Showing 25 results for Nanoparticle
M Shirzad Siboni, M. T Samadi, A.r Rahmani, A.r Khataee, M Bordbar, M.r Samarghandi,
Volume 3, Issue 3 (10-2010)
Abstract
Backgrounds and Objectives: Industrial wastewater included the heavy metal is one of the important sources of environmental pollution. Hexavalent chromiumand divalent nickel are founded in plating wastewater which is harmful for human health and environment. Therefore, the purpose of this research is investigation of photocatalytic removal of hexavalent chromium and divalent nickel from aqueous solution using UV/TiO2 process in a batch system.
Materials andMethods: At first, reactor was designed. Then, optimumdosage of TiO2 was obtained equal to 1 g/L, with variation TiO2 dosage at constant pH and initial concentrations of hexavalent chromium and divalent nickel. The effect of pH, contact time and initial concentration of hexavalent chromium was studied at the constant amount of TiO2 (1gr/L).
Results: The result showed that photocatalytic removal efficiency increased with increasing reaction time and TiO2 dosage. In addition, it was found that removal efficiency of hexavalent chromium was decreased by increasing initial chromium concentration and pH. But, photocatalytic removal efficiency of nickel ion was increased and decreased by increasing of pH and initial nickel concentration, respectively.
Conclusion: The results showed that UV/TiO2 was an effective method in removal of hexavalent chromium and divalent nickel from aqueous solutions
K Naddafi, M.r Zare, M Younesian, M Alimohammadi, N Rastkari, N Mousavi,
Volume 4, Issue 2 (9-2011)
Abstract
Background and Objectives: This study was conducted to investigate the toxicity of Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles as two of most widely used nanoparticles. The result of this study can help to designing environmental standard and legislations for nanoparticles.
Materials and Methods: Different concentrations of nano ZnO and TiO2 nanoparticles were added to nutrient Agar culture media. Then, definite numbers of Escherichia coli and Staphylococcus aureus bacteria were added to culture media and inhibition of these bacteria growth was measured in comparison to controls. Obtained data were analyzed to determine nanoparticles' EC50 and NOEC (No Observed Effect Concentration) using SPSS ver.16 and Probit standard test.
Results: 24-hours EC50 of nano ZnO using E. coli and S. aureus determined to be 5.47 mg/L and 2.38 mg/L respectively. In addition, 24-hours EC50 of nano TiO2 using E. coli and S. aureus determined to be 5366 mg/L and 3471 mg/L respectively. In the case of ZnO nanoparticles, no observed effect concentration determined to be 1.15 and 3.28 mg/L for E. coli and S. aureus respectively and in the case of TiO2 nanoparticles no observed effect level determined to be 1937 and 1184 mg/L for E. coli and S. aureus respectively.
Conclusion: This study showed that acute toxicity of nano ZnO is by far more than that of nano TiO2. Regarding the EPA acute toxicity criteria, nano ZnO is categorized as moderately toxic and nano TiO2 is categorized as practically non toxic. Hence, regarding the acute toxicity, in recommending exposure criteria and environmental disposal standards, compared to nano TiO2, nano ZnO requires more attention.
Hamid Reza Salari-Joo, Mohammad Reza Kalbassi, Seyed Ali Johari,
Volume 5, Issue 1 (4-2012)
Abstract
MicrosoftInternetExplorer4
Background
and Objectives: Nanotechnology defined as understanding
and controlling of materials at dimension between 1-100 nm, which show unusual
physical and chemical properties. With Increasing development of
nanotechnology, concerns associated with release of materials containing
nanoparticles into the environment is rising. The purpose of this study is
investigation of salinity effect on the acute toxicity of silver nanoparticles
in rainbow trout fry (Oncorhynchusmykiss).
Materials
and Methods: In order to conduct the toxicity tests,
the Caspian Seawater(12±0.2 ppt) and (0.4 ppt) as sources of brackish water and
freshwater were used, respectively. Toxicity of silvernano particles were
evaluated in brackish water and freshwater at concentrations of1, 2, 4, 8, 16,
32and64ppm and 0.12, 0.25, 0.5, 1, 2, 4
and8 ppm, respectively. In addition, in order to investigate the quality of the
used silver nanoparticles the Zetasizer, ICP, and TEM method were applied.
