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HATA, Toshimitsu

IMAMURA, Yuji

ISHIHARA, Shigehisa

PULIDO, Lilibeth L.

Kyoto University Research Information Repository

TitleResearch and Development of Carbon Composites from WoodCharcoal for Environmental Clean-up and their ApplicationsAuthor(s)PULIDO, Lilibeth L.; ISHIHARA, Shigehisa; IMAMURA,Yuji; HATA, ToshimitsuCitationWood research : bulletin of the Wood Research Institute KyotoUniversity (1996), 83: 43-46Issue Date1996-09URL http://hdl.handle.net/2433/53213RightType Departmental Bulletin PaperTextversionpublisherKyoto UniversityPreliminaryResearch and Developmeht of Carbon Compositesfrom Wood Charcoal for Environmental Clean-upand their A.j)plications*lLilibeth L. PULIDO*2, Shigehisa ISHIHARA*2,Yuji IMAMURA*2 and Toshimitsu HATA*2(Received May 31, 1996)Keywords: carbonized wood materials, adsorption, heavy metals, water treatment, environmentaldean-upIntroductionRecently, attempts to purify the waste water systems which are heavily polluted withvarious detrimental and toxic substances have been attracting interests in the field ofenvironmental protection.Activated carbons, charcoal activated with steam or carbon dioxide at highertemperatures 1), have been widely used as adsorbents for the water treatment of industrialwaste water and drinking water2,3) or for removal of metal ions from liquid solutions4).Although wood has been essentially excluded as a starting material for the production ofactivated carbon because of its poor strength and friabilitl), powder-wood based activatedcarbons are still being used in water treatment and other applications of liquid purification.However, the capability of powder-wood based charcoal to use as adsorbent is not yet knownin detail and few studies have been conducted in harnessing its potential as adsorptionmaterials especially in water treatment.This study was conducted to investigate the possibility of using carbonized woodmaterials from sugi (Cryptomeria japonica D. Don) as adsorbent materials in single andmixture aqueous solutions of some of the toxic materials such as heavy metals.Materials and MethodsSmall diameter logs were cut into flakes and ground to powder and they werecarbonized at varying temperatures at 200, 400, 600, 800, 1000, 1200, 1400, 1600, 2000 and*1 Part of this report was presented at the 21lth American Chemical Society National Meeting, New Orleans,LA, March 24-28,1996, and the 46th Annual Meeting ofJapan Wood Research Society at Kumamoto,April 3-5, 1996.*2 Laboratory of Wood Composites.- 43-WOOD RESEARCH No. 83 (1996)24000e using a furnace; Single and mixture solutions of heavy metals of mercury (Hg),lead (Pb), zinc (Zn), arsenic (As) and cadmium (Cd) were prepared at 1,5, 10, 50 and 100ppm concentrations, and carbonized wood powder, raw wood powder and activatedcharcoal were mixed in these solutions as the adsorbents. The mixed solutionsiwere stirredcontinuously in a constant· temperature bath at 300e for different periods. Theconcentration of heavy metal in the filtrates were analyzed using atomic absorptionspectrometer or Inductively Coupled Plasma to determine the adsorptive capacity of thesamples. The physical, chemical and anatomical characteristics of wood carbonized atdifferent temperatures were also evaluated.Results and DiscussionIn low concentrations of mercuric chloride solutions, carbonization was not necessarywhen using wood powder as adsorbents. The tested materials have sufficient capacities toadsorb the mercury in the solutions although the adsorption rate varies depending on thetype of adsorbents. Only small amounts of lead and zinc were adsorbed in raw woodpowder and wood powder carbonized at low temperatures. Wood powder carbonized at1000°C showed the limited capacity for adsorbing lead and zinc although the adsorption ratewas very, fast. All types of adsorbent attained the saturation point within only one hour forany kinds of heavy metals.When different metallic compounds were present