Showing 26 results for Toc
H Masombaigi, A Rezaee, A Nasiri,
Volume 2, Issue 3 (11-2009)
Abstract
Backgrounds and Objectives: Textile industrial wastewaters are one of the important sources of environmental contaminants. In the recent years, use of advanced oxidation processes, by producing highly active and reactive components such as hydroxyl radicals has been proposed. The aim of this research is photocatalytic degradation of methylene blue dye using the ZnO-nanoparticle with UVA irradiation.
Materials and Methods: photocatalytic degradation of methylene blue color using the ZnO- nanoparticles excited with UVA irradiation. In this research, photocatalytic degradation of methylene blue dye was study using different concentration of ZnO-nanoparticles under UVA irradiation in a batch reactor.
Results: The results of this research show that removal of methylene blue dye has direct correlation with UVA intensity. The best results of dye degradation were reported in concentration of 150 mg/L ZnO nano-particles and the radiation intensity of 240 µW/cm2. Rate of dye removal was decrease with increasing of color concentration. Subsequent of color degradation, the initial COD were decresed by %60.
Conclusion: The photocatalytic degradation process using ZnO nano-particles under UVA irradiation could be remove the methylene blue dye and 60% of COD.
M Ahmadimoghadam, H Amiri,
Volume 3, Issue 2 (7-2010)
Abstract
Backgrounds and Objectives: Formaldehyde and phenol are key precursors in the industrial manufacture of resins. Toxicity of these compounds prevents function of microbial populations, so they affect the biological treatments. The aim of this study was investigation of TOC removal from phenol-formaldehyde resin manufacturing wastewater by electrocoagulation using Al- electrodes.
Materials and Methods: This study is the laboratory scale experiment was conducted as a pilot. Wastewater sample was adjusted in the desired pH, electrical conductivity and current density, then it was placed in to the reactor contains four electrodes in aluminum. The electrodes were connected to a DC power supply (0-40V, 0-3A). Samples were collected for TOC determination in the middle of cell at regular time intervals. Collected samples were analyzed using TOC analyzer.
Results:The results indicated that the optimum conditions for the removal of TOC were current density 75 A/m2, solution pH 4 and Conductivity 3 mS/cm. In this condition energy consumption was found 22.5 kWh m-3 after 60 min reaction.
Conclusion: This study shows that electrocoagulation of wastewater from phenol-formaldehyde resin manufacturing can be used as a pretreatment process.
M.t Ghaneian, M.h Ehrampoush, Gh Ghanizadeh, M Dehvary, M Abootoraby, T Jasemizad,
Volume 3, Issue 2 (7-2010)
Abstract
BackgroundandObjectives: Dyes are organic compoundswith complex structures,which due to toxicity, carcinogenicity and nonbiodegredabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this researchwas to study the feasibility of the application of solar irradiation in presence of potassium persulfate (K2S2O8) for the removal of Reactive blue19 (RB19) from synthetic wastewater.
Materials and Methods:This research wascarri edoutin laboratory scalewith using of 200ml volume of batchphotoreactor.The effectsofoperatingparameters suchas concentrationofK2S2O8,pH,photoexposure time and preliminary concentrations of dye on decolorization have been evaluated.Different concentrations of pollutant inwastewaterwere prepared by solution of variousmasses of RB19 on tapwater. The reactors were exposedwith natural solar irradiation as aUVAsource from11 amto 14 pm.Themaximumabsorbtion wave length of this dye (!max) was determined by spectrophotometer (Unico, 2100). The measurement of dye concentrations was determined with using of standard curve and its best line equation
Results:Analysis of absorbtion spectra showed that the !max of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 µW/Cm2. The results of decolorization process showed that 38.2%of this dye can be removed within 3 hr in the presence of potassium persulfate and decreasing of pH leads to the elevation of dye removal efficiency. Based on these findings, the efficiency of dye removal with 3h photoexposure time and pH ranges of 4,6 and 8 were found to be 98.2 88.5 and 78.5%, respectively.Also, the results showed that increasing of K2S2O8 dosage leads to elevation of dye removal efficiency in 3h photoexposure time and K2S2O8 dosages within 1-5mmol/L, with the removal efficiency of 75,86,92,95 and 98.5%, respectively.Analysis of data indicates that the kinetic of the removal of RB19 with this process is a first order reaction which its rate constant is 0.01min-1.