Results: Results of 96-hour median lethal concentration(LC50 96h), showed that toxicity
of silver nanoparticles for rain bow trout fry in brackish water is 12 times
less than its toxicity in freshwater.
Conclusion: According to the toxicity categories, analysis of the results showed that, for
rainbow trout fry (1g), silver nanoparticles are classified as highly toxic
agent substances in fresh water, and little toxic in brackish water,
respectively.
Ruhollah Rostami, Ahmad Jonidi Jafari, Roshanak Rezaee Kalantari, Mitra Gholami,
Volume 5, Issue 1 (4-2012)
Abstract
Normal
0
false
false
false
EN-US
X-NONE
AR-SA
MicrosoftInternetExplorer4 Background and Objectives:Benzene,
toluene and Xylenes (BTX) are organic pollutants, which are mainly associated
with oil and its derivatives. BTX is environmental contaminants and considered
harmful to human health. Application of surface absorbents such as zeolite is
one of several methods for the removal of these compounds. In this study,
BTX compounds'
removal efficiencies were
investigated and compared by using
clinoptilolite
type zeolite
and zeolite
with copper
oxide nanoparticles.
Materials
and Methods: In this study, the modified zeolite by
hydrochloric acid in the grain size 1-2 mm and modified zeolite with nano
particle of copper oxide were used. Artificially- Contaminated Air
flow was used
continuously .To determine
BTX concentrations,
samplings were done by charcoal tube in
current input and output. The
concentrations of contaminants were determined by gas chromatography with FID
detector.
Results: Removal efficiency of benzene,
toluene, p-xylene, m-xylene and o-xylene by clinoptilolite were 78.3%, 62.1%,
32.2% 32.15% and 18.8%, respectively. For the clinoptilolite
containing copper oxide nano particles efficiency were 25.42%, 35.65%, 36.33%,
33.24% and 29.39%, respectively. Average removal efficiency of BTX compounds
observed when the zeolite without nanoparticles used (43.31%) was more than
zeolite with nanoparticles (32%). The results showed that the concentration of
CO2 in the outlet air of the zeolite-containing nanoparticle (550
ppm) was more than the zeolite without nanoparticle (525 ppm).
Conclusion: Results showed that adding nanoparticles to the
zeolite, although the removal efficiency of benzene and toluene
can be reduced.
The results showed that adding
nanoparticles to the zeolite, although can be reduced removal efficiency of
benzene and toluene, which may be due to occupying or blocking of the pollution
absorption sites by the nanoparticles on the zeolite, but It cause promote more
catalytic effect of zeolite in the decomposition process of contaminants by
breaking the molecules of pollutants and their further degradation progress is
done for conversion to carbon dioxide
Emad Dehghani Fard, Ahmad Jonidi Jafari, Roshanak Rezae Kalantari, Mitra Gholami, Ali Esrafili,
Volume 5, Issue 2 (10-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Aniline has been used in different processes of chemical
industries, however due to its side effects on the environment, several methods
have been considered for its removal. In this study, we evaluated the
performance of photocatalytic process using ZnO nanoparticles (nZnO) and
ultraviolet (UV) irradiation for removal of Aniline from a synthetic effluent.
Materials and Methods: A 5L photocatalytic reactor made from Plexiglas, which the UV lamp (20w)
installed in the center of that (inside a quartz jacket), was designed and nZnO
(0.2-0.5 g/l) was being added into synthetic effluent with Aniline concentration
of 250 ppm. After retention times of 30, 60, and 90 min, samples were
centrifuged and supernatant was filtered using a 0.2 µ PTFE filter. The
liquid-liquid method and Gas Chromatography instrument was used for extraction
and analysis respectively.
Results: Results
showed that the photocatalytic process of nZnO+UV could effectively remove
Aniline from effluent. Increasing trend in the removal efficiency of Aniline
using nZnO = 0.5 g/l was slower in comparison with other nZnO concentrations
and the ANOVA analysis shows no significant difference between removal
efficiency of Aniline in different concentrations of nZnO. The most removal
efficiency of Aniline (76.3%) was observed in alkaline pH, retention time of 90
min and nZnO of 0.5 g/l.
