Showing 21 results for Kinetic
M Delnavaz, B Ayati, H Ganjidoust,
Volume 2, Issue 1 (7-2009)
Abstract
Background and Objectives: Experiments were conducted to investigate the behavior of Moving Bed Biofilm Reactor (MBBR) as a novel aerobic process for treatment of aniline synthetic wastewater as a hard biodegradable compound is commonly used in number of industrial processes. The objective of this paper is evaluation of MBBR in different conditions for treatment of aniline and determination of reaction kinetics.
Materials and Methods: In the MBBRs, different carriers are used to maximize the active biofilm surface area in the reactors. In this study, the reactor was filled with Light Expanded Clay Aggregate (LECA) as carriers. Evaluation of the reactor efficiency was done at different retention time of 8, 24, 48 and 72 hours with an influent COD from 100 to 3500 mg/L (filling ratio of 50%). After obtaining removal efficiencies, effluent concentration of aniline was measured by adsorption spectrum and maladaptive municipal wastewater treatment plant sludge in batch conditions for confidence of aniline biodegradation and its adsorption to the sludge mass.
Results:The maximum obtained removal efficiencies were 91% (influent COD=2000 mg/L) after 72 hours. Biodegradation of aniline in MBBR has been also approved by NMR spectrum tests. Finally experimental data has indicated that Grau second order model and Stover-Kincannon were the best models to describe substrate loading removal rate for aniline.
Conclusion:biological treatment of aniline wastewater compared to other researchers methods.
F Rashid Ashmagh, R Rezaei Kalantary, M Farzadkia, A Joneidy Jafari, R Nabizadeh,
Volume 2, Issue 3 (11-2009)
Abstract
Backgrounds and Objectives: Polycyclic aromatic hydrocarbons (PAHs) are a group of hazardous pollutants which have carcinogenic and mutagenic properties and accumulated in environment by different actions, therefore treatment of them is important. Biological treatments are simple and cheep technologies. This technology was recommended as a cost- effective method for treatment of these pollutants. In order to investigate the trend of pollution reduction of petroleum hydrocarbons in bioremediation, the phenanthrene biodegradation&aposs model in contaminated soils was studied.
Materials and Methods: Firstly, PAHs capable degrading bacteria was isolated from petroleum contaminated soils and then their ability for biodegradation of phenanthrene was assessed in slurry phase. After that by using Acinetobacter which have the most potential of removing phenanthrene from soil, the biodegradation model was investigated in bench scale.
Results: Phenantherene removal efficiency was obtained 99.4% for 100 mg/kg and 96 % for 500 mg/kg concentrations in 33 and 60 days biodegradation period respectively. Phenantherene reduction rate varied from 2.99 to 8.86 and 1.4 to 11.09 mg/kg/day for 100 and 500 mg/kg concentrations, respectively.
Conclusion: Rate of phenantherene removal is depended on primary concentration of contamination and by increasing of primary concentration, phenantherene removal rate was increased. Also removal efficiency followed zero and first order kinetic model with good correlation.
A.r. Talaie Khozani, N Jafarzadeh Haghighi Fard, M.r Talaie Khozani, M. Beheshti,
Volume 3, Issue 2 (7-2010)
Abstract
Backgrounds and Objectives: Oil pollution can be generated as a result of spillage, leakage, discharge, exploration, production, refining, transport and storage of crude oil and fuels in the environment. Consequently, many researchers have developed and studied the chemical, physical and biological methods to degrade crude oil. Among them, the biological treatments are the most interesting as they are simple and economical methods. The aim of this study was to determine biokinetic coefficients of crude oil degradation by pseudomonas aerogenusa. This microorganism was isolated in our previous work.
Materials and Methods: In this study the bio-kinetic coefficients of crude oil biodegradation were evaluated. Pseudomonas aerogenusa bacteria which had been isolated from the soil sample taken from a gas station in our previous work were used in this study. This microorganism was cultured in the liquid medium containing crude oil as sole carbon source. Finally with determining the amount of microorganisms and crude oil concentration during biodegradation process, the bio-kinetic coefficients based on modified Monod equation were calculated.
