[Study of eggshell performance as a natural sorbent for the removal of reactive red 198 dye from aqueous solution]

Dye compounds is one of the most critical contaminant for natural ecosystems. The aim of this study were to determine the primary concentrations of reactive red 198 dye [RR 198], adsorbent dosage and pH influences for the adsorption of RR 198 onto chicken's eggshell [ES] as an adsorbent. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Surface characteristics and measurement of the adsorbent surface area was carried out with Scanning electronic microscope [SEM] and via N2 gas adsorption with Brunauer-Emmett-Teller isotherm. The maximum absorption wave length of this dye [lamda-max] was determined by spectrophotometer [Optima SP-3000 Plus]. Analysis of absorption spectra showed that the lamda-max of RR198 is 518 nm. The results show the Calcium components are the main constituent of ES with 1.2 m[2]/g. Elevation of the ES dose [2 to3 g] lead to increasing of dye removal from 80% to 92%. The results show that elevation of pH from 4 to 10 would lead to increasing of RR 198 adsorption from 44% to 64% but increasing of preliminary dye concentration would lead to decreasing of dye adsorption from 72% to 23%. The kinetic studies revealed that the adsorption of RR 198 is rapid and complying with second-order kinetic [R2=0.995] which the kinetic constant is 0.0004min-1. Eggshell is a cheap adsorbent that can be used for the removal of dye components from alkaline solutions

Removal of methylene blue dye from textile simulated sample using tubular reactor and TiO[2]/UV-C photocatalytic process

In this study, photocatalytic degradation of methylene blue was examined using different concentrations of TiO[2] nano-particles [diameters less than 21 nm] and ultraviolet [UV-C] radiation in a tubular reactor. Different concentrations of catalyst [0.3-1.2 g/L], different pH conditions [3, 7 and 9] and dye concentration [15, 30 and 60 mg/L] as well as sample rotation level [125 mL/min] were studied. The sample passed 1-7 times through the quartz reactor exposed to UV-C ray [constant intensity = 2.8 mW/cm[2]] [every rotation time was 8 min]. Results of this research showed clearly that methylene blue is significantly degradable by TiO[2] and UV-C radiation. Increasing dye concentration resulted in decreased efficiency and thus, as more samples passed through quarts tube, removal efficiency increased. Methylene blue with concentration of 15 mg/L and after 7 rotations in the reactor [56 min] was removed with the efficiency of 98%. Subsequent to dye removal, 47% of initial COD decreased simultaneously

Equilibrium and kinetics study of reactive red 123 dye removal from aqueous solution by adsorption on eggshell

The aim of this study was to determine the equilibrium and kinetics adsorption of reactive red 123 dye [RR 123] from aqueous solution with chicken's eggshell as an adsorbent. The initial concentrations of reactive red 123 dye were selected in the range of 25 and 50 mg/L. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Measurement of the adsorbent surface area was carried out via Brunauer Emmett-Teller isotherm. The experimental data were analyzed with Langmuir, Freundlich and Temkin isotherm models. The results showed that the calcium components were the main constituents of eggshell [around 95% Ca]. The experimental adsorption isotherm was in good concordance with Langmuir and Freundlich models [R[2]>0.90] and based on the Langmuir isotherm the maximum amount of adsorption [q[max]] was 1.26 mg/g. Increase of the eggshell dose and the solution temperature beyond 45 Degree C led to decrease of the adsorbed dye per mass unit of the adsorbent, but increase of the solution pH up to 9 led to the improvement of dye adsorption. The kinetic studies revealed that the adsorption of reactive red 123 was rapid and complied with pseudo-second order kinetic [R[2]= 0.99], with the kinetic constant of 0.02 g/mg.min

Adsorption of reactive red 198 dye on TiO[2] nano-particle from synthetic wastewater

Dyes are one of the most important existing pollutants in textile industrial wastewater. They are often toxic, carcinogenic, teratogenic, and non-biodegradable. Reactive red 198 dye is one of the azo dyes that is currently used in the textile industry. This study was conducted with the aim of investigating on reactive red 198 dye absorption process titanium dioxide nanoparticles from synthetic textile wastewater. This applicable research was performed in a batch reactor on synthetic wastewater with dye concentrations of 100, 150 and 200 mg/L and the effects of parameters such as concentrations of initial dye and TiO[2] nanoparticles, time, and pH[s] on dye absorption efficiency were investigated. The dye concentrations were measured via spectrophotometer [518 nm wavelength]. Results: The RR 198 absorption capacity rates were 92.5, 70, and 37.5 mg/g respectively at pH of 4, 7 and 10 for the initial dye concentration of 100 mg/L and 0.4 g/L absorbent mass at 180 minute. Also dye absorption rates were 51.8, 56.1, and 61.4 mg/g on absorbent respectively for 100, 150, and 200 mg/1 dye concentration, at pH of 4, 1 g/L absorbent mass, and 180 minutes time and the studied dye absorption isotherm was fitted Langmuir model [R[2]=0.98] which was 38.46mg/g for maximum adsorption. The results of absorption studies showed that reactive red 198 absorption/removal rates would increase with increasing the primary dye concentration, reaction time, absorbent mass, and decreasing pH. On the basis of the results, titanium dioxide nanoparticles can absorb reactive red 198 dye appropriately and efficiency of the process is higher in acidic pH. Regarding to TiO[2] application as a photocatalyst in environmental pollutant removal, more pollutant absorption on nanoparticles in acidic condition increases photocatalyst process efficiency