Conclusion: It could be concluded that the
photocatalytic process of nZnO+UV could be suitable technique for Aniline
removal from effluents.
Ehsan Olyaie, Hossein Banejad, Ali Reza Rahmani, Abbas Afkhami, Javad Khodaveisi,
Volume 5, Issue 3 (10-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Arsenic is one of the most toxically contaminants in groundwater and
soils. Due to the ability of bio-accumulation of arsenic III in plants through
irrigation with contaminated water and its entrance to the food chain,
irreparable hazards would be caused. The aim of this research is the
feasibility study of arsenic III removal from polluted water using calcium
peroxide nanoparticles synthesized and also studying the effective parameters.
Moreover, the adding effect of nanoparticles on the important parameters of
irrigation would be assessed.
Materials and Methods:
In this research, we first synthesized CaO
2 nanoparticles through
chemical precipitation and then studied the arsenic removal efficiency from
contaminated water samples. Nevertheless, the impact of the effective
parameters including pH, initial arsenic III concentration, and CaO2
nanoparticles concentration were investigated. Finally, relevant results to
nanoparticles effect on the important irrigation water quality parameters were
presented.
Results: Our results
showed that synthesized particles were in the range of 25-50 nanometers. In
addition, the efficiency of the CaO
2 nanoparticles in arsenic III
removal was 88 percent under following conditions: irrigation pH range 6.5-8.5, nanoparticles
dosage 40 mg/L, arsenic initial concentration 400 µg/L, and 30 minuts retention
time. Moreover, the nanoparticles synthesized did not have any undesirable
impact on significant parameters in irrigation water.
Conclusion: Generally,
it can be concluded that CaO
2 nanoparticles based on the in situ
chemical oxidation had significant effect on the reduction of arsenic III until
lower than recommended standards for irrigation water. High rate of process and
relatively short reaction time, and having no negative effects on the
significant parameters of irrigation indicate that CaO
2 nanoparticles
have significant potential in removal of arsenic III from contaminated water.
Hafez Golstanifar, Simin Nasseri, Amir Hossin Mahvi, Mohamad Hadi Dehghani, Anvar Asadi ,
Volume 5, Issue 4 (2-2013)
Abstract
Background and Objectives: The contamination of nitrate (NO3−) in groundwater resources causes two adverse health effects: induction of “blue-baby syndrome” (methemoglobinemia), especially in infants, and the potential formation of carcinogenic nitrosamines. The aim of this research is to investigate nitrate removal from groundwater using alumina nanoparticles and to determine the adsorption isotherms.
Materials and Methods: This analytical-descriptive study was carried out at lab-scale, under batch conditions, and at room-temperature. The structure of alumina nanoparticles was determined using XRD, SEM, and TEM techniques. The concentration of nitrate in the solutions was determined by spectrophotometer at wavelengths of 220 and 275 nm. In addition, we investigated the impact of the important operational parameters including initial dose of Al2O3 (0.06-0.25 g/l), initial concentration of the solution (50- 300 mg/l), contact time (5-60 min), and pH (3-9). Moreover, we used Freundlich and Langmuir isotherm models to calculate equilibrium constant.
Results: It was found that nitrate removal efficiency increased as we increased contact time, initial concentration and pH in batch system. A maximum of 60% nitrate removal was achieved under following conditions: 60 min contact time, pH 5, and initial nitrate concentration of 300 mg/l as N. The obtained results showed that the adsorption of nitrate by Nano-Gamma-Alumina follows Langmuir isotherm equation with a correlation coefficient equal to 0.982.
Conclusion: Overall, our findings showed that the alumina nanoparticles can be used as an effective adsorbent to remove NO3 from aqueous solutions.
