Showing 57 results for Adsorption
Mr Mehrasbi, Z Farahmand Kia,
Volume 1, Issue 1 (10-2008)
Abstract
Background and Objectives: Heavy Metals in Water resources is one of the most important environmental problems of countries. Up to now various methods of removing of these metals is considered, which is including using of low prices materials. In this study the potential of banana shells was assessed for adsorption of heavy metal ions such as Pb and Cd from aqueous solution.
Materials and Methods: Banana shells were pretreated separately with 0.4 mol/L NaOH, 0.4 mol/L HNO and distilled water and their adsorption ability were compared. Batch adsorption experiments were carried out as a function of the initial ion concentration, pH and adsorbent dosage. Adsorption isotherms of metal ions on adsorbents were determined and correlated with common isotherm equations such as Lungmuir, Freundlich and BET models.
Results: The maximum adsorption capacities were achieved by alkali modified banana shells (36 mg/g) for Pb and by acidic modified banana shells (16 mg/g) for Cd. Experimental results showed that the best pH for adsorption was 6 and the adsorption values decreased with lowering pH. Isotherm models indicated best fit for Freundlich model for modified banana shells.
Conclusion: In comparing the parameters of models, it was observed that the capacity of banana shells for adsorption of lead is higher than for adsorption of cadmium, but the adsorption of cadmium is stronger than the adsorption of lead.
Gh Ghanizadeh, Gh Asgari,
Volume 2, Issue 2 (9-2009)
Abstract
Backgrounds and Objectives: Dyes are organic materials with complex structures, toxic, carcinogenic, teratogenic,nonbiodegredable properties and!the most!important pollutants of textile industrial wastewaters. The goal of this study was to survey the feasibility application of bone char (BC) as a sorbent for the of methylene blue (MB) from synthetic wastewater.The sub goals of the research!were to determine!the adsorption isotherm, !effects of primary concentration of dye, adsorbent!dose, contact!time, and pH for the adsorption of MB with BC.
Materials and Methods: BC was prepared under laboratory conditions by using of electrical furnace at 400°C for 2h. The prepared BC was crushed and pulverized by standard ASTM sieves with range of 10-16mesh(1.18-2mm).The chemical composition and solid structure of BC was analyzed using X-ray diffraction(XRD) and scanning electronic microscopy (SEM). Measurement of the surface area was carried out by N2 gas via BET isotherm and Belsorb software. The concentration of dye was measured by photometric!method (663nm).
Results: Predominant!compositionof BC is calcium hydroxyl apatite (Ca5 (PO4)3OH with 14m2/g surface area. The results of this study showed that increasing of primary concentration of dye, adsorbent dose and pH (5 to12) would lead to increasing of adsorption/removal of MB dye.Equilibration of dye adsorption was reached at lapse of 2h andoptimum pH for adsorption of MB with BC found in the rage of 8.5-12.Adsorption of MB witht BC complies witht freundlich isotherm(R2:0.99).
Conclusion: Bone char is a cheap component that can be used as an adsorbent in water and wastewater treatment. Based on optimum pH of 8.5-12 found for the removal of MB and the fact that many of textile!industrial wastewaters have an alkaline pH, this adsorbent can be!used for the removal of dyes from these wastewaters.
M.t Samadi, R Nourozi, S Azizian, Y Dadban Shahamat, M Zarabi,
Volume 2, Issue 3 (11-2009)
Abstract
Backgrounds and Objectives: Determination of Fluoride in drinking water has received increasing interest, duo to its beneifical and detrimental effects on health. The aim of this research is investigation of Effect of activated alumina in fluoride concentration reduction in drinking water.
Materials and Methods: Expriment in batch system and with change effective parameters such as pH(5, 7,9), equilibration time (30, 60, 90, 120 minute), initial fluoride concentration(1.4, 2, 2.4 mg/l) and activated Alumina dosage (0.1, 0.2, 0.3 gr/l) was investigated. Also found data of this research were fited with Langmuir and Freundlich models, kinetic data with pseudo- first order, pseudo- second order and modifited pseudo- first order models.
