11 research outputs found

    Optimization and Modeling of Ammonia Removal from Aqueous Solutions by Using Adsorption on Single-walled Carbon Nanotubes

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    Due to the health effects of ammonia as an environmental pollutant, such as its odor, corrosion, algae phenomenon, etc., a method should be adopted to remove it from wastewater. In this study, removal of ammonia from hypothetical wastewater was investigated using adsorption on SWCNTs. The Design-Expert software was used to design the experiments and optimize the parameters that are effective in the adsorption performance of carbon nanotubes (CNTs), such as contact time, adsorbent dosage, pH, temperature, and ammonia concentration. The results revealed that the maximum adsorption with a performance of 90% was attained at a pH of 9.5. In addition, the adsorption performance was enhanced by increasing adsorption time and adsorbent dosage. Furthermore, increasing the temperature and the adsorbate quantity led to a decrease in the adsorption performance

    Arsenic, Cadmium, Chromium, and Lead in Childrenā€™s Products in Iran

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    Background: Non-standard creativity tools and entertainment products may contain heavy metals. Children are more sensitive than adults to this potentially toxic chemicals. This study aimed at investigating harmful elements in childrenā€™s products in Iran. Methods: In this descriptive-analytical study, Iranian samples (13 play dough samples, 6 finger paint, and 1 face paint sample) and 10 imported samples were investigated by atomic absorption spectrophotometry. The statistical analyses were performed using the SPSS statistical package (version 19). Results: The results of this study showed that the lead content of 2 samples of play dough (76%), 10 samples of finger paint (100%) and 3 samples of face paint (100%) was higher than the permissible limits set by the Iranian National Standards Organization. Lead and cadmium contents of 100% of the samples of play dough, along with the face and finger paints exceeded the permissible limits set by the European Union. Conclusion: Research on prolonged exposure to harmful elements and comprehensive risk characterization for toys is recommended


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    <p>Purpose: The purpose of this study describes the results of a survey of the practices of Iranian Wrestling League strength and conditioning (IWL S&C) coaches. Material: The response rate was 88.5% (100 of 113). The contents survey examines include: (a) background information, (b) physical testing, (c) flexibility development, (d) speed development, (e) plyometrics, (f) strength/power development, (g) unique aspects, and (h) comments from coaches providing additional information. Results: Results indicate, in part, that coaches assess an average of 7.3 parameters of fitness, with tests speed being the most common. All coaches used a variety of flexibility development strategies. Results reveal that all of IWL S&C coaches follow a periodization model. Speed as the first priority (100%) and muscular endurance, power and strength as second priority (97%) of importance in evaluating their athletes. Sixty-six percent coaches (66%) indicated that their athletes used Olympic-style lifts. All coaches employed plyometric exercises with their athletes. Ninety-two percent (92%) of the coaches reported that used plyometric trainings for increasing the speed of their wrestlers and 82% of the coaches used plyometric jump in place exercises as regular practice in their trainings. Conclusions: The squat and its variations, as well as the Olympic-style lifts and their variations, were the most frequently used exercises. The survey serves as a review and a source of applied information and new ideas.</p

    Removal of 17Ī²-estradiol (E2) from Aqueous Solutions by Adsorption Using Oak Jaft and Tea Waste, Isotherm Investigation, and Adsorption Kinetics

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    The present study aims to investigate wastewater treatment of hormones by oak jaft and tea waste adsorbents. Various factors were used to evaluate the adsorption process, such as the initial pollutant concentration, adsorbent concentration, contact time, and pH. The results showed that both adsorbents, jaft, and tea waste, can adsorb 17Ī²-estradiol. Maximum adsorption was 82.4% for jaft adsorbent and 81.5% for tea waste at 85 min, 7 g/L of adsorbent dose, and pH = 4.5, respectively. The adsorption equilibrium was performed using Langmuir, Freundlich, and Liu models, based on the results, Freundlich model with R2 values >0.97 demonstrated better agreement with the adsorption experimental data. To obtain information on adsorption velocity, three models of pseudo-ļ¬rst-order, pseudo-second-order, and Elovich were used. The findings revealed that the pseudo-second-order model with R2 > 0.98 is a better fit for the experimental data. Therefore, the jaft adsorbent and tea waste can be used as effective and economical adsorbents for the removal of organic pollutants in wastewater treatment plants