نوع مقاله : مقاله پژوهشی

نویسنده

گروه محیط زیست، پژوهشگاه علوم و تکنولوژی پیشرفته و علوم محیطی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان، ایران

چکیده

در این تحقیق، جذب متیلن بلو (MB) از محلول آبی بر روی گرانول‌های مس(II)-آلژینات (Cu (II) -A) حاوی کربن فعال مشتق شده از پلی اتیلن ترفتالات (PAC) تحت شرایط تجربی مختلف مورد بررسی قرار گرفت. ترکیب و ساختار گرانول‌ها با روش‌های SEM و BET مورد مشخصه‌یابی قرار گرفت. تأثیر پارامترهای مختلف از قبیل: غلظت رنگزا، pH، مقدار جاذب و زمان تماس بوسیله روش ناپیوسته بررسی شد. داده‌های تعادلی با استفاده از ایزوترم لانگمویر، فرندلیچ و تمکین مورد ارزیابی قرار گرفت. مدل لانگمویر، جذب MBرا به بهترین شکل توصیف کرد، که نشان دهنده همگن بودن فرآیند جذب MB بر روی گرانول‌ها می‌باشد. بیشینه ظرفیت جذب تحت شرایط بهینه (مقدار جاذب: g 04/0، زمان تماس:h 3، pH~6، دما:C º 25) برای حذف متیلن بلو مقدارmg g-1 96/86 بدست آمد. داده‌های سینتیکی با استفاده از معادله شبه مرتبه اول و شبه دوم لاگرگرن مورد تجزیه و تحلیل قرار گرفت. مدل شبه مرتبه دوم بهترین تناسب را برای مطالعات سنتیکی نشان داد (9997/0R2=)، که نشان دهنده جذب شیمیایی MBمی‌باشد. علاوه بر این، هیچ کاهش آشکاری پس از پنج چرخه جذب مشاهده نشد، که نشان می‌دهد جاذب PAC/Cu (II) -A پایداری و قابلیت استفاده مجدد خوبی دارد. در مجموع، نتایج نشان داد که گرانول‌های آماده ‌شده می‌تواند به عنوان یک جاذب کارآمد برای تصفیه پسآب‌های رنگی مورد استفاده قرار گیرد. همچنین، این تحقیق راه‌ جدیدی برای تهیه مواد کامپوزیتی مبتنی بر کربن فعال حاصل از مواد زاید برای حذف آلاینده‌های محیط زیست می‌گشاید.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Adsorption of Methylene blue Dye Using Carbon-Alginate Beads

نویسنده [English]

  • Maryam Fayazi

Department of Environment, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran

چکیده [English]

Various pollutants such as dyes and heavy metal ions following the arrival to ecosystems lead to the serious global environmental pollution. Large amounts of dyes are used in textile, leather, paper, rubber, cosmetics and synthetic detergents industries. Dye effluents discharged from mentioned industries possess serious environmental and health problems. Colored substances like dyes usually have a synthetic origin and complex aromatic molecular structure which makes them highly resistant to biodegradation with conventional physical and biological oxidation treatment processes. Methylene blue (3,7-Bis(dimethylamino)phenothiazin-5-ium chloride, MB) is a water soluble organic dye, widely used in textile industries and is the most commonly used substance for dying cotton, wood and silk. However, MB can cause eye burns which may be responsible for permanent injury to the eyes of human and animals. It can result in nausea, diarrhea, vomiting, breathlessness and mental confusion. Accordingly, effective removal of MB in the environmental area has attracted considerable attention. Dyes cannot be completely removed by means of conventional biological treatment processes, such as activated sludge and anaerobic digestion: due to their low biodegradability, nearly 90% of reactive dyes remain unchanged after undergoing an activated sludge process. Several physicochemical technologies, including coagulation/flocculation, membrane separation, ion exchange, chemical oxidation, electrochemical techniques and photocatalysis protocols have been studied for the purpose of removing dye from wastewater. Compared with these methods, the adsorption of dyes from aqueous solution has proven to be an excellent approach to treating effluents as well as a cost-effective technique. Among different adsorbents, activated carbons (ACs) have received significant attention due to their unique properties such as chemical stability, low price, high specific surface area and outstanding adsorption capacity. Moreover, another important advantage for ACs is their potentially low environmental issue, stems from most industrial waste or biomass residue can be employed as carbon precursors for preparation of AC adsorbents.

In this study, the adsorption of methylene blue (MB) from aqueous solution on copper(II)-alginate (Cu(II)-A) granules containing activated carbon derived from polyethylene terephthalate (PAC) with different experimental conditions was investigated. The residual concentration of MB in the solution was monitored for every 5 min intervals using the UV–vis spectrophotometer at 655 nm (λmax of the dye). The composition and structure of the granules were characterized by SEM and BET methods. The effect of various variables including: dye concentration, pH, adsorbent amount and contact time was investigated by batch method. Equilibrium data were evaluated using Langmuir, Friendlich and Tamkin isotherms. The Langmuir model best describes the MB dye adsorption, which shows that the MB dye adsorption on the granules is homogeneous. The maximum adsorption capacity under optimal conditions (adsorbent: 0.04 g, contact time: 3 h, pH~6, temperature: 25 ° C) for removal of MB was 86.96 mg/g. Kinetic data were analyzed using the first-order and second-order Lagergren equations. The quasi-second-order model showed the best fit for the synthetic studies (R2 = 0.9997), which indicates that MB adsorption is limited by the chemical adsorption process. In addition, no obvious decrease was observed after up to five adsorption cycles, indicating that the PAC/Cu (II) -A adsorbent has a good stability and reusability. Overall, the results show that the prepared granules can be use as an efficient adsorbent for the treatment of colored effluents. Also, this research opens a new way to prepare activated carbon-based composite materials from waste materials to remove environmental pollutants.

کلیدواژه‌ها [English]

  • Alginate
  • Polyethylene terephthalate
  • Absorption
  • Activated carbon
  • "
  • Methylene blue:"