This study employed an electrochemical process to eliminate formaldehyde from contaminated air streams. Various factors that influence the process, including electrode material, inter-electrode distance, air injection site, applied voltage, electrical power, current density, pH, reaction time, electrolyte type, concentration, and formaldehyde's initial concentration were investigated. Findings revealed optimal percentage decrease in concentration (chi), reaching 100 %, using aluminum (Al) electrodes with a 1 cm gap between them. Potassium Persulfate (PP) was found to have superior chi compared to sodium thiosulfate (STH). Regarding the air injection site, the higher chi was noted at the cathode (98.9 +/- 0.85 %) than at the anode (95.2 +/- 0.99 %). Efficiency escalated from 85.1 % at 7.5 volts to 100 % at 15 volts and, for current density, from 89.18 % at 0.042 amps to 100% at 0.159 amps. Conversely, efficiency for air flow diminished from 100% at 0.1 l/min to 27.32 +/- 2.7% at 4.4 l/min. Additional factors were also explored, including removing formaldehyde in the reactor's liquid phase and mineralization. Outcomes suggest that formaldehyde reacts with water, eventually transforming into carbon dioxide. Moreover, the reaction kinetics for both electrolytes demonstrated a tendency toward a second-order kinetic model.

Inhalation of radon gas and its decay products is the first natural source of human exposure to radioactive radiation. Due to its health effects, the World Health Organization (WHO) has recommended guidelines (100 Bq/m 3 ) for indoor environments. The aim of this study was to determine the radon concentration according to the characteristics of residential buildings. Detectors CR-39 were used to determine the radon concentration over a period of three months. Radon concentrations were different in villa buildings, apartment floors, and basements and depended on building materials, age, and ventilation.

حضور و سرنوشت آلاينده‌هاي نوپديد 17 بتا استراديول و تستوسترون در فاضلاب و پساب بيمارستاني: تاثير فرآيندهاي لجن فعال و كلريناسيون

Widespread and unsupervised use of pesticides in the rice fields of northern Iran has greatly increased the concern about their presence in drinking water resources. This study aimed to determine the effect of spraying of rice fields on the concentration of diazinon in rural underground drinking water resources with depth and water table of about 120 and 30 m respectively. Sampling was performed at regular intervals, before the first and after the last spraying. Diazinon extraction was carried out by USEPA liquid-liquid extraction method and the concentration of diazinon was measured by GC / Mass Spectrometry. No diazinon was observed in any of water resources before spraying, while the average concentration of diazinon after spraying was 0.005 +/- 0.007 mu g/l. Also there was a significant difference in diazinon concentration between water resources after spraying rice fields. There was a reverse significant correlation between the diazinon concentration and longitudinal distance from water resources to rice farms. Moreover, there was a significant direct correlation between the diazinon concentration in post-spraying samples and water turbidity. In general, spraying rice fields can cause diazinon to enter underground water resources near farms and it can be present in water resources for at least one month after the last spraying.

This study investigated to assess and identify the vulnerable points in Semnan water supply system based on Water Safety Plans (WSP) in 2018. The water safety plan quality assurance tool (WSP QA tool) software was used as a tool to measure the weaknesses and the progress of the water safety plan. At the first step, WSP checklists were prepared and completed up by experts' staff and data analysis using WSP QA tool. In the next step, system hazards were listed and ranked according to WHO matrix by team member's expert's view and the risk analyses were arranged. The results show that the highest compliance with the implementation of the water safety plan related to the step system description is achieved with (100%) and the lowest match for the step improvement plan with (0%). It can be said that old infrastructure, old pipes, and consequently pressure drop in point of use were identified as the most important hazardous events. Considering that Semnan water supply is groundwater, by further focusing on other areas such as basin, transmission and distribution lines and point of consumption, as well as full implementation of the water safety program in this system, more favorable results and coordination rates are achieved.

Removal of the fluoride ion of drinking water requires an effective technique. In study zeolite clinoptilolite by Al+3ions and nanoscale iron (nZVI) modify was used to remove fluoride from water. Contact was done by a fixed bed absorbent column. In this column, experiments were carried out using aqueous solutions and drinking water with mass. The dynamics of the adsorption process were fitted to Langmuir and Freundlich models. The results showed that highest uptake capacities 1.14 and 2.4mg/g for the modified zeolitic Al and nanoscale iron (nZVI) respectively, were obtained with a 5g mass column, an inlet 10 mg/L fluoride solution, and a flow rate of 3mL/min, but the sorption capacities decreased when drinking water used. Experimental data were fitted to both models Langmuir and Freundlich, and the methods indicated that these materials are suitable for the removal of fluoride from water in fix bed systems. In general, it can be concluded that modified zeolite clinoptilolite with fixed bed an effective and economical method to remove fluoride from groundwater.