[Application of solar irradiation / K2S2O8 photochemical oxidation process for the removal of reactive blue 19 dye from aqueous solutions]

Dyes are organic compounds with complex structures, which due to toxicity, carcinogenicity and nonbiodegradabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this research was to study the feasibility of the application of solar irradiation in presence of potassium persulfate [K[2]S[2]O8] for the removal of Reactive blue19 [RB19] from synthetic wastewater. This research was carried out in laboratory scale with using of 200ml volume of batch photoreactor. The effects of operating parameters such as concentration of K[2]S[2]O[8], pH, photo exposure time and preliminary concentrations of dye on decolonization have been evaluated. Different concentrations of pollutant in waste water were prepared by solution of variousmasses of RB19 on tap water. The reactors were exposed with natural solar irradiation as a UVA source from11 am to 14 pm. The maximum absorption wave length of this dye [lambda[max]] was determined by spectrophotometer [Unico, 2100]. The measurement of dye concentrations was determined with using of standard curve and its best line equation Analysis of absorbtion spectra showed that the lambda[max] of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 microW/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 photo exposure 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 K[2]S[2]O[8] dosage leads to elevation of dye removal efficiency in 3h photo exposure time and K[2]S[2]O[8] 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. 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

comparison between tubular and batch reactors in removal of methylene blue dye from simulated textile wastewater using TiO[2]/UV-C photocatalytic process

Dyes are structurally complex materials which enter the environment due to various textile industry processes like dyeing and cloth completion processes. Methylene blue is one of the cationic dyes which is now used in textile industry. Textile industrial wastewaters are one of the important sources of environmental contaminants. The aim of this research is photo catalytic degradation of methylene blue dye with the TiO[2] Nan particle with UV-C irradiation using batch and tubular reactor. In this research, photo catalytic degradation of methylene blue dye was studied using different concentration of TiO[2] Nan particles [with lower than 21 nm of size] under UV irradiation in a batch and tubular reactor. The variables were: concentrations of color, titanium dioxide nana-particles and air Bubbling. The results of this research show that removal of methylene blue dye has direct correlation with the time of UV irradiation. All tests were performed in neutral pH [pH:7]. The best efficiency results for dye removal and COD in the batch reactor were 100 and 42.2% respectively. However the best color removal efficiency and COD results in tubular reactor were 93 and 47.8% for titanium dioxide nana particle concentration of 1.2 gr/1[-1] during 60 minutes. Furthermore as color concentrations increased, color removal rate decreased. Finally, it was concluded that model of batch reactor is the best efficiency that may be selected with regard to the characteristic of textile wastewater, desired treatment efficiency and the discharge standards

Application of ozonation on the removal of reactive red 198 dye at alkaline condition

Dyes are the most important pollutants of textile industries which have complex structures as well as toxic, carcinogenic, teratogenic and nonbiodegredable properties. This research was performed to compare the efficacy of removal and mineralization of Reactive Red 198 dye at alkaline and neutral pH. The effect of different pH: 7,9,10 and 11 in dye and COD removal from 250 mg/1 aqueous solution of RR198 was evaluated. Dye removal efficiency was measured by UV-vis spectrophotometer and data were analyzed using SPSS 16, via statistical tests including One-Way ANOVA. COD removal efficiency was also measured by closed reflex method. Dye removal efficiency was higher than 96% in all different types of pH and also showed significant difference in different time intervals [P<0.05]. COD removal was lower than dye removal and in different types of pH: 7, 9, 10 and 11 which after 60 minutes of reaction reached to 31, 40, 43 and 53% respectively. From the collected data it is obvious that rapid dye removal is due to the reaction of both molecular ozone and free radicals with dye molecules but more COD was removed only after the generation of hydroxyl radicals via pH elevation

Application of iron impregnated activated carbon for removal of arsenic from water

