Reduction of nitrate by nanoscale zero-valent iron supported on mesoporous silica beads

Abstract

The use of zero-valent iron (ZVI) represents one of the latest innovative technologies for groundwater remediation. The reactivity of ZVI is enhanced when the particle size is in the nanometer range. However, nanoscale ZVI has limited field applications for in-situ groundwater remediation such as permeable reactive barriers due to its powdery form. Therefore, a method of adhering nanoparticles on a supporting material was suggested. In this paper, functionalized mesoporous silica beads were created using 3-mercaptopropyltrimethoxy silica, tetrabutyl orthosilicate, and cetyltrimethyl ammonium bromide, and their physical and chemical characteristics were measured. The highly active ZVI nanoparticles were adhered on these mesoporous silica beads. The reactivity of the resulting material was tested using nitrate solution. The reductive reaction of nitrate indicated that the degradation of nitrate appeared to be pseudofirst order with a high reaction rate constant of 0.1619 h -1 . The reaction constant decreased to 0.0122 h -1 after 3 h of experiment due to mass transfer limitation. The higher dose of the supported nanosized ZVI increased the removal rate as well as the removal efficiency of nitrate.

Archives of Environmental Protection

“…Use of zero-valent iron (ZVI) for the removal of nitrates as an alternative method to the ones mentioned previously, has been tested in recent years (Park et al 2008, Fu et al 2014, Liu et al 2019, Sun et al 2016, Makota et al 2017, Liu et al 2018, Liu P. 2016. However, most studies have been limited to the laboratory scale.…”

“…Rate end effi ciency of the method is also connected with the surface area of Fe 0 particles; nanoscale Fe 0 with higher specifi c surface area is more reactive than larger ZVI particles (Park et al 2008). The process can be slowed down by the formation of a ferrous deposit (green rust) on the surface of the iron metal.…”

Preparation and application of oyster shell supported zero valent nano scale iron for removal of natural organic matter from aqueous solutions

“…Several studies have been conducted using various materials such as mesoporous silica beads [ 25 ], carbon and titanium dioxide [ 26 ], chitosan beads [ 27 ], ceramic membranes [ 12 ], kaolin [ 28 ], and betonite [ 13 ] as a bases for nanoparticles. In southern coasts of Iran, there is a considerable amount of oyster shells which may have the potential to be used for a perfect bases for nanoadsorbents, and so far no study and information are achieved on the use of the shell as adsorbent.…”