The main goal of this study is to investigate the efficiency of the silica derived from the raw rice husk in the removal of methylene blue from aqueous solutions. The effects of initial concentrations of methylene blue, pH, the adsorbent dose, and the contact time on methylene blue removal efficiency were carried out in batch reactors. The silica derived from the raw rice husk was prepared in a furnace at 800°C for 4 hours after acid leaching with sulfuric acid and chloridric acid. The rice husk silica showed more porosity than the raw rice husk with a median pore radius of 2.4 nm and a high specific surface area up to 226.3 m2g-1. The maximum removal efficiency of methylene blue by the rice husk silica under the initial concentration of 10 mgL-1 methylene blue, 1 gL-1 adsorbent mass, 60 min contact time, and pH 8 was 96.7%. Correlation coefficients of the adsorption models have shown a better matching of methylene blue adsorption by the rice husk silica with the Langmuir isotherm model. The results of this study show that the rice husk silica can be applied to remove environmental pollutants such as methylene blue due to the low cost and availability of rice husks.

This study investigated the effect of organic base adsorbents derived from agricultural wastes; namely rice husk silica (RHS), raw rice husk (RRH), and rice bran (RB) on removing lead ions from aqueous solutions. RRH and RB are collected from the agricultural wastes of north of Iran farms and RHS prepared at 800 degrees C temperature after acid leaching. The adsorption rate examined in different contact times (CT from 5 to 90 min), initial pH (pH(0) = 5, 6, 7, 8 and 9), adsorbents dosages (AD = 0.5, 1 and 1.5 mg/L) and initial concentration of lead (C-0 = 1, 5, 10 and 15 mg/L). The optimum conditions for adsorption of lead were pH of 6, adsorbent dosage of 1 g/L and contact time of 60 min, and RHS showed maximum efficiency up to 96.4%. The results were admissibly confident with linear and non-linear Langmuir, Freundlich and pseudo first-order models. Langmuir isotherm indicated q(m) for the RHS up to 15.6 mg/L compared to RRH with 7.3 mg/g and RB with 4.8 mg/g. Adsorption process in this system was limited by mainly sorption process and bulk or boundary layer diffusion. The dominant reaction was estimated to be the ion-exchange according to the obtained energy values of sorption.

Introduction Diabetes is one of the most public and chronic metabolic diseases which results from the lack of insulin or the presence of insulin resistance in peripheral tissues or both, leading to an increased concentration of glucose in the blood (1-3). It is estimated that diabetes rates rise from 108 million afflicted people in 1980 to 522 million by 2038 (4). The Middle East and North Africa have the highest prevalence of diabetes worldwide and Iran has the third rank (5). Based on the reports, about 11.4% of people in Iran aged 25-70 years are afflicted with diabetes (6) and approximately 1% of the population over age 25 are yearly diagnosed with diabetes (7). A change in lifestyle, followed by physical inactivity and obesity, aging, genetic factors, and air pollution are the factors affecting the prevalence of diabetes (8, 9). Air pollution is a serious problem worldwide and one of every eight deaths is attributed to air pollution (10). In addition, particulate matter (PM) is one of the most important air pollutants (11) and PM2.5, can penetrate into the lower respiratory tract and even blood vessels because of its small sizes (12). It can be composed of various components such as organic and elemental carbon, metals, acidic chemicals, and the like. As a result, it can cause different effects on different parts of the human body (13). Many epidemiological studies indicate that exposure to PM2.5 can cause several diseases including diabetes (1420). There is a significant positive correlation between long-term exposure to PM2.5 and an increase in the risk of diabetes occurrence by 11% (21-26). PM affects humans through biological pathways including the increasing of arteriosclerosis, instigating changes in coagulation and blood cell response, and causing endothelial dysfunction and vasoconstriction (27,29). Further, particles affect the body through the biological routes of injection and spasm. Considering the importance of diabetes and the effect of PM2.5 on its prevalence, as well as the importance of Mashhad in terms of population, air pollution, and religious tourism, the current study aimed to evaluate the correlation between PM2.5 concentration and prevalence of diabetes among the residents of Mashhad-Iran.