Results: bio-kinetic coefficients obtained from laboratory studies are vital factors in industrial applications. As a result, the bio-kinetic study was performed to find bio-kinetic coefficients for biodegradation of crude oil using the isolated bacteria. The results showed that ,Y, k and were equal 0.107 , 0.882 , 9.39 and 169.3 respectively.
Coculusion:Our results showed that pseudomonas aerogenusa is usable for treatment of oily wastewaters in the full scale facility. Results of this study indicated bio kinetics confections.
R Shokohi, M.r Samarghandi, F Pourfarzi, M Shirzad Siboni, H Vahedi,
Volume 4, Issue 1 (5-2011)
Abstract
Background and Objectives: Industrial wastewater included the dyes one of the important sources of environmental pollution, that founded in loom wastewater which are harmful for human health and environment. Therefore, the purpose of this research was investigated removal of RB5 dye from aquatic solution by using of adsorption onto synthesized magnetic sodium alginate beads.
Material and Methods: At first, synthesized magnetic sodium alginate beads. Then, acquired beads optimum dosage equal to 18 g/100CC, with constant other parameters. The effect of pH, contact time and initial RB5 dye concentration was studied at the constant of beads (18 g/100CC).
Results: Results showed that removal efficiency was decreased by increasing of initial RB5 dye concentration. Also the results showed the removal efficiency was increased by increasing of adsorbent dose and contact time. The results showed data were explained acceptably by Langmuir isotherms and pseudo-second-order kinetics models respectively.
Conclusion: The results showed that removal of RB5 dye from aqueous solution by using of magnetic sodium alginate beads can be done cheaper and effective.
M Shirzad Siboni, M.r Samarghandi, M Farrokhi, H Piri Dogahe, M Zarrabi,
Volume 4, Issue 3 (10-2011)
Abstract
Background and Objectives: Industrial wastewater included the cyanide is one of the important sources of environmental pollution which founded in Industrial wastewater which are harmful for human health and environment. Therefore, the purpose of this research that was fundamental designed is investigation of Removal of cyanide from aquatic solution by using of iron and copper powder in experimental scale.
Material and Methods: At first, pilot was designed. Then, acquired pH optimum equal to 2,7 for copper and iron by variation pH= (2,4,6,8,12) and constant other parameters. The effect of initial cyanide concentration (40,60,80 mg/l), initial iron and copper dosage (0.08-1 g/100CC) and contact time (15-12 min) studied at the constant of optimum pH.
Results: The result showed removal efficiency Increased from 46.6% to 90.56% and 31% to 93.78% for copper and iron by increasing of contact time from 15to 120 minute in constant conditions, respectively. Also result showed Removal efficiency decreased and increased by increasing initial cyanide concentration and initial iron and copper dosage. The results showed equilibrium data were explained acceptably by Langmuir isotherms and kinetic parameters were obtained by application of Langmuir&Hinshelwood equation.
Conclusion: The results showed that removal of cyanide can be quick and effective done by iron and copper in experimental scale.
Majid Kermani, Mitra Gholami, Abdolmajid Gholizade, Mahdi Farzadkia, Ali Esrafili,
Volume 5, Issue 1 (4-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Phenols in trace quantities are usually present in the treated
effluent of many wastewater-treatment plants. Phenol compounds even at low
concentration can cause toxicity, health and significant taste and odor problem
in drinking waters. This research focuses on understanding the sorption process
and developing a cost-effective technology for the treatment of water
contaminated with phenolic compounds, which are discharged into the aquatic
environment from a variety of sources. In order to remove phenolic compounds
from water, a new natural sorbent, rice husk ash, was developed.
