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تورم تناوبی پلیمرهای ابرجاذب در محیط متخلخل خاک | ||
| تحقیقات مهندسی صنایع غذایی | ||
| مقاله 1، دوره 8، شماره 4، اسفند 1386، صفحه 1-18 اصل مقاله (1.82 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| نویسندگان | ||
| سهیلا ابراهیمی1؛ مهدی همایی2؛ ابراهیم واشقانی فراهانی* 2 | ||
| 1دانشجوی سابق کارشناسی ارشد دانشگاه تربیت مدرس | ||
| 2دانشیار دانشگاه تربیت مدرس | ||
| چکیده | ||
| پلیمرهای ابرجاذب قابلیت جذب مقادیر زیادی آب و مواد غذایی دارند و افزون بر تأمین بهینة آب مصرفی گیاهان هدرروی آب از طریق تبخیر و آبشویی نیزدر آنها بسیار کم است. بنابراین، بررسی رفتاراین مواد در خاک، بهویژه در چرخههای متناوب خشک و ترشدن ضروریاست. هدف از این پژوهش، بررسی رفتار تورم تناوبی دو نمونه پلیمر از خانواده پلیآکریل آمید با نام اختصاری "طراوت 100A-" و "طراوت 200A-" و تعیین توانایی آنها در جذب آب، در چرخههای مکرر خشک و ترشدن در محیط متخلخل خاک است. بدین منظور، رفتار تورمی ایندو پلیمر در دو نوع خاک لوم و شنی بررسی شد. تیمارها شامل 0،25/0، 5/0، 75/0، و 1 گرم پلیمر در کیلوگرم خاک با سه تکرار بود. مقدار آب خاک برای هر تیمار در فشارهای 0، 100،300، 500،1000، 3000، 5000، 15000 کیلوپاسکال اندازهگیری شد و منحنیهای رطوبتی برای هر نمونه آزمایشی بهدست آمد. نمونهها در آون خشک و دوباره مرطوب شدند. این روند 5 بار تکرار و منحنیهای رطوبتی مربوطه برای تمام دورهها ثبت شد. نتایج نشان داد در هر مکش، با افزایش مقدار پلیمر در خاک، رطوبت حجمی خاک افزایش مییابد. بیشترین دامنة تاثیر پلیمر بر قابلیت نگهداشت آب خاک در مکشهای پایینتر (5000-0 کیلوپاسکال) مشاهده شد. همچنین، در تمام دورههای تر- خشکی و در هر مکش مقدار نگهداشت آب خاک در پلیمر طراوت 200A- بیشتر از طراوت 100A- بود. در هر دو نوع پلیمر و در همه تیمارهای به کار برده شده، افزایش ناگهانی رطوبت حجمی خاک- پلیمر از دوره اول به دوم، مشاهده شد. از سیکل دوم تا چهارم، رطوبت حجمی خاک- پلیمر در هر دو نوع پلیمرتغییرات همسویی نشان داد. در تناوب پنجم، پلیمر 100T-A افتی جزیی نسبت به دوره قبل نشان داد. بررسی پارامتریک منحنیهای رطوبتی هر دو پلیمر نیز نشان داد که با افزایش مقدار پلیمر کاربردی، پارامترهای qs،n، وqr در تمام تیمارها افزایش مییابد، اما تغییرات پارامترqr چندان قابل توجه نبود. مقدار پارامتر αبرای هر دو پلیمر در خاک شنی کاهش و در خاک لومی افزایش یافت. | ||
| عنوان مقاله [English] | ||
| Cyclic Swelling of Superabsorbent Polymers in Soil Porous Media | ||
| چکیده [English] | ||
| Both arid and semi-arid regions, which make up the greatest portion of the earth, suffer from a lack of precipitation and unsuitable water distribution. The agricultural sector consumes most of the fresh water resources in comparison with other sectors. Thus, it is important to increase water use efficiency (WUE) and practical ways to maintain soil water. Superabsorbent polymers are water containers that absorb and retain large quantities of water when applied to the soil. These materials release the absorbed water, allowing the plants to consume adequate amounts of water at all growth stages. This study investigated the cyclic swelling behavior of superabsorbent polymers. Two polymers, TA-100 and TA-200, were applied to loamy and sandy soils. The treatment levels consisted of 0, 0.25, 0.5, 0.75 and 1 gr of both polymers per kg of dry-weighed soil in 3 replicates. The water content for each treatment was measured at 0, 100, 300, 500, 1000, 3000, 5000 and 15000 kPa and soil water retention curves (WRC) were obtained for each soil sample. The samples were then oven-dried and re-wetted five times and the WRCs were again obtained. The results indicated that, by applying more polymers to the soil, the water content at any soil water pressure head increased. However, this influence declined for the next four drying-wetting cycles. The most dominant influence of the superabsorbent polymers on water retention for each drying-wetting cycle appeared in the lower soil water pressure heads (0-5000 kPa). A comparison of the TA-100 and TA-200 polymers indicated that the TA-200 has a larger water retention capacity and also appeared to absorb more water than did the TA-100 during the subsequent four cycles. Parametric analysis of the retention curves indicated that qs و n and qr parameters in all treatments increased when more polymer was applied. However, the variation of magnitude of qr was small. It was also observed that when any type of superabsorbent was applied, the α parameter decreased in sandy soil and increased in loamy soil. | ||
| کلیدواژهها [English] | ||
| Cyclic Swelling, polymer, Retention Curve, superabsorbent, water holding capacity | ||
| مراجع | ||
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