Results: The results showed that with increasing of pH of solution, removal efficiency was decreased and optimum pH was found to be in the range of 5 to 7. Also removal efficiency of fluoride was increased with increasing of adsorbent dosage and decreasing of initial concentration of fluoride. Adsorption isotherm data show that the fluoride sorption followed the Langmuir model (r2=0.98). Kinetics of sorption of fluoride onto Activated alumina was well described by pseudo- second order model.
Conclusion: The concentration of Activated Alumina had significant effect on the reduction of fluoride ions concentration in water.The higher fluoride removals were observed for batch experiments at pH=5 because no free fluoride ion is present in the solutions, and it could be casued by electrostatic interactions between the surface of alumina and the dominant fluoride species in solution The kinetic model can adequately describe the removal behaviors of fluoride ion by alumina adsorption in the batch system.
H. Asilian, G.r Moussavi, M. Mahmoudi,
Volume 3, Issue 1 (4-2010)
Abstract
Backgrounds and Objectives:Much attention has been recently paid on using waste materials as adsorbents for removal of contaminants from water and wastewater. A new low cost waste was examined for its capacity to adsorb RR198, an azo reactive model dye, from an aqueous solution.
Materials andMethods: The waste was dried, powdered and characterized before being used as an adsorbent. The effects of pH (3-10), adsorbent dose (0.2-3 g), dye concentration and contact time on the adsorption efficiency were investigated. Equilibrium study data were modeled using Langmuir and Freundlich models.
Results: The characterization analysis indicated that itwas composedmainly of ferric hydroxide. The powder had a BET and average pore size of 107 m2/g and 4.5 nm, respectively. The results showed that dye removal was highest at a solution pH of 7 to 8 and a powder dose of 2 g/L. The RR198 removal percentage decreased from 100& to 43& at 140 min contact time when the concentration of dye was increased from 25 mg/L to 100 mg/L, at optimum pH and dosage. The Langmuir equation provided the best fit for the experimental data. The maximum adsorption capacity was calculated to be 34.4 mg/g.
Conclusion: According to the obtained results, the water coagulation waste sludge appears to be a suitable low cost and effcient adsorbent for removing reactive azo dyes from waste streams.
M.t Samadi, M.h Saghi, K. Ghadiri, M. Hadi, M. Beikmohammadi,
Volume 3, Issue 1 (4-2010)
Abstract
Backgrounds and Objectives:Phosphate discharges from domestic and industrial waste water to water bodies. High concentrations of phosphate in water stimulate the eutrophication phenomenon that causes taste and odor in water, losing dissolved oxygen and aquatic life in rivers or surface waters. Aim of this study is survey of phosphate adsorption on simple nano zeolite Y and nano zeolite Y that was modified with a cationic surfactant (HDTMA-Br).
Materials and Methods:In This study we used simple nano zeolite Y and nano zeolite Y in form of Surfactant Modified Zeolites (SMZs) using batch tests to adsorption of Phosphate fromAqueous Solutions. The adsorbants were contacted with different initial phosphor concentrations (5, 10 and 15 mg/l), pH (4, 7, 12), contact time (30, 60, 90, 120, 150 and 180 minutes) and weight of adsorbant (0.2, 0.4, 0.6, 0.8 and 1g). the extracted solution was determined for Phosphate concentration by the ammonium molybdate and tin chloride method with spectrophotometric detection at 680 nm. Results:Results of this study show that, with increase in contact time, decrease in pH, increase in zeolites concentration and decrease in initial phosphate concentration, the removal efficiency increased. And the Both isotherm of Langmuir and Freundlich models (r2 > 0.997 and r2 > 0.996 respectively) were agreement with adsorption equilibrium of phosphate. Reduced Chi-Sqr For Langmuir and Freundlich models were (0.00079) and (0.0011) respectively. Pseudo first-order kinetic models fits well with experimental data (r2>0.963).
Conclusion: From this survey, it is concluded that performance of modified nano zeolite Y for adsorption of phosphate in same conditions is better than non-modified zeolite Y. In general the modified nano zeolite Y presented a good profile for removal of phosphate. Therefore SMZs is a suitable candidate for removal of Phosphate molecules from contaminated solutions in contaminated waters.
