Improvements in nanoscale zero-valent iron production by milling through the addition of alumina

Abstract

A new milling procedure for a cost-effective production of nanoscale zero-valent iron for environmental remediation is presented. Conventional ball milling of iron in an organic solvent as Mono Ethylene Glycol produces flattened iron particles that are unlikely to break even after very long milling times. With the aim of breaking down these iron flakes, in this new procedure, further milling is carried out by adding an amount of fine alumina powder to the previously milled solution. As the amount of added alumina increases from 9 to 54 g l-1, a progressive decrease of the presence of flakes is observed. In the latter case, the appearance of the particles formed by fragments of former flakes is rather homogeneous, with most of the final nanoparticles having an equivalent diameter well below 1 µm and with an average particle size in solution of around 400 nm. An additional increase of alumina content results in a highly viscous solution showing worse particle size distribution. Milled particles, in the case of alumina concentrations of 54 g l-1, have a fairly large specific surface area and high Fe(0) content. These new particles show a very good Cr(VI) removal efficiency compared with other commercial products available. This good reactivity is related to the absence of an oxide layer, the large amount of superficial irregularities generated by the repetitive fracture process during milling and the presence of a fine nanostructure within the iron nanoparticles.Peer ReviewedPreprin

Improvement of Phosphate Adsorption Kinetics onto Ferric Hydroxide by Size Reduction

“…Top-down methods such as high energy ball milling are very effective alternatives that have been used for size reduction other water treatment materials such as nano-zero valent iron [27,28] and calcite [29]. Ultra-sonication is another top-down size reduction method able to produce microparticles and nanoparticles directly from some soft bulk material as hematitic/goethitic iron ore fines [30], talc [31], or TiO 2 [32].…”

High reactive nano zero-valent iron produced via wet milling through abrasion by alumina

“…Here, the iron particles were deformed and flattened, producing very thin flakes. In the second step, with the introduction of alumina in the milling, the flakes were broken and smaller iron particles were obtained [25]. The initial iron powder was Carbonyl Iron Powder (CIP-SM, BASF), having an iron content of >99%, a carbon content of ≤ 0.1%, and a narrow size distribution with a d 50 =2.34 µm (BASF SE).…”

“…1. In this figure, the results from [25] have been included, since here, medium-carbon steel shots (0.80-1.20% wt.% C) (Ref. S660, Pometon) of 2 mm diameter were used as grinding media.…”

“…In order to break the iron flakes during the milling of pure iron in a protective organic solvent such as Mono Ethylene Glycol (MEG), a novel milling technique was presented in a previous publication [25]. In this case, instead of using a very high milling speed [21], the technique consisted of introducing an abrasive material such as fine alumina powder during the milling process.…”

Different effects of nano-scale and micro-scale zero-valent iron particles on planktonic microorganisms from natural reservoir water

“…The nZVI particles had a mean diameter of 160 nm, a maximum size of 540 nm (determined by scanning electron microscopy [SEM]), a specific surface area of 29.6 m 2 g −1 and contained 74.0% Fe(0), 2.7% carbon and 23.3% of iron oxide. 45 The mZVI reactive powder (no: 72052910) was provided by Hepure Technologies (USA) and had a specific surface area of 0.487 m 2 g −1 , 95% Fe(0), 1.8% carbon, <1% oxygen, 1% silicon, 0.1% phosphorus and 1% sulphur. A 10 g L −1 stock suspension of ZVI in deionised water was freshly prepared before the experiment.…”