Fractionation of heavy metals in liquefied chromated copper arsenate 9-treated wood sludge using a modified BCR-sequential extraction procedure.
Chromated copper arsenate (CCA)-treated wood was liquefied with polyethylene glycol/glycerin and sulfuric acid. After liquefaction, most CCA metals (98% As, 92% Cr, and 83% Cu) were removed from liquefied CCA-treated wood by precipitation with calcium hydroxide. The original CCA-treated wood and liquefied CCA-treated wood sludge were fractionated by a modified Community Bureau of Reference (BCR) sequential extraction procedure. The purpose of the BCR-sequential extraction used in this study was to examine the availability of CCA metals in treated wood for reuse. Both As and Cr had a slightly higher concentration in the sludge sample than in original CCA-treated wood. The sequential extraction showed that As and Cr were principally existed in an oxidizable fraction (As, 67%; Cr, 88%) in original CCA-treated wood. Only 1% of both As and Cr were extracted by hot nitric acid with the last extraction step. The distribution of As and Cr changed markedly in liquefied CCA-treated wood sludge. The amount of As in the exchangeable/acid extractable fraction increased from 16% to 85% while the amount of Cr increased from 3% to 54%. Only about 3% of As was present in the oxidizable fraction. However, there was still about 34% of Cr in the same fraction. Based on these results from sequential extraction procedures, it can be concluded that the accessibilities of CCA metals increase markedly by the liquefaction-precipitation process.
Pan
Hui
H
Louisiana State University Agricultural Center, Calhoun, 71225, United States. hpan@agcenter.lsu.edu
Hse
Chung-Yun
CY
Gambrell
Robert
R
Shupe
Todd F
TF
D001149:Arsenates / Q000737:chemistry*; D002126:Calcium Hydroxide / Q000737:chemistry; D002384:Catalysis; D052918:Environmental Restoration and Remediation; D019216:Metals, Heavy / Q000737:chemistry* / Q000302:isolation & purification; D011092:Polyethylene Glycols / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry
D001149:Arsenates; D019216:Metals, Heavy; D012722:Sewage; D013464:Sulfuric Acids; C040890:chromated copper arsenate; D011092:Polyethylene Glycols; C033158:sulfuric acid; D002126:Calcium Hydroxide