G.r Moussavi, A Khavanin, H Mokarami,
Volume 3, Issue 3 (10-2010)
Abstract
Backgrounds and Objectives: Volatile organic compounds (VOCs) are one of the common groups of contaminants encountered in the industrial activities, emitted through air stream into the atmosphere. To prevent the human and environmental health from the adverse effects of VOCs, air streams containing VOCs need to be treated before discharging to environment. This study was aimed at investigating the catalytic ozonation process for removing xylene from a contaminated air stream.
Materials and Methods: In the present work, a bench scale experimental setup was constructed and used for catalytic ozonation of xylene. The performance of catalytic ozonation process was compared with that of single adsorption and ozonation in removal of several concentration of xylene under the similar experimental conditions.
Results: The results indicated that the efficiency of catalytic ozonation was higher than that of single adsorption and ozonation in removal of xylene. The emerging time and elimination capacity of xylene for inlet concentration of 300 ppm was 1.4 and 5.8 times of those in adsorption system. The activated carbon acted as catalyst in the presence of ozone and thus attaining the synergistic effect for xylene degradation.
Conclusion: catalytic ozonation process is an efficient technique the treatment of air streams containing high concentrations of xylene. The adsorption systems can also be simply retrofitted to catalytic ozonation process and thereby improving their performance for treating VOCs.
A.r Rahmani, M Solaimany Aminabad, Gh Asgari, F Barjasteh Askari,
Volume 3, Issue 4 (1-2011)
Abstract
Backgrounds and Objectives: High level of nitrate ion in the water resources cause some health and environmental problems. The aim of this research is to study nitrate removal by Zero-Valent Magnesium (ZVM) and MgCl2-modified pumice from aqueous solutions.
Materials and Methods: The pumice granules were modified by MgCl2 . The removal of nitrate was studied in a batch system. The pH, initial nitrate concentration and sorbent mass parameters and the Langmuir and Freundlich models were studied in the sorption of nitrate onto the pumice. The ZVM was also used in a bach system and the previous parameters were studied.
Results: The removal efficiencies of nitrate by ZVM at the the initial pH of 3, 5 and 7 with controlling the pH were 70%, 40% and 30% ,respectively. These values are much higher than the values of the condition during which the pH was not controled. The nitrate removal efficiency increased by increasing of initial nitrate concentration in a constant molar ratio of Mgo/NO3. The removal efficiencies of nitrate by the modified pumice at the the initial pH of 3, 6.5 and 10 (when pH kept under control) were 49%, 29% and 16%, respectively. By increasing of the initial nitrate concentration the removal efficiency increased. The values of R2 for the Langmuir and Freundlich models were 0.944 and 0.810, respectively. The sorption process Fitted well the Langmuir model with a monolayer sorption capacity of 0.68 mg/g.
Conclusion: The modified pumice had lower efficiency than ZVM in the removal of nitrate ion and its usage is not considerably affected bye the pH in comparison with ZVM. The pH of the solution should be cansiderd as a main controling parameter to get an optimum efficiency in the nitrate-ZVM process.
A Maleki, A Eslami,
Volume 3, Issue 4 (1-2011)
Abstract
Backgrounds and Objectives:Water contamination with arsenic has been recognized as a serious problem and its epidemiological problems to human health have been reported. The objective of this study was to explore the possibility modified wheat straw using sodium bicarbonate for removing arsenic from aqueous solution.
Materials and Methods: Adsorption process was accomplished in a laboratory-scale batch with emphasis on the effect of various parameters such as pH, contact time, arsenic concentration and adsorbent dosage on adsorption efficiency. In order to understand the adsorption process, sorption kinetics and equilibrium isotherms were also determined.
Results: It was found that adsorption of the arsenic was influenced by several parameters such as arsenic initial concentration, adsorbent dosage and solution pH. Maximum absorption efficiency was achieved at pH 7. As expected the amount of arsenic adsorbed on wheat straw incresed as its concentration went up. Among the models tested, namely the Langmuir, Freundlich, and Dubinin Radushkevich isotherms, the adsorption equilibrium for arsenic was best described by the Langmuir and Freundlich models. It was also found that adsorption of arsenic by wheat straw followed pseudo second-order kinetics. Mean free energy of adsorption (15.8 kJ mol-1) indicates that adsorption of arsenic by wheat straw might follow a chemisorption mechanism. Desorption studies show that arsenic ions are strongly bounded with the adsorbent and exhibit low desorption.
