Showing 27 results for Isotherm
M Nourinejad, N Arsalani, H Namazi,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: Nicotine as the most toxic alkaloid in tobacco is one of the compounds which causes human death over the past few decades. The purpose of this paper was to remove nicotine environmental pollution from aqueous solutions using halloysite-polythiophene nanocomposite.
Materials and Methods: Halloysite-polythiophene nanocomposite was prepared using a homogeneous solution of HNT and FeCl3 at 0-5°C by the ball milling technique. In this study, parameters such as pH, contact time and initial concentration of nicotine in laboratory scale were studied and the physical properties of the adsorbent were characterized via fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Then, the absorption results were described using Langmuir and Freundlich isotherms.
Results: The results showed that the pH, initial concentration of nicotine and contact time had a direct effect on the nicotine adsorption process. The adsorption of nicotine followed Langmuir isotherm (R2 < 0/995). Moreover, the best adsorption result was achieved at pH=7, 50mg adsorbent, contact time of 90 min and 50mg/L of nicotine.
Conclusion: The results of this study showed that the Halloysite modification as a mineral composite with polythiophene and the synthesis of HNT@PTh nanocomposite can be used as an effective adsorbent to adsorb the nicotine.
A Seid-Mohammadi, Ar Rahmani, Gh Asgari, S Bajalan, A Shabanloo,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: Main sources of 4-chlorophenol wastewater are petroleum industry, coal, paper and resin production. The aim of this study was to compare the performance of raw and cationic surfactant modified nanoclay in removal of 4-chlorophenol from aqueous solutions.
Materials and Methods: The influence of contact time, initial pH of solution, adsorbent dosage and 4-chlorophenol concentration as effective parameters in adsorption process and the influence of modification solution pH and surfactant loading rates were investigated. The modified nanoclay was characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopy. Finally, the isotherm and adsorption kinetics were investigated.
Results: The removal efficiency of 4-chlorophenol was increased by increasing the initial pH from 3 to 11, so that after of 120 min, the absorption efficiency at an initial 4-chlorophenol concentration of 100 mg/L and 0.25 g adsorbate was 26 and 95.5 % at pH 3 and 11, respectively. Under the same conditions the removal efficiency for the raw nanoclay was 2 and 9% at pH 3 and 11, respectively. The FTIR and XRD analyses revealed that the nanoclay structural changed from hydrophilic to hydrophobic and the interlayer spacing was increased. The adsorption of 4-chlorophenol on raw and modified nanoclay was consistent with Langmuir and pseudo-second-order kinetics. The maximum absorption capacity of raw and modified nanoclay was 0.5 and 25.77 mg/g, respectively
Conclusion: The modification of nanoclay with cationic surfactant increased the adsorption efficiency of 4-chlorophenol.
Z Esdaki, R Ansari, F Ostovar,
Volume 12, Issue 3 (12-2019)
Abstract
Background and Objective: Due to the existence of industries such as stainless steel, the presence of nickel (II) ions in water and wastewater has been reported at high concentrations. Removal of nickel (II) ions from wastewater and the environment are of primary importance. In this study, iron (III) oxide nanoparticles were studied as an adsorbent for removal of Ni (II) ions from water in the batch equilibrium system.
Materials and Methods: FT-IR, SEM and XRD techniques were used to characterize the structure of the sample. To determine the optimum adsorption, the effect of important parameters such as pH, contact time, adsorbent weight and initial concentration were investigated. Also, thermodynamic study (Gibbs standard energy variations, enthalpy and entropy), isothermal studies (absorption capacity) and kinetic studies (absorbent effect with time) were investigated.
Results: The results showed that the magnetic adsorbent had the highest removal efficiency of nickel (II) at pH 7, contact time 60 min, adsorbent dosage of 200 mg, and maximum removable concentration of 400 mg/L.
Conclusion: With thermodynamic studies, it was determined that the reaction was endothermic and the spontaneous process was controlled using the entropy factor (ΔG°=-2.7 KJ/mol, ΔS°=+165.17 J/mol.K). In order to better understand the mechanism of adsorption, kinetics studies were carried out using the pseudo-first-order and pseudo-second-order models. Then, Langmuir and Freundlich adsorption isotherms were investigated to determine the adsorption capacity, and it was found that the adsorption data were well fitted to Freundlich model and the maximum adsorption capacity was 43.5 mg/g, which indicated high adsorption capacity and its multi-layers.Then, Langmuir and Freundlich adsorption isotherms were investigated and it was found that the adsorption data were well fitted to Freundlich model and maximum adsorption capacity (qmax=43.5 mg/g) was obtained which indicates good adsorption capacity of adsorbent and its multi-layers.
H Niknejad, M Farzadkia, A Esrafili, M Kermani,
Volume 12, Issue 4 (2-2020)
Abstract
Background and Objective: 2,4 dinitrophenol is observed in sewage produced from chemical and petrochemical industries. Contamination of drinking water with these pollutants causes toxicity, health problems and change in taste and odor. The present study was developed to evaluate the efficiency of removal 2,4-DNP through dried sludge adsorbent and modified calcium chloride sludge adsorbent.
Materials and Methods: At first, sludge was dried at temperature of 60 °C. Next, CaCl2 was used to improve adsorption capacity. The removal efficiency of 2,4 dinitrophenol were determined by HPLC at wavelength of 360 nm. The effects of influencing factors including pH, initial pollutant concentration, contact time, and adsorbent dose were examined.
