E53 Determining the moisture content of wood by - - PowerPoint PPT Presentation

E53

Determining the moisture content of wood by free-induction-decay (FID NMR) signal

Maks Merela*, Igor Serša, Urša Mikac and Primož Oven

MOISTURE DETERMINATION

methods methods

• Determination by oven dry method (SIST EN 13183-1:2003)

E i i b l i l i h d

• Estimation by electrical resistance method (SIST EN 13183-

2:2003)

• Estimation by capacitance method (EN 13183-3:2005)

y p

( )

• Standard Test Method for Moisture in Wool by Distillation

With Toluene (ASTM D2462 - 90(2008)

• Using the Karl Fischer titration method (the Reaction of

Iodine with Water) (ASTM D6869 – 03)

• Measurement of MC in wood with a CT scanner

Measurement of MC in wood with a CT scanner

• Optimal Signal Conditioning in the NIR Moisture Meter
• Neutron Imaging MC determination

g g

• Method and apparatus for colorimetric analysis (US Patent

4005983)

d

• and …
• Nuclear Magnetic Resonance MC determination

NMR BACKGROUND NMR BACKGROUND

• at magnetic resonance method we operate with

ti ti f t hi h l i h magnetic properties of atoms which nuclei have magnetic dipole (hydrogen atom)

• method detects different concentrations of

h d t hydrogen atoms VERY CONVINIANT FOR WATER DETECTION

Because of its heterogeneous structure and moisture content WOOD is a very appropriate material for NMR studies

NMR EQUIPEMENT

• magnetic field: 2,35 T

SAMPLE PREPARATION

• FID signal:
• FID signal:
• detection in 15 sec.

and weighting of a sample

• and weighting of a sample

sample in RF coil

OVEN DRY METHOD MC in wood is defined as: ti b t th f t ( ) i th l ratio between the mass of water (mw) in the sample and mass of oven dry sample (m0):

[ ]

% 100 m 100 m m MC

w g

⋅ = ⋅ − =

[ ]

% 100 m 100 m MC ⋅ = ⋅ =

RESULTS

NMR FID signal vs. mass of water

30.000

NMR FID = 100137 * mass of water + 452,84 R2 = 0,9982

25.000 30.000 20.000

gnal

15.000

R FID sig

10.000

NMR

5.000 0,05 0,1 0,15 0,2 0,25

mass of water (g)

• NMR FID signal is linear proportional to mass of water
• NMR FID signal is not dependant on tree species

Linear relation between FID and mass of water:

84 , 452 m 137 100 FID NMR

w +

⋅ =

84 452 FID NMR

mw for our experimental setup can be expressed as:

137 100 84 , 452 FID NMR mw − = 137 100

m m m

• g

w

m m m − =

⎟ ⎟ ⎞ ⎜ ⎜ ⎛ − − = 84 , 452 FID NMR m m

from FID signal we get m without

⎟ ⎟ ⎠ ⎜ ⎜ ⎝ = 137 100 m m

g

we get m0 without

• ven drying

[ ]

% 100 ⋅ = m MC

w

OVEN DRY METHOD EQ

[ ]

m

METHOD EQ.

137 100 84 , 452 FID NMR mw − =

⎟ ⎞ ⎜ ⎛ − 84 , 452 FID NMR ⎟ ⎟ ⎠ ⎜ ⎜ ⎝ − = 137 100 , m m

g

FINAL RESULT IS:

[ ]

% 100 84 , 452 FID NMR 84 , 452 FID NMR MC NMR ⋅ ⎥ ⎤ ⎢ ⎡ ⎟ ⎞ ⎜ ⎛ − − = 137 100 84 , 452 FID NMR m 137 100

g

⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅

RESULTS

Oven dry method vs. NMR MC determination

140% 120%

R2 = 0,996

100% 60% 80%

• Grav. MC

40% 20% 0% 0% 20% 40% 60% 80% 100% 120% 140% NMR MC

experimental data of samples (different wood species and size) excellent agreement between both methods (R2 = 0,9961).

CONCLUSIONS:

☺NMR b d th d bl t d i l ☺NMR based method enables accurate and simple moisture content determination ☺ th d b i ll d f NMR t ☺method can be universally used for any NMR setup ☺once the system is calibrated, MC of any sample, not l f d b d t i d f it FID

• nly of wood, can be determined from its FID

amplitude and its weight ☺ th d ld th f b d f l b t d ☺method could therefore be used for laboratory and industrial purposes to obtain MC quickly and t l t th it f th accurately at the site of the use Di d t Disadvantages:

• method can be used only for small samples

i f th i t

• price of the equipment

3D MR SCANING OF A LIVING BRANCH

RESULTS

MR IMAGING AND MC DISTRIBUTION DETERMINATION

K OAK

li h i light microscopy 2D MR image MC surface plot

ECH BEE

MOISTURE GRADIENT DETERMINATION

REZULTATI 300

Beech (88 %)

%)

150 200 250

• st (%)

content (%

50 100 150 vlažno

Moisture c

1 2 3 4 5 premer vejice (mm)

Branch diameter (mm) M

250 300

Oak (91 %)

%)

150 200 ažnost (%)

content (%

50 100 vla

Moisture c

1 2 3 4 5 6 7 premer vejice (mm)

Branch diameter (mm) M