20 Pyrolysis for the P r o d u c t i o n of Activated C a r b o n f r o m Cellulosic Solid Wastes PAUL V. ROBERTS and JAMES O. LECKIE Downloaded by MICHIGAN STATE UNIV on February 19, 2015 | http://pubs.acs.org Publication Date: June 1, 1978 | doi: 10.1021/bk-1978-0076.ch020
Department of Civil Engineering, Stanford University, Stanford, CA 94305 PAUL H. BRUNNER EAWAG, Swiss Federal Institutes of Technology, CH 8600 Dübendorf, Switzerland Municipal s o l i d wastes can be pyrolyzed to produce a carbonaceous, s o l i d char (1). Such a char potentially could be activated to generate a product with large internal surface area and favorable adsorptive properties. The production of activated carbon i n this manner offers the combined benefits of reducing the volume of s o l i d wastes with a minimum ofairpollutant emissions and producing a valuable product for a growing market i n water and wastewater treatment. Presently, carbonaceous raw materials such as bituminous coal, l i g n i t e and peat are used i n the manufacture of activated carbon (2). The properties of the f i n a l product are strongly influenced by the chemical composition and physical structure of the raw material (2, 3). If s o l i d wastes are to be used as raw materials for activated carbon manufacture, it is important to understand the effects of waste composition, pyrolysis conditions, and activation conditions on the y i e l d and properties of the intermediate product, char, and the f i n a l product, activated carbon. Municipal s o l i d wastes vary widely i n composition both geographically and temporally (4, 5). Their potential for activated carbon preparation can be gauged crudely from their content of organic material. Municipal s o l i d wastes contain from 50 to 75 percent organic material, the primary constituent being paper (5). Thus, cellulose i s a l o g i c a l choice for a model substance to investigate the behavior of s o l i d wastes i n pyrolysis. The elemental composition of the organic fraction of s o l i d wastes can be given approximately asC6H10O4(4,5,6), which agrees closely with the empirical formula for cellulose (C6H10O5)n
(
6)·
Objectives This work was undertaken to: 1. Determine the effects of pyrolysis and activation conditions on the yields and properties of char and activated carbon prepared from cellulose and municipal s o l i d waste. 0-8412-0434-9/78/47-076-392$05.00/0 © 1978 American Chemical Society In Solid Wastes and Residues; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1978.
20.
ROBERTS
2. 3.
4.
E T
Activated Carbon from Cellulosic Solid Wastes
393
A s c e r t a i n the i n f l u e n c e o f the composition o f the educt on the p r o p e r t i e s and y i e l d o f the f i n a l product. Evaluate the e f f e c t i v e n e s s o f a i r c l a s s i f i c a t i o n i n r e moving i n o r g a n i c i m p u r i t i e s and improving the q u a l i t y o f the f i n a l product. Evaluate the f e a s i b i l i t y o f producing from m u n i c i p a l s o l i d waste an a c t i v a t e d carbon comparable i n q u a l i t y to commercially a v a i l a b l e products.
Experimental
Downloaded by MICHIGAN STATE UNIV on February 19, 2015 | http://pubs.acs.org Publication Date: June 1, 1978 | doi: 10.1021/bk-1978-0076.ch020
A L .
Procedure
Twenty-gram samples o f p u r i f i e d α-cellulose were p y r o l y z e d i n a 500-ml quartz g l a s s r e t o r t which was p l a c e d i n a temperaturec o n t r o l l e d m u f f l e furnace and purged w i t h argon ( 6 ) . Two a n a l y t i c a l grade c e l l u l o s e products were compared: Merck m i c r o c r y s t a l l i n e c e l l u l o s e f o r packing o f chromatographic columns (designated here a f t e r as C e l l u l o s e A ) , and S c h l e i c h e r and S c h u e l l No. 2181 f i l t e r paper f o r p r e p a r a t i v e chromatography (designated as C e l l u l o s e B ) . The c h a r a c t e r i s t i c s o f the two α-cellulose products are given i n Table I . The samples were f i r s t d r i e d a t 65°C. The ash content was estimated as the r e s i d u e a f t e r h e a t i n g a t 550°C f o r 24 hours. The metal contents were determined a f t e r d i g e s t i o n w i t h p e r c h l o r i c acid. The char formed by p y r o l y s i s o f c e l l u l o s e was a c t i v a t e d i n a steam-C02 atmosphere a t temperatures i n the range o f 700 t o 1000°C. Char samples weighing one to three grams were placed on a g l a s s f r i t i n the neck o f an i n v e r t e d 750-ml quartz b o t t l e , which was heated i n the same furnace used f o r p y r o l y s i s . Table I C h a r a c t e r i s t i c s o f C e l l u l o s e Used i n P y r o l y s i s (Reference 6) Cellulose A
Cellulose Β
Merck microcrystalline chromatographic cellulose
S c h l e i c h e r and S c