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Andrew Wong and Lai Huat Choi

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),

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Andrew Wong and Lai Huat Choi

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  1. 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

  2. INTRODUCTION

  3. 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

  4. 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?

  5. 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.

  6. MATERIALS & METHODS

  7. Wood Material Preparation Preservative treatment and conditioning 14-days laboratory leaching tests Elemental analysis of leachates Data analysis

  8. 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

  9. Preservative Treatment & Storage Periods • Replicated Kempas wood blocks impregnated with Type C CCA-salt to target uptake retention of 5.6 kg/m3 • Freshly treated wood stored for periods of 0 day, 2 days, 1 week, 2 weeks & 4 weeks at ambient temperature 30 min 2 hr Initial vacuum (1 kgf/cm2) Pressure (14 kgf/cm2)

  10. Laboratory Leaching Tests

  11. 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

  12. RESULTS

  13. Cumulative Cu leaching (µg/ml) by 3 lab. methods EN84 EN84-1 EN84-2

  14. Cumulative Cr leaching (µg/ml) by 3 lab. methods EN84 EN84-1 EN84-2

  15. Cumulative As leaching (µg/ml) by 3 lab. methods EN84 EN84-1 EN84-2

  16. 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

  17. 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

  18. 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

  19. Table: Total Leaching (µg/ml) of CCA Components for Menggris by EN84, EN84-1 & EN84-2 Methods • Within- column values sharing the same letter do not differ significantly (multiple comparisons)

  20. CONCLUSIONS

  21. 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

  22. 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

  23. 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)

  24. THANK YOU!

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