1998), (Sayer et al. 1997). In nature, the radioactive wastes and heavy metals can be present in a number of forms such as oxides, superoxides, peroxides, sulphates, nitrates, citrates, carbonates etc. Microorganisms change these forms or states of toxic substances into less toxic or non toxic states. They carry out these transformations due to their sensitivity towards presence or absence of free electrons.
Understanding these trends is important because it allows these same natural processes to be taken advantage of for the purposes of remediation and removal of chromium from the environment. Redox reactions can be facilitated to promote the conversion of oxidized Cr(VI) to the more benign form of Cr(III); once in this form, it becomes nontoxic and immobile. However, there is always the risk of the chromium being oxidized back to its hexavalent form by manganese oxides present in the natural environment . By causing the chromium to precipitate out as Cr(III) hydroxide, such as by reaction with Fe(II) or Mn(II) [1,6], this risk can be mitigated and the chromium can be rendered inert and immobile. Adsorption reactions are another promising method of removing Cr(VI) from environmental systems.
a) Basis of Safety of a Chemical Reactor Process or manufacturing industries usually uses chemicals in their processes or produces chemicals as the end products. Whenever chemicals are involved in the process industries, a concern of possible hazard should be raised. Chemicals not only pose a substantial hazard due to its properties, but also due to the chemical reaction itself. Runaway reaction as a result from exothermic reaction from chemical reaction could lead to serious hazard as seen in previous major accident such as Bhopal and Seveso disaster. Reaction of chemicals with water or air also exhibit serious attention as seen in several major disasters before (Sanders, 1999).
Radioactive waste has become quite a large issue, having dangerous impacts on humans and the environment. Radioactive waste is materials that are by-products of laboratory work or chemical processes. Radioactive waste is being emitted frequently by the nuclear reactors we use to generate energy. Although nuclear reactors do have its advantages, a major disadvantage is the amount of radioactive material being released into the world. Common radioactive wastes from nuclear plants include the isotopes, iron-55, cobalt-60, nickel-63, and carbon 14 (“New UK Waste Facilities Completed”).
Radiation is harmful because of its interactions with the environment and the body and in turn, the Chernobyl disaster was harmful because it released large amounts of radiation into the environment, exposing the population. Radiation is broken up into four types: alpha particles, beta particles and positrons, gamma rays and x-rays. Electron volt is the conventional energy unit for ionizing radiation (1 eV = 1.6 x 10-19 J). Alpha particles and beta rays have energy equal to their kinetic energy (E=1/2mv2, m = mass, v = velocity) while gamma rays and x-ray... ... middle of paper ... ...after the Chernobyl disaster. Environ Health Perspect.
During reduction of Cr6+ to Cr3+ it generates reactive oxidation species which damage DNA. Chromium associated pollution is of increasing concern now days. Some conventional methods for treatment of chromium includes chemical precipitation, ion exchange, filtration, adsorption, electro chemical precipitation
One thing to notice from the chart is the extremely high ODP for the Halon compounds. These compunds (as can be seen from their formulas) contain a bromine atom that can destroy more ozone when compared to a chlorine. This occurs because it takes longer for a bromine atom to be taken out of the stratusphere. Halons were used in foam blowing apparatuses for fire-retarding systems, but were phased out along with CFCs. Innovative chemical companies With the advent of the Montreal Protocol and other legislation to reduce the production and use of CFCs, companies have increased research and development of replacement system and/or chemicals.
They are used to detect Beryllium. They also played a very important role in the development of the atomic bomb. Gamma Rays can be very dangerous to use or be in contact with. Gamma rays bombard our bodies constantly. They come from the naturally radioactive materials in rocks and soil.
How the chemicals are being disposed of should be monitored (Howells). Marcellus Shale drilling is a dangerous process with many consequences. The Marcellus Shale industry is said to create new jobs and be a source of “clean” energy (Environmental) (Griswold). However, this process uses hundreds of deadly chemicals, it causes pollution, and it has few regulations. A solution to these negative consequences would be to create and enforce more regulations.
Oxidation state of cobalt in EDTA complex play a major role and determine the stability and mobility of cobalt near waste disposal sites. Oxidized form of cobalt, Co(III) has a stronger affinity to EDTA than that of the Co(II), that is why [Co(III)-EDTA]– has higher stability and solubility.8 Since, most transportable form of 6... ... middle of paper ... ...t are expected to have higher radiotolarance.26 These habitats might act as rich repositories for the isolation of novel microorganisms with potential bioremediation applications for radioactive nuclear waste.26 In this present study, a [Co(III)-EDTA]- reducing bacterium Bacillus licheniformis SPB2 was isolated from a solar salt pan and reduction conditions for [Co(III)-EDTA]- were optimized. We report the reduction of [Co(III)-EDTA]- to [Co(II)-EDTA]2- by B. licheniformis SPB2 at much higher concentration (i.e. 1 mM) than the reported value in post-decontamination nuclear waste processing (0.01 mM). Various aspects of [Co(III)-EDTA]- reduction were also studied.