nZVI TESTER: the measurement of nZVI content in a slurry PDF Print E-mail

nZVI TESTER is destined for the measurement of zero-valent iron nanoparticles content in a slurry. The method is based on the measurement of hydrogen volume, which is evolving during chemical reaction of zero-valent iron and an acid. This test is very simple and particularly fair minded: the volume of hydrogen is directly proportional to the amount of zero-valent iron, the amount of iron-oxides does not influence the volume of generated hydrogen, it only slows down the reaction speed.

The "Hydrogen method" was compared to Mössbauer spectroscopy and X-ray powder diffraction - please see the following chart [thanks to Prof. Radek Zbořil, Ph.D.; Regional Centre of Advanced Technologies and Materials (RCPTM)].

 

 

Reaction of nZVI and the acid (KHSO4) proceeds according to the following formula:

2KHSO4 + Fe -> FeSO4 + K2SO4 + H2

55,85 g Fe -> 22,41 dm3 H2

From previous formula it comes through, that 22,41 dm3 of hydrogen is generated by reaction of 55,85 g of iron and sufficient amount of acid (2KHSO4). The weight and the concentration of nZVI in slurry is consequently calculated from the volume of evolved hydrogen.

 

NZVI tester

 

Measurement process brief description:

1. Set-up nZVI TESTER.

2. Take a sample of slurry by syringe and apply it to the reaction bottle containing acid.

3. The weight of applied sample mslurry = weight of syringe containing sample - weight of empty syringe (after sample application).

4. Read the volume of evolved hydrogen (VH2 [ml])

5. Calculate nZVI weight: mnZVI = (55,85 • 101,325 • VH2) / [8314,3 • (273,15 + t)]

6. Calculate nZVI slurry content: cnZVI = (mnZVI ÷ mslurry) • 100

aplikace suspenze do reakční nádoby

slurry application to the reaction bottle (2)

odečet objemu vyvinutého vodíku

read the volume of evolved hydrogen (4)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EXAMPLE OF MEASUREMENT

Sample: Nanofer 25S (20% of iron nanoparticles; 80% of water+stabilizer), age: 3days

Manufacturing date: 4.5.2010 ; Measurement date: 7.5.2010

Sample weight: mslurry = 4,95g

Volume of evolved hydrogen: VH2 = 350ml

Teperature = 20°C

nZVI weight: mnZVI = (55,85 • 101,325 • 350) / [8314,3 . (273,15 + 20]= 0,81304g

nZVI in slurry content: cnZVI = (0,81304 ÷ 4,95) • 100 = 16,43%

Iron-oxides content: cFe(oxides) = 20 - 16,43 = 3,57%

Ratio cnZVI to cFe(oxides) : 82% nZVI; 18% Fe(oxides)