Abstract
The paper is devoted to the development of a method for obtaining and using iron-containing sorption materials for the effective removal of arsenic compounds of different oxidation states from an aqueous medium. It is known that arsenic compounds have a harmful effect on biota due to high toxicity. The paper theoretically and experimentally substantiates the choice of iron-containing materials as the main sorbent material for arsenic compounds removal from the aqueous medium. A series of iron-containing adsorbents, including powder, activated carbon-based granular and suspension sorbents, was synthesized by different methods (heterogeneous and homogeneous precipitation). Experimental studies have confirmed that the adsorption of arsenate ions on iron-containing sorption materials corresponds to the pseudo-second order of the reaction (R2=0.999), which is inherent in adsorption processes. It was determined that oxyhydroxide sorption materials obtained by the homogeneous precipitation demonstrate higher sorption activity (up to 70 mg/g for As(III) and over 70 mg/g for As(V)). It was found that activated carbon-based iron-containing sorption materials showed approximately 2 times lower efficiency than powder iron(III) oxide, iron(III) oxyhydroxide and amorphous iron(III) hydroxide. It was shown that the use of microfiltration membranes is promising for the removal of spent suspension iron-containing sorption materials. Experimental studies have confirmed that the use of the combination “fine-particle iron(III) oxyhydroxide/membrane” allows removing arsenic compounds from contaminated water to the sanitary requirements level (less than 10 μg As/l) and separating effectively the spent fine-particle sorbent from water
Highlights
Arsenic-containing compounds have a harmful effect on living organisms due to high toxicity
It is shown that powder sorbents based on iron-containing materials are effective in relation to arsenate ions, while iron(III) oxyhydroxide is the most active in removing arsenic compounds from water
It was determined that the kinetics of adsorption of arsenate ions on iron(III) oxides, iron(III) oxyhydroxides, and iron(III) hydroxides is described by the pseudo-second-order model
Summary
Arsenic-containing compounds have a harmful effect on living organisms due to high toxicity. Long-term intake of arsenic-containing compounds with drinking water can lead to cancer of the blood, liver, lungs, skin and many other organs. The increased arsenic content in artesian waters of Central Europe in the Carpathian Mountains region is due to the leaching of arsenic-containing rocks cropped up from deep layers and can reach several thousand μg/l[3]. Such arsenic-containing natural waters are found in the central and eastern regions of Europe, since deposits of coal, iron ores and non-ferrous metal ores are often accompanied by the presence of arsenic-containing rocks [4]. The development of methods for highly efficient removal of As(V) and As(III) compounds from water, including in the presence of humates, is relevant for many countries
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