Conclusion: It is concluded that that adsorption by modified wheat straw is an efficient and reliable method for arsenic removal from liquid solutions.
M.r Samarghandi, M Noori Sepehr, M Zarrabi, M Norouzi, F Amraie,
Volume 3, Issue 4 (1-2011)
Abstract
Backgrounds and Objectives: Treatment of colored wastewater is one of the important challenges of environmental engineers. Adsorption process is a key option for removal of organic matter from wastewater. The aim of present work was to investigate pumice stone as an adsorbent for removal of Acid Black 1 from aqueous solution.
Materials and Methods: Removal of Acid Black 1 by pumice stone was investigated. Acid Hyrdo Chloric(HCL) 1 N was used to increse adsorbent porosity. Various parameters such as pH, initial dye concentration and contact time were studied.
Results: Results showed that removal of Acid Black 1 was increased by increasing of contact time and initial dyeconcentration although it was decreased by increasing of pH. Experimental data was best fitted to Longmuir isotherm model (r2>0.98). Study of diffusion model revealed that intraparticle diffusion is rate-controlling step in removal of Acid Black 1 by pumice stone.
Conclusion : The results indicated that pumice stone was a dominant adsorbent for Acid Black 1 removal.
K Naddafi, R Nabizadeh Nodehi, M Jahangiri Rad,
Volume 3, Issue 4 (1-2011)
Abstract
Backgrounds and Objectives: Anthraquinone dyes such as reactive blue29 in water resources and industrial wastewater effluents are one of the most environmental setbacks in many countries. Various methods have been considered to remove these dyes One of which is adsorption.
Materials and Methods: All adsorption experiments were conducted in different pHs and various concentrations of adsorbents. The initial concentration of reactive blue 29 chosen in this study was 30mg/L.Adsorption isotherms were determined and correlated with Longmuir, Freundlich and BET models.
Results: The maximum adsorption capacity of reactive blue 29 onto single wall carbon nanotubes was 496mg/g.Results showed that the best pH for adsorption was 5 followed by pH3 and 8. Kinetic study showed that the equilibrium time for adsorption of RB 29 to SWCNT is 4 hr.
Conclusion:According to the results obtained BET isotherm fitted well the experiment. It shows the adsorption of reactive blue 29 onto single wall carbon nanotubes is multilayers and the mechanism of SWCNTs adsorption toward RB29 is based on weak van der waals forces.
S Jorfi, R Rezaei Kalantary, A Mohseni Bandpi, N Jaafarzadeh Haghighifard, A Esrafili, L Alaei,
Volume 4, Issue 1 (5-2011)
Abstract
Background and Objectives: Fluoride is widely used in industries such as manufacture of semiconductors, power plants, glass production etc and release to the environment via their effluents. The purpose of this sturdy was to compare the efficiency of low price adsorbents in fluoride removal from water.
Materials and Methods: The optimum values of pH, contact time and adsorbent dosage were determined and different concentrations of fluoride were experimented in lab scale conditions for bagasse, modified bagasse and chitosan. Then Langmuir and Freundlich coefficient were determined based on optimum conditions.
Results: The pH value of 7, contact time of 60 min and adsorbent dosage of 2 g/L were determined as optimum conditions for all three adsorbents. The most fluoride removal efficiency of 91% was obtained for modified bagasse in optimum conditions.
Conclusion: Based on data obtained in this study, it can be concluded that adsorption by modified bagasse is an efficient and reliable method for fluoride removal from liquid solutions.
Y Hamzeh, S Izadyar, E Azadeh, A Abyaz, Y Asadollahi,
Volume 4, Issue 1 (5-2011)
Abstract
Background and Objectives: The dyestuff manufacturing and textile industries consume a high volume of water and produce a great amount of wastewater containing various toxic substances. Different methods are used to remove dye compounds from wastewaters. Removal of dyes from water by adsorption processes received considerable attention and a number of studies focused on the adsorption of some dyes by non-conventional low cost and effective adsorbents. In this study, the suitability of the canola stalks for Acide orange 7 adsorption was assessed.
