Removal of Amoxicillin from Aqueous Media by Fenton-like Sonolysis/H2O2 Process Using Zero-Valent Iron Nanoparticles.

High concentrations of antibiotics have been identified in aqueous media, which has diminished the quality of water resources. These compounds are usually highly toxic and have low biodegradability, and there have been reports about their mutagenic or carcinogenic effects. The aim of this study was to apply zero-valent iron-oxide nanoparticles in the presence of hydrogen peroxide and the sonolysis process for the removal of the amoxicillin antibiotic from aqueous media. In this study, zero-valent iron nanoparticles were prepared by an iron chloride reduction method in the presence of sodium borohydride (NaBH4), and the obtained nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating-sample magnetometry (VSM). Then, using a Fenton-like process, synthetic wastewater containing 100 to 500 mg/L amoxicillin antibiotic was investigated, and the effects of different parameters, such as the frequency (1 and 2 kHz), contact time (15 to 120 min), the concentration of hydrogen peroxide (0.3%, 0.5%, and 6%), the dose of zero-valent iron nanoparticles (0.05, 0.1, 0.5 g/L), and pH (3, 5, 10) were thoroughly studied. A pH of 3, hydrogen peroxide concentration of 3%, ultrasonic-wave frequency of 130 kHz, zero-valent iron nanoparticles of 0.5 g/L, and contaminant concentration of 100 mg/L were obtained as the optimal conditions of the combined US/H2O2/nZVI process. Under the optimal conditions of the combined process of zero-valent iron nanoparticles and hydrogen peroxide in the presence of ultrasonic waves, a 99.7% removal efficiency of amoxicillin was achieved in 120 min. The results show that the combined US/H2O2/nZVI process could be successfully used to remove environmental contaminants, including antibiotics such as amoxicillin, with a high removal percentage.

Health risk assessment and spatial distribution of nitrate, nitrite, fluoride, and coliform contaminants in drinking water resources of kazerun, Iran.

Exposure to nitrate, nitrite, and fluoride through drinking water consumption, especially in arid and semi-arid regions, has been considered by many researchers. Therefore, the present study aimed to investigate the status of nitrate, nitrite, fluoride, and total coliforms in water supply sources of Kazerun located in Fars province, Iran, determine their spatial distribution, and perform health risk assessment in four age groups (infants, children, teenagers, and adults). In this research, the concentration data of 25 groundwater wells were examined. Then, the spatial distribution of the contaminants was determined using the Arc GIS software (v. 10.5) and their health risk assessment was performed via the standard method of the US Environmental Protection Agency. The maximum concentrations of nitrate, nitrite, and fluoride were 25.5, 0.056, and 0.72 mg/l, respectively and their mean concentrations were 13.5, 0.008, and 0.52 mg/l, respectively. In addition, the mean and maximum concentrations of coliforms were 371.21 and 2694.50 CFU/100 ml, respectively. The total coliforms value was higher than the permissible limit in 60 % of the cases. The highest Chronic Daily Intake (CDI) of the studied contaminants was related to nitrate among children (range: 0.21-1.45, with an average value of 0.77 mg/kg-day). Moreover, the Hazard Quotient (HQ) values were below 1 for all contaminants and in all age groups. The highest HQ value (0.9) belonged to nitrate amongst children. Furthermore, the Hazard Index (HI), as a cumulative effect of HQ, was calculated for all three contaminants and the results showed that it was greater than 1 in 56 % of the cases among children, which was considered a serious risk. The findings revealed no significant relationship between nitrate and nitrite concentrations and total coliforms. Overall, nitrate seemed to play a more critical role in the health risk of the exposed age groups in comparison to nitrite and fluoride. Hence, appropriate managerial measures are recommended to be taken.

Characteristics and health effects of formaldehyde and acetaldehyde in an urban area in Iran.

This study reports a spatiotemporal characterization of formaldehyde and acetaldehyde in the summer and winter of 2017 in the urban area of Shiraz, Iran. Sampling was fulfilled according to EPA Method TO-11 A. The inverse distance weighting (IDW) procedure was used for spatial mapping. Monte Carlo simulations were conducted to evaluate carcinogenic and non-cancer risk owing to formaldehyde and acetaldehyde exposure in 11 age groups. The average concentrations of formaldehyde/acetaldehyde in the summer and winter were 15.07/8.40 µg m-3 and 8.57/3.52 µg m-3, respectively. The formaldehyde to acetaldehyde ratios in the summer and winter were 1.80 and 2.43, respectively. The main sources of formaldehyde and acetaldehyde were photochemical generation, vehicular traffic, and biogenic emissions (e.g., coniferous and deciduous trees). The mean inhalation lifetime cancer risk (LTCR) values according to the Integrated Risk Information System (IRIS) for formaldehyde and acetaldehyde in summer and winter ranged between 7.55 × 10-6 and 9.25 × 10-5, which exceed the recommended value by US EPA. The average LTCR according to the Office of Environmental Health Hazard Assessment (OEHHA) for formaldehyde and acetaldehyde in summer and winter were between 4.82 × 10-6 and 2.58 × 10-4, which exceeds recommended values for five different age groups (Birth to <1, 1 to <2, 2 to <3, 3 to <6, and 6 to <11 years). Hazard quotients (HQs) of formaldehyde ranged between 0.04 and 4.18 for both seasons, while the HQs for acetaldehyde were limited between 0.42 and 0.97.

Radon 222 in drinking water resources of Iran: A systematic review, meta-analysis and probabilistic risk assessment (Monte Carlo simulation).

The current study was performed to review the conducted studies regarding the concentration of radon 222 in the tap drinking water; furthermore, by estimation of ingestion and inhalation effective dose, the health risk assessment in the adults and children using MCS technique was assessed. All related studies published among January 1990 to October 2016; were screened in the available databases such as Web of Science, PubMed, Science Direct, Scopus, SID, and Irandoc. The total effective dose was estimated by calculating Eing (Effective dose of ingestion) and Einh (Effective dose of inhalation) by Monte Carlo simulation (MCS) method. The range of ND ─ 40.9 Bq/L for radon 222 in water resources was proposed after evaluation of data collected from 13 studies with 1079 samples. The overall concentration of radon 222 in drinking water in Iran was 3.98: 95%CI (3.79 ─ 4.17 Bq/L). Also, the effective ingestion dose of radon 222 in adults age groups was 1.35 times higher than children. The rank order of drinking water resources based on the concentration of radon 222 was Spring > Spring and Well > Well > Spring and Qanat > Tap water. The overall concentration of radon 222 in drinking water in Iran was lower than WHO and EPA standard limits. Also, the rank order regarding area studied based on the concentration of radon 222 was Gillan > Mashhad > Mazandaran > Kerman > Yazd > Tehran > Kermanshah > Golestan > Hormozgan. The effective ingestion dose of radon 222 to consumers in the Gillan, Mashhad, Mazandaran, and Kerman were higher than WHO guidance (0.1 mSv/y). Also except consumers in the Hormozgan, inhalation effective dose radon 222, in the other investigated areas were higher than WHO guidance (0.1 mSv/y). Therefore, it is recommended to conduct the required programs regarding control and elimination of radon 222 concentration in Iranian drinking water supply.