Contaminants Of Chromium

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and is even considered an essential micronutrient for humans and animals. Cr(VI) has several common industrial uses, including in manufacturing and electroplating, and it is often released into the environment due to spills associated with these industries [6]. Once in the environment, it becomes a contaminant in both groundwater and soil.
The fate of chromium in the environment is controlled by a variety of processes and mechanisms, including redox conversions, precipitation, dissolution, and adsorption reactions. 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 [1]. 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. These reactions play an important role in determining the fate of chromium in natural systems. They affect whether the contaminant will enter into the ground or surface water or remain in the soil, thus influencing mobility and transport, as well as the concentration at which the contaminant will be present. Hydrous oxides of Al and Fe are often used as adsorbents in such reactions, as they are common in the natural envi...

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...atively charged sites increases and number of positively charged sites decreases. A negatively charged surface site on these adsorbents does not favor the adsorption of Cr (VI) [4].

The results of this study provide a spectroscopic characterization of Ferrihydrite substituted on Al and Cr (VI) adsorption in different pHs. The results concluded when pH increased, Cr (VI) adsorption decreased. Adsorption was not affected by pH in acid (4 - 7) but decreased when pH sifted to alkaline (8-10) conditions. This happen because Cr as an anionic nature is adsorbed by Fe but Al substitution helps to reduce Cr adsorption. When pH increases, the negative charge increase and cation charge on the surface decreases which impact on the adsorption of Cr (VI). This investigation can be useful to do an adsorption modeling to prevent Cr (VI) pollution in the environment.
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