Xinan Zhang Research AssistantLouisiana Forest Products Development Center School of Renewable Natural Resources Louisiana State University FPS 65th International Conference
Introduction Chromate Copper Arsenate (CCA)-- an inorganic waterborne wood preservative There was a rapid expansion of the use of CCA wood preservative between 1975 and 1990, as a result of high consumer acceptance of the product for decks, fences and other residential applications and industrial products such as poles, timbers and marine piling.
Introduction The US and Canadian wood preservation industry voluntarily withdraw the use of CCA treated wood for residential uses on January 1, 2004 Currently, most of the out-of-service treated wood ends up in landfills. (diffusion into soil and ground water?) It is estimated that CCA-treated wood being removed from service annually in the US would increase to 16x106 m3 by 2020 (Copper 1993).
Introduction Management of spent treated wood productsTo recycle spent CCA treated wood (1) Burning (diffusion into air ?) (2) Reuse to make composites (3) Biological detoxification (4) Chemical extraction prior to disposal or recycling
Literature Review Kartal et al. (2008) evaluated the effects of various adsorbents (activated carbon, Sugi wood charcoal) from industrial and agricultural process in removal of Cu, Cr, As from CCA treated wood by using bath extracting experiments. Kartal and Imamura (2005) found that exposing 3g CCA-treated sawdust to a 200 ml solution containing 2.5 g chitin (biopolymer) for 10 days removed 74% Cu, 62% Cr and 63% As.
Literature Review Extraction with 1% ethylenediaminetetracetic acid (EDTA) solution for 24 h of sawdust samples results in 93% Cu, 36% Cr and 38% As removal (Kartal, S. N. 2003). CCA treated wood can be decontaminated to a high degree by 10% aqueous hydrogen peroxide (H2O2) at 50℃ water bath and 6h. 95% Cr, 94% Cu, 98% As were removed. (Kazi and Cooper 2006). Clausen and Smith (1998) found that extraction with oxalic acid as a precursor to bacterial fermentation with B. licheniformis CC01 removed 90% Cu, 80% Cr and 100% As from treated chips.
Literature ReviewKazi and Cooper (2002) extracted CCA from sludge inthree stages, (1) simultaneous extraction and oxidation by aqueous sodium hypochlorite (5.25%), 2h, 100℃, R:S 100 recover 51% (2) extraction of the remaining CCA salts by phosphoric acid (2.5%) rest components were removed after 2h, 100℃ and R:S 100 (3) oxidation of phosphoric acid leachate by aqueous sodium hypochlorite (5.25%).
Objective Evaluate the effect of acid extraction microwave treatment Investigate the possibility of reusing the soaking solution Evaluation of antifungal activities of recycled soaking solution against white-rot and brown-rot fungi
Material and Method Wood particles preparation cut into smalla piece of retired utility piecespoleground in a Wiley Mill air driedThe wood particles which passed the 40-mesh sieve werecollected
Material and Method Acid preparation 1:1 acetic acid phosphoric acid 2.75% 0.75% mixed acids
Material and Method microwave extraction 1 g CCA-treated vs 20 ml acids waste wood particle microwave reactor (Milestone, Sheton, CT) treatment time temperature 20 min 145℃.
Material and Method Reuse extraction liquidsmicrowave vaccum filter the collect extraction measure thetreatment extraction liquid Ⅰ liquid Ⅰ volume made up lost volume by fresh analysis of CCAA new batch of wood mixed acids to obtain the concentrationpowder was added to cycle 2 acidscycle 2 acidsmicrowave vaccum filter the collect extraction measure thetreatment extraction liquid Ⅱ liquid Ⅱ volume made up lost volume by fresh …….. mixed acids to obtain the analysis of CCA cycle 3 acids concentration
Material and Method Determination of copper, chromium and arsenic concentrationsrinse wood residue 1 g wood residue and 15 oven driedof each cycle with ml nitric acid was mixeddeionized (DI) water in a 100 ml test tube obtain a transparent liquid, heat to a volume of 1 ml, slowly warmed andQuantitative transfer into a 25 ml maintain temperatureelemental analysis of volumetric flask and at120 ℃copper, chromium diluted into 25 mland arsenic solution with distilled water
Material and Method Evaluation of antifungal activities against white-rot ( Trametes versicolor) and brown-rot fungi (Gloeophyllum trabeum)malt extract medium-- 2% malt extract, 1.5% agar and 0.005% yeast extractextraction liquid 1--mixed into 100 ml media to make a series of solutions with different concentrations
Material and MethodWhere D2 is the diameter growth in the control dishes and D1 isdiameter growth in the experimental Petri dishes with extract liquids.The estimation of antifungal activities was carried out with repetition.
Result and discussion 1000 900 800 As Concentration (mg L-1) 700 600 Cr 500 400 Cu 300 200 100 0 1 2 3 4 5 6 7 8 9 10 11 12 CycleFig. 1. The concentration of Arsenic (As), Chromium (Cr) and Copper (Cu) in each extraction liquid of each cycle (unit: ppm)
Result and discussion 100 90 80 70Recovery rate (%) 60 50 AS Cr 40 Cu 30 20 10 0 1 2 3 4 Extraction cycle Fig. 2. The recovery rate of Arsenic (As), Chromium (Cr) and Copper (Cu) in wood residue from first 4 cycle
Result and discussionFig. 3. Antifungal effects of cycle 1 extraction liquid from different concentration (white rot fungi)
Result and discussionFig. 4. Antifungal effects of cycle 1 extraction liquid from different concentration brown rot fungi)
Result and discussion 100 90 80Anti fungal index (%) 70 60 50 TV 40 GT 30 20 10 0 1.92 2.53 2.84 3.15 3.45 3.76 4.06 4.36 4.66 4.96 5.55 6.14 7.30 9.55 11.72 Copper concentration in medium (mg L-1) Fig. 5. Plots of antifungal index (AI) versus copper concentration
Summary Acid extraction microwave treatment is a fast and effective method to remove Cu, Cr and As from CCA-treated waste wood. Soaking solution has the potential to continue remove Cu, Cr and As from CCA-treated waste wood. Soaking solution showed the antifungal activities against white-rot and brown-rot fungi.