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Showing 5 results for Nanocomposite
Synthesis and efficiency evaluation of magnetic nanocomposite of activated carbon- zero valent iron/silver (PAC-Feº/Ag) in phenol removal from aqueous solution
B. Kakavandi, M. Mokhtari, R. Rezaee Kalantari, E. Ahmadi, N. Rastkari, M. Fatehi, A. Azari,
Volume 7, Issue 3 (5-2014)
Abstract

Background and Objectives: Phenol is one of priority pollutants produced through leather, paint, resin, and pharmaceutical industries and it can contaminate groundwater after entering to the environment. Hence, it is necessary to use a suitable method for its removal. The aim of this study was synthesize and efficiency evaluation of magnetic nanocomposite of activated carbon powder-zero valent iron/silver (PAC-Feo/Ag) in the removal of phenol from aqueous solution. Material & Methods: Reduction method was used for converting bivalent iron to zero valent iron and co-precipitation method for depositing of iron on activated carbon. For coating silver on nano zero valent iron, rapid mixing at high temperature was used. The adsorbent was characterized using SEM, TEM, and XRD techniques. Then, the impact of pH, contact time, agitation speed, temperature, adsorbent, and initial phenol concentration were evaluated and optimized by one factor at the time method. Reaction kinetics and isotherms were also determined. Results: It was found that PAC-Feo/Ag has cubic and intertwined structure and has a diameter in the range from 40 to 100 nm. The optimum conditions for phenol removal by PAC-Feo/Ag were as pH=3, 90 min contact time, 200 rpm agitating speed and adsorbent concentration equal to 1 g/l. Isotherm and kinetic equations showed that the experimental data of phenol adsorption onto PAC-Feo/Ag are correlated to the Langmuir (R2>0.969) and pseudo-second order (R2<0.965) models, respectively. Conclusion: Under optimum conditions, modified adsorbent by zero valent iron and silver with maximum efficiency of 97% has quickly and effectively ability in removal of phenol and it can be easily separated from the solution sample by magnet because of its magnetic properties.


Removal of Uranium (VI) from aqueous solution by Uranium Benzamide Complex using AC_Fe3O4 Nanocomposite
Z Akbari Jonoush, M Farzadkia, S Naseri, H.r Mohajerani, A Esrafili Dizaji, Y Dadban Shahamat,
Volume 7, Issue 4 (1-2015)
Abstract

Background and Objectives: Increased growing nuclear industry has increased the researchers concerns on uranium presence in the environment and its effects on human health. Uranium is a dangerous radioactive heavy metal with high half-life and chemical toxicity. Therefore, the main objective of this study was to removal uranium (VI) from aqueous solution by uranium benzamide complex using AC_Fe3O4 nanocomposite. Materials and Methods: AC_Fe3O4 nanocomposite was synthesized using co-precipitation method. The experiments were designed as one factor at the time method. The optimum range of pH, contact time, amounts of adsorbent, and concentration of benzamide were determined. Then, kinetic and isotherm of uranium adsorption were studied. In addition, the properties of this adsorbent were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). Results: The SEM and FTIR analysis confirmed that activated carbon is coated with Fe3O4 nanoparticles and the magnetic property of AC-Fe2O3 was approved. According to the results, the optimum conditions were pH =6, contact time =30 min, and 0.06 g of adsorbent dose. The adsorption of uranium on the AC_Fe3O4 nanocomposite fitted to Langmuir isotherm and pseudo-second order kinetic model. The removal of U(VI) was increased about 6% with increasing in benzamide concentration to 50 mg/L. The best percentage removal of uranium in aqueous solution was 95%. Conclusion: The removal of U(VI) on AC_Fe3O4 nanocomposite with the aid of benzamide is a rapid and highly pH depended process. The maximum sorption capacity (15/87 mg/g) of AC_Fe3O4 nanocomposite shows that this method is a suitable method for Uranium removal.


Photocatalytic Removal of Formaldehyde from Air Using Titanium Oxide-Reduced Graphene Composite
N Rastkari, F Izadpanah ,
Volume 9, Issue 1 (6-2016)
Abstract

Background and Objective: Formaldehyde is a toxic volatile organic compound, which its removal from polluted air is essential. One of the techniques available for removing such compounds is photocatalytic degradation. The aim of this study was to investigate the photocatalytic degradation of gaseous formaldehyde on TiO2 nanoparticles coated on reduced graphene oxide

Materials and Methods: The synthesized reduced graphene oxide- TiO2 nanocomposite was characterized using SEM, EDS, and FTIR spectra. The photocatalytic activity of prepared reduced graphene oxide- TiO2 nanocomposite was investigated for degradation of gaseous toluene under different operational conditions such as different initial concentration, flow rate, and time.

