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مطالعة آزمایشگاهی اثر نانوذرات آهن بر حذف آرسنیک در محیط آبی | ||
| محیط شناسی | ||
| مقاله 11، دوره 39، شماره 4، اسفند 1392، صفحه 149-156 اصل مقاله (710.55 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22059/jes.2014.36468 | ||
| نویسندگان | ||
| مهدیه جانباز فوتمی* 1؛ مجید خلقی2؛ عبدالحسین هورفر3؛ داوود حق شناس4 | ||
| 1کارشناس ارشد گرایش مدیریت منابع آب، گروه آبیاری و آبادانی پردیس کشاورزی و منابع طبیعی دانشگاه تهران | ||
| 2دانشیار گروه مهندسی آبیاری و آبادانی دانشگاه تهران، پردیس کشاورزی و منابع طبیعی دانشگاه تهران | ||
| 3دانشیار گروه مهندسی آبیاری و آبادانی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران | ||
| 4دکتر مواد گروه شیمی دانشگاه امیرکبیر | ||
| چکیده | ||
| آلودگی آبخوان، یکی از مسائل مطرح در آب زیرزمینی است که با افزایش فعالیتهای صنعتی، دفع فاضلاب در چاههای جذبی و برداشت بیرویه از سفره در دهههای اخیر افزایش یافته و با توجه به اینکه حدود 60 درصد از آب مصرفی سالانة کشور از آب زیرزمینی تأمین میشود، پالایش آن بسیار حائز اهمیت است. یکی از آلودگیهای رایج، سمی و خطرناک در آب زیرزمینی، آلایندة آرسنیک است که غلظت بیش از حد مجاز آن در چند استان ایران گزارش شده است. یکی از راههای جدید، کارآمد و کمهزینه برای کاهش غلظت آرسنیک از آب زیرزمینی، تزریق درجای نانوذرات آهن به محیط آبخوان است که امروزه در جهان به آن توجه شده است. هدف از این مقاله بررسی روند کاهش آرسنیک در محیط آبی از طریق نانوذرات آهن صفر است که با انجام آزمایشهای پیمانهای شکل گرفته است. در این آزمایشها اثر زمان، غلظت اولیة آلاینده و واکنشگر، دما و pH بر تغییرات غلظت نانوذرات آهن و آرسنیک مطالعه شده است تا سرعت واکنش و نحوة کاهش آرسنیک در محیط آبی بررسی شود. نتایج این آزمایشها نشان دادند نانوذرات آهن، غلظتی در حدود 10 برابر مجاز غلظت آرسنیک را در یک ساعت به زیر غلظت مجاز استاندارد آب شرب ایران میرسانند. در نهایت، نتایج آزمایشها نشان دادند که نانوذرات آهن بازده بسیار زیادی برای پالایش آب آلوده به آرسنیک در محیط آبی دارند. | ||
| کلیدواژهها | ||
| آزمایشهای پیمانهای؛ پالایش آب؛ حذف آرسنیک؛ نانوذرات آهن | ||
| عنوان مقاله [English] | ||
| Experimental Investigation of Arsenic Removal by Using Fe Nano Particles in Batch Experiment | ||
| نویسندگان [English] | ||
| Mahdieh Janbaz Fotemi1؛ Majid Kholghi2؛ Abdolhossein Horfar3؛ Davoud Haghshenas4 | ||
| 1M.Sc. water resource management,University of Tehran, Karaj, Iran, 31587-77871. | ||
| 2Associate professor,Department of Irrigation and Drainage,University of Tehran, Karaj, Iran, 31587-77871 | ||
| 3Associate professor,Department of Irrigation and Drainage,University of Tehran, Karaj, Iran, 31587-77871 | ||
| 4PhD, Department of Chemistry, Amirkabir University, Tehran, Iran. | ||
| چکیده [English] | ||
| Introduction Toxic and dangerous pollution in groundwater is enormous. This assenic pollution is concentrated more than its permissible limits. It can be observed in different countries like India, Nepa l,Bangladesh, Pakistan, Taiwan, Thailand, Vietnam, Argentina, Brazil, Chili and Mexico. In some places in Iran like Hashtgerd and Kordestan the arsenic pollution has been observed more than the permissible concentration. As the arsenic pollution is increasing, many studies have been done to find different treatment options. Due to rapid removing of the As (V) and As (III) by using Iron Nano particles, this method have recently been considered useful. In this paper arsenic removal process was investigated by using nanoparticles. Based on batch experiments, the influence of Zero-valent iron nanoparticles concentration, tem perature, pH, time, and arsenic initial concentration were observed in arsenic removal process. The results of this study indicated that the Iron nanoparticles have high performance in arsenic pollution removal. Experimental Method The purpose of the current experimental study was to investigate the arsenic remediation process by using iron nanoparticles in batch experiment. Specific concentration of iron nanoparticles produced by PNF Corporation along with the arsenite sodium salt was used. Specification of iron nanoparticle and arsenic has been shown in table 1 and 2. Table 1. Arsenic proportions in arsenic sodium salt Element Valance Percent % gr/ 1000ppm