A comparative study of the degradation efficiency of chlorinated organic compounds by bimetallic zero-valent iron nanoparticles

Abstract

Various bimetallic nZVI were used in the degradation of chlorinated volatile organic compounds (CVOC) in spiked water and real groundwater. It was found that Ni may be a good alternative to Pd to be used along with nZVI for dechlorination of CVOC.

Synthesis and Characterization of Zero-Valent Fe-Cu and Fe-Ni Bimetals for the Dehalogenation of Trichloroethylene Vapors

“…To improve ZVI reactivity, transition metals with a redox potential higher than iron have been used as catalysts for dechlorination through the enhancement of iron corrosion or hydrogenation [2,5,12,14]. Among transition metals, the most studied as cata-lysts for the degradation of chlorinated compounds induced by iron were palladium (Pd) [2,3,[15][16][17][18][19], nickel (Ni) [2,15,17,18,[20][21][22][23][24][25][26], and copper (Cu) [2,5,12,15,17,18,20]. To a lower extent, ruthenium (Ru) [3], silver (Ag) [3,15,18], cobalt (Co) [17], zinc (Zn) [27,28], and platinum (Pt) [3,17] were also tested.…”

“…Among transition metals, the most studied as cata-lysts for the degradation of chlorinated compounds induced by iron were palladium (Pd) [2,3,[15][16][17][18][19], nickel (Ni) [2,15,17,18,[20][21][22][23][24][25][26], and copper (Cu) [2,5,12,15,17,18,20]. To a lower extent, ruthenium (Ru) [3], silver (Ag) [3,15,18], cobalt (Co) [17], zinc (Zn) [27,28], and platinum (Pt) [3,17] were also tested. In general, adding these metals to iron creates a galvanic cell [15,23].…”

“…To a lower extent, ruthenium (Ru) [3], silver (Ag) [3,15,18], cobalt (Co) [17], zinc (Zn) [27,28], and platinum (Pt) [3,17] were also tested. In general, adding these metals to iron creates a galvanic cell [15,23]. In these conditions, greater corrosion of ZVI occurs with a consequent increase in the release of electrons necessary for the reduction of chlorinated contaminants [5,29].…”

“…In contrast, with the use of Ni, the dissociation of H 2 and hydrogenation occur predominantly. In addition, these effects are prevalent compared with the electron transfer for the enhancement of dechlorination as the presence of atomic hydrogen allows the breakage of the Cl-C bond replacing chlorine, which is released as a gas [15,24,29,35]. Indeed, Kim and Carraway, [2] and Venkateshaiah et al [15] obtained different performances in the removal of TCE in the aqueous phase depending on the secondary metal used in combination with iron for the different effects that secondary metals induced on dechlorination, obtaining better performance using Pd and Ni compared with Cu.…”

“…Among the chemical methods, the most commonly used is chemical solution deposition (CSD), in which a redox reaction takes place between iron and a secondary metal, where the latter is added as chloride or sulfate [2,5,36,37]. With the use of this technique, a bimetal is synthesized by spontaneous adsorption and deposition of the secondary metal on the iron particles, resulting in surface coverage of the primary metal particles [3,15,24,30,37,38]. The structure of this bimetal (i.e., core-shell) guarantees a lower oxidation of iron, which constitutes the core, due to the surface coating of the secondary metal that acts as a protection for the formation of iron oxides and as a catalyst for electrons release by the ferrous core during dehalogenation reactions [25].…”