Materials and Methods: Removal of phenol, 2-chlorophenol and 4-chlorophenol were characterized by
spectrophotometric technique at wavelengths of 269.5, 274 and 280 nm,
respectively, under batch equilibrium conditions and via changing the
parameters of contact time, initial pH, and initial concentration of adsorbates
and dosages of sorbent. Finally, the results were analyzed by the kinetic and
isotherm models.
Results: in this
study, the equilibrium time was found to be 240 min for full equilibration of
adsorbates. Removal percent of 2-chlorophenol was lower than two others. The
maximum removal of phenol, 2-CP and 4-CP was observed at an initial pH of 5.
The percentage removal of these phenolic compounds increased with increasing
adsorbent dose and decreasing initial concentration. In kinetics studies,
correlation coefficient and ARE factor showed that the sorption of phenol
(R2=0.9999), 2-chlorophenol (R
2=0.9992) and 4-chlorophenol (R
2=1)
fitted by pseudo second order model. Isotherm studies also revealed that,
Langmuirmodel for phenol (R
2=0.9499), Freundlich model for
2-chlorophenol (R
2=0.9659) and 4-chlorophenol (R
2=0.9542)
were the best choices to describe the sorption behaviors.
Conclusion: Sorption
process is highly dependent on the pH and it affects adsorbent surface
characteristics, the degree of ionization and removal efficiency. At high pH
hydroxide ions (OH-)
compete for adsorption sites with phenol molecules. The sorption was done
rapidly and a plateau was reached
indicating the sorption sites occuupied till
they were saturated. Since the increasing sorbent dose would improve
sorption site, its increasing enhances phenolic compounds removal.
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Ali Reza Rahmani, Ghorban Asgari, Mehrdad Farrokhi, Mahdi Shirzad Siboni,
Volume 5, Issue 4 (2-2013)
Abstract
Background and Objectives: Dyes are one of the main environmental pollutants in the industrial effluents including textile industries, which are harmful for human health and environment. The purpose of this research was to investigate removal efficiency of Reactive Black 5 (RB5) dye using adsorption onto strongly basic anion exchange resin as an appropriate adsorbent.
Materials and Methods: After preparing materials and equipment required, removal efficiency of Reactive Black 5 (RB5) dye using adsorption onto strongly basic anion exchange resin was investigated with respect to the variation of pH, contact time, adsorbent dosage, and initial RB5 dye concentration in batch system. Then results were analyzed using Excel software.
Results: Our results showed that removal efficiency was decreased by increasing pH and initial RB5 dye concentration. Moreover, we found that the removal efficiency was increased by increasing adsorbent dosage and contact time. The kinetics and equilibriums data were explained acceptably by Langmuir isotherms and pseudo-second-order kinetics models respectively.
Conclusion: Overall, our findings revealed that removal of RB5 dye from aqueous solution using adsorption onto strongly basic anion exchange resin can be considered as an effective and quick method.
Amir Sheikh Mohammadi, Mahdieh Sardar,
Volume 5, Issue 4 (2-2013)
Abstract
MicrosoftInternetExplorer4
Background
and Objectives: Antibiotics are
potential pollutants that represent an important environmental problem because
of their toxic effects on the food chain and aqueous streams. The objective of
this research was to study the adsorption of penicillin G on to chestnut shell
as an inexpensive adsorbent.
Materials and Methods: This study was performed at laboratory scale
and batch system. We studied the influence of process variables such as
adsorbent dose, initial PEN G concentration, pH of solution, contact time, and
breakthrough curves. In order to find out the possibility of reuse, desorption
study was also carried out. The surface characteristics of adsorbent were
investigated using Fourier Transform Infra-Red and Scanning electron
microscope. Equilibrium study data were modeled using Langmuir, Freundlich, and
D-R models. Moreover, kinetic studies
were done by three models of pseudo first order, pseudo second order, and
intra-particle diffusion.