Na 23 0.18 0.31 As 74.9 0.58 1 O2 32 0.25 0.43 NaAsO2 129.9 1 1.73 Table 2. Specifications of iron nanoparticles Actual density (gr/Cm3) Bulk density (gr/Cm3) Specific surface (Cm2/gr) Purity (%) 99.9 8-6 0.25-0.1 7.9 Firstly, the polluted arsenic solutionw as put on shaker with a speed of around 250 rpm . Then specific concentration of iron nanoparticles were added to the solution and the test was begun. The arsenic reducing process was investigated with sampling, conducted during the experiments. Samples were kept in dark glassetos prevent the arsenic oxidation. It should be m entioned that iron nanoparticles were separated from samples by filtering papers S&S with the size of 11m. Arsenic was measured by coupling VGA and atomic adsorption machineries and the results were finally analyzed. In batch experiments, the effect of five parameters, i.e. time, pH, temperature, initial concentration of arsenic and injection concentration of nanoparticles were investigated. Specifications of the experiment have been showed in Table 3. Table 3. Specifications of experimental Time (min) Iron nanoparticles concentration (gr/lit) Arsenic initial concentration (ppm) Specifications Experimental Time 0.5 1 2,5,10,15,30,60,90,120 Iron nanoparticles concentration 0.5 0.5, 2 30,60,90,120 Arsenic initial concentration 0.5, 5 1, 2 30,60,90,120 Temperature 0.5 1 15,30,45,60 pH 0.5 1 30,60,90,120 In the first test, the solution containing 0.5 gr/lit arsenic and 1 gr/lit nanoparticles reacted after 1 hour and the results showed that arsenic concentration reduced to below the allowable concentration by using Fe nanoparticles in this time interval (Fig. 1 and 2). In pH test, alkaline, acidic and natural environments were investigated and the result indicated that the reaction rate increased with decreasing of pH. The results also indicated that pH increased during the test (Fig4) and this result was one reason for decreasing reaction rate with time. For studying the temperature effect, two similar tests were done in 60C and 30C temperatures. In these tests, the reaction rate increased with increasing the temperature. Initial arsenic concentration and injection iron concentration affected the reaction rate significantly. Consequently, the experiments were conducted by considering different concentration of iron nanoparticles and arsenic thawt ere for arsenic concentration 5 and 0.5 ppm and for iron nanoparticles of 2 and o.5 gr/lit (Table 3). After that, the results indicated that the reaction rate increased with increasing the arsenic or iron nanoparticles concentration (Fig. 3) because of the increase in the contact between arsenic pollution and iron nanoparticles as reactive. Finally, the results revealed that iron nanoparticles could effectively been used to eliminate the arsenic pollution. Conclusion Nowadays, arsenic remediation as a toxic and widespread pollution is important in groundwater studies. One of the methods for the arsenic remediation is using the iron nano particles. This method involves lower costs with high performance and can be used for in-site pollutant remediation in aquifers. The result of this investigation indicated that the reaction between iron nanoparticles and arsenic lasts only about several minutes. Increase in the temperature and decrease in pH reduced the reaction rate. Investigation of arsenic concentration com pared with iron nanoparticles injection concentration revealed that the arsenic removal rate is increased by an increase in the ratio of nanoparticles to arsenic. For removing 500 ppb of arsenic concentration by using 1 gr/lit of iron nanoparticles, an exponential decreasing process was observed so that the arsenic concentration was reached to less than the arsenic permissible concentration during two hours. Finally it can be concluded that the capability of the Zero-valent Fe nanoparticles is a useful tool for removing the arsenic pollution in the groundwater. | ||
| کلیدواژهها [English] | ||
| arsenic pollution removal, Batch experiment, iron nanoparticles, remediation water | ||
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