Colloidal nanomaterials for water quality improvement and monitoring

Abstract

Water is the most important resource for all kind forms of live. It is a vital resource distributed unequally across different regions of the globe, with populations already living with water scarcity, a situation that is spreading due to the impact of climate change. The reversal of this tendency and the mitigation of its disastrous consequences is a global challenge posed to Humanity, with the scientific community assuming a major obligation for providing solutions based on scientific knowledge. This article reviews literature concerning the development of nanomaterials for water purification technologies, including collaborative scientific research carried out in our laboratory (nanoLAB@UA) framed by the general activities carried out at the CICECO-Aveiro Institute of Materials. Our research carried out in this specific context has been mainly focused on the synthesis and surface chemical modification of nanomaterials, typically of a colloidal nature, as well as on the evaluation of the relevant properties that arise from the envisaged applications of the materials. As such, the research reviewed here has been guided along three thematic lines: 1) magnetic nanosorbents for water treatment technologies, namely by using biocomposites and graphite-like nanoplatelets; 2) nanocomposites for photocatalysis (e.g., TiO2/Fe3O4 and POM supported graphene oxide photocatalysts; photoactive membranes) and 3) nanostructured substrates for contaminant detection using surface enhanced Raman scattering (SERS), namely polymers loaded with Ag/Au colloids and magneto-plasmonic nanostructures. This research is motivated by the firm believe that these nanomaterials have potential for contributing to the solution of environmental problems and, conversely, will not be part of the problem. Therefore, assessment of the impact of nanoengineered materials on eco-systems is important and research in this area has also been developed by collaborative projects involving experts in nanotoxicity. The above topics are reviewed here by presenting a brief conceptual framework together with illustrative case studies, in some cases with original research results, mainly focusing on the chemistry of the nanomaterials investigated for target applications. Finally, near-future developments in this research area are put in perspective, forecasting realistic solutions for the application of colloidal nanoparticles in water cleaning technologies.

Recent Advances in Advanced Micro and Nanomanufacturing for Wastewater Purification

“…However, due to its low solubility and propensity to aggregate, pristine graphene poses difficulties in the treatment of wastewater. To overcome these limitations, researchers have worked on the synthesis of similar compounds, for example, graphene oxide (GO) and graphite-like nanoplatelets (GNP) . Further, graphene-based adsorbents are accompanied by several other challenges such as the production and utilization of these adsorbents in wastewater treatment may involve energy-intensive processes, influencing overall energy consumption.…”

“…To overcome these limitations, researchers have worked on the synthesis of similar compounds, for example, graphene oxide (GO) and graphite-like nanoplatelets (GNP). 98 Further, graphenebased adsorbents are accompanied by several other challenges such as the production and utilization of these adsorbents in wastewater treatment may involve energy-intensive processes, influencing overall energy consumption. Second, achieving long-term stability and durability of graphene-based adsorbents in harsh wastewater conditions poses a challenge, given the susceptibility of graphene materials to degradation over time, impacting their adsorption capacity.…”

Surface-enhanced Raman scattering detection of thiram and ciprofloxacin using chitosan–silver coated paper substrates

“…In the past few years, surface-enhanced Raman scattering (SERS) spectroscopy has been explored as a powerful tool in water quality monitoring due to its ability to detect trace levels of several contaminants, including pesticides and pharmaceuticals. [6][7][8][9][10][11] The SERS technique relies on the interaction of analyte molecules with metal surfaces, particularly those of gold and silver colloids, which greatly amplify the Raman signal, enabling the detection of low analyte concentrations. 12,13 The SERS effect is the result of the contribution of two mechanisms: the electric field enhancement due to the metal surface (electromagnetic mechanism) and the chemical interaction, namely charge transfers, of the analyte molecules with the metal surface (chemical mechanism).…”

MoS2 and MoS2 Nanocomposites for Adsorption and Photodegradation of Water Pollutants: A Review

“…Along with the advances in environmental research, in the past few years, several authors have suggested nanomaterials to enhance primary and advanced water treatment [ 9 ]. Due to its small size and, consequently, high surface and reactive areas, the use of nanomaterials enables the improvement of several properties compared to bulk material [ 9 ]. More recently, two-dimensional (2D) nanomaterials have gained importance.…”