تصفیه محلولهای آبی آلوده به عناصر سرب، کروم و کادمیم با جاذبهای فسفاتی

نوع مقاله: مقاله پژوهشی

نویسنده

عضو هیئت علمی پژوهشگاه علوم و فنون هسته‌ای، پژوهشکده چرخه سوخت

چکیده

جذب سه عنصر سمی در نمونه‌های آبی شامل سرب، کروم و کادمیم با استفاده از دو جاذب فسفاتی معدنی مورد آزمایش قرار گرفت. ابتدا تبادلگرهای فسفاتی مورد نظر تهیه شد و Mg2+ ، Pb2+ ، فسفر و نیتروژن اندازه‌گیری شدند. برای تعیین ظرفیت تبادلی، نسبت‌های متفاوتی از محلول با نمونه‌های فسفاتی مورد آزمایش قرار گرفت و سپس غلظت کاتیون‌های Pb2+، Cd2+ و Cr3+ اندازه‌گیری شد. اندازه‌گیری Pb2+، Cd2+ و Cr3+ توسط اسپکتروفتومتر جذب اتمی انجام شد. انحراف استاندارد نسبی به‌ترتیب 4/7 و 2/17 و 1/61 درصد و حد تشخیص آنها به‌ترتیب 5 میکروگرم در لیتر و 0/05 و 0/1 میلی‌گرم در لیتر بود. نشان داده شد که این ترکیبات استعداد بالایی در تصفیه آلاینده‌های فلزی دارا هستند. دو جاذب فسفاتی Mg3(PO4)2.6H2O و MgNH4PO4.H2O در تصفیه محلولهای آلوده به سرب و کروم و کادمیم تحت شرایط ایستا کارایی بالایی نشان می‌دهند به‌طوری‌که ظرفیت جذبی آنها در عمل برای یون سرب، به‌ترتیب 9/8 و 8/9 میلی‌مول بر گرم، برای یون کادمیم، 10/5 و 9 میلی‌مول بر گرم و برای یون کروم 6/6 و 5/3میلی‌مول بر گرم است. Mg3(PO4)2.6H2O بهترین جاذب تحت حالت پویا است. کارایی این دو ترکیب در شرایط متحرک نیز مورد بررسی و آزمایش قرار گرفت. جذب Pb2+، Cd2+ و Cr3+ با این جاذبهای فسفاتی با تبدیلات شیمیایی پیچیده‌ای در ماده جاذب همراه است. نتایج جذب تحت شرایط ایستا و نیز شرایط متحرک، به‌صورت جدول و نمودار ارائه شد. منظور از شرایط ایستا تماس 24 ساعته محلول کاتیون‌های Pb2+، Cd2+ و Cr3+ با MgNH4PO4.H2O و Mg3(PO4)2.6H2O در دمای20 درجه سلسیوس است.

کلیدواژه‌ها


عنوان مقاله [English]

Lead, Chromium and Cadmium Removal from Contaminated Water Using Phosphate Sorbents

نویسنده [English]

  • Fariborz Riahi
Faculty Member of Nuclear Fuel Cycle Research Center, Nuclear Science and Tech. Research Institut
چکیده [English]

Sorption of 3 poisonous metal ions (Pb2+, Cd2+, Cr3+) in aqueous solutions by two phosphate sorbents under dynamic and static conditions was studied. Phosphate sorbents (MgNH4PO4. H2O, Mg3(PO4)2. 6H2O) were synthesized by known procedures. The resulting crystalline samples were analyzed for the contents of Mg2+, Pb2+, P, N using spectrophotometric and elemental analysis methods. Likewise, the amounts of Pb2+, Cd2+, Cr3+ in solutions were determined before and after the sorption process using the atomic absorption method. The relative standard deviations for Pb2+, Cd2+, Cr3+ were 4.7%, 2.17%, and 1.61% and the detection limits were 5 g/L, 0.05 mg/L, and 0.1 mg/L, respectively. The sorbents showed a high performance in the purification of contaminated solutions under static conditions. The sorption capacity levels of Mg3 (PO4)2. 6H2O and MgNH4 PO4. H2O were 9.8m.mol/gr and 8.9m.mol/gr for Pb2+; 10.5m.mol/gr and 9m.mol/gr for Cd2+; and 6.6m.mol/gr and 5.3m.mol/gr for Cr3+, respectively. Pb2+ , Cd2+, Cr3+. sorption by inorganic phosphate sorbents from solutions is associated with complicated chemical transformations of the sorbents. A proper account of these transformations allows for the sorption process to be optimized. The data on Pb2+, Cd2+, Cr3+ sorption under static conditions (24-h contact of Mg3 (PO4)2. 6H2O, MgNH4PO4. H2O, with solutions at 20oC) and under dynamic conditions were obtained and the sorption behaviors of the metal ions were investigated in response to the sorbents used. It was found that Mg3 (PO4)2. 6H2O was the best sorbent for Pb2+, Cd2+, Cr3+ under dynamic conditions.

کلیدواژه‌ها [English]

  • Phosphate Sorbent
  • Sorption
  • Contaminated Water
  • Phosphate Exchanger
  • Inorganic Phosphate
  • Cadmium
  • Lead
  • Chromium
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