Conclusion: Due to the operation problems presented in heterogeneous photocatalitical processes such as catalysts separation and high costs of operation and maintenance of these processes caused by manmade sources of irradiations homogeneous photocatalitical process with using of potassium persulfate associated with natural solar irradiation can be used as a suitable process for the removal of dyes from textile industries wastewaters.
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
S Hemmati Borji, S Nasseri, R Nabizadeh Nodehi, A.h Mahvi, A.h Javadi,
Volume 3, Issue 4 (1-2011)
Abstract
Backgrounds and Objectives: Phenol and phenolic compounds are widely used in industry and daily liFe, and are of high interest due to stability in the environment, dissolution ability in water and health problems. In this regard, phenol removal from water is of high importance. The purpose of this study was to investigate the efficiency of photodegradation process for removal of phenol from aqueous system by use of Fe-doped TiO2 nanoparticles prepared by sol-gel method.
Materials and Methods: Phenol concentrations of 5, 10, 50 and 100 mg/L were prepared and exposed to UV and Fe-doped TiO2, separately and simultaneously. Also the effect of initial phenol concentration, Fe-doped TiO2 loading and pH were studied. Various doses of photocatalist investigated for Fe- doped TiO2 were 0.25, 0.5 and 1 g/L. pH was studied at three ranges, acidic (pH=3), neutral (pH=7) and alkaline (pH=11).
Results: Maximum degradation was obtained at acidic pH, 0.5 g/L of Fe-doped TiO2 for all of phenol concentrations. With increasing initial concentration of phenol, photocatalytic degradation decreased. In comparison with Fe-doped TiO2/UV process, efficiency of UV radiation alone was low in phenol degradation (% 64.5 at 100 mg/l of phenol concentration). Also the amount of phenol adsorbed on the Fe-doped TiO2 was negligible at dark conditions.
Conclusion: Results of this study showed that Fe(III)- doped TiO2 nanoparticles had an important effect on photocatalytic degradation of high initial phenol concentration when Fe(III)-doped TiO2/ UV process applied.
M.b Miranzadeh, M Sabahi Bidgoli, A.r Zarfeshani, M Heidari,
Volume 4, Issue 4 (3-2012)
Abstract
Background and Objectives Autoclaving is one of the methods which sterilizes infectious solid wastes. Since variety of parameters such as temperature, time, and pressure influence autoclave performance, this study was carried out to evaluate the parameters and set optimum condition for the autoclave apparatus applied in Shahid Beheshti Hospital in Kashan.
Materials and Methods: In this descriptive-analytical study, the performance of subjected autoclave was surveyed based on biological index and through setting 144 tests. Variables were packaging type in two groups (open and wrapped), loading type in three groups (light, medium and heavy), and four temperature-time features in fixed pressure equal to 101 kpa. Biological index was ATCC 7953 which contained Stearotermophilus Geobacillus spores. Finally obtained results were analyzed by Chi-Square test.
Results: The results of statistical test showed that there isn't any meaningful relation between packaging type of waste, system loading, and efficiency of sterilization(P>0.05),while meaningful relation was found between system performance and variety states of temperature-time feature(P<0.05), illustrating temperature and time effects in fixed pressure on sterilization of solid waste.
Conclusion: Based on the results, the best autoclave operational condition for sterilizing infectious solid wastes are: temperature-time equal to 10 min-140°C and 15 min-134°C in fixed pressure of 101 kpa, respectively. It was also revealed that temperature-time condition suggested by manufactory, i.e. 20min-121°C, is not sufficient for complete sterilization of solid waste.
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.
Saeed Parastar, Simin Nasseri, Amir Hossein Mahvi, Mitra Gholami, Amir Hossein Javadi, Saeedeh Hemmati,
Volume 5, Issue 3 (10-2012)
Abstract
Background and Objectives: Pollution of water resources to nitrate is an
environmental problem in many parts of the world. This problem possibly causes
diseases such as methemoglobinemia, lymphatic system cancer and Leukemia.
Hence, nitrate control and removal from water resources is necessary.
Considering that application of nanomaterials in treatment of environmental pollutants
has become an interesting method, in this research use of Ag-doped TiO2 nanoparticles synthesized through photodeposition produced under UV irradiation
was studied for removal of nitrate from aqueous solutions.
