نتایج جستجو برای: chromium reduction
تعداد نتایج: 513315 فیلتر نتایج به سال:
The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that t...
Electrochemical reduction of nitrates and nitrites in alkaline media at constant current is rendered inoperable in the presence of hexavalent chromate. Even at chromate concentrations as low as 9mgdm, the chromium hydroxide ®lm, formed by the reduction of chromate, interferes with the reduction of nitrate and nitrite. We show that reversing the polarity of the electrodes at constant time interv...
a new simple arid rapid catalytic kinetic method for determination of trace amounts of chromium (110 isdescribed. the method is based on the catalytic effect of chromium (iii) on the reduction of methylene blue byascorbic acid in acidic media. the reaction monitored smectrophotomenically by measuring the decrease ofabsorbance at 664 nm at 25 c. the fixed-time method was used for the first 300 s...
This report demonstrates a novel strategy of chromium-assisted synthesis of platinum nanocubes as electrocatalysts for oxygen reduction reaction with enhanced specific activity.
Absorptive characteristics of polyaniline synthesized in different solvents were studied. Water and mixture of water with other solvents were implemented for polyaniline synthesis. Synthesized polyanilines in powder shape is used as an adsorbent to remove toxic hexavalent chromium from aqueous solutions. Experiments were conducted in batch mode. Removal mechanism involving polyanil...
In this paper, the chromium doped spinel zinc ferrite nanoparticles were synthesized by using of glycine as a fuel with microwave combustion method. After preparing the samples with x = 0.0, 0.5, 1.0, 1.5, 2.0, the electromagnetic and electrical properties such as dielectric constant, ac conductivity, dielectric loss factor (and Curie temperature were investigated. According to the results, in...
Chromium through natural processes and human activities enters the air, soil and water. Chromium-resistant bacteria are capable of reducing toxic Cr(VI) to less toxic Cr(III). In this work, batch studies were conducted to evaluate the effect of environmental factors on the rate of Cr(VI) reduction from synthetic wastewater of metal plating industry by Bacillus cereus under aerobic conditions. T...
A study of alternative chromium reduction methods was performed for wastewater or contaminated water. Two existing chromium reduction treatment methods were tested on the wastewater samples: treatment with (1) zero-valent iron, and (2) bacteria cultures. We found that both methods can reduce chrome. However, the chrome reduction process using bacteria is considerably slower than that using iron...
Chromium (Cr), a widespread environmental pollutant, is released from various industries including tanneries, metal cleaning and processing, chromium plating, wood processing, and alloy formation. In the developing as well as in the underdeveloped countries, the industrial effluents are released directly or indirectly into the natural water resources, mostly without proper treatment, posing a m...
Scientific interest on chromium removal from water and wastewater has escalated recently. Chromium compounds exist in the environment naturally but are mostly found due to anthropogenic activities (tanning, paint, cement industries, etc.). Hexavalent chromium [Cr(VI)] is of major environmental importance because it is one of the most stable chromium forms found in the environment. It is soluble...
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