Resuls: The maximum
PEN G removal achieved was 92%, at pH 3, adsorbent dose 0.1 g/l and contact
time 120 min. The Langmuir equation (R
2=0.99) provided the best fit
for the experimental data. It was also found that adsorption of PEN G by
chestnut shell followed pseudo- second order model (R
2= 0.992).
Conclusion: According to the results obtained, chestnut
shell appears to be a suitable, low cost and efficient adsorbent for removing
PEN G from waste streams.
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
Mohammad Ali Baghapour, Babak Jahed, Gholam Hossein Joshani,
Volume 6, Issue 3 (12-2013)
Abstract
Background and Objectives: Increasing waste tiers production has made the recycling of this solid waste a critical issue in the world. On the other hand, it seems contamination of groundwater to the petroleum pollutant like gasoline is a great threat to the health of societies in developing countries. The main objective of this study was gasoline removal from aquatic environment by waste tire derived activated carbon.
Materials and Methods: In this study for preparation of activated carbon from waste tires, KOH was used for chemical activation process. We used argon gas to prevent precursor oxidation . We applied N2 gas and BET isotherm for characterization of the prepared activated carbon texture. Isothermal and kinetic models were used for defining gasoline adsorption characteristic to adsorbent, and thermodynamic studies were used to determine the effect of temperature.
Results: Characterization results revealed that SBET and VTOTAL were 111.702m2/g and 0.124cc/g respectively. Langmuir and pseudo-second order models were the best isotherm and kinetic models for prediction of the adsorbent behaviors to adsorb gasoline. The Gibbs free energy changes were negative at all temperatures applied.
Conclusion: Produced activated carbon has desired surface area and adsorptive capacity for gasoline adsorption in aquatic environments and it seems preparation activated carbon from waste tiers is cheap, effective and environment friendly.
Ali-Reza Chackoshian Khorasani, Mansur Mashreghi, Soheila Yaghmaei,
Volume 6, Issue 3 (12-2013)
Abstract
Background and Objectives: Modelling and specifying mathematical equations to predict and estimate a bioprocess is one of the important applications of bioengineering. Objective of this study was to identify proper and exact equations to describe various changes in biodegradation of heavy fuel oil through investigating kinetic models and third parametric equation of Ch. Materials and Methods: To submit an exact and perfect enough statement, two different experimental conditions were used in which isolated indigenous bacteria from environment were employed. Experiments were carried out during ten days and microbial growth, mazut concentration, pH, and electric potential curves were drawn. Fitting data onto kinetic models and Ch equation resulted accuracy and their constants. Results: We found that kinetic models were not capable to present an accurate and appropriate statement under different conditions. On the other hand, Ch equation by extending very accurate equations could satisfyingly illustrate mazut, pH, and electric potential changes based on time and microbial growth. Conclusion: Ch equation by reason of using two variables for computation of third variable and correctly selecting variables could describe various changes in mazut biodegradation under different conditions via mathematical statements. Moreover, it is possible that this equation can be used to study other various phenomena in future.
Mohamad Hadi Dehghani , Mamood Alimohammadi , Amir Hossein Mahvi, Noushin Rastkari, Masoome Mostofi, Maryam Gholami ,
Volume 6, Issue 4 (3-2014)
Abstract
Background and Objective: Various industries such as petrochemical, oil refinery, pharmaceutical, plastics, paper, steel and, resin produce a substantial of phenol and its derivatives. Wastewaters containing phenol need careful treatment before discharging into the environment due to their poor biodegradability and high toxicity. The objective of this study was to remove phenol by multiwall carbon nanotubes from aqueous solution. Materials and Methods: Adsorption process was implemented in a laboratory-scale batch with emphasis on the effect of various parameters such as contact time (5 to 120 minutes), pH (3- 11), initial concentration of phenol (5 - 50 mg/l) and the sulfate and chloride ions (20 - 200 mg/l) on adsorption process. To achieve a better realization of adsorption process, sorption kinetics and equilibrium isotherms were also determined. Results: The results indicated that maximum adsorption capacity occurred at concentration 50 mg/L and t =30 minutes. The uptake fluctuated very little in the pH range of 3–9, and at greater than 9 the absorption decreased suddenly. Moreover, the presence of sulfate and chloride ions had no effect on the process. It was found that adsorption kinetics and equilibrium data follow a pseudo-second-order kinetics model and a Freundlich isotherm model respectively. Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.
