Analytical characterisation of nanoscale zero-valent iron: A methodological review

Abstract

Zero-valent iron nanoparticles (nZVI) have been widely tested as they are showing significant promise for environmental remediation. However, many recent studies have demonstrated that their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Both the mobility and reactivity of nZVI mainly depends on properties such as particle size, surface chemistry and bulk composition. In order to ensure efficient remediation, it is crucial to accurately assess and understand the implications of these properties before deploying these materials into contaminated environments. Many analytical techniques are now available to determine these parameters and this paper provides a critical review of their usefulness and limitations for nZVI characterisation. These analytical techniques include microscopy and light scattering techniques for the determination of particle size, size distribution and aggregation state, and X-ray techniques for the characterisation of surface chemistry and bulk composition. Example characterisation data derived from commercial nZVI materials is used to further illustrate method strengths and limitations. Finally, some important challenges with respect to the characterisation of nZVI in groundwater samples are discussed.

Simultaneous determination of arsenic and cadmium by hydride generation atomic fluorescence spectrometry using magnetic zero-valent iron nanoparticles for separation and pre-concentration

“…Therefore, nZVI has emerged as an alternative for the treatment of heavy metals like Pb, Cr, Cu in recent years [23]. However, the majority of them was aimed at single element, it is still a great challenge to simultaneously pre-concentrate and separate As and Cd with nZVI [24].…”

APLICAÇÃO DE NANOPARTÍCULAS DE FERRO ZERO-VALENTE (nFeZ) NA REMEDIAÇÃO DE SOLOS E ÁGUAS SUBTERRÂNEAS CONTAMINADAS: UMA REVISÃO

“…Isso também é destacado por Chekli et al 11 tendo em vista que em muitos estudos a mobilidade e reatividade do nFeZ em ambientes subsuperficiais pode ser afetada, pois dependem principalmente de propriedades tais como tamanho de partícula, composição química da superfície e composição em massa. Desse modo, a remediação eficaz deve aliar a avaliação precisa das variáveis envolvidas, compreendendo as implicações dessas propriedades antes de implantar esse nanomaterial em áreas contaminadas.…”

“…13 A compreensão do potencial de remediação ambiental do nFeZ não pode se limitar a experimentos laboratoriais, mas incluir estudos piloto e de campo. 11 Análise da toxicidade do nFeZ em micro-organismos foram realizados em escala de bancada, mostrando que a nanopartícula tem um alto potencial biocida quando usado sem estabilizante. No entanto, após o nFeZ tornar-se oxidado, sua influência sobre os micro-organismos se inverte, tornando-o um excelente estimulante da atividade microbiológica pela biodisponibilidade do ferro oxidado.…”

“…9 Há evidências comprovadas sobre a efetividade e eficácia da aplicação da nanotecnologia em processos de remediação de solos e águas subterrâneas contaminadas por metais pesados, contaminantes inorgânicos, orgânicos e emergentes, sendo que se tem observado o uso predominante de nanopartículas à base de ferro. 10,11 As nanopartículas de ferro na valência zero (nFeZ) agem como agentes redutores de compostos orgânicos e inorgânicos. 12 Essas partículas podem variar de 10 a 100 nm de diâmetro, permitindo um maior acesso aos contaminantes.…”

Polydimethylsiloxane as a Matrix for the Stabilization and Immobilization of Zero‑Valent Iron Nanoparticles. Applications to Dehalogenation of Environmentally Deleterious Molecules

“…Also, some nanotechnologies for water treatment are promising as efficient 'remediators' because of the high surface/volume ratios intrinsic to nanomaterials. 14 In that regard, zero-valent iron nanoparticles (nFe 0 ) are useful for the dehalogenation of HOCs; [15][16][17] they are highly reactive toward halogenated molecules and low in cost. 14,18 However, they react rapidly as well with oxygen in the air or dissolved in a liquid, 19 leading to iron oxides which are less efficient as dehalogenation agents.…”