Excessive intake of fluoride can cause adverse health effects. Consumption of tea as a popular drink could be a potential source of fluoride exposure to humans. This research aimed to evaluate the fluoride concentration in tea among the Iranian people using the available data in the literature and to assess the health risk related to the consumption of tea in men, women, and children. The health risk assessment was conducted using the chronic daily intake and hazard quotient according to the approach suggested by the Environmental Protection Agency. The fluoride content in published studies varied noticeably, ranging from 0.13 to 3.27 mg/L. The results revealed that the hazard quotient (HQ) in age groups of women (21–72 years) and children (0–11 years) was within the safe zone (HQ < 1) which showed that there was no potential of non-carcinogenic risk associated with drinking tea in these groups. However, in one case of the men (21–72 years), the HQ > 1 which shows a probable risk of fluorosis. The order of non-carcinogenic health risks in the studied groups was in the order of men > women > children. The results of this can be useful for organizations with the responsibility of human health promotion.

This study aimed to assess the groundwater quality and human health risks of nitrate, nitrite, and fluoride contamination in rural areas of Khaf County, Iran. For this aim, 28 groundwater samples were collected from open dug wells during August 2018. Twelve parameters (pH, EC, TDS TH, Cl-, SO₄^2-, HCO₃⁻, NO₃⁻, F⁻, Ca²⁺, Mg²⁺, and Na⁺) have been used to evaluate the water quality index. Also, point estimation using HQ formula and sensitivity analysis using the Monte Carlo Simulation (MCS) method, by 10,000 repetitions in Oracle Crystal Ball®, were applied to determine the additional risk of non-carcinogenicity in Nitrate, Nitrite, and Fluoride in four groups: infant, children, teenager, and adult. WQI showed that 7%, 60%, 10% and 21% of groundwater samples fall within the class of excellent, good, poor, and very poor quality, respectively. The HQ values of nitrate for infant, children, teenagers, and adults in 32%, 14%, 10% and 7% of the samples from rural areas were above the safe limit of 1. The HQ values of nitrite were mostly acceptable for infants, children, teenagers, and adults in all the rural areas because the mean HQ values of fluoride were lower than 1. Also, the calculated HQ values of fluoride for infants, children, and teenagers in 60.7%, 21.4% and 10% of the rural areas were above the safe limit. The results of HQ point estimation showed that nitrate and fluoride had non-carcinogenic risk in most exposed population groups, but exposure to nitrite did not have non-carcinogenic risk. The results of sensitivity analysis, to determine the most effective parameter in increasing non-carcinogenic risk, showed that the concentration parameter of Nitrate, Nitrite, and Fluoride had the most effect on increasing sensitivity in the four studied exposed groups.

An (Fe, Ag) co-doped ZnO nanostructure was synthesized by a simple chemical co-precipitation method and used for the degradation of dibutyl phthalate (DBP) in aqueous solution under visible light-emitting diode (LED) irradiation. (Fe, Ag) co-doped ZnO nanorods were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, UV–VIS diffuse reflectance spectroscopy, elemental mapping, Field emission scanning electron microscopy, transmission electron microscope and Brunauer–Emmett–Teller surface area analysis. A Central Composite Design was used to optimize the reaction parameters for the removal of DBP by the (Fe, Ag) co-doped ZnO nanorods. The four main reaction parameters optimized in this study were the following: pH, time of radiation, concentration of the nanorods and initial DBP concentration. The interaction between the four parameters was studied and modeled using the Design Expert 10 software. A maximum reduction of 95% of DBP was achieved at a pH of 3, a photocatalyst concentration of 150 mg L⁻¹ and a DBP initial DBP concentration of 15 mg L⁻¹. The results showed that the (Fe, Ag) co-doped ZnO nanorods under low power LED irradiation can be used as an effective photocatalyst for the removal of DBP from aqueous solutions.

Dyes are one of the most important environmental pollutants that have a significant impact on the environment, especially water resources. Dyes are toxic compounds that have severe effects on the environment. Methylene blue dye (MBD) causes problems like nausea, profuse sweating, vomiting, mental confusion, and methemoglobinemia. In this study, ZIF-8 with leaf-shaped morphology was used for MBD adsorption. All experiments were performed in batch conditions. The Leaf-shaped ZIF-8 is obtained at the molar ratio of 2-methylimidazole/Zn = 8. The prepared leaf-shaped ZIF-8 was white powder. The as-synthesis adsorbent is in the form of the leaves of a tree. The thickness of Leaf-shaped ZIF-8 is about 6–98 nm. Alkaline conditions were much more favourable than acidic to MBD adsorption. By increasing the dosage of Leaf-shaped ZIF-8, MBD adsorption increased until reaching an equilibrium dose at 0.5 g/L. the kinetic model of pseudo-first-order and the isotherm model of Langmuir have the highest coefficient of determination (R-square). Based on the Langmuir model, the maximum capacity of MBD adsorption on the Leaf-shaped ZIF-8 was 205 mg/g. In this study, the R_L was less than one which indicates MBD adsorption is favourable. Also, based on the Freundlich model, 1/n was 0.26, favourable adsorption condition was favourable.