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.
Soil Pollution
Mahmood Kasaei; Nasrin Gharahi; Rafat Zare Bidaki
Abstract
Introduction: Nitrogen is the nutrient in plants production which usually can be added as a fertilizer into the soil. Nitrate is one of the pollutants which is mainly caused by agricultural activities which contaminants groundwater and surface water and threatens human health. Investigating an effective ...
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Introduction: Nitrogen is the nutrient in plants production which usually can be added as a fertilizer into the soil. Nitrate is one of the pollutants which is mainly caused by agricultural activities which contaminants groundwater and surface water and threatens human health. Investigating an effective factor on water and minerals movement in soil and applying the new modifiers such as inorganic nanoparticles and biochar might be useful in reducing nitrate leaching and avoiding underground waters pollutions. Due to this difficulty, some situations to preserve nitrogen in the upper layers of soil such as increasing the absorbent surfaces for minerals, zeolite modifier, and biochar are considered by researchers. As many research have been conducted on using biochar in agricultural systems in terms of organic carbon sequestration in soil and reducing the greenhouse gases, its influence on other processes such as nitrate leaching has been considered as well. The purpose of this study was to investigate the effect of mineral nano-particles and biochar on nitrate leaching in soil and aggregate stability.Materials and Methods: This study had been conducted in the laboratory in faculty of natural resources and geology science, Shahrekord University. Treatments in this study included zeolite, cloisite, and biochar at three levels. PVC pipes with 3 cm in diameter and 40 cm in height were used for the soil columns. Urea fertilizer included 46% pure nitrogen was applied to the soil columns. The amount of the Urea fertilizer was employed as an applied fertilizer for corn plants (200 g Nitrogen per hectare). Urea fertilizer was added as a solution to the soil in irrigation 1, and 5 from irrigation events. At the end of each irrigation event, nitrate effluent was measured using Spectrophotometry method.Results and Discussion: The results showed a significant reduction of nitrate leaching in treatments, 1g biochar, 1g zeolite, and 1g cloisite compared to the control treatment. There was no significant difference between reduction of nitrate leaching in the three treatments, 1g biochar, 1g Zeolite, and 1g cloisite. Furthermore, nitrate leaching in treatments, 5g biochar, 5g zeolite, and 5g cloisite compared to the control treatment was decreased significantly. In all irrigations, 5g biochar had the smallest amount of nitrate leaching comparing 5g zeolite, and 5g Clozite. In general, the results showed that nitrate leaching would be decreased significantly by adding biochar and mineral nano-particles (5%) into the soil. According to the present results and previous findings, it can be mentioned that adding biochar into the soil will cause improving the soil physical properties and reducing nitrate leaching. Thus, we show here, that biochar and nano-particles soil application decreased nitrate leaching and enhanced soil aggregate stability.