Fatemeh Hashemi, Hatam Godini, Ghodratolah Shams Khorramabadi, Loqman Mansouri,
Volume 7, Issue 2 (10-2014)
Abstract
Background and Objective: Phenol presence in water and wastewater is interesting because of its stability in environment and health problems. Therefore, it must be removed for water pollution prevention. The aim of this study was to evaluate phenol adsorption from aqueous solutions using walnut green hull. Materials and Methods: This was an experimental study in which walnut green hull was used as biosorbent with a range of mesh 40. In this study, stock solution of phenol was prepared and effects of effective parameters such as pH (4,6,8, and10), contact time (3-60 min), adsorbent dosage (0.25-5 g/L), and initial phenol concentration (10,20,40, and 50 mg/L) on adsorption process were evaluated. Moreover results were evaluated using Langmuir and Freundlich isotherms and first order and pseudo-second order kinetics. All experiments were conducted in double and the mean adsorption rate was reported. Results: The maximum adsorption capacity of 30.30 mg/g corresponded with Langmuir model. Kinetic evaluation indicated that the adsorption of phenol by the walnut green hull clearly followed the pseudo-second order reaction. It was found that increasing contact time and adsorbent dosage would lead to increasing of adsorption of phenol and increasing pH and initial phenol concentration lead to decreasing of phenol adsorption. Maximum phenol removal was achieved at pH 4, with more than 99.9 % efficiency. Conclusion: The results of this study show that the walnut green hull can be used effectively in phenol removal, because walnut green hull is agriculture waste and is produced annual in high volume hence, it can be used as adsorbent in phenol removal from wastewater.
M Abtahi, K Naddafi, A.r Mesdaghinia, K Yaghmaeian, R Nabizadeh, N Jaafarzadeh, N Rastkari, R Saeedi, Sh Nazmara,
Volume 7, Issue 4 (1-2015)
Abstract
Background and objectives: Dichloromethane (DCM) is one of the hazardous contaminants of the environment, especially ambient air that threatens human health at both acute and chronic exposures. In this study, the performance of a pilot-scale hybrid bubble column/biofilter (HBCB) bioreactor was studied for the removal of DCM from waste gas streams at steady state. Materials and methods: The experiments were conducted in four stages with relatively constant concentrations of DCM (approximately 240 ppm) and variable empty bed residence time (EBRT) of 50, 100, 150 and 200 s. In addition to determining DCM removal rate and efficiency, quality parameters of mixed liquor of the bubble column bioreactor were studied and kinetic of biofiltration was analyzed. Results: The average DCM removal efficiency of the HBCB bioreactor at EBRT of 200 and 150 s were 79 and 71% respectively. However, further reduction of EBRT resulted in significantly decreased DCM removal efficiency, so that at EBRT of 50 s, the DCM removal efficiency decreased to 32%. In addition, the EBRT reduction from 200 s to 50 s through increasing DCM loading rate resulted in increasing DCM removal rate from 12.1 to 19.6 g/m3.h. The results of kinetic analysis showed that the kinetic data of biofiltration were in the best fitness with the first order rate equation (R2>0.99 and &epsilon%<2.2) and the DCM removal rate constant was determined 0.0114 s-1. The mixed liquor characterization indicated that the daily adjustment of pH and EC was sufficient to prevent any limitation in the performance of the HBCB bioreactor. Conclusion: This study indicated that the DCM removal rate and efficiency of the HBCB bioreactor were relatively high and the HBCB bioreactor had reliable performance during the variable operational conditions.