Somayeh Alijani, Mohammad Vaez, Abdolsamad Zaringhalam Moghadam,
Volume 6, Issue 2 (9-2013)
Abstract
Background and Objectives: The development a low-cost and high efficiency water treatment technology to decolorize the organic dye effluents is desirable due to overwhelming discharge of organic synthetic dyes into the natural water cycle during the dying process. In this study, the decolorization of Acid Black 26, as the model organic contaminant, was investigated using immobilized nano-sized TiO2 particles as the photocatalyst. Material and Methods: Sackcloth fiber was used as a support to immobilize TiO2 nanoparticles. The structural properties of the immobilized photocatalysts were characterized by XRD and SEM. UV-Vis absorption spectroscopy and the measurement of the chemical oxygen demand (COD) were also used for the process performance studies. Moreover, we investigated the effects of the oxidant H2O2, initial dye concentration, the presence of anion and pH on the photocatalytic degradation efficiency. Results: The XRD results did not show significant changes in the structure of TiO2 as a consequence of the immobilization procedure. The formation of titania crystallites in the sackcloth fiber was confirmed by SEM. Experimental results showed that after 60 min, the degradation percentage of Acid Black 26 with the immobilized TiO2 particles was about 60%, which was higher than that with TiO2 slurry. Based on the COD results, after 3 h, the TiO2-coated sackcloth fiber effectively decomposed 94% of the organic compounds presenting in dye solution during the degradation of Acid Black 26. Conclusion: The titania nanoparticles immobilized on the sackcloth fiber can be used as an effective and environmental friendly photocatalyst in the degradation of colored wastewater.
Mehdi Bahrami, Saeeid Brumand-Nasab, Heydar-Ali Kashkooli, Ahmad Farrokhian Firouzi, Ali-Akbar Babaei,
Volume 6, Issue 2 (9-2013)
Abstract
Background and Objectives: Among the heavy metals cadmium is of considerable environmental and health significance because of its increasing mobilization and human toxicity. The objectives of this research were to synthesize SDS modified magnetite nanoparticles (Fe3O4) and to determine its efficiency in cadmium removal from aqueous solutions.
Materials and Methods: Modified magnetite nanoparticles were synthesized and the effects of pH and contact time on cadmium removal efficiency were investigated in batch system. Then kinetics and isotherm models coefficients were determined in the optimum pH and equilibrium time conditions. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infra red (FTIR) were used to characterize the modified magnetite nanoparticles synthesized.
Results: The SEM results showed that the diameter of the particles is 40-60 nm. It was found that the optimum pH value for maximum adsorption of 10 mg/L cadmium by 0.1 g adsorbent in 12 hr was 6. Kinetic study showed that the equilibrium time was 30 min. The adsorption kinetics fitted well using the Ho pseudo second-order kinetic model however, the adsorption isotherm could be described by the Freundlich model. The maximum adsorption capacity of modified magnetite nanoparticles for Cd2+ was found to be 9.604 mg/g.
Conclusion: The results of this study indicated that the modified magnetite nanoparticles can be employed as an efficient adsorbent for the removal of cadmium from contaminated water sources
Bijan Bina, Mohamadmahdi Amin, Mohamadreza Zare, Ali Fatehizadeh, Mohsen Mohseni, Mahdi Zare, Ali Toulabi,
Volume 6, Issue 2 (9-2013)
Abstract
Background and Objectives: Toxicity assessment of material related to nanotechnology is
necessary before excess development of this industry. On the other hand, specific
characteristic of nanomaterials can be used in disinfection of other material. In
this study toxicity and antibacterial properties of nano-TiO2 and nano-CuO
were investigated with four bacterial species in solid media.
Material and Methods: Stock
suspension of nanoparticles (10g-TSS/L) was diluted using Muller Hinton Agar to
achieve 5-6000mg-TSS/L concentration. We prepared three Petri dishes for each concentration
and refined bacteria were cultured on these Petri dishes. After culturing of these
bacteria on the media containing nanoparticles, growth inhibition was determined.
According to this data, 50% growth inhibition (EC50), no observed effect
concentration (NOEC) and 100% growth inhibition were determined.
Results: Our results showed
that toxicity of TiO2 is more than CuO in solid media. In this regard,
nano-TiO2 EC50 for Escherichia coli, Bacillus subtilis, Staphylococcus
aureus, and Pseudomonas aeruginosa was calculated 181, 571, 93 and 933mg-TSS/L respectively.
These figures for nano-TiO2 were 2550, 1609, 946, and 1231mg-TSS/L respectively.
Conclusion: This study
showed that compared with other bacteria studied, E. aureus due to high sensitivity
and E. coli due to high resistance to both TiO2 and CuO nanoparticles
are more proper as bioindicator in toxicity test and antibacterial test respectively.
