ABSTRACT
Background: Phenol is an organic pollutant found in industrial effluents that is very toxic to humans and the environment. This study used pomegranate peel ash as a natural absorbent to remove phenol from aqueous solutions
Methods: In this study, pomegranate peel ash in different doses was used as a new adsorbent for the removal of phenol. The effects of contact time, pH, adsorbent dose and initial phenol concentration were recorded. Then, the adsorption data was described with Langmuir and Freundlich adsorption isotherms; Excel software was used for data analysis
Results: The highest percentage of phenol adsorption was observed at pH = 7. The optimum amount of adsorbent was 0.6 g/l, and after 120 minutes, the process reached an equilibrium state. The adsorption of phenol decreased following an increase in the pH of the solution. It was also observed that contact time significantly affected the rate of phenol adsorption. The experimental data fit much better in the Freundlich [R[2] = 0.9056] model than in the Langmuir [R[2] = 0.8674] model
Conclusion: Pomegranate peel ash has the potential to be utilized for the cost-effective removal of phenol from aqueous solutions
ABSTRACT
Background: Phenol, as a pure substance, is used in many fields because of its disinfectant, germicidal, local anesthetic, and peptizing properties. Aqueous solutions of phenol are produced as waste in industries and discharged into the environment. Therefore, elevated concentrations of phenol may be found in air or water because of industrial discharge or the use of phenolic products
Method: The strains of Saccharomyces cerevisiae used in this project were natural strains previously purchased from Razavy company. They were grown at 30[degree]C on Petri plates containing yeast extract glucose [YGC] and then purified by being spread onto new plates, and isolated colonies were obtained. These colonies provided the basis of selection. Prepared strains were applied in anaerobic sequencing batch reactors [ASBRs] as first seed. The experiment conditions were optimized using response surface methodology [RSM]. After the determined runs were performed using Design-Expert software, data were analyzed using mentioned software as well
Results: This study evaluated the capability of baker's yeast to remove phenol in high concentrations. The tested strains showed excellent tolerance to phenol toxicity at concentrations up to 6100 mg/L. Study of the batch degradation process showed that the phenol removal rate could exceed 99.9% in 24 hours at a concentration of 1000 mg/L. The results showed catechol is the first intermediate product of phenol degradation. In survey results of the Design-Expert software, R2 and Adeq precision were 0.97 and 25.65, respectively
Conclusion: The results demonstrated that ASBR performs robustly under variable influent concentrations of inhibitory compounds. The high removal performance despite the high phenol concentration may be a result of reactor operating strategies. Based on the progressive increase of inlet phenol concentration, allowing for an enhanced biomass acclimation in a short time, results at the microbiological levels showed that the increase of phenol concentration was accompanied by a decrease in the microbial community and a progressive selection of the most adapted phenotypes
ABSTRACT
Background: The presence of heavy metals in the environment especially in water supplies have caused many concerns because of their toxicity and non-degradability. Hexavalent Chromium [Cr] is one of the most toxic metals which is used in many industries, so it is essential to remove it from industrial wastewater. In this study, we made a comparison between different adsorption isotherms in the chromium [VI] removal process using carbon nano tubes from aqueous solutions
Methods: This experimental study used atomic absorption spectrophotometry. To determine the adsorption isotherms, a synthetic sample with defined concentration of Cr [VI] was prepared and different doses of adsorbent were added to it. The effect of initial Cr concentration, pH, adsorbent dose, and reaction time on removal of Cr was investigated. Temperature and mix rate were steady during a defined time. At the end, Cr [VI] concentration measured and adsorbents equality capacities were calculated via formulas and graphs. Data analysis were performed using descriptive statistics
Results: Adsorption capacities [q[e]] increased with increasing of initial Cr concentration, and reaction time decreased with increasing adsorbent dose and pH. Correlation coefficients for Langmuir, and Freundlich isotherms in oxidized Multi-Walled Carbon Nano Tubes [MWCNTs] were 0.93, 0.874, and 0.714 and in oxidized Single-Walled Carbon Nano Tubes [SWCNTs] were 0.904, 0.868, and 0.711 respectively
Conclusion: Chromium ions adsorption in carbon nano tubes is accordant to Langmuir isotherm model, and MWCNTs have more cc than SWCNTs. Carbon nano tubes are effective adsorbents in removal of Cr [VI] from aqueous solutions
ABSTRACT
Background: In large cities, the share of vehicles in air pollutants emissions is nearly 70% that is mainly due to use of fossil fuels. Environmental simulation has many advantages such as accuracy and speed of modeling. Present study was conducted to create a model of air pollution [Carbon Monoxide [CO] and Nitrogen Oxides [NO[x]]] from vehicles in fifty following years, in Mashhad
Methods: According to the collected data from license plate, traffic and transportation organizations, modeling of CO and NO[x] was performed by STELLA software. Hence, five strategies, including reduction in the number of imported vehicles and the proportion of distance traveled by vehicles, increase in the number of junked vehicles, application of Euro 4 standards instead of Euro 3 and a combination of their application, were applied in the model
Results: In the current condition, CO and NO[x] concentrations are 27,894 and 2,121, and after 50 years they would be 26,227,930 and 2,070,011 ton/year, respectively. Applying the aforementioned strategies, their concentrations were declined approximately [35% and 35%], [50% and 50%], [16% and 16%], [7% and 47%] and [75% and 85%], correspondingly
Conclusion: Developed model showed that if the present condition remains stable, air quality will be more and more undesirable in the 50 following years. However, application of the second method, reduction of the distance traveled, was the most effective strategy in reducing the amounts of ones, so it will be better that this strategy is considered in the administrative policies. Nevertheless, as far as possible all of them ought to be taken advantage of