Abstract
Heavy metals are common inorganic pollutants found in the environment that have to be removed from wastewaters and drinking waters. In this work, silica-derived aerogels and xerogels were modified via a co-precursor method to obtain functional adsorbents for metal cations. A total of six formulations based upon four different functional precursors were prepared. The materials′ structural characterization revealed a decreased porosity and surface area on modified samples, more prominent in xerogel counterparts. Preliminary tests were conducted, and the prepared samples were also compared to activated carbon. Three samples were selected for in-depth studies. Isotherm studies revealed that the pre-selected samples remove well copper, lead, cadmium and nickel, and with similar types of interactions, following a Langmuir trend. The adsorption kinetics starts very fast and either equilibrium is reached quickly or slowly, in a two-stage process attributed to the existence of different types of active sites. Based on the previous tests, the best sample, prepared by mixing different functional co-precursors, was selected and its behavior was studied under different temperatures. For this material, the adsorption performance at 20 °C is dependent on the cation, ranging from 56 mg·g−1 for copper to 172 mg·g−1 for lead.
Highlights
Since their conception in 1931 by Kistler, aerogels have gained growing interest from the scientific community due to their unique outstanding properties [1,2,3]
We focus on the synthesis of silica-based aerogels and xerogels modified with those functional groups [29,30,31]
We focus on the synthesis of silica-based aerogels and xerogels modified with material
Summary
Since their conception in 1931 by Kistler, aerogels have gained growing interest from the scientific community due to their unique outstanding properties [1,2,3]. As a result, their production methods as well as their fields of application have been diversified [1,4,5]. For example, in carbon dioxide capture and removal of organic compounds and heavy metals [3,6,7,8,9,10,11]. Different materials [14], including aerogels (silica-based, carbon, organic, other inorganic types and composites thereof) have been studied as heavy metal adsorbents by several authors [6,7,8,9,15,16,17,18,19]
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