In recent years, the removal of chemical contaminants from water continues to be a central issue in environmental remediation. Chemical industries have focused on sustainable development approaches, promoting materials that offer performance at lower cost and significantly reducing environmental impact. Silica-based mesoporous materials have been synthesized and extensively studied for various applications, as they possess attractive characteristics such as high specific surface area, large pore size, and chemical inertness[1]. A promising innovative sol-gel-derived organosilica material for pollutant adsorption is represented by Swellable Organic Modified Silica (SOMS), whose structure allows for an expansion of three to five times its volume in the presence of organic compounds, thus enabling their adsorption[2]. SOMS silicas do not expand in water, making it a useful absorbent for wastewater treatment because volume increase occurs only when organic molecules are absorbed[3]. SOMS are synthesized by polycondensation of bis-(trimethoxysilylethyl) benzene using tetrabutylammonium fluoride as a catalyst. The methoxysilane groups react to form Si-O-Si bonds forming a network with bridging aryl groups to produce a porous and mechanically flexible matrix. Subsequently, to achieve swelling, the residual silanols on the surface are chemically modified with a chlorosilane to prevent condensation reactions during gel drying. In this work, SOMS silicas were synthesized and then tested as an adsorbent of organic pollutants from the aqueous phase. The physico-chemical properties of SOMS were determined using various experimental techniques. The ability of silica to remove a model organic pollutant (Rhodamine B) from an aqueous solution was evaluated by UV-Vis spectroscopy [4]. Adsorption tests were performed, both using the powder as it is, and after swelling with different organic solvents (acetone, acetonitrile and ethanol). The reference material is able to remove 42% of Rhodamine B after 24 hours of contact, while SOMS swelled with Acetone, Ethanol, or Acetonitrile is able to remove 100% of the pollutant concentration in solution. Specifically, after only 15 minutes of contact there is a removal of Rhodamine B concentration of 64% for SOMS swelled with acetonitrile, 70% for SOMS swelled with ethanol, and 98% for SOMS swelled with acetone. The adsorption of hybrid materials will be compared with that of different mesoporous silicas (i.e. MCM-41, SBA-15 and silica monoliths).
Swellable Organic Modified Silica for the Removal of Pollutants from Aqueous Phases
Miglio V.;Maccarino L.;Marchese L.;Bisio C.
2022-01-01
Abstract
In recent years, the removal of chemical contaminants from water continues to be a central issue in environmental remediation. Chemical industries have focused on sustainable development approaches, promoting materials that offer performance at lower cost and significantly reducing environmental impact. Silica-based mesoporous materials have been synthesized and extensively studied for various applications, as they possess attractive characteristics such as high specific surface area, large pore size, and chemical inertness[1]. A promising innovative sol-gel-derived organosilica material for pollutant adsorption is represented by Swellable Organic Modified Silica (SOMS), whose structure allows for an expansion of three to five times its volume in the presence of organic compounds, thus enabling their adsorption[2]. SOMS silicas do not expand in water, making it a useful absorbent for wastewater treatment because volume increase occurs only when organic molecules are absorbed[3]. SOMS are synthesized by polycondensation of bis-(trimethoxysilylethyl) benzene using tetrabutylammonium fluoride as a catalyst. The methoxysilane groups react to form Si-O-Si bonds forming a network with bridging aryl groups to produce a porous and mechanically flexible matrix. Subsequently, to achieve swelling, the residual silanols on the surface are chemically modified with a chlorosilane to prevent condensation reactions during gel drying. In this work, SOMS silicas were synthesized and then tested as an adsorbent of organic pollutants from the aqueous phase. The physico-chemical properties of SOMS were determined using various experimental techniques. The ability of silica to remove a model organic pollutant (Rhodamine B) from an aqueous solution was evaluated by UV-Vis spectroscopy [4]. Adsorption tests were performed, both using the powder as it is, and after swelling with different organic solvents (acetone, acetonitrile and ethanol). The reference material is able to remove 42% of Rhodamine B after 24 hours of contact, while SOMS swelled with Acetone, Ethanol, or Acetonitrile is able to remove 100% of the pollutant concentration in solution. Specifically, after only 15 minutes of contact there is a removal of Rhodamine B concentration of 64% for SOMS swelled with acetonitrile, 70% for SOMS swelled with ethanol, and 98% for SOMS swelled with acetone. The adsorption of hybrid materials will be compared with that of different mesoporous silicas (i.e. MCM-41, SBA-15 and silica monoliths).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