Materials and Methods: The dry canola stalks obtained from the research farm were milled and screened and the particles size ranged between 0.4-0.7mmwere used in all experiments. Acid orange 7 supplied by Alvan Sabet. Initially, the effects of initial dye concentration, pH and temperature on adsorption were examined. The kinetic and equilibrium data obtained for various concentrations of evaluated on the basis of Langmuir and Freundlich isotherms.
Results: The results showed that the absorption efficiency depended strongly on pH and slightly on the temperature. Absorption of acid orange 7 on the canola stalks was fairly rapid and more than 95% of adsorption occurred within the initial 5 minutes of the treatment. Both Langmuir and Freundlich models were applicable for the description of acid orange 7 dye adsorption by canola stalks.
Conclusion: According to the Langmuir model, the highest capacity of canola stalks for acid orange 7 adsorption was found 24.8 mg/g which was higher than the capacity of beech wood sawdust and soil mixture with fly ash.
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.
Laleh Divband, Majid Behzad, Saeed Boroomand Nasab, Sara Divband,
Volume 5, Issue 1 (4-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Existence of Heavy metals in water resources is one of the
most important environmental problems in many countries. These metals have
dangerous effects on human health. The purpose of this study is to investigate and compare lead removal by
nanometer and millimeter absorbents of Zizyphus Spinachristi fly ash.
Materials and Methods: This study was non-continuous experiment which was implemented under laboratory
conditions with and by changing effective factors such as pH (3, 4, 5, 6, 7,
8), contact time (5, 10, 15, 30, 45, 60, 90, 120 minutes) and adsorbent
concentration (1, 2, 5, 10, 20 and 50 mg/ L). The data was fitted based on four
models including Ho et al, Lagergern, Lungmuir and Freundlich which the first
two models used for absorption kinetic and the latter two considered as
absorption isotherm.
Results: The Result of
this study showed that as the pH increases from 3 to 5 adsorption efficiency
increased as well. Furthermore, when pH was over 5, the metal ions settled
down. With increasing contact time, adsorption efficiency increased as well.
With increasing the amount of nanometer as an adsorbent, removal efficiency
increased and then decreased. Also the adsorption process followed precisely Ho
et al kinetic and Langmuir isotherm, for both absorbents.
Conclusion: Based on
the obtained results, specific area of the nano particles was more than
millimeter particles (29.56 m2/g & 17.80 m2/g), therefore adsorption
capacity of nano absorbent was four times more than adsorption capacity of
millimeter (19.93 mg/g & 17.80 mgr/g). Furthermore, the findings concluded
high capability of nano particles towards Sorption of lead ions (Pb) from
aqueous solutions.
Meghdad Pirsaheb, Kiumars Sharafi, Abdollah Dargahi,
Volume 5, Issue 1 (4-2012)
Abstract
MicrosoftInternetExplorer4
Background and
Objectives: 2, 4-dichlorophenoxy acetic acid is a well-known herbicide
which can be dangerous for both human
and animal health in different ways such as its presence in drinking water.
This study aimed at Performance of granular activated carbon to 2-4-D removal
from aqueous solution and assessing the relationship between COD and 2-4-D
concentration
Materials and Methods: This study is a lab-scale study. Firstly, different 2-4-D concentrations were
prepared from Stock solution (1000 mg/L), and then their CODs were measured.
Optimum pH for 2-4-D removal was determined and its absorption rate at
different concentrations was measured.
Results: Results
showed a clear relationship between COD and 2-4-D concentration. On the other
hand, COD removal increased as time elapsed, so that maximum removal 90% and
84% at initial 2-4-D concentrations of 50 and 100 mg/L were observed at contact
time of 50 min respectively. Optimum pH for all concentrations was determined
as 6.
Conclusion: According
to present study it can be concluded that activated carbon have be up to 90% of
2-4-D removal from water environment. In addition, a significant relationship
was observed between COD and 2-4-D concentration, so that direct measurement of
COD can be used instead of 2-4-D measurement.
Omol Banin Naeej, Anoushiravan Mohseni Bandpi, Ahmad Jonidi Jafari, Ali Esrafili, Roshanak Rezaei Kalantary,
Volume 5, Issue 3 (10-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Nitrate is one of the most groundwater pollutants in world.
Reduction of nitrate to nitrite by microorganisms cause serious health hazards.
