پديد آورندگان :
حسن‌زاده، پريسا نويسنده دانشجوي دكتري دانشكده‌ي مهندسي عمران و محيط زيست، دانشگاه تربيت مدرس Hassanzadeh, P , گنجي‌دوست، حسين نويسنده استاد دانشكده‌ي مهندسي عمران و محيط زيست، دانشگاه تربيت مدرس Ganjidoust, H , آيتي، بيتا نويسنده دانشيار دانشكده‌ي مهندسي عمران و محيط زيست، دانشگاه تربيت مدرس Ayati, B
كليدواژه :
سينتيك , مكانيسم , يون‌هاي مزاحم , DO , ORP , PH
چكيده فارسي :
تصفيه‌ي فاضلاب محتوي اكسي‌تتراسايكلين (OTC) به‌دليل مشكلات جدي در محيط زيست اهميت خاصي دارد. در اين پژوهش، حذف كامل 155 (mg/L) OTC توسط 1000 (mg/L) نانو ذرات آهن در pH برابر 3 با توان تابشي 200 وات در ناحيه‌ي UV-A در مدت 14 ساعت انجام و با بررسي تغييرات پارامترهاي ORP، pH و DO در مدت 5/6 ساعت، زمان شروع واكنش فتوكاتاليستي هيدروكسيد اكسيد آهن پس از 3 ساعت به‌دست آمد. محصولات عمده‌ي ناشي از شكست مولكول OTC تعيين و ثابت‌هاي سينتيكي آنها به ترتيب 0099/0، 0021/0، 0049/0 و 0074/0 (min-1) محاسبه شدند. اثر حضور يون‌هاي كلسيم، منيزيم، كلر، نيترات، سولفات و بي‌كربنات با غلظت‌هاي 10، 50، 100 و 200 (ppm) در فرايند بررسي شدند. با افزايش غلظت يون‌ها به ترتيب NO3- > Ca2+?Mg2+ > Cl- اثر منفي در حذف داشتند و يون‌هاي سولفات و بي‌كربنات بي‌اثر بودند. همچنين مدل سينتيكي و ثابت‌هاي سرعت حذف OTC در حضور يون‌هاي رقيب محاسبه شدند.
چكيده لاتين :
A large amount of antibiotics consumed ends up in wastewater, in which they may exert selective pressure on or maintain resistance against microorganisms. Antibiotic resistant bacteria and genes encoding antibiotic resistance are commonly detected in wastewater, often at higher rates and concentrations compared to surface water. Wastewater can also provide favorable conditions for the growth of a diverse bacterial community, which constitutes a basis for the selection and spread of antibiotic resistance, including genetic resistance to humans, livestock and poultry. Their elimination is very difficult by traditional biological treatment methods because they are hard biodegradable. Oxy-tetracycline (OTC) is one of the famous tetracyclines that have environmental risk. Nano zero valent Iron (NZVI) particles can be a new suggestion for OTC remediation. In this study, 155 ppm of OTC by 1000 ppm nano-scale zero valent iron with 200 W, UV-A radiation at pH of 3, were completely removed after 14 hours. The final products were carbon dioxide and water that were measured by a CO2 analyzer. The iron compound on the surface of the nano zero valent Iron particles was Fe(OOH), which was determined by XRD analysis. Variations of parameter, including ORP, pH, and DO, during the removal process, were investigated for 6.5 hours. After 3 hours, the photocatalytic reaction by Fe(OOH) was started. The mechanism of OTC degradation was proposed by HPLC / ESI-MS and four by-products were obtained. The kinetic models for by-products were first order, and the rate constants, by the first order kinetic model, were found to be equal to 0.0099, 0.0021, 0.0049 and 0.0074 min-1, respectively. The effect of competitive ions, including calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), nitrate (NO3), sulfate (SO42-) and bicarbonate (HCO3-), with 10, 50, 100 and 200 ppm concentration, on OTC removal, were investigated. The results showed the negative effect of OTC removal by increasing the concentration of competitive ions, NO3- > Ca2+ ? Mg2+ > Cl- . But SO42- and HCO3- had no considerable effect. The kinetic model for OTC removal in the presence of all competitive ion concentrations was first order, but, for 10 ppm of NO3-, Ca2+ and Mg2+, were pseudo first order.