M Malakootian, A. H Mahvi, H Jafari Mansoorian, M Alizadeh, A.r Hosseini,
Volume 8, Issue 2 (8-2015)
Abstract
Background and Objective: Phenol and phenol derivatives in industrial wastewater are among the pollutants with priorities. The high cost and low efficiency of some routine treatment processes of industrial wastewater has limited their use. One of the new methods under consideration is, nowadays, adsorption using carbon nanotubes. This study was conducted in order to evaluate the application of alumina-coated multiwall carbon nanotubes in eliminating phenol from synthetic wastewater. Materials and Methods: This study was performed in laboratory at batch scale. Multi-wall carbon nanotubes were coated with Alumina. The concentration of phenol was determined by spectrophotometer through photometry. The effect of pH changes, dosage of adsorbent, contact time, the initial concentration of phenol, temperature, and the concentrations of different salts on the efficiency of absorption was evaluated. Then, the absorption results were described using the Langmuir and Freundlich isotherms and the synthetics of absorption. Results: It was found that absorption efficiency increased significantly by decreasing the initial concentration of phenol and pH and by increasing the carbon nanotube dosage, temperature, and contact time. On the other hand, the maximum elimination of phenol from the solution (98.86%) occurred at 4 mg/l phenol concentration, under acidic conditions (pH=3), at adsorbent dosage of 0.05 g/l, at temperature of 45°C, and contact time of 10 min. Evaluation of the regressions isotherms showed that the process follows the Langmuir model and second-degree synthetic absorption. Conclusion: The high efficacy (98%) of the adsorption process in this study showed that alumina-coated multiwall carbon nanotubes have a good capability in eliminating phenol and can be used as an appropriate and new method for eliminating phenol and its derivatives from wastewater.
A Shahbazi,
Volume 8, Issue 3 (12-2015)
Abstract
Background and Objectives: Rapid growing of Triton X-100 application in industries results in its appearance in effluents and threaten the aqueous ecosystems. Triton X-100 is not biodegradable and can accumulate in food chain.
Materials and Methods: In this study, sorption capacity of six synthesized zeolites with different regular porous structure was studied for triton X-100 (TX-100) surfactant and the results were compared with Clinoptilolite natural zeolite of Damavand region.
Results: Within all zeolite studied, Beta(200) showed the highest sorption capacity (about 575 mg/g), which is due to its regular pore structure with large pore diameter, channel intersections, high SiO2/Al2O3 ratio and high surface area. Langmuir monolayer isotherm and pseudo-second-order kinetic equation could provide well-fitted to the experimental data in simulating adsorption behavior of TX-100 over Beta(200) zeolite.
Conclusion: The adsorption feature was internal sorption and the intraparticle diffusion might be a rate-limiting control for Beta(200) zeolite. Results of experiments demonstrated that the hydrophobic zeolites with large pore diameter such as Beta(200) could be effective sorbents for industrial wastewater treatment features.
M Leili, Gh Asgari, A. A Eskandari, L Borzoei, B Ramavandi,
Volume 8, Issue 3 (12-2015)
Abstract
Background and Objectives: Furfural is one of the toxic chemical compounds used in many industries such as petrochemical, food, paper products, pharmaceutical, etc., due to having some characteristics. Therefore, furfural could be found at different concentrations in the effluent from these industries and can enter the environment. Hence, the aim of this study was the assessment the efficiency of a low cost bentonite modified with cationic surfactant in the removal of furfural from aqueous solution.
Material and Methods: In this experimental study, bentonite was purchased from one of the Mines of Zanjan Province, Iran and then the efficiency of bentonite modified with the cationic surfactant CTAB (CTAB-Bent) was assessed in the adsorption of furfural from aqueous solution. Activated carbon (AC) was also purchased as commercial grade.