Nitrate can be eliminated using either adsorbtion or reduction. In this study,
we investigated the adsorption of nitate on zeolite and the feasibility of
removal improvement using supported zero
valent nano iron on zeolite via the reduction process.
Materials and Methods: The study was done in two phases investigation the
zeolite and modified zeolite with zero valent nano iron in nitrate removal from
water. First, we determined the optimum pH and time then the effect of
adsorbent and nitrate concentration was investigated in one factor at the time.
The adsorption isotherm was calculated according to the optimum condition. The
physical characteristics of adsorbents were determined using SEM and TEM.
Results: The morphology investigation of adsorbent showed that the
particle size of supported zero valent nano iron on zeolite was approximately
30-50 nm in diameter. The best conditions were pH 5, contact time of 120 min
and 15 g/L for zeolite, while pH 3, contact time of 50 min and 7.5 g/L for
supported zero valent nano iron on
zeolite. The isotherm equations revealed that nitrate adsorption follows
Langmiur in both cases.
Conclusion: The supported zero
valent nano iron on zeolite could be considered as a high potential adsorbent
for nitrate because it has several adsorbent sites, and Fe
0 as a
function for nitrate reduction.
Mohamad Taghi Samadi, Roghaye Nourozi, Mohamad Hadi Mehdinejad, Reza Aminzadeh,
Volume 5, Issue 4 (2-2013)
Abstract
Backgrounds and Objectives: Determination of arsenic(As) in drinking water has received increasing interest due to its detrimental effects on health. The aim of this research is to investigate effect of coating coral limestone using aluminum sulfate as an adsorbent on the arsenic(V) removal efficiency from aqueous solution.
Materials and Methods: In this laboratory scale study, we prepared coral lime granules using mesh 30 during several stages. Then, we investigated the arsenate removal efficiency under different conditions and changing main factors including pH, contact time and amount of no coated and aluminum sulfate-coated adsorbent. Moreover, we fitted our results with Langmuir and Freundlich models and kinetic data with pseudo- first order, pseudo- second order and modified pseudo- first order models.
Results: We found that increasing pH from 3 to 10 at arsenate concentration of 500 ppb and 5 g/l adsorbent and 120 min contact time, removal efficiency for no coated and coated adsorbent was reduced from 100 to 86.2% and from 100 to 92.2% respectively. Increasing concentration of both adsorbents from 1 to 5 g/l at contact time 120 min increased the removal efficiency from 76 to 99.2% and from 66.3 to 91.1% respectively. Arsenate removal efficiency was directly proportional with the amount of adsorbent and contact time and reversely proportional with the initial concentration of arsenate and pH. The removal efficiency of the coated adsorbent was more than uncoated adsorbent. Langmuir was the best sorption isotherm model for arsenate in these two processes and absorption kinetic was well described with second order models.
Conclusion: Excellent removal efficiency, cost-effectiveness process, and lack of environmentally harmful substances make application of the Persian Gulf offshore corals a reasonable adsorbent to remove environmental contaminants such as arsenate.
Afshin Maleki, Amir Hossein Mahvi, Reza Rezaee, Behrouz Davari,
Volume 5, Issue 4 (2-2013)
Abstract
Background and Objectives: Dyes are an important class of pollutants, which can even be identified by naked eye. Disposal of dyes in precious water resources have been prohibited, however, various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. Therefore, natural zeolite (clinoptilolite) and acid modified zeolite were used as a low-cost adsorbent to evaluate their ability to remove color from aqueous solution using a batch adsorption experiments.
Materials and Methods: Modification of zeolite surface was carried out with two acids sulfuric acid and phosphoric acid, to improve the removal efficiency of reactive blue 19. We studied the influence of acid concentration, contact time, solution pH, initial dye concentration, and adsorbent dosage on the removal efficiency.
Results: The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. It was also found that adsorption of dye by zeolite followed pseudo first-order kinetics. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dye but can be distinctly improved by modifying its surfaces with acid. Experimental results also showed that sulfuric acid has better performance than phosphoric acid in the modification of zeolite for dye adsorption.
Conclusion: We achieved the best results in terms of removal efficiency (41-72%) for the zeolite modified with Si/Al ratio of 7.5 after 3 h of contact.
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.
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.
