نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی شیمی، دانشکده مهندسی شیمی و نفت، دانشگاه تبریز، تبریز، ایران

2 گروه مهندسی شیمی، دانشکده مهندسی شیمی و نفت- دانشگاه تبریز، تبریز، ایران

3 گروه شیمی کاربردی، دانشکده شیمی، دانشگاه تبریز، تبریز، ایران

چکیده

آلاینده‌های دارویی یکی از معضلات مهم محیط‌زیستی محسوب می‌شوند که باید قبل از اینکه وارد محیط‌زیست شوند، محیط‌های آبی از این آلاینده‌ها عاری گردند. روش‌های مختلفی برای حذف و تخریب این نوع آلاینده‌ها وجود دارد. روش جذب سطحی، در صورتی که جاذب مورد استفاده، گران‌قیمت نباشد، از نظر عملیاتی آسان و از نظر اقتصادی مقرون به صرفه است. هدف از مطالعه‌‌‌ی حاضر، بهینه‌سازی فرآیند حذف داروی آنتی‌بیوتیک تتراسایکلین از محلول‌های آبی توسط جاذب نانورس و بررسی سینتیک و ایزوترم‌های جذب است. در این پژوهش، پس از آماده‌سازی فیزیکی نانورس و انجام آزمون‌های شناسائی نانورس همچون FTIR، XRD و SEM، بهینه‌سازی پارامترهای موثر بر جذب توسط نرم‌افزارDesign Expert انجام گرفت. اثر پارامترهایpH، غلظت اولیه و مقدار جاذب بررسی انجام گردید. مقادیر بهینه پارامترهای pHبرابر با 5/9، مقدار جاذب برابر با g/L2/1 و غلظت اولیه جاذب نیز برابر با mg/L 15/21 در دمای °C 25، مدت زمان جذب min 30 و سرعت همزن rpm1000 به دست آمد. بررسی مدل‌های سینتیکی و ایزوترم‌های تعادلی نشان داد که سینتیک جذب از مدل شبه درجه دوم (R2=0.999) و ایزوترم جذب از مدل ایزوترم لانگمویر پیروی می‌کند. در شرایط بهینه، نانورس بعنوان جاذبی کم‌هزینه و سازگار با محیط‌زیست، در جذب تتراسایکلین از محیط‌های آبی، توانایی مطلوبی می‌تواند داشته باشد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigating the removal efficiency of tetracycline antibiotic from aqueous solutions using nanoclay adsorbent and study of effective parameters, kinetic models and adsorption isotherms

نویسندگان [English]

  • Parisa Mechinchi 1
  • Hassan Aghdasinia 2
  • Seyed Jamaleddin Peighambardoust 1
  • Mahmoud Zarei 3

1 Department of Chemical Engineering, Faculty of Chemical and Petroleum engineering, University of Tabriz, Tabriz, Iran

2 Department of Chemical Engineering, Faculty of Chemical and Petroleum engineering, University of Tabriz, Tabriz, Iran

3 Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran

چکیده [English]

Drugs, as a group of environmental pollutants, contaminate surface and groundwater resources in industrial and residential communities. Among the drugs, the entry of tetracycline antibiotics into the environmental cycle causes damage to the ecosystems of areas exposed to wastewater, both chemically and microbiologically.

Using physical techniques is a good solution to remove this contaminant and the adsorption method is one of the most desirable ones due to its effectiveness and simplicity operationally, lack of toxicity and its cheapness finally.

In this process, fabrication of adsorbents with high adsorption capacity and suitable catalysts is required for rapid and easy separation of pollutants. Clays due to the exchange capability of ions with medicinal compounds, has a special application in the field of drug removal.

The aim of this study was to optimize the adsorption process of tetracycline by nanoclay adsorbent. The effect of each of the parameters like: adsorbent amount, pH, initial antibiotic concentration on removal efficiency, and the adsorption kinetics and equilibrium isotherms were studied.



Materials and Methods

In this study, we used natural clay (prepared from Ajabshir city), tetracycline, distilled water, hydrochloric acid (Iran, Mojallali, 37%) and sodium hydroxide (Iran, Mojallali, 97%) as well as devices was used, UV-Vis spectrophotometer (SPECORD 250, analytkjena, Germany), digital scale (KERN, Germany), pH meter (Iran, ZAG CHEMIET), standard screen sieve 854 mm, centrifuge (HS 18500 R, Iran). To prepare the stock solution, 1g of the drug was added to distilled water of 1000 ml and solutions with lower concentrations were prepared from it. The structure of nanoclay adsorbent was investigated using Fourier transform infrared spectroscopy (Germany Brucke TENSPR 27), scanning electron microscope (Germany, MIRA3, TESCAN) and X-ray diffraction (Brucker AXS D8 ADVANCE).

In order to optimize the process, using Design Expert Ver.7 software, a central composite design consisting of 20 experiments and response surface method was used and independent parameters including initial concentration, adsorbent amount and pH of the solution were considered. The range of parameters was obtained by performing preliminary experiments and the equilibrium time was considered to be 30 min. Analysis of variance (ANOVA) was performed to determine the significant quadratic model, which fits the experimental responses and independent variables. To investigate the kinetics of adsorption process, concentrations were obtained at different times until the equilibrium time was reached and experimental data were compared with three kinetic models of first order, second order and inter-diffusion. In order to study the isotherms, three isotherm models of Langmuir, Freundlich and Tamkin were studied.

Results

FTIR analysis was used to determine the nanoclay functional groups before the adsorption process in the wave number range of 4000-400. The peaks showed compliance with C-H flexural bonds, asymmetric Si-O-Si tensile, aromatic C = C, C = O tensile, Si-OH tensile (hydroxyl group). X-ray analysis of nanoclay showed that calcium carbonate (calcite), silicon oxide (quartz) and 5-aqueous calcium sulfate were present in the nanoclay structure.

SEM images magnification 1µm showed that the nanoclay has irregular and uneven surfaces with large pores. The presence of these empty spaces makes the adsorbent effective.

The coefficient R2 measures the share of total changes described by the model and for a good fit R2 should be close to 1 and at least 0.8. For modeling, the removal of tetracycline was 0.831. Also, the significance of the model was evaluated by F and P values. Larger values of F and smaller values of P mean that the applied model is more meaningful. The value of F was 7, which was higher than the value of F Fisher (2.37), which shows the consistency of the model in the process description.

کلیدواژه‌ها [English]

  • Adsorption
  • Tetracycline
  • Optimization
  • Design Expert
  • Nano clay