B Kakavandi, R Rezaei Kalantary, A Jonidi Jafari, A Esrafily, A Gholizadeh, A Azari,
Volume 7, Issue 1 (7-2014)
Abstract
Background and Objective: Extreme use of antibiotics and discharging them to the environment lead to serious consequences. Activated carbon is the most commonly adsorbent for these contaminants but its main drawback is difficulty of its separation. The objective of this study was synthesis of magnetic activated carbon by Fe3O4 and investigating its efficiency in adsorption of amoxicillin from synthetic wastewater. Materials and Methods: Materials and Methods: Physical and structural characteristics of the adsorbent synthesized were analyzed using SEM, TEM, XRD and BET techniques. The effect of factors like pH, initial concentration of amoxicillin and adsorbent, contact time, and temperature were investigated to determine thermodynamic parameters, equilibrium isotherms, and kinetics of adsorption process. Results: Physical characteristics of the magnetized activated carbon showed that Fe3O4 nanoparticles had the average size of 30-80 nm and BET surface area was 571 m2/g. The optimum conditions of adsorption were: pH=5, contact time=90min, adsorbent dose of 1g/L and temperature 200C. The equilibrium isotherms data showed that the adsorption process fitted both Freundlich and Longmuir models with the maximum capacity of 136.98 mg/g. The kinetic of the adsorption process followed pseudo second-order model. The negative values of &DeltaH0 and &DeltaG0 obtained from studying the adsorption thermodynamic suggested that amoxicillin adsorption on magnetic activated carbon was exothermic and spontaneous. Conclusion: The present study showed that the magnetic activated carbon has high potential for adsorption of amoxicillin, in addition to features like simple and rapid separation. Therefore, it can be used for adsorption and separation of such pollutants from aqueous solutions.
Leila Karimi Takanlu, Mahdi Farzadkia, Amir Hossein Mahvi, Ali Esrafily, Masoumeh Golshan,
Volume 7, Issue 2 (10-2014)
Abstract
Background and Objectives: Cadmium can enter water resources through the industrial wastewater. It could cause intensivly damages to the liver and kidney of humans. Magnetic iron nanoparticles are used to control and eliminate heavy metals from industrial effluents through the mechanisms of adsorption, ion exchange and electrostatic forces. The aim of this study was to evaluate the efficiency of magnetic nanoparticles for adsorption of cadmium. Methods: The magnetite nanoparticles were prepared by co-precipitation method through the addition of bivalent and trivalent iron chloride under alkaline conditions. Characteristics of nanoparticles including particles structure, composition and size were determined using analytical devices such as XRD, SEM, and FT-IR. For optimization of adsorption process of cadmium, some parameters such as pH, contact time, initial concentration of cadmium, nanoparticles concentration, and temperature were studied under different conditions. Results: It was found that 95% of cadmium could be removedAt pH &ge 5.6, 10 mg/L initial cadmium concentration, a dose of 1 mg synthesized magnetite nanoparticles, 10 minutes contact time, and 200 rpm mixing rate at 25 °C. The isotherm of adsorption follows the Langmuir model (R2 < 0.995). Maximum capacity of cadmium adsorption was found to be 20.41 mg/g. Conclusion: Magnetite nanoparticles exhibit high capability for removal of cadmium. The nanoparticles synthesized could be used at industrial scale because of having the magnetic property, which make them easily recovered from aqueous solution through applying a magnetic field.