Results: The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite was much higher than P25 TiO2. The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite decreased by increasing the flow rate so the flow rate is a key factor for the use of RGO-TiO2 nanocomposite as a photocatalyst. The results showed that the photocatalytic degradation rates decreased from 89 to 30% with increasing formaldehyde initial concentration from 0.1 to 1 ppm.

Conclusion: This research indicated that RGO-TiO2 nanocomposite can be effectively used as suitable photocatalyst to remove gaseous pollutants. One of the advantages of the as-prepared composite was using visible light instead of UV to activate the oxidation process.


Feasibility study of silica aerogel nanocomposites application to enhance acoustic properties
Mansoureh Hamidi, Parvin Nassiri, Homayoon Ahmad Panahi, Lobat Taghavi, Saeed Bazgir,
Volume 13, Issue 3 (11-2020)
Abstract
Background and Objective: Noise pollution is one of the serious environmental issue. Sound control technologies based on sound absorption and sound insulation are considered as the two widely used methods. Therefore, the aim of this study was to modify silica aerogel nanocomposites to improve its acoustic properties.
Materials and Methods:  This applied experimental research involved in examining eight various types of nanocomposites to evaluate their performance of acoustic properties. In this study, nanocomposites were synthesized by sol-gel method. For this purpose, TEOS and ethanol were added to SiO2 which subsequently stirred and diluted with ethanol as a precursor of silica sol. A solution of 5.5 M ammonium hydroxide is added drop-wise to the silica sol and then was stirred. The activated silica sol was quickly poured into the mold in which the samples were placed and finally placed in an oven at 150 °C for 3 hours. The acoustic properties of the samples were measured by the impedance tube and the reduction sound pressure level using a sound level meter. Each sample morphology was characterized by scanning electron microscopy.
Results: The sound absorption properties of as prepared nanocomposite relatively increased at high frequencies. The results indicated > 0.6 sound absorption coefficient by the modified nanocopmosites at higher frequencies. The sound absorption coefficient and transmission loss of D1 nanocomposite were higher at medium and low frequencies as compared to other nanocomposites. 4.6 and 9.73 dB average reduction of sound pressure level were achieved by either with or without nanocomposite enclosure, respectively, at a distance of 1 meter.   
Conclusion: The results of the current study showed that the simultaneous addition of organic and mineral materials to silica aerogels (especially with the highest amounts of nanoclay) improves its acoustic properties, especially at medium and low frequencies. Among the samples, D1 nanocomposite shows better acoustic properties at medium and low frequencies. The sound absorption coefficient of D1 nanocomposite at frequencies of 315, 400, 500, 1000, 1250, 2000 Hz were obtained as 0.27, 0.38, 0.51, 0.78, 0.83 and 0.84, respectively. The findings also indicated 9.37 dB reduction of sound pressure level using D1 nanocomposite.

A comparison on the effects of alginate and chitosan in the synthesis of granular zeolite adsorbents used for arsenic removal
Maryam Tahmasebpoor, Leila Sanaei, Masoomeh Chaharkam,
Volume 16, Issue 3 (12-2023)
Abstract
Background and Objective: Zeolites are among the widely used adsorbents for the removal of arsenic-toxic pollutants. The objective of this study is to prepare granulated zeolite adsorbents using chitosan (CS/Fe-Clin) and alginate (Alg/Fe-Clin) and compare them in terms of physical appearance and arsenic adsorption efficiency.
Materials and Methods: Granular adsorbents were prepared via the ionotropic gelation method. The effects of the type and concentration of the cross-linking solution and the initial ratio of materials in granules formation, as well as the effect of initial arsenic concentration, and the amount of adsorbent used on the adsorption efficiency, were investigated. SEM, XRD, FTIR, and AAS analyses were used to confirm the results. Equilibrium data were matched with Freundlich and Langmuir isotherms.
Results: A weight percentage of 2 % iron chloride (III) and an initial ratio of 1:4 of alginate: nanocomposite for Alg/Fe-Clin and a weight percentage of 2 % (1 % sodium hydroxide + 1 % sodium tripolyphosphate) and an initial ratio of 1:3 of chitosan: nanocomposite for CS/Fe-Clin were chosen as the optimal values. Maximum adsorption efficiency of Alg/Fe-Clin and CS/Fe-Clin adsorbents was determined 88.1 and 92.9 % at dosages of 0.6 and 1 g/L and at initial concentrations of 200 and 300 µg/L, respectively. The qmax values for Alg/Fe-Clin and CS/Fe-Clin adsorbents were 11.11 and 10 mg/g, respectively. Results better fitted with Freundlich isotherm.
Conclusion: Due to the proper adsorption capacity, both synthesized adsorbents showed the ability to effectively remove arsenic; whoever, alginate binder was more efficient.
 

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