Materials and Methods: Three nitrate concentrations of 20, 50, and 100 mg/L were considered. In order
to determine the effect of Ag-doped TiO2 nanoparticles on nitrate removal, dosages of 0.1, 0.4, 0.8 and 1.2 g/L nanoparticles were
used pH range of 5-9 was also considered. The effect of Ag-doped TiO2 nanoparticles both in darkness and under UV irradiation was studied. Moreover,
the presence of chloride and sulfate anions on the system removal efficiency
was investigated.
Results: The optimum
performance of nitrate removal (95.5%) was obtained using nitrate concentration
of 100 mg/L, in acidic pH and 0.8 g/L Ag-TiO2. Increase of
nanoparticle dosage up to 0.8 g/L, increased the removal efficiency, but for
1.2 g/L dosage of nanoparticles, the removal efficiency decreased. Maximum
reduction performance without nanoparticles, under UV irradiation and under
darkness conditions were 32% and 23.3% , respectively. In addition, we found
that presence of sulfate and chloride anions in aqueous solution reduced
efficiency of nitrate removal.
Conclusion: Results of
this study showed that Ag-doped TiO2 nanoparticles may be
efficiently used for nitrate removal 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.
Amir Hossein Mahvi, Noushin Rastkari, Ramin Nabizadeh Nodehi, Shahrokh Nazmara, Simin Nasseri, Mahboobeh Ghoochani,
Volume 6, Issue 3 (12-2013)
Abstract
Background and Objectives:Chlorination is the most common method of water disinfection. Chlorine reaction with natural organic compounds nor removed completely during treatment process would result in forming disinfection byproducts. Followed by trihalomethanes, Haloaceticacides are the second main byproducts of chlorination in water. The research works conducted in Iran have assessed trihalomethanes. Hence, this is the first time we are reporting haloacetic acids in Iran.
Materials and Methodology: We collected samples from surface water resources and treated water in Tehran for six consecutive months (first half, 2010). We measured temperature, pH, UV adsorption at 254 nm and TOC in each surface water sample and analyzed pH, residual chlorine, and haloacetic acids in the treated water samples.
Results: We found that TOC in surface water resources is 3.6-4.42 and 1.78-2.71 mg/l in spring and summer respectively. Moreover, haloacetic acids concentration was found to be 41.7-55.56 and 34.83-43.73 μg/l in spring and summer respectively.
Conclusion: Our results revealed that concentration of NOM, TOC, and HAAs was more in spring than summer. In addition, concentration of HAAs was depended up on NOM and TOC. Considering maximum permeable concentration of HAAs (60 μg/l) by EPA, it can be claimed that concentration of HAAs was less than the maximum permissible level in all of the samples. However, the immanency of the monitored values to the standard values can be a warning for concerned authorities in water industry.
M Zamani, N Khorasani, A.r Riahi Bakhtiari, K Rezaei,
Volume 7, Issue 4 (1-2015)
Abstract
Background and Objectives: This study was performed to determine and identify the origin, concentration and source of perylene entry and some PAH compounds in surface sediments of Ghalam Goodeh (A), Siyah Kashim (B), and Talab Markazi (C) in Anzali wetland. Materials and methods: We collected 22 samples of sediments (from each region) and 2 samples of soils (from A region) in April of 2012. Sampling was performed from soil for proving the condition of concentration and origin of perylene in under investigating sediments. GC-MS was applied for extraction of PAH compounds using organic solvents and 2-phase column chromatography. Diagnostic ratios of Ph/An, Flu/Pyr, Flu/Flu+Pyr, BaA/BaA+Chr and IP/IP+BghiP were used to determine the origin of PAH compounds. Results: In all sediment samples, the origin of perylene and PAH compounds were found to be natural and petrogenic, respectively. The total concentration of PAH compounds were ranged between 560.05 to 1051.93 ng/g dry weight and perylene concentration were obtained between 70.65 to 204.41 ng/g dry weight. Total concentration of PAHs and perylene was significantly more in area A compared with other two area, whereas no relationship was found between normalized values of PAHs and TOC in sediments of all areas. Conclusion: With respect to the petrogenic source of PAHs in the surface sediments, the main sources of the PAH compounds entry are the discharge of domestic and industrials wastewater, the port and shipping activities, the exploration, excavation and refining activities of crude oil in offshore region and transportation of fishing and tourism boat but diagnosis of natural origin of perylene in the samples of surface sediment and soil implicated that this compound can be produced in terrestrial section due to activity of termites and fungi on the woody and cellulosic materials of forest floor, decaying wood and their fossilized remains and then their discharge to the wetland.