E. Karimi Pasandideh, R. Rezaei Kalantary, S. Nasseri, A. H. Mahvi, R. Nabizadeh, A. Esrafili,
Volume 7, Issue 3 (5-2014)
Abstract
Background and Objective: The presence of natural organic materials (NOM) in water resources affects its quality (i.e. color, odor, and taste). In addition, it leads to the fouling of filters and membranes and reduces water treatment efficiency during flocculation/ coagulation. Moreover, NOM reacts with disinfectants and produces byproducts (DBPs), which are harmful to human health. Magnetic nanoparticles have been reported as effective adsorbents for the removal of pollutants from the aqueous media. In this study, we applied SiO2coating on these nanoparticles in order to enhance their stability and dispersion in aqueous media and investigated their capability in NOM adsorption from water. Materials and Methods: Iron oxide magnetic nanoparticles were prepared by co-precipitation. Then, we added Tetraethoxysilane (TEOS) to the solution in order to coat it with SiO2 . The adsorbent characteristics were determined by SEM and XRD. Then, we carried out the adsorption experiments under different pH(3-12) and contact time (5-240 min)performance conditions. The adsorption kinetic was determined with respect to different Humic acid adsorption times. Later, we determined the effect of different concentrations of adsorbent on different concentrations of Humic acid, and Langmuir and Freundlich coefficients based on the optimum conditions. Results: The morphology investigation of adsorbent showed the average size of Fe3O4/SiO2nanoparticles was 30-130 nm. The pH value of 10.5 and the contact time of 90 min at room temperature were determined as optimum conditions for removal of humic acid using Fe3O4/SiO2 nanoparticles. The maximum adsorption capacity of Fe3O4/SiO2 was192.30. The adsorption isotherm was fitted well by Langmuir model (R2>0.90) and the pseudo-second order model (R2>0.98) could better explain humic acid adsorption. Conclusion: Having high number of active surface sites, magnetic properties, easily separation using magnetic field, and its cost-effectiveness, the Fe3O4/SiO2 nanoparticles could be used as an efficient adsorbent in removal of humic acid from water.
K Yaghmaeian, N Jaafarzadeh, R Nabizadeh, H Rasoulzadeh, B Akbarpour,
Volume 8, Issue 4 (3-2016)
Abstract
Background and Objective: Arsenic is one of the most toxic pollutants in groundwater and surface water. Arsenic could have lots of adverse impacts on human health. Therefore, access to new technologies is required to achieve the arsenic standard.
Materials and Methods: The present study was conducted at laboratory scale in non-continuous batches. The adsorbent of zero-valent iron nanoparticles -Chitosan was produced through reducing ferric iron by sodium borohydride (NaBH4) in the presence of chitosan as a stabilizer. At first, the effect of various parameters such as contact time (5-120 min), pH (3-10), adsorbent dose (0.3-3.5 g/L) and initial concentration of arsenate (2-10 mg/L) were investigated on process efficiency. Then optimum conditions in terms of contact time, pH, adsorbent dose and initial concentration of arsenate were determined by RSM method. Freundlich and Langmuir isotherm model equilibrium constant, pseudo-first and second order kinetic constants were calculated. The residual arsenate was measured y using ICP-AES.
Results: The optimum values based on RSM for pH, absorbent dose, contact time, and initial concentration of arsenate were 7.16, 3.04 g/L, 91.48 min, and 9.71 mg/L respectively. Langmuir isotherm with R2= 0.9904 for Arsenate was the best graph for the experimental data. According to Langmuir isotherm model, the maximum amount of arsenate adsorption was 135.14mg/g. . The investigation of arsenate adsorption kinetics showed that arsenate adsorption follows the pseudo-second kinetics model.
Conclusion: This research showed that the adsorption process is depended on pH. With increasing pH, the ability of amine groups in chitosan are decreased to protonation, caused to decrease the efficiency of arsenate removal at high pH.
S Sobhanardakani, R Zandipak,
Volume 9, Issue 2 (9-2016)
Abstract
Background and Objective: Dyes are important pollutants that lead to producing serious hazards to human, other animals and organisms. Dyes are not biodegradable by aerobic treatment processes. Therefore, their removal from industrial effluents before discharging into the environment requires extreme and great attention. The aim of this research was to evaluate removal efficacy of methyl orange dye from aqueous solutions using NiFe2O4 nanoparticles.
Materials and Methods: This study was an empirical investigation in which NiFe2O4 nanoparticles were synthesized by co-precipitation method and were used as an adsorbent for the removal of methyl orange from aqueous solution. NiFe2O4 nanoparticles were characterized using X-Ray Diffraction (XRD), Transmission Electronic Microscopy (TEM), pHpzc and SEM-EDX elemental analysis methods. Experiments were conducted discontinuously using 20 mL methyl orange solution of 40 mg/L. The effect of variables such as pH (2-8), amount of adsorbent (0.009-0.07 g) and contact time (2-70 min) on the efficacy of dye removal was studied. Finally, experimental data were compared by Langmuir, Freundlich, and Temkin isotherms and pseudo-first-order and pseudo-second-order kinetic models.