The presence of arsenic in drinking water is one of the greatest threats to public health. The aim of this experimental investigation was to study the removal efficiency of As [v] from water by application of iron-impregnated activated carbon [Fe-AC]. Coating of activated carbon with iron salt was carried out by impregnation method and thermo-chemical reactions with using of 100 mM FeCl3 solution. The Fe-AC was pulverized using ASTM standard sieves with the range of 16-20 mesh. The solid structure and surface characteristics of Fe-AC were determined using conventional techniques. Batch adsorption experiments were carried out with 300 and 600 micro Lig/L arsenate. Langmuir, Freundlich and Dubinin-Radushkevich models were used to describe the isotherm and energy of adsorption. The results of this study showed that 2.5 h contact time was enough to achieve the equilibrium. The adsorption of As [v] had a good compliance with Langmuir model [R[2]= 0.995] and the maximum adsorption capacity was obtained as 0.024 mg/g. The results of kinetic studies showed that As[v] adsorption on Fe-AC may be limited by film diffusion step [m=0.26]. The mean free energy of adsorption [E] calculated from Dubinin-Radushkevich isotherm was found to be 1.52 kj/mol which implies that the adsorption of As[v] on Fe-AC is a physical adsorption. The results indicated that Fe-AC is one of the suitable adsorbents which can be used for the treatment of arsenic contaminated waters

[Application of enzymatic polymerization process for the removal of phenol from synthetic wastewater]

Phenolic compounds are presence in many industrial wastewaters, and have been classified as priority pollutants. Application of several conventional processes due to high cost and low efficiency has been limited. Thus, new methods such as enzymatic polymerization seem to be preferable and effective processes with high potential to substitute the conventional processes. This study was carried out to evaluate Raphanus sativus extract as a peroxides enzyme source for polymerization and removal of phenol from synthetic wastewater in the presence of hydrogen peroxide. The study was performed in batch reactor at room temperature. Peroxidase enzyme was extracted from Raphanus sativus plant roots. Primary concentration of phenol in wastewater was 1000 mgl[-1]. The concentration of phenol and enzymatic activity was been measured by photometric assay. The results show that Raphanus sativus extract is a suitable source of peroxidase enzyme. Mean enzymatic activities in this extract was 3.107 Uml[-1]. Also, our results showed that elevation of extract volume lead to high efficiency of phenol removal, in which the increase in the extract volume from 5 to 50 ml, resulted in the efficiency of processes increased from 7.6 to 98.2%. Also, sequencing addition of H2O2 and extract has improved the effects. The phenol removal efficiency of the reaction time after 3 h with single and three stages adding of reactants was 84.2 and 93.1%, respectively. Enzymatic polymerization can be used as an appropriate process for the removal of phenolic compounds from wastewaters. To meet the optimized condition in process, the ratios of phenol/ enzyme and H2O2/ phenol and sequences of the adding of reactants should be considered

Photochemical oxidation of reactive blue 19 dye [RB19] in textile wastewater by UV/K[2]S[2]O[8] process

In textile industry, advanced oxidation processes are used for degrading and removing color from dye baths which allow wastewater reuse. In this study, photochemical oxidation processes [UV-A/K2S2O8, UV-C/K2S2O8] and chemical oxidation process [dark/K2S2O8], were investigated in a laboratory scale photoreactor for decolorization of the Reactive blue 19 [RB19] dye from synthetic textile wastewater. The effects of operating parameters such as potassium persulphate dosage, pH, reaction time and UV source, on decolorization have been evaluated. The results of direct chemical oxidation showed that 50% of the dye was been removed using K2S2O8 in dark condition after 5h reaction time and photochemical oxidation showed that UV-C irradiation is more effective than UV-A for RB19 dye removal. The RB19 solution was completely decolorized under optimal potassium persulphate dosage of 5mmol/L and low-pressure mercury UV-C lamps [15w] in less than 30min. UV/K2S2O8 experiments showed higher color removal performance under acidic conditions [pH=3], and in this condition with 5mmol/L of potassium persulphate, 78.5% COD has been removed after 3h irradiation time. The decolorization rate fitted to pseudo-first order kinetics with respect of dye concentration. The reaction rate constants for photochemical degradation of RB19 were 0.014 and 0.237 for UV-A/K2S2O8 and UV-C/K2S2O8 processes respectively

Photocatalytic decomposition of gaseous toluene by TIO[2] nanoparticles coated on activated carbon

