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Showing 3 results for Davari
Removal of Reactive Blue 19 using Natural and Modified Zeolites
Afshin Maleki, Amir Hossein Mahvi, Reza Rezaee, Behrouz Davari,
Volume 5, Issue 4 (15 2013)
Abstract
Background and Objectives: Dyes are an important class of pollutants, which can even be identified by naked eye. Disposal of dyes in precious water resources have been prohibited, however, various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. Therefore, natural zeolite (clinoptilolite) and acid modified zeolite were used as a low-cost adsorbent to evaluate their ability to remove color from aqueous solution using a batch adsorption experiments. Materials and Methods: Modification of zeolite surface was carried out with two acids sulfuric acid and phosphoric acid, to improve the removal efficiency of reactive blue 19. We studied the influence of acid concentration, contact time, solution pH, initial dye concentration, and adsorbent dosage on the removal efficiency. Results: The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. It was also found that adsorption of dye by zeolite followed pseudo first-order kinetics. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dye but can be distinctly improved by modifying its surfaces with acid. Experimental results also showed that sulfuric acid has better performance than phosphoric acid in the modification of zeolite for dye adsorption. Conclusion: We achieved the best results in terms of removal efficiency (41-72%) for the zeolite modified with Si/Al ratio of 7.5 after 3 h of contact.
Investigation of aflatoxin status in foreign black tea in Tehran, Iran
Leila Faramarz, Mahdi Davari, Rouhollah Karami Osboo,
Volume 18, Issue 2 (9-2025)
Abstract
Background and Objective: Aflatoxins are among the most important and hazardous fungal secondary metabolites, commonly produced in food and animal feed by certain Aspergillus species. Tea is one of the most widely consumed non-alcoholic beverages worldwide and is regarded as a healthy drink, with approximately two-thirds of the global population consuming it daily, particularly in the morning. This study aimed to monitor the presence of aflatoxins in black tea samples collected from Tehran, and to assess the safety of this commonly consumed beverage in the country.
Materials and Methods: In this study, 31 tea samples from different brands were collected in Tehran in May 2023 and analyzed for aflatoxin contamination using a nanoextraction method, followed by high-performance liquid chromatography (HPLC) equipped with a fluorescence detector.
Results: The limit of detection (LOD) values for aflatoxins G1, G2, B1, and B2 were 0.06, 0.35, 0.06, and 0.35 ng/g, respectively, and the limit of quantification (LOQ) values were 0.2, 1, 0.2, and 1 ng/g, respectively. The LOQ values of the present method are comparable to those reported in recent studies conducted in Spain, Austria, and Iran, which reported LOQs higher than 1 ng/g. According to the results obtained, none of the black tea samples from different brands available in the Tehran market contained detectable levels of the four types of aflatoxins (B1, B2, G1, and G2), even below the globally permissible limits (AFs ≥ 10 µg/kg).
Conclusion: Despite the absence of aflatoxin contamination in tea samples consumed in Tehran, previous studies worldwide suggest that tea can be contaminated with fungi and may support mycotoxin production under favorable temperature and humidity conditions. Therefore, ensuring tea safety requires attention to proper processing, adequate storage conditions, and the prevention of aflatoxin-producing fungal growth during production stages.
 

Study of mycotoxins in wheat flour manufactured in Ardabil factories
Mahdi Davari, Habibollah Eskandari, Mahin Pouresmaeil,
Volume 18, Issue 3 (12-2025)
Abstract
Background and Objective: Mycotoxins are toxic secondary metabolites produced by fungi that contaminate food products such as wheat and pose significant health risks when consumed by humans.
Materials and Methods: This study aimed to analyze eight mycotoxins—deoxynivalenol, zearalenone, ochratoxin A (OTA), total aflatoxins, and the individual aflatoxins B1, B2, G1, and G2—in flour samples collected from factories in Ardabil city. To this end, eight samples were analyzed, including six lavash bread flour samples and two barbari bread flour samples. Solid-phase extraction using immunoaffinity columns, followed by high-performance liquid chromatography (HPLC) with spectrofluorimetric detection, was employed to measure the concentrations of the targeted mycotoxins.
Results: The results showed that deoxynivalenol was detected in three lavash flour samples at concentrations of 178.7, 136.4, and 188 ng/g. In contrast, the remaining lavash samples and all barbari flour samples had deoxynivalenol levels below the instrument’s detection limit of 100 ng/g. Additionally, all other analyzed mycotoxins were below the detection limits in all flour samples.
Conclusion: This study found that the levels of all eight fungal mycotoxins in wheat flour were below the permissible limits defined by Standard No. 5925 of the National Standards Organization of Iran, indicating no significant threat to human health. Despite these reassuring results, it is recommended to regularly monitor various types of flour and other wheat-based products across different seasons, due to potential variations in wheat supply from different regions of the country or from international sources.
 

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