Results: TEM images showed that the NiFe2O4 nanoparticles had spherical shapes with the size of 12 nm. The results indicated that removal efficiency increased up to 0.04 g adsorbent and 20 min contact time. The optimum pH for methyl range removal was 2. Moreover, under these conditions, the adsorption process followed the Langmuir adsorption isotherm with a correlation coefficient of 0.995 and pseudo-second-order kinetic model with a correlation coefficient of 0.999. Also, the maximum adsorption capacity of the prepared adsorbent was 135 (mg/g) for Langmuir isotherm.
Conclusion: The NiFe2O4 nanoparticles are effective and available adsorbents for the removal of methyl orange from industrial wastewater.
S Dehestaniathar, Sh Amini, A Maleki, B Shahmoradi, N Reshadmanesh, P Teymouri,
Volume 9, Issue 2 (9-2016)
Abstract
Background and Objectives: Fluoride has both beneficial and detrimental effects on health. Therefore, it is important to determine its concentration in drinking water. Dental fluorosis and skeletal fluorosis are health effects caused by long term exposure to high levels of fluoride in drinking water. The aim of this research was to investigate fluoride removal using modified diatomite-supported ferric oxide nanoparticles and to determine the adsorption kinetics and isotherm.
Materials and Methods: This fundamental and practical study was performed at laboratory scale. The effects of pH (3.5-9.5), contact time (20-100 min), adsorbent dosage (1-5 g/L), and initial concentrations of fluoride (5-25 mg/L) on the adsorption efficiency were evaluated. The properties of adsorbent were investigated using XRD, XRF, FTIR and FESEM. Finally, the suitability of pseudo first and second order kinetics, and Langmuir and Freundlich isotherms for the data were investigated.
Results: This study showed that the removal efficiency of F- increased with increase in contact time, decrease in pH, increase in adsorbent dose, and increase in initial fluoride concentration. The highest removal efficiency was observed at pH=3.5, 60 minutes contact time, and 3 g/L of adsorbent dose in the initial concentration of 5 mg/L F-. Pseudo first order and Freundlich were the best fitted kinetic and isotherm models, respectively, for describing F- adsorption process.
Conclusion: The present study indicates that the modified diatomite-supported ferric oxide nanoparticles can be used as an effective and environmentally friendly biosorbent for the removal of fluoride ions from aqueous solutions.
S Abbasi,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: Owing to the extended usage in the safekeeping of environments, the photocatalytic materials have been widely applied. The purpose of the present study was to investigate the photocatalytic activity of ZnO and SnO2 nanoparticles in removal of methyl orange from aqueous media.
Materials and Methods: ZnO and SnO2 nanoparticles were synthesized through sol-gel and chemical precipitation respectively. Methyl orange was selected as model pollutant. The effect of weight fraction on the removal of pollutant was investigated in the range of 0.25, 0.5, and 1 weight percent. Meanwhile, for investigating the effect of radiation time, the suspension containing pollutant and nanoparticles was irradiated. The obtained results were analyzed by MSTATC, Ver 1.42 software and Duncan’s multiple range test.
Results: The analysis of variance results of removal efficiency of methyl orange showed that in the suspension involving ZnO and SnO2, radiation time, weight fraction and the combined effect of them have a significant effect on the removal of methyl orange at 5% level of probability. Meanwhile, by increasing irradiation time from 5 to 25 min, the removal efficiency in suspensions containing ZnO and SnO2 reached 97.42 and 65.55% respectively. Investigation on the effect of concentration on the removal of methyl orange shows that the removal of methyl orange increases with respect to the weight fraction.
Conclusion: According to the obtained results, it was observed that the photocatalytic activity of ZnO is higher than that of SnO2. Therefore, the application of ZnO is more effective for removal of methyl orange from aqueous media.
H Irvani, H Shojaee - Farah Abady, M Shahryari, M Nakhaei Pour,
Volume 10, Issue 2 (9-2017)
Abstract
Background and Objective: Styrene monomer is a volatile organic compound that is used in the various industries. Due to the hazardous effects of this chemical substance on the environment and humans, control and elimination of this vapour is necessary. Therefore, the aim of this study was to remove the styrene vapors from air flow using photocatalytic activity of zinc oxide immobilized on ZSM-5 zeolite.