M.s Mansoury, H Godini, Gh Shams Khorramabadi,
Volume 8, Issue 2 (8-2015)
Abstract
Background and Objective: Natural organic matters (NOM) are known as precursors to disinfection byproducts. As conventional treatment processes cannot get disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/ZnO process is one of the advanced oxidation processes using photocatalytic technology. The present study aims to investigate the effect of UV/ZnO photocatalytic technology on the NOM removal from aqueous solution. Materials and methods: This study was conducted in a lab-scale batch photocatalytic reactor. The volume of reactor was 1liter and covered with UV lamps. Peristaltic pump was used for complete mixing. Humic acid is a key component of natural organic matter and it was used in this study. Each of the samples taken from the UV/ZnO process and other processes were analyzed for their UV absorbance at 254 nm by spectrophotometric. Initial concentration of Humic acid, contact time, pH, and UV irradiation were investigated. Results: The highest efficiency of the UV/ZnO photocatalytic process for removal of Humic acid from aqueous solution was achieved at initial concentration = 2 mg/L, contact time = 120 min, UV irradiation = 3950 µw/cm2, and pH=3. In this process, the removal efficiency for 2 mg/L humic acid was 100 % at 2h retention time. Conclusion: The research showed that performance of system was increased by increasing contact time and UV irradiation and was decreased by increasing HA initial concentration and pH and UV radiation with ZnO agent could not remove NOM lonely. Photocatalytic system using zinc oxide immobilized on glass have high performance to remove humic acid from aqueous solution. The UV/ZnO process was efficient and environmental friendly for natural organic matter removal.
N Rastkari, F Izadpanah ,
Volume 9, Issue 1 (6-2016)
Abstract
Background and Objective: Formaldehyde is a toxic volatile organic compound, which its removal from polluted air is essential. One of the techniques available for removing such compounds is photocatalytic degradation. The aim of this study was to investigate the photocatalytic degradation of gaseous formaldehyde on TiO2 nanoparticles coated on reduced graphene oxide
Materials and Methods: The synthesized reduced graphene oxide- TiO2 nanocomposite was characterized using SEM, EDS, and FTIR spectra. The photocatalytic activity of prepared reduced graphene oxide- TiO2 nanocomposite was investigated for degradation of gaseous toluene under different operational conditions such as different initial concentration, flow rate, and time.
Results: The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite was much higher than P25 TiO2. The photocatalytic degradation efficiency of the RGO-TiO2 nanocomposite decreased by increasing the flow rate so the flow rate is a key factor for the use of RGO-TiO2 nanocomposite as a photocatalyst. The results showed that the photocatalytic degradation rates decreased from 89 to 30% with increasing formaldehyde initial concentration from 0.1 to 1 ppm.
Conclusion: This research indicated that RGO-TiO2 nanocomposite can be effectively used as suitable photocatalyst to remove gaseous pollutants. One of the advantages of the as-prepared composite was using visible light instead of UV to activate the oxidation process.
M Jalili, M Mokhtari, Aa Ebrahimi, F Boghri,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: About 1.35×105 tons of pistachio waste are produced in annually Iran that can result in environmental problems if managed improperly. . The purpose of this study was to investigate in-vessel composting of pistachio residuals with addition of cow manure and dewatered sludge as a recycling alternative.
Materials and Methods: Pistachios wastes were combined with weight ratio of 5.5:10 (dewatered sludge: pistachio waste) and weight ratio of 1:10 (Cow manure: pistachio waste) to achieve the carbon to nitrogen ratio of 25:1. The parameters measured were pH, EC, percentage of moisture, total and volatile solids, ash, organic carbon, temperature, and phenol. The 20th edition of SPSS software was used for t-test statistical analysis and comparing the results with standards and Microsoft Excel 2007 was used for drawing the plots.
Results: During the 60-days process of in-vessel composting of pistachio residuals with addition of cow manure, the ratio of carbon to nitrogen reduced from 25:1 to 13:1, dewatered sludge from 25:1 to 14:1; phenol amount in cow maneuver decreased from 4980 to 254 ppm and in dewatered sewage sludge from 6100 to 254 ppm. The maximum temperature in cow manure and dewatered sewage sludge treatments in the composting process reached to 51.9 and 48.9 ˚C respectively.
Conclusion: Results showed that the produced compost with cow manure has a higher fertilizing value compared with the dewatered sewage sludge due to its better organic degradation.
