Bentonite Functionalised with 2-(3-(2-aminoethylthio)propylthio)ethanamine (AEPE) for the Removal of Hg(II) from Wastewaters (PDF)

Inhaltsangabe:Abstract:
Mercury is a natural occurring liquid heavy metal, which refers to high-density metallic elements such as cobalt, copper, iron etc. By the decomposition of minerals in rocks, in the ground and by water and wind erosion, mercury is released to the nature. Moreover, human activities have raised the natural concentrations decisively because of large application of mercury compounds in the industry, e.g. in the chlorine-alkali manufacturing industries for the production of chlorine and sodium hydroxide by means of mercury cathodes, the paint and battery manufacturing industries and oil refinery. As a result, mercury is found in an increasing amount in the sewage of these branches of industries. This can lead to severe environmental problems if mercury is introduced into natural water sources without proper treatment.
Mercury compounds cause serious health damages. All mercury compounds are toxic for human and in particular organic mercury compounds. The major effects of mercury poisoning manifest as neurological and renal disturbances as it can easily fit the blood-brain barrier and affect the foetal brain. High concentrations of mercury cause impairment of pulmonary function and kidney, chest pain and dyspnousea. Mercury can also be accumulated in the food chain, e.g. in fish, and will be taken up with consumption, leading to poisoning. Therefore, the removal of mercury in water and wastewaters is important and necessary.
The removal of mercury by adsorption using clay minerals: Many applications are already set up for the removal of mercury out of wastewater as for example precipitation, coagulation and flocculation, solvent extraction, complexation, adsorption, filtration, membrane processes and activated carbon adsorption. However, most of these techniques have some disadvantages, which make the application sometimes problematic. To remove heavy metals by precipitation as hydroxide or sulphide compounds, the dosage necessary for sulphide precipitation is difficult to determine and the process requires a specific pH range to operate.
For coagulation and flocculation, the process is to combine colloidal particles into larger aggregates that can also adsorb dissolved organic and inorganic contaminants. The removal is facilitated by subsequent sedimentation and filtration processes. The most commonly used coagulants are aluminium or iron(III)-based salts (e.g., aluminium sulphate and ferric sulphate). However, the [...]