Use of nanomaterials in the pretreatment of water samples for environmental analysis

The challenge of providing clean drinking water is of enormous relevance in today’s human civilization, being essential for human consumption, but also for agriculture, livestock and several industrial applications. In addition to remediation strategies, the accurate monitoring of pollutants in water sup-plies, which most of the times are present at low concentrations, is a critical challenge. The usual low concentration of target analytes, the presence of in-terferents and the incompatibility of the sample matrix with instrumental techniques and detectors are the main reasons that renders sample preparation a relevant part of environmental monitoring strategies. The discovery and ap-plication of new nanomaterials allowed improvements on the pretreatment of water samples, with benefits in terms of speed, reliability and sensitivity in analysis. In this chapter, the use of nanomaterials in solid-phase extraction (SPE) protocols for water samples pretreatment for environmental monitoring is addressed. The most used nanomaterials, including metallic nanoparticles, metal organic frameworks, molecularly imprinted polymers, carbon-based nanomaterials, silica-based nanoparticles and nanocomposites are described, and their applications and advantages overviewed. Main gaps are identified and new directions on the field are suggested.publishe

Efficient dual-function inhibitors for prevention of gas hydrate formation and CO2/H2S corrosion inside oil and gas pipelines

In this study, an effective hybrid inhibition of gas hydrates and corrosion was investigated to overcome compatibility problems between inhibitors and reduce the cost of production and transportation operations in the oil and gas industry. The newly synthesized waterborne polyurethanes (WPUs) were appraised as efficient dual-purpose gas hydrate and corrosion inhibitors through experimental and computational approaches. The onset temperatures of C1/C3 hydrates in the presence of WPUs were measured using a high-pressure autoclave to evaluate the performance of WPUs as gas hydrate inhibitors. The potential of WPUs as anti-agglomerants and the rheological behaviors of C1/C3 hydrates in the presence of WPUs were investigated using a high-pressure rheometer. All WPUs (WPU1, WPU2, WPU3, WPU4, and WPU5) were found to function as hydrate inhibitors and contribute to the prevention of agglomeration for C1/C3 hydrates. Molecular dynamics simulations revealed that the long-chained anionic parts of WPUs were adsorbed onto the hydrate surface while small cationic parts moved freely in the solution; thus, the interaction between the anions and water molecules was a dominant factor for C1/C3 hydrate inhibition. The corrosion inhibition activity of WPUs was evaluated by open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques in H2S and CO2-saturated oilfield-produced water. The electrochemical measurements indicated that WPUs improved the polarization resistance of mild steel and significantly protected its surface against corrosive gases. The experimental and computational results indicated that WPUs can be used as efficient dual-function inhibitors for prevention of gas hydrate formation and CO2/H2S corrosion inside oil and gas pipelines, and also have potential as antiagglomerant hydrate inhibitors