Materials and Methods: In this experimental study, the fabricated catalysts were characterized using analysis of BET, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dynamic Concentrator System were used to generate styrene vapors at a certain concentration and flow, and then removal efficiency of the styrene vapors was investigated using UV/ZnO and UV/ZSM-5/ZnO.
Results: The results of XRD analysis and SEM images showed that produced zinc oxide had nano dimensions. In addition, these nanoparticles was successfully stabilized on ZSM-5 zeolite. The results of the photocatalytic removal showed that ZnO and ZSM-5/ZnO catalysts at the concentrations of 50 ppm eliminated the styrene vapor 14% and 37%, respectively.
Conclusion: Findings of this study showed that stabilization of zinc oxide nanoparticles on ZSM-5 zeolite had an ssynergistic effect on the photocatalytic degradation of styrene. According to this finding, the use of adsorption-photocatalyst hybrid systems can be an appropriate technique to remove styrene vapors and other similar pollutants.
S Bita, M Mesbah, A Shahryari, M Ghorbanpoor Najafabadi,
Volume 10, Issue 3 (12-2017)
Abstract
Background and Objective: Nanoparticles are already widely used in technology, medicine and consumer products, but there are limited data on their effects on the aquatic environments. The aim of this study was to evaluate the response of antioxidant defense system in common carp gills exposed to silver nanoparticles, which are produced by bioreduction method.
Materials and Methods: Common carp fish were exposed to the silver nanoparticles at concentrations of 0.11, 1.13 and 5.67 mg/L for 14 days. A treatment without silver was considered as a control. After sampling, 1 g of gill was weighed and homogenized in 5 mL phosphate buffer. The homogenized samples were analyzed for measuring the activity of catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), total antioxidant capacity (TAC) and malondialdehyde (MDA).
Results: CAT activity in gill at the concentrations of 1.13 and 5.67 mg/L AgNPs was significantly reduced compared to that of the control (p<0.05). When the activities of GSH and TAC of different treatments and the control were compared, no significant difference (p>0.05) was observed. Activity of SOD and MDA of all treatments sampled at different days was fluctuated, that is, it was either increased or decreased. However, superoxide dismutase activity was significantly higher in exposure to concentrations of 5.67 mg/L and 1.13 mg/L.
Conclusion: According to the results, fish gills are one of the most susceptible organs of oxidative damage in exposure to silver nanoparticles. This can affect the health of common carp and thus increase the risk of disease in the fish.
M Sabonian, Ma Behnajady,
Volume 11, Issue 2 (9-2018)
Abstract
Background and Objective: Chromium is present in two oxidation forms of Cr(III) and Cr(VI). Cr(III) is less toxic than Cr(VI). The aim of this article was to optimize an artificial neural network structure in modeling the photocatalytic reduction of Cr(VI) by TiO2-P25 nanoparticles.
Materials and Methods: In this work, an artificial neural network (ANN) for the modeling photocatalytic reduction Cr(VI) by TiO2-P25 nanoparticles were used and its structure was optimized. The operating parameters were initial concentration of chromium, amount of photocatalyst, ultraviolet light irradiation time and pH. All the experiments were conducted in a batch photoreactor. The Cr(VI) concentration was measured with a UV/Vis spectrophotometer. ANN calculations were performed using Matlab 7 software and the ANN toolbox.
Results: The results show that the optimization of the ANN structure and the use of an appropriate algorithm and transfer function could significantly improve performance. The proposed neural network in modeling the photoactivity of TiO2-P25 nanoparticles in reducing Cr(VI) was acceptable, based on a good correlation coefficient (0.9886) and a small mean square error (0.00018). All the input variables affected the reduction of Cr(VI), however the effect of pH with an impact factor of 34.15 % was more significant than the others. The results indicated that pH = 2 was the best pH for photocatalytic reduction of Cr(VI). Increasing photocatalyst dosage and irradiation time in the investigated range increased Cr(VI) photocatalytic reduction.
Conclusion: Optimized structure of the ANN includes a three-layer feed-forward back propagation network with 4:10:1 topology and the most appropriate algorithm is a scaled conjugate gradient backpropagation algorithm.
