Transcript Comparative Laboratory Leaching Test Methods to Study Post

Comparative Laboratory Leaching Test
Methods to Study Post-Treatment
Storage Period Impacts on CCA
Leachability and Fixation in Treated
Kempas (Koompassia malaccensis)
Heartwood
Andrew Wong and Lai Huat Choi
Faculty of Resource Science & Technology,
University Malaysia Sarawak (UNIMAS),
Kota Samarahan,
Sarawak, Malaysia
INTRODUCTION
CCA Preservatives
 CCA preservatives is one of the most
effective wood protecting chemical for many
years
 Environment issues of CCA components
leaching in the media - lead to restrictions
of CCA application.
 Many countries have even switched to
organic-based preservative
Laboratory leaching test studies
– some concerns
 Need to devise suitable harmonise leaching test
methods for comparison of biocide risk
assessments between labs leaching test
 But also need to have a lab leaching test that is
realistic to actual environmental exposures of
wood preservatives - trying to relate lab results to
the “real world” - the extent of rainfall and other
climatic effects between regions
 EN84 leaching test may be too severe for natural
non-aquatic exposures of treated wood
 Any prospects for a relatively milder lab leaching
test system?
Aim of Study
 Compare 3 laboratory leaching test
methods (denoted as: EN84, EN84-1 and
EN84-2, severe to mild leaching).
 Leachability of CCA in heartwood of freshly
treated Kempas (Koompassia
malaccensis).
 To determine if CCA leaching from kempas
is arrested with longer storage fixation
periods.
MATERIALS & METHODS
Wood Material Preparation
Preservative treatment and conditioning
14-days laboratory leaching tests
Elemental analysis of leachates
Data analysis
Wood Material Preparation
 Timber species:
-Kempas …permeable heartwood
(Koompassia malaccensis)
Structural-used Malaysian hardwood (roof truss,
utility poles)
 Air dried wood block samples (20 x 20 x 20
mm) cut from sawn timber
 Test blocks end-grain sealed with Nippon
paint and conditioned at 1050C, 48 hours,
and weighed oven dry (g) before CCA
treatment
Preservative Treatment & Storage Periods
 Replicated Kempas wood blocks impregnated
with Type C CCA-salt to target uptake retention
of 5.6 kg/m3
30 min
2 hr
Initial vacuum
(1 kgf/cm2)
Pressure
(14 kgf/cm2)
 Freshly treated wood stored for periods of 0 day,
2 days, 1 week, 2 weeks & 4 weeks at ambient
temperature
Laboratory Leaching Tests
Test
EN84
EN84-1
Initial Vacuum
Impregnation?
Yes (30 min)
No
Initial Dipping
in Water?
No
Yes
Leaching
Periods
Immersion in
Water
Water
Change?
EN84-2
2 weeks
24 hours
2, 24, 48, 72,
96 hr and
every 48 hr
24, 48, 72, 96
hr and every
48 hr
Only 5 hr
daily
Daily
CCA Component Analysis in Leachates
 Cu & Cr determined by FAAS
 As determined using AAS EDL Lamp
system
 Component losses expressed in µg/ml
 Cumulative leaching losses (µg/ml) for
each of Cu, Cr & As over the leaching
test duration
RESULTS
Cumulative Cu leaching (µg/ml) by 3 lab. methods
EN84
EN84-1
5
4
3
2
1
5
Cu Leaching (ppm)
Cu Leaching (ppm)
Cu Leaching (ppm)
5
EN84-2
4
3
2
1
0
0
0
50 100 150 200 250 300 350
4
3
2
1
0
0
50 100 150 200 250 300 350
Hours
Hours
Hours
4 Weeks
2 Weeks
2 Days
0 Day
0 50 100 150 200 250 300 350
1 Week
Cumulative Cr leaching (µg/ml) by 3 lab. methods
EN84-1
EN84-2
6
6
5
5
5
4
3
2
1
0
Cr Leaching (ppm)
6
Cr Leaching (ppm)
Cr Leaching (ppm)
EN84
4
3
2
1
3
2
1
0
0
0 50 100 150 200 250 300 350
4
0
50 100 150 200 250 300 350
Hours
2 Weeks
2 Days
0 Day
50 100 150 200 250 300 350
Hours
Hours
4 Weeks
0
1 Week
Cumulative As leaching (µg/ml) by 3 lab. methods
EN84-1
5
EN84-2
4
3
2
1
0
0 50 100 150 200 250 300 350
As Leaching (ppm)
5
As Leaching (ppm)
As Leaching (ppm)
EN84
4
3
2
1
0
0
50 100 150 200 250 300 350
5
4
3
2
1
0
0 50 100 150 200 250 300 350
Hours
Hours
4 Weeks
2 Weeks
2 Days
0 Day
1Week
Hours
Cumulative plot for leaching of Cu (ppm) among 3
leaching methods
0 day
2 days
1 wk
EN84
EN84-1
EN84-2
2 wk
4 wk
Cumulative plot for leaching of Cr (ppm) among 3
leaching methods
0 day
2 days
1 wk
EN84
EN84-1
EN84-2
2 wk
4 wk
Cumulative plot for leaching of As (ppm) among 3
leaching methods
0 day
2 days
1 wk
EN84
EN84-1
EN84-2
2 wk
4 wk
Table: Total Leaching (µg/ml) of CCA Components for Menggris by
EN84, EN84-1 & EN84-2 Methods
Fixation periods
Leaching
methods
4 wk
EN84
4 wk
Cu
Cr
As
-----------------(µg/ml)----------------1.1 abcde
1.6 ab
1.4 bcd
EN84-1
0.7 abc
1.7 ab
0.9 ab
4 wk
EN84-2
0.5 a
0.6 a
0.5 a
2 wk
EN84
1.5 de
2.1 b
1.8 cd
2 wk
EN84-1
0.9 abcd
1.8 ab
1.1 bc
2 wk
EN84-2
0.7 ab
0.6 a
0.5 a
1 wk
EN84
1.7 e
1.5 ab
2.0 d
1 wk
EN84-1
1.5 de
2.1 b
1.8 cd
1 wk
EN84-2
0.7 abc
0.7 a
0.5 a
2 days
EN84
1.4 bcde
1.6 ab
1.6 cd
2 days
EN84-1
1.8 e
2.0 ab
2.1 d
2 days
EN84-2
1.4 cd
1.2 ab
0.9 ab
0 day
EN84
2.6 f
3.7 c
3.1 e
0 day
EN84-1
2.4 f
4.7 cd
2.9 e
0 day
EN84-2
4.0 g
5.8 d
4.0 f
• Within- column values sharing the same letter do not differ significantly (multiple comparisons)
CONCLUSIONS
 Among the CCA components for the 3
laboratory leaching tests, the order of
leaching severity was: Cr > As > Cu.
 EN84-2 method gave expectedly milder
leaching than EN84 and EN84-1.
 No significant difference (P<0.05) in CCA
leachability between methods EN84 and
EN84-1
 Wood blocks (4 wk fixation / EN84-2
method) showed the lowest CCA
components leaching.
 Obviously, wood blocks (0 day fixation /
EN84-2 method) showed the highest CCA
components leaching.
 Overall increasing storage period improves
CCA fixation (reduces leachability) but
does not appear to completely fix CCA on
to Kempas heartwood
ACKNOWLEDGEMENT
 Unimas Fundamental Research Grant
 Unimas Postgraduate Fellowship for H.C.Lai
 Mr Nigel Lim from Sarawak Forestry
Corporation
 IUFRO SAP partial travel support donated by
Korea Forest Research Institute (FRFI)
THANK YOU!