Adsorbent properties and aqueous characteristics are very important parameters in the removal efficiency (RE) of environmental pollutants. The main goal of this study was to investigate the effects of pH, particle size and porosity of raw rice husk and its silica on removing lead and hexavalent chromium (Cr^+6) from aqueous solution. The raw rice husk was collected from north of Iran and the rice husk silica was prepared at 800ºC after acid leaching. The effects of the adsorbent particle sizes (0.07-0.1, 0.1-0.5, 0.5-1.0 and 1.0-1.5 mm), porosity and pH from 2 to 8 were investigated by varying any of the process variables while keeping the other variables constant (adsorbent dosage = 1.5 g.l ^-1, contact time = 60 min, chromium and lead initial concentration = 5 mg.l ^-1). The results of this study showed that the RE of Cr+6 is intensively pH - dependent. Using 1.5 g.l ^-1 adsorbents, particle size = 0.5 - 1.0 mm, 5.0 mg.l ^-1 initial concentration of Cr+6 and 60 min contact time, the maximum RE obtained by raw rice husk and its silica at pH 2 were up to 98.8 and 88.4%, respectively. However, at the same condition with changing pH (pH 7), the maximum RE decreased up to 69.4 and 60.4%, respectively. Moreover, a positive strong significant correlation was detected between decreasing the adsorbents particle sizes and lead removal efficiency in the two adsorbents (P < 0.01). The scanning electron microscope images of the two adsorbents showed that silica derived from raw rice husk has more porosity. In conclusion, the acidic condition of aqueous for Cr+6 and neutral condition for lead, increases the adsorbents porosity, while decreased adsorbent particle sizes causes an elevation in the RE of the two pollutants.

Background: Fluoride is an essential nutrient for the human body.The major routes of fluoride intake include food and drinking water, though the absorption of fluoride from food is much easier.The aim of this study was to evaluate the amount of fluoride in the soil and tomato and onion crops on farms of Zanjan.Methods: Three farms of each crop (tomato and onion) were selected randomly.Each farm was divided into 10 sections, and one sample of soil and crop of each section was taken which means 120 samples in total.Fluoride concentrations in the soil and crops were measured using the Ion Selective Electrode (ISE) and repeated 3 times.Results: The mean concentration of fluoride in soil samples from studied farms in Zanjan was 0.83 ± 0.17 mg/kg.The mean concentrations of fluoride in tomatoes and onions of Zanjan were observed 2.10 ± 0.80 and 2.23 ± 0.64 mg/kg, respectively.Conclusion: There was no significant difference between fluoride concentration in tomatoes and onions, although there was a significant difference between the amount of fluoride in the soils of studied farms (Pv < 0.024).No significant correlation was observed between the fluoride levels of soils and the fluoride levels of tomatoes (R 2 = 0.126) and onions (R 2 = 0.008).

Introduction: Production of adsorbent using agricultural wastes has important economic and environmental advantages. The aim of this study was Production of silica absolutely using agricultural wastes and determination of efficiency of produced adsorbents in removal of cadmium from aqueous solutions. Materials and Methods: In this experimental study, two different type of acidic pretreatment and then thermal treatment was used for silica production from rice husk. The efficiency of the produced adsorbents was studied in four pH states, four cadmium concentration values, five adsorbents dosages and six different contact times. Cadmium concentration was determined by atomic absorption spectrophotometry. Results: silica was produced in the two procedures and both produced silica had good morphological and physical characteristics. The maximum efficiency of cadmium removal at pH= 6, adsorbent dosage of 3 g/l, contact time of 120 min and initial cadmium concentration of 5 mg/l, for rice husk silica produced by strong inorganic acids and waste lemon juice were respectively %90.1, %60.8. The adsorption processes followed the Freundlich isotherm)generally R2 ≥0.99(. Conclusion: According to the results of this study, good rice husk silica can be produced using absolutely agricultural wastes (rice husk and lemon juice) and produced silica can be used as an effective and cheap adsorbent for removal of cadmium from aqueous solutions

Introduction: Groundwater is the main source of drinking water and the life of many human societies depend on it. Continuous monitoring and assessment of groundwater quality changes are necessary because improvement and decontamination of polluted groundwater is very difficult and costly. The aim of this study was to determine the groundwater quality trend changes in Lordegan city (Iran) during one decade (2002-2012). Materials and Methods: The required data were collected from the results recorded in the years 2002-2012 and analyzed by descriptive and analytical statistics (correlation coefficients). Results: changes of all of them were ascending. In the first and end year of the study period, the number of fecal coliform positive samples were 9(6.25%) and 14(9.75%) and the mean±SD of fecal coliform's MPN in positive samples were 0.24±0.04 and 0.83±0.40 respectively. Also the mean±SD of nitrate (as nitrate, mg/l), total hardness (as calcium carbonate, mg/l) and electrical conductivity (as micromhos/cm) in the first and end year of the study period were 16.6±6.56 and 21.7±10.76, 254±47 and 298±34 and 507±92 and 529±98 respectively. On the basis of spearman's correlation coefficient, the ascending trend of some parameters concentration with time was significant at the level of 95% of confidence limits (α≤0.05). Conclusion: The ascending trend of concentration of all the parameters shows gradual declining of drinking water resources quality. Continuing the ascending trend of the parameters concentration and declining the quality of water resources and incompatibility with Iranian drinking water standard can lead to significant health risks, therefore, tracking the trend changes, investigating the reasons and preventive measures are important.

