Exploring the effects of nanoscale zero-valent iron (nZVI) on the mechanical properties of lead-contaminated clay

Nanoscale zero-valent iron (nZVI) is a well-known efficient nanomaterial for the immobilization of heavy metals and has been widely applied in the remediation of contaminated groundwater and soils. In this study, a series of field emission scanning electron microscopy (FESEM) analyses, vane shear tests, triaxial compression tests, and oedometer tests was conducted on lead-contaminated clay using four dosages of nZVI treatment (0.2%, 1%, 5%, and 10%). The geotechnical properties, including basic index properties, stiffness, shear strength, and compressibility, were assessed after the reaction procedure. FESEM analysis was performed to explore the potential mechanisms of nZVI treatment in terms of morphological characteristics. It was found that the plasticity index decreased gradually with increasing nZVI dosage. Treating contaminated soil with nZVI caused an increase in the vane shear strength, stiffness, and friction angle. The compression index increased gradually because of the nZVI treatment. Based on the FESEM analysis, a conclusion can be deduced that larger aggregates and conjoined structures resulting from nZVI treatment can lead to the strengthening of lead-contaminated clay. Key words: nanoscale zero-valent iron, lead-contaminated clay, strength enhancement, mechanical properties, compressibility. Le fer a valence zero a l'echelle nanometrique (nZVI) est un nanomateriau efficace bien connu pour l'immobilisation de metaux lourds. Il a ete largement utilise dans des activites de depollution des eaux souterraines et des sols contamines. Dans cette etude, une serie d'analyses en microscopie electronique a balayage a emission de champ (FESEM), d'essais de cisaillement des aubes, d'essais de compression triaxiale et d'essais redometriques ont ete effectues sur de l'argile contaminee au plomb a l'aide de quatre doses de traitement par nZVI (0,2,1, 5 et 10%). Les proprietes geotechniques, y compris les proprietes d'indice de base, la rigidite, la resistance au cisaillement et la compressibilite ont ete evaluees apres la procedure de reaction. Une analyse FESEM a ete realisee pour explorer les mecanismes potentiels du traitement nZVI quant aux caracteristiques morphologiques. Il a ete constate que l'indice de plasticite diminuait progressivement avec l'augmentation de la dose de nZVI. Le traitement du sol contamine avec du nZVI a entrame une augmentation de la resistance au cisaillement, de la rigidite et de l'angle de friction de l'aube. L'indice de compression a augmente progressivement a cause du traitement nZVI. Sur la base de l'analyse FESEM, on peut deduire que de plus grands agregats et des structures jointes resultant du traitement au nZVI sont en mesure d'assurer le renforcement de l'argile contaminee au plomb. [Traduit par la Redaction] Mots-cles: fer nanometrique a valence zero, argile contaminee au plomb, renforcement de la resistance, proprietes mecaniques, compressibilite.
Introduction Some heavy metals are toxic even at low concentrations, and their toxicity increases as they accumulate in water and soils (Gulson et al. 2012; Qiu et al. 2016; Ren [...]