Sorption of Copper by Wood ConstituentsNATURE 267Belford, Myers and Preston 1 have directed attention to the fact that cellulose and wood absorb copper ions and that they appear to bo regularly spaced on a grid pattern not corresponding to the unit cell of cellulose. Bayley and Rose• consider that IX-cellulose has only a small cation binding power and that the complexes formed in wood consist of metal cations bound on the non-cellulosic constituents. Belford et az.a observed that in wood impregnated with preservatives containing copp~r-sa.lts the middle lamella in particular stained very deeply with dithio-oxamide. In the work now reported the copper sorption of isolated wood constituents has been measured and tho copper has been located in sections of treated wood by staining methods and electron microscopy.'Milled wood lignin' prepared by the method of Bjorkman', wood IX-cellulose (40 mesh) and purified cotton cellulose ( 40 mesh) have been examined for their copper binding capacity by the following method. A specimen of each material, 0•1-0•5 g, was shaken for 1 h in 5 ml. of 0•3 per cent copper acetate solution at about 20° C. Tho mixture was then filtered, tho specimen washed with distilled water and the filtrate discarded. It was then washed three times with 10 per cent acetic acid and the combined acetic acid filtrates evaporated to dryness on a steam bath. Tho organic matter present was destroyed by heating on a hotplate with sulphuric-nitric acid mixture and the copper determined by the spectrophotometric rubea.nic acid (dithio-oxamide) method of Center and Macintosh•. Tho results are given in Table 1. A similar test on the residual lignin after the acetic acid washing showed that it retained no significant amount of copper.These copper sorptions of cellulose are much lower than those recorded by Belford, Myers and Proston 1 and consistent with those observed by Michie•, allowance being made for the different conditions by his equation (1) . However, the absorption of copper by the milled wood lignin was, as shown in Table 1, much higher than for cellulose.
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