Water Pollution
Maedeh Parichehre; Fardin Sadeghzadeh; Bahi Jalili; Mohammad Ali Bahmanyar; Abd Wahid Samsuri
Abstract
Introduction: The increase of various industries and the ever-increasing growth of the population of the planet have caused all kinds of contamination in the environment. One of the most important contaminants in water, which has many risks for human health and living organisms and important environmental ...
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Introduction: The increase of various industries and the ever-increasing growth of the population of the planet have caused all kinds of contamination in the environment. One of the most important contaminants in water, which has many risks for human health and living organisms and important environmental risks, is anionic compounds in high concentration. Chromium is one of these contaminants that causes contamination in the environment and brings many risks to human health and other living organisms. Various methods have been evaluated to remove heavy metals from water, which often include chemical or energy-intensive processes. Therefore, it is important to modify these sources with the help of affordable adsorbents and with low energy consumption. Previous studies showed that biochar, metal-coated biochars and carbon-metal composites are highly effective in removing chromium contaminants with a concentration of 20 mg/liter from water, but so far the effect of these adsorbents on removing this anionic contaminant in high concentrations has not been investigated.Materials and Methods: In this research, the efficiency of different adsorbents (biochar, copper-coated biochar, aluminum-coated biochar, iron-coated biochar, biochar-copper composite, biochar-aluminum composite and biochar-iron composite) on the removal of chromium, with a concentration of 300 mg per liter, from water was investigated. Metal-coated biochars were prepared from the combination of metals (copper, iron and aluminum) with a concentration of 10000 mg/kg with biochar produced at 600 degrees Celsius and various biochar-metal composites were prepared from the combination of these metals with rice straw and then the samples were pyrolyzed at 600 degrees Celsius. In order to determine the efficiency of the adsorbents, 0.5 grams of each adsorbent was mixed with 40 ml of chromium solution with a concentration of 300 mg/l and pH= 6 and shaken for three hours until they reached equilibrium. Then the samples were centrifuged for 5 minutes at 6000 rpm and after the filtration, the final concentration of the contaminant was obtained and the percentage of chromium removal was calculated.Results: The results of the present study showed that all of the applied adsorbents were effective in removing high concentrations of chromium from water. The lowest removal rate of this contaminant was related to the biochar sample, which only removed 15.28% of this contaminant from water; And the highest amount of removal was achieved using iron composite, which removed 44.45% of the contaminant from the aqueous solution. According to the results of this research, it can be observed that coating biochar and rice straw with metals has been able to increase the efficiency of this adsorbent in removing chromium from water. For example, iron composite and iron-coated biochar were able to remove 44.45 and 30.86% of chromium contaminant from the aqueous solution, respectively, while rice straw biochar was only able to remove 15.28% of this contaminant from water.Discussion: The results of present study showed that iron coated biochar and biochar-iron composite had more ability to remove chromium contaminant from aqueous solution than other metal coated biochars and biochar-metal composites and were able to perform more successfully. Therefore, the use of these adsorbents can be effective in the treatment of chromium-contaminated water.
Air ppllution
Samane Komeili; Abdollah Mostafaei; Morteza Jalali Lichei
Abstract
Nitrogen oxides are one of the most important pollutants in the air, which releasing into the atmosphere causes to produce of dangerous secondary pollutants. Identifying the various methods of reducing this pollutant in the chimney is an important guide for choosing an effective method to achieve the ...
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Nitrogen oxides are one of the most important pollutants in the air, which releasing into the atmosphere causes to produce of dangerous secondary pollutants. Identifying the various methods of reducing this pollutant in the chimney is an important guide for choosing an effective method to achieve the desired level of this pollutant according to the type of industry for experts. In this paper, methods for reducing nitrogen oxides in flue gas flow are reviewed. These methods include chemical processes such as plasma and non-plasma oxidation by an oxidizing agent, catalytic and non-catalytic reduction, electron irradiation, biological process, and physical adsorption processes on the surface. These methods separate nitrogen oxide from a gaseous stream and convert it into inert materials. These methods are very effective for industries that use old technologies and are highly polluting. The main technologies introduced in this article are among the four main methods with developed technology or they are close to development and can be used in Iranian industries.