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.
F Akhlaghian, H Azadi,
Volume 10, Issue 2 (9-2017)
Abstract
Background and Objective: All around the worlds, wastewater containing dye pollutants are considered serious problem. Rhodamine B dye which is used in textile, leather, drug, and cosmetic industries exert carcinogenic and strong toxic effects. The aim of this research was to remove of Rhodamine B dye by nanowires of zinc oxide doped with lanthanum.
Materials and Methods: In this work, nanowire of zinc oxide doped with lanthanum was synthesized by hydrothermal method. The obtained photocatalyst was characterized by XRF, XRD, and SEM method. Effects of batch process variables such as pH, initial concentration of Rhodamine B, and photocatalyst dose were investigated. The kinetics of the reaction was also studied.
Results: The SEM images showed a hexagonal structure of ZnO, and La/ZnO nanowires. XRD results also confirmed the formation of ZnO with wurtzite hexagonal structure in both samples (ZnO and La/ZnO). The kinetics studies showed that the reaction was a pseudo first order. The apparent constants of ZnO and 2%La/ZnO nanowires were 0.0045 min-1 and 0.0074 min-1; respectively. In a batch experiment, the degradation yield of 99.8% was obtained at operating conditions of 1.25 g/L of 2% La/ZnO photocatalyst, initial concentration of Rhodamine B solution 4.78 mg/L, and pH=9 under ultra violet irradiation for 4 h.
Conclusion: The nanowire of La/ZnO with an optimum load of lanthanum has a better photocatalytic activity than nanowire of ZnO for degradation of Rhodamine B in aqueous solution.
N Golchinpour, N Rastkari, R Nabizadeh Nodehi, M Abtahi, A Azari, E Iravani, K Yaghmaeian,
Volume 10, Issue 4 (3-2018)
Abstract
Background and Objective: Triclosan is one of the substances as anti-microbial that is used in many of these pharmaceutical products. This compound can affect human such as reduction of thyroid hormone levels, antibiotic resistant, and increasing skin cancer. This study evaluated the performance nanophotocatalysis process UV/Xe/TiO2-GO on triclosan removal from aqueous solutions.
Materials and Methods: Synthesis of TiO2@GO and its structure was analyzed by SEM, EDX and FTIR. The effects of pollutant concentration, catalyst dosage, and contact time on the removal of Triclosan were studied by DOE software according to response surface methodology. Analysis of variance test was considered for the influence of parameters. Optimum process condition was determined by desirability factor.
Results: Optimum conditions regarding concentration of pollutant, contact time, and catalyst dosage were determined as 0.205 g/L, 14.898 min, and 0.487 mg/L, respectively. Maximum removal efficiency in optimum condition was 97.542 percent. The catalyst dosage was the most effective parameter in removal of Triclosan.
Conclusion: Using of TiO2@GO and xenon lamp had acceptable efficiency for the removal of Triclosan. The use of Xenon lamps alone was economically affordable.
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.
Sakine Shekoohiyan, Mobina Hadadian, Mohsen Heidari,
Volume 14, Issue 3 (12-2021)
Abstract
Background and Objective: Changes in the quantity and quality of waste produced as a result of compliance with health protocols are the result of the COVID-19 outbreak. The present study aimed to determine the quantity of personal protection equipment produced in Tehran and people’s knowledge of its management.
Materials and Methods: The present cross-sectional and descriptive-analytical study was carried out on 2560 participants in Tehran through an online survey in spring 2020. Based on the percentage of using masks and gloves, the amount of produced waste was calculated, and Mann-Whitney and Kruskal-Wallis statistical tests were run to explore the relationship between the variables.
Results: The overall Cronbach's alpha coefficient of the questionnaire was 0.94, and the rate of mask and glove use was 90.7% and 65.7%, respectively. 70.3% and 52% of the population used two masks and one pair of gloves on a daily basis. The number of daily produced masks and pairs of gloves was 14530407 and 5262666, respectively. Mann-Whitney U-test showed a statistically significant difference between gender and marital status with people’s knowledge of waste management (p <0.05). Kruskal-Wallis test showed a significant difference between the economic status and people’s knowledge of separating the produced waste (p <0.05). People with an increasing income tended to separate the waste more.
Conclusion: Due to the high volume of personal protective wastes and the lacking knowledge of one-third of the participants about the transmission of the virus through contaminated waste, it is necessary to raise awareness of breaking the virus transmission chain.