The present study investigates the effectiveness of a new adsorbent prepared from agricultural wastes, namely rice husk silica as well as raw rice husk and rice bran to remove Cr from aquatic solutions. +6 The raw rice husk was collected from North of Iran. But rice husk silica was prepared by burning of clean rice husk inside a muffle furnace at a temperature of 800°C for 4 hours after acid leaching. The effects of four parameters: contact time (30 to 90 min), pH values (2 to 9), adsorbents dosages (0.5 to 1.5 g/L) and initial concentration (1.0 to 15 mg/L) were investigated to remove Cr . The silica derived from rice husk showed a +6 high percentage of SiO up to 94.24%. But Carbone was the highest element in raw rice husk up to 35.92%. 2 The maximum removal efficiency (RE) of Cr was obtained by rice bran up to 98.8% at 5.0 mg/L initial +6 concentration of Cr, 60 min of contact time, pH = 2 and adsorbents dosage of 1.0 g/L. However, at the same condition the maximum RE by raw rice husk and rice husk silica were 82.3 and 88.4%, respectively. Moreover, a negative strong significant correlation between increasing of initial concentration of Cr and RE was detected +6

BACKGROUND AND OBJECTIVE: Lately, extensive attention has been devoted to the study of heavy metals removal from water and wastewater by the adsorbents resulted from agricultural wastes. The aim of this study was to investigate the removability of cadmium (Cd) from aqueous solutions using raw rice husk, rice bran and Silica from rice husk in different conditions. METHODS: In this experimental research, the adsorption of cadmium using three adsorbents (raw rice husk, rice bran and rice husk silica) carried out in bath reactors. Raw rice husk and rice bran were collected from north of Iran. Rice husk silica was prepared in a furnace at 800 ºC for four hours, after acid leaching. The efficiency of the adsorbents was studied in four different statuses: different values of pH (5, 6, 7, 8 and 9), different concentrations of cadmium (1, 5, 10 and 15), different dosages of adsorbents (0/5, 1 and 1/5) and different contact times (30, 45, 60, 75 and 90). The standard method of atomic adsorption was used to measure the concentration of cadmium. FINDINGS: The maximum removal efficiency of cadmium was obtained by rice bran up to 96.8% at 5 mg/l initial concentration of Cd, 90 min of contact time and adsorbents dosage of 1.0 g/l. However, at the same condition, the maximum removal efficiency of cadmium by raw rice husk and rice husk silica was 69.3% and 74.7%, respectively. Moreover, this study showed that there was a significant relationship between the increase of the contact times and removal efficiency of Cd in aquatic environments by three adsorbents (p<0.01). CONCLUSION: Rice husk and the adsorbents derived from it could be considered as effective and inexpensive adsorbents for removal of cadmium.

Background and purpose: Aflatoxin M1 is a toxic compound that is placed in class IIB (carcinogenic) by the WHO- International Agency for Research on Cancer, so its monitoring in milk is a great public health issue. The purpose of this study was to determine the concentration of aflatoxin M1 in raw, pasteurized milk and samples of milk produced for school milk project in Shahrood, Iran. Materials and methods: In this descriptive-analytical study, 130 raw milk samples were collected from 4 collection centers and 14 production sites. Also, samples of 28 pasteurized milk from 3 producing company and 13 samples prepared for school milk project (in autumn and winter) from two brands were collected in summer and winter and analyzed by HPLC-fluorescence following immunoaffinity purification. Results: In samples of raw milk the mean concentration of Aflatoxin M1 in summer and winter were110.3± 137.5 and 24.8± 36.51ng/kg, respectively. In summer and winter the level of Aflatoxin M1 contamination in pasteurized milk and school milk were 52.1± 36.6, 16.8± 13.0, 28.1± 14.8, and 32.5± 171ng/kg, respectively. In all samples significant differences were observed between seasons. The minimum and maximum levels of aflatoxin M1 in raw milk were determined zero (undetectable) in winter and 743 ng/kg in summer, respectively. Conclusion: Significant differences in the mean concentration of aflatoxin M1 in studied seasons, indicates the necessity for appropriate monitoring on animal food in summer and winter and more controlling measurements in summer on type, processing and storage of animal food.