Results: Under optimum conditions, the removal efficiency of AC and CTAB-Bent was about 52 and 66%, respectively. For both adsorbents used in this study, the increase of contact time and sorbent dosage resulted in increasing the removal efficiency, but the removal efficiency was decreased with the increase of furfural initial concentrations. Regarding pH, the removal efficiency was the highest in relative acidic and neutral environment, (60 and 69% for AC and CTAB-Bent respectively). The kinetics studies revealed that the highest correlation coefficients were obtained for the pseudo-second order rate kinetic model. Adsorption data from both adsorbents was also fitted with Langmuir isotherm.
Conclusion: It was found that modified bentonite with CTAB as a natural adsorbent could have better efficiencies compared with activated carbon in the furfural removal, although more contact times is needed.
Y Azimzadeh, N Najafi, A Reyhanitabar, Sh Oustan,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: Phosphorus (P), as one of the agricultural, industrial and urban wastewater pollutants, plays an important role in eutrophication of surface waters. Use of cationic sorbents for removal of anions including phosphate from aqueous environments is a well-known and effective method. Meanwhile, layered double hydroxides (LDHs) are known as effective anion exchange sorbents. In this study, the efficiency of Mg-Al layered double hydroxide (Mg-Al-LDH) for P removal from aqueous solutions was investigated.
Methods and Materials: The Mg-Al layered double hydroxide (Mg-Al-LDH) was synthesized by co-precipitation method and used for removing of P from aqueous solutions. The kinetics and equilibrium studies of phosphate adsorption by Mg-Al-LDH were performed using a batch experiment at different contact times, initial phosphate concentrations, pH values, ionic strengths and doses of sorbent.
Results: The results of the kinetics experiments showed that sorption of P with LDH reached equilibrium after 30 min. The highest correlation coefficient was obtained for the pseudo-second order model, indicated that chemical sorption controlled the rate of phosphate sorption by LDH. The results showed that the sorption experiments data were in good agreement with Langmuir model and the maximum adsorption capacity predicted by this model was 37.83 mg P/g LDH.
Conclusion: The current study revealed that P adsorption by LDH was increased by increasing contact time and concentration of LDH, but decreased by increasing initial concentration of P, pH and ionic strength. The optimum conditions for phosphate anion adsorption by Mg-Al-LDH were determined as P initial concentration of 20 mg/L, contact time of 120 min, pH of 3.0, sorbent dose of 10 g/L and ionic strength of 0.03 mol/L.
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.
Mohsen Shaban, Daryoush Yousefi Kebria, Marzie Razavi,
Volume 14, Issue 1 (5-2021)
Abstract
Background and Objective: Application of chemical fertilizers in agricultural industry is known as one of the methods of crop enhancement. However, chemical fertilizers application can lead to an increased risk of chemical pollutants entering the human food cycle. The aim of current research was feasibility study and evaluation of nickel from paddy soils in Lorestan province.
Materials and Methods: Sampling was done from 15 stations and randomly from rice cultivation areas in Silakhor plain of Lorestan province. Then, electrokinetic modification method was carried out in three reactors with lengths of 5, 10 and 15cm. After sample preparation, the initial and final concentration of nickel were measured and calculated using inductively coupled plasma - optical emission spectrometry (ICP-OES).
Results: The results showed that electrokinetic modification method was effective in reducing the concentration of heavy metals in agricultural soil samples and reduced the amount of nickel in soil to the permissible limits of the Iranian soil national standards (50 mg/kg). The initial values of nickel in paddy soil of composite samples were 108 mg/kg. Nickel maximum removal efficiency of 90.84% and 93.75% were observed in cathode and anode regions, respectively.
Conclusion: The health and quality of agricultural products depend on the use of safe soil within the limits of environmental standards. The results of this study showed that the EKR process is able to remove nickel from soil. As a result of the present process, nickel concentration has reached the permissible amount and even lower than the soil quality standard set by the Iranian Environmental Protection Agency.
