Adsorption Properties of Magnetic Sorbent Mn_0.25Fe_2.75O₄@SiO₂ for Mercury Removal

Abstract

<jats:p>Mercury pollution through water causes several dangerous diseases. Various efforts have been made to reduce mercury pollution. One of them is by using sorbent. Many ways to improve absorption efficiency, one of which is using magnetic sorbents. This study focused on the effect of grain size and the concentration of Mn<jats:sub>0.25</jats:sub>Fe<jats:sub>2.75</jats:sub>O<jats:sub>4</jats:sub>@SiO<jats:sub>2</jats:sub> core-shell on mercury absorption efficiency. The synthesis of Mn<jats:sub>0.25</jats:sub>Fe<jats:sub>2.75</jats:sub>O<jats:sub>4</jats:sub>@SiO<jats:sub>2</jats:sub> with 6 and 8 mL of TEOS was carried out through coprecipitation and sol-gel methods. The characterization using XRD, VSM, and FTIR was conducted to determine grain size, properties, and material functional groups proving that SiO<jats:sub>2</jats:sub> was successfully covered on the Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> surface. The percentage of absorption was found by using the AAS instrument. Diffraction data confirmed the presence of Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub> and the amorphous SiO<jats:sub>2</jats:sub> phase. According to the Rietveld analysis of all samples demonstrated the particle size of Mn<jats:sub>0.25</jats:sub>Fe<jats:sub>2.75</jats:sub>O<jats:sub>4 </jats:sub>around 11-12 nm. The Mn<jats:sub>0.25</jats:sub>Fe<jats:sub>2.75</jats:sub>O<jats:sub>4</jats:sub> core had superparamagnetic properties for magnetic separation, and the SiO<jats:sub>2</jats:sub> shell could protect the core of being oxidized or dissolved under acid condition. FTIR results showed the sample had a functional group of the main components of Fe-O and SiO<jats:sub>2</jats:sub> at a wavenumber of 420-507 cm<jats:sup>-1</jats:sup> and 801 cm<jats:sup>-1</jats:sup> (stretching) and 1078 cm<jats:sup>-1</jats:sup> (bending), respectively. The results of the mercury absorption test indicated that the smaller the grain size and the higher the concentration of TEOS, the percentage of mercury uptake would increase. In addition, the absorption percentage increased with the duration of absorption time given.</jats:p>

Testing of Natural Sorbents for the Assessment of Heavy Metal Ions’ Adsorption

“…Natural sorbents are interesting due to their low cost, efficiency and availability of large reserves. They have the functional ability to act not only as sorbents, but also as ameliorants [13][14][15].…”

Preparation of Poly(acrylic acid-acrylamide/starch) Composite and Its Adsorption Properties for Mercury (II)

“…Mercury (II) ions in the environment mainly come from chlor alkali, battery manufacturing, chemical fertilizer, paper making, plastics, refining and paint industries [14,15]. The methods of mercury removal in water include chemical precipitation, coagulation, ion exchange, membrane filtration and adsorption [16,17]. Since most adsorption processes are exothermic and spontaneous.…”