Results: The optimum pH of adsorption for both adsorbents was found to be 7. The optimum concentration of 2,4-DNP was 10 ppm. The results obtained from the present research showed that the removal of the contaminant using dried and modified sludge sorbent was increased from 72.6% to 86% at a dosage of 1.5 g. The adsorption kinetics were fitted with the pseudo second order kinetics model for both adsorbents. The isotherm data also showed that the adsorption of this pollutant on both adsorbents is fitted with the Freundlich model.
Conclusion: Results obtained from the present study indicated that the efficiency of the modified sludge ash is more than the non-modified sludge in 2,4 dinitrophenol removal. This can reduce adsorbent consumption in industrial treatment plants.
Azadeh Modiri, Shadab Shahsavari, Ali Vaziri Yazdi, Ali Akbar Seifkordi,
Volume 13, Issue 1 (4-2020)
Abstract
Background and Objective: Arsenic has long been considered as a heavy metal and toxic pollutant due to its potential to harm the human health and the environment. Adsorption is one of the mechanisms for arsenic removal from wastewater. Therefore, the purpose of this research was to investigate the feasibility of synthesized chitosan-zirconium magnetic nano fiber on arsenic adsorption from wastewater and to evaluate its kinetic and isotherm models.
Materials and Methods: Synthesis of nanofibers was performed by electrospinning method and the optimal formulation was determined following the experimental design. Then, kinetics and isotherms of arsenic adsorption on the as synthesized nanofibers were investigated. The prepared nanofiber was characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Infrared Fourier Transform (FT-IR) and Vibrational Sampler Magnetic Meter (VSM).
Results: The optimal formulation was obtained: 2.84% chitosan, 0.97% nano-zirconium and 0.94% nano-iron. The adsorption of arsenic on synthetic fibers was found to follow quasi-first-order kinetics and the Freundlich isotherm. Furthermore, the effect of initial concentrations of arsenic, contact time, temperature and pH on arsenic adsorption were surveyed. The optimal condition for nitrate arsenic adsorption was obtained at initial concentration of 70 mg/L, 45 min contact time and at pH 3.
Conclusion: According to the results, the synthesized nanofiber displayed a regular network structure with the distribution of the Zr-nanoparticles in its shape. Also, according to the form of magnetometric analysis, it was found that chitosan-nanosirconium magnetic nanofibers are well magnetized and are free magnetic. Finally, it can be concluded that the synthesized nanosorbent has a high potential for arsenic removal from industrial effluents.
Arezoo Balighian, Mitra Ataabadi,
Volume 13, Issue 2 (8-2020)
Abstract
Background and Objective: Hexavalent chromium is reported to be highly toxic, mutagenic and carcinogenic; hence treatment of water and wastewater contaminated with this element by low-cost and environmentally friendly methods is of great importance. Therefore the aim of present study was to evaluate the efficiency of Fe(II) modified bentonite for hexavalent chromium removal from a simulated wastewater.
Materials and Methods: In this study, Fe(II) modified bentonite was synthesized. Structure and morphology of bentonite were investigated by XRD and SEM techniques. Experiments were carried out as central composite design with three input parameters namely initial hexavalent chromium, pH and adsorbent dosage at 5 levels. Finally, the results were assessed by adsorption isotherm models.
Results: The findings revealed that complete removal efficiency of Cr (VI) achieved at pH of 2, initial hexavalent chromium concentration of 20 mg/L and adsorbent dose of 5 g/L. The adsorption isotherm model found to fit well with Langmuir isotherm model and revealed that the monolayer adsorption of hexavalent chromium at adsorbent surface was happened. The equilibrium data better fitted the Langmuir isotherm model suggested a monolayer adsorption nature of the modified bentonite.
Conclusion: The findings in this study showed the promise of use of Fe(II) modified bentonite for Cr (VI) removal. Moreover, response surface methodology can be used as an effective method to optimize hexavalent chromium removal from wastewaters.
Mohammad Ghafoori, Mehrdad Cheraghi, Maryam Kiani Sadr, Bahareh Lorestani, Soheil Sobhanardakani,
Volume 16, Issue 2 (9-2023)
Abstract
Background and Objective: Antibiotics are emerging pollutants that enter the human environment through pharmaceutical, hospital, and urban wastewater. Therefore, this study was conducted to investigate of removal efficacy of tetracycline (TC) from aqueous solutions using GO@Fe3O4@β-CD.
Materials and Methods: In this descriptive study, GO@Fe3O4@β-CD was synthesized and then used as an adsorbent for the removal of TC from aqueous solution. GO@Fe3O4@β-CD was characterized using X-ray diffraction (XRD), Scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometry (VSM) methods. Also, the influence of variables including pH (3-9), amount of adsorbent (0.003-0.050 g), contact time (0-100 min), and temperature (25-55 °C) so assessed on the efficacy of TC removal.
Results: The results of TGA analysis showed that GO@Fe3O4@β-CD nanoparticles were resistant to temperatures up to 400 °C. Also, the results indicated that β-cyclodextrin was uniformly dispersed on the surface of GO@Fe3O4.
The results indicated that removal efficiency increased up to 60 min contact time, 0.01 g of adsorbent, and decrease temperature to 25 °C. The optimum pH for TC removal was 7.0. Also, under these conditions, the adsorption process followed the Langmuir adsorption isotherm with a correlation coefficient of 0.992 and the pseudo-second-order kinetic model with a correlation coefficient of 0.997, 0.999, and 0.998. The maximum adsorption capacity of the prepared adsorbent was 357 mg/g.
Conclusion: The GO@Fe3O4@β-CD could be an effective and efficient adsorbent for the removal of TC from industrial wastewater.