Volatile organic compounds are considered as a group of major environmental pollutants and toluene is recognized as one of the representatives. In this research, the photocatalytic activity for toluene removal was studied over TiO2 nanoparticles embeded on activated carbon. Laboratory-scale experiments were conducted in a fixed-bed reactor equipped with 4 w and 8 w UV lamps [peak wavelength at 365 nm] to determine the oxidation rates of toluene. The photocatalyst was extensively characterized by means of X-ray diffraction and scan electronmicroscopy. Experiments were conducted under general laboratory temperature [25°C +/- 2] while the irradiation was provided by the UV lamps. The dependence of the reaction rate on light intensity as well as the deactivation of the catalyst were determined. The results indicated that the rate of the photocatalytic process increased with increasing the intensity of UV irradiation. Using the UV-A lamps, the decomposition rate of toluene was 98%. The stabilized photocatalyst presented remarkable stability [no deactivation and excellent repeatability]. The catalyst could be regenerated by UV irradiation in the absence of gas phase. The control experiments confirmed that the photocatalytic effects of toluene onto the TiO2/activated carbon catalysts in the dark conditions were negligible. Reproducibility tests proved that the photocatalytic activity of the photocatalyst remains intact even after several experiments of new added toluene quantities. The study demonstrated that the TiO2/activated carbon catalyst may be a practical and promising way to degrade the toluene under ultraviolet irradiation

Study of the effeciency of volcanic rock bed filters in enhanced ammonia and fecal coliform removal from khoy wastewater treatment plant

Ammonia and fecal coliform removal from wastewater is of high necessity because of its inappropriate impact on environment where wastewater accumulates. Aerated lagoons as well as polishing ponds would not be able to decrease ammonia and fecal coliforms in an efficient way. Different procedures are usually applied for the removal of ammonia and fecal coliform in wastewater treatment plants. In this study, effluent of polishing pond in wastewater treatment plant of Khoy in North-West Azerbaijan with three different loading flow rates [0.3, 0.6, 0.9 m[3]/m[3].d] was entered into the rock filter with volcanic rock bed, rock diameter size of which was 50 mm. To determine the efficiency of rock filter in any loading flow rates, 10 samples of influent and effluent were taken. The results showed that mean of effluent ammonia level changed from 16.8 to 4.8 mg/1 and effluent fecal coliform from 1.9xl0[4] MPN/l00ml to SJxl0[3] MPN/lOOml. Rock filter efficiency for Ammonia and fecal coliform removal of pond effluent were 71.4% and 70% respectively. Ammonia and fecal coliform decreased in all loading flow rates but in the first rate changes were more remarkable than the two other rates. As loading flow rate increased, removal efficiency decreased. This is probably due to low hydraulic retention time that resulted in decreasing nitrification. Thus it is concluded that rock filter here presented has better efficiency than what were used in similar studies

Survey of corrosion and precipitation potential in dual water distribution system in kharanagh district of yazd province

Corrosion and precipitation in drinking and sanitary water in distribution systems leads to economic and health damages. The goal of this study was to survey the chemical quality of water in Kharanagh ward in Yazd province and to predict the potential of corrosion and precipitation in these waters. For determining the chemical quality of water, some cross-sectional samples with 2-4L of water volume were taken. All of the samples were collected, stored and preserved in glass or polyethylene containers and were analyzed based on standard methods. The potential of corrosion and precipitation in waters was calculated by Langelier Saturation Index [LSI], Risnar Index [RI] and decision was made based on calcium carbonate resistance. Based on the values of LSI, drinking and sanitary waters showed precipitative properties. Based on RI, the waters showed a corrosive quality from the point of corrosion and precipitation potential. Based on calcium carbonate resistance parameter, the waters had precipitative quality. The chemical quality of water in Kharanagh district is non-balanced that leads to precipitation in water distribution and other equipments thus planning water quality stabilization for the elimination of economics damages is necessary

Investigation of physical, chemical and microbial characteristics of ahrestan subterranean canal [sc] water in yazd district for water resources conservation and sustainable development

Present Qanats are considered as enovmous investments in Iran, which have old history and great energy and much costs have been covered for them, Attention and protection for Qanats is necessary. In this study, we investigated Ahrestan Qanats water to analyze its quality condition [physical-chemical and microbial] and compare it with standards. For this purpose, sampling was done from 5 station along this Qanat in 4 stages, every month. Different tests were performed on these samples and the results were set in some tables. Results in station one showed that, turbidity, TDS, TSS, electrical conductivity, total hardness, chloride, sulfate, alkalinity in Ahrestan Qanat water were FTU, 7.25mg/L, 2368.8mg/L, 2378.8micros/cm, 563.7mg/LcaCO[3], 391.08mg/LCL-, 61.25mg/LSO[4] ,268 mg/LcaCO[3] respectively. Results in the last station showed that these parameters were 4FTU, 3.75mg/L, 654.3mg/L, 1278jas/cm, 379.35mg/LcaCO[3], 189.44mg/LCL-, 35.5mg/LSO[4], 167mg/LcaCO[3] respectively. According to the results and by comparing them with related standards we can use this water for other consumptions, for example, for fish breeding consumption by animals, drinking [after filtration and chlorination], watermills, for tourism industry as well as in agriculture