelwood model was well fitted with removal results (R(2): 0.939-0.988 for different initial dye concentration). In the case of real textile wastewater, the sequence coagulation-UVA/MgO nanoparticles photocatalytic degradation yielded considerable total COD and TOC removal 98.3% and 86.9%respectively, after 300 min.

A seroepidemiological survey for toxoplasmosis among schoolchildren of Sari, Northern Iran

A seroepidemiological survey for toxoplasmosis among schoolchildren of public schools of the urban areas of the Sari, Mazandaran province, Iran, was carried out from September 2006 to March 2007. A total of 1209 serum samples (686 males, 523 females) were examined for IgG antibodies by ELISA. Questionnaires were completed for all participants. In regard to criteria>10 IU/mL as positive, the infection coefficient (IC) was 266 (22%), of which 161 were males (IC=23.5) and 105 females (IC=20.1) (P=0.15). No age-antibody association was detected, although an increase in positivity with increasing age was observed, reaching 23.1% in the oldest group (P=0.84). A significant association was observed with the presence of cat, contact with soil, washing hands before meals and eating raw or undercooked meat. An improvement in personal hygienic conditions and behavioral characteristics such as eating cooked meat is important in reducing the rate of Toxoplasma infection.

Seroprevalence of toxocariasis in schoolchildren in Northern Iran

This cross-sectional study was carried out on 1210 randomly selected schoolchildren, attending sixteen primary and secondary schools, during the period between November 2005 and June 2006. Parents who accepted to include their children were requested to be present at sampling time and to fill in a simple questionnaire with personal and epidemiological data. Three milliliter of venous blood were taken by vein puncture under sterile conditions from each subject for detection and titration of antibodies to T. canis and eosinophil counts. Total IgG anti-Toxocara antibodies was evaluated by T. canis IgG ELISA kit. According to the manufacture recommendations, an index positivity >11 U was considered positive. Of the 1210 serum specimens tested, an overall seroprevalence for Toxocara antibodies of 25% was obtained. There was no association between positive seroprevalence and age (p = 0.34). Boys and girls differed significantly with regard to Toxocra titre (p = 0.003). Eosinophilia in peripheral blood (> or = 5%) was detected in 24.5% (297/1210) of the population studied, 97/297 (32.8%) of whom were seropositive for toxocariasis. The findings of this study confirmed that infection with Toxocara is quite high and widespread in children in Northern Iran. Therefore, health promotion efforts must be directed at increasing the awareness of the population about the potential zoonotic hazards associated with the disease and how to minimize them.