Abstract
In present work, mesoporous silica nanoparticles (MSNs) were prepared with a surface area of 1048 m2g-1 and a large pore size of ca. 6 nm, using Stöber process in the presence of expanding reagent ( n -hexane). The surface of MSNs was modified with three different functional groups (amine, iminodiacetic acid, and glycine) and characterized by a variety of physicochemical techniques. The adsorption studies were carried out at different pH values in two extraction systems. In batch method, the maximum adsorption efficiency of heavy metals was measured to be 95% for all fabricated MSNs at pH 9. At pH 3, the adsorption efficiency of Pb and Cu was observed to be affected by the carboxylic moiety involved in the functional group. As the number of carboxylic moieties increase, the removal efficiency of Pb and Cu ions increased by two folds. The results demonstrated the selectivity of IDA-MSNs for the removal of Pb and Cu ions, even though the multielements are present in an aqueous solution. On the other hand, the incorporation of MSNs into the polymeric membrane showed high water permeability ( 9.96 ± 3 L / m 2 . h . bar ), and 98% rejection was achieved at pH 7 for Cu+2 and Pb+2 ions.
Highlights
The 2018 edition of the UN World Water Development Report stated that more than 5 billion people could experience severe water scarcity by 2050
The morphology, means diameter, and size distribution of the silica nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
The mesopores size was estimated from the Transmission electron microscopy (TEM) image to be ca. 6 nm, which is larger than those of typical mesoporous silica nanoparticles, due to the pore expanding effect of nonpolar n-hexane [15, 36]
Summary
The 2018 edition of the UN World Water Development Report stated that more than 5 billion people could experience severe water scarcity by 2050 This is due to the increased demand for water, limited water resources, and increasing pollution of water, which is caused by dramatic population and economic growth [1]. Emerging contaminants such as heavy metals (e.g., Hg, As, Pb, and Cd) in the treated wastewater is of concern for the environment and human health. The surface modification of silica nanoparticle with a suitable functional group could enhance the efficiency, sensitivity, and selectivity of the material towards hazardous heavy metal ions [13,14,15]. Thiol terminated silica surfaces showed an improvement in adsorption of Ag, Hg, Cu, Zn, and Ni ions from aqueous
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