in a solution, the adsorption followeda certain order depending on the metal-base. The presence of different metal ions in asolution in equal quantities decreased the adsorption of each of them. Apart from the factthat the metal ion was seleCtively adsorbed, the one was preferentially adsorbed preventingthe adsorption of other ions. In this study, mercury was found to be more readilyadsorbable and followed by lead. Arsenic and cadmium were not adsorbed in woodcharcoal at all except in activated charcoaI6).Wood powder carbonized at higher. temperature have higher adsorption capacity thanactivated charcoal, raw wood powder, and wood powder carbonized at lower temperature.However, further increase in the carbonization temperature reduced the adsorptiveeffectivity of wood charcoal and it was assumed that the optimum range of carbonizationtemperature existed from 1000 to 1400°C.In highly concentrated aqueous solutions of mercuric chloride, carbonized woodpowder could still be used as adsorbent with a greater adsorptive power than activatedcharcoal (Fig. 1). The maximum capacity of adsorption was found to be higher in woodpowder carbonized at 10000e than raw wood powder and wood powder carbonized at 2000eor 6000e as well as activated ch~rcoal. The optimum soaking time was also shorter, thatwas, 1 hour for 10000e carbonized charcoal compared to 8 hours for activated charcoal.-44-PULIDO et al.: Carbon Composites from Wood Charcoal for Environmental Clean-up8~I504010o 20 30Soaking time (hrs)Fig. 1. Relationship between soaking time and adsorbed amount of mercury in differentadsorbent materials.Note: One gram of each adsorbent material was mixed into 50 ml of 50 ppm HgChaqueous solutions.Legend: --.-- Wood powder ovedried at 105°C--0-- Wood powder carbonized at 200°C--L:::,.-- Wood powder carbonized at 600°C--0-- Wood powder carbonized at 1000°C--....-- Activated charcoal from coconut shell powderAlthough raw wood powder and wood powder carbonized at 200 and 600°C showed therelatively larger pores with non-uniform distribution, the wood powder carbonized at1000°C created micropores of specific dimensions which was similar to that of the activatedcharcoal. The large value of the cumulative pore volume was also observed for the woodpowder carbonized at the higher temperature. The large difference of the specific surfacearea was detected between wood powder carbonized at 600 and 1000°C, and the valueincreased rapidly as the carbonization temperature was raised up.SEM observations visualized the cellular structure ofcarbonized wood with the peculiarfeatures of the cell walls even the high carbonization temperature at 2400°C was applied.AcknowledgmentThe authors thank Mr. Takeshi Kajimoto ofWakayama Industrial Technology Center,Wakayama Prefecture for his valuable help in analyzing the concentration ofliquid samples.References1) N.!. NIKITIN: The Chemistry of Cellulose, 25, 581 (1966).2) T. ASAKAWA and K. OGINO: Journal of Colloid and Interface Science, 102, 348 (1984)- 45-)(WOOD RESEARCH No. 83 (1996)3) S. GAO, S. ~ANADA, I. ABE, M. KATAGAWA and Y. MATSUBARA: Tanso, 166, 8 (1995)."d", ,4) K. QADEERa~~ J. HARIF: Carbon, \~2, 1433 (1994).,,;5) ]AGTOYEN, M.H. BLACK and F. DERBYSHIRE: Carbon '95-22nd Biennial Conference on Carbon. Extended Abstractsand Program, p.398 (1995). " ,'C',",.\, ,6) L. PULIDO, S.ISHIHARA, Y. IMAMURA, T. HATA and T. KAJIMOTO: Research on Carbonized Wood asAdsorbents of Mg~allic Compounds. f. Physical Properties of Carbonized W~od Powder from Sugi1(, ;s(Cryptomeriajaponica D. Don) and Its Performance as Adsorbent Materials in Aqueous Solutions ofMetallicCompounds. To be pub1i~hed in Carbon.- 46-

Research and Development of Carbon Composites from Wood Charcoal for Environmental Clean-up and their Applications

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Research and Development of Carbon Composites from Wood Charcoal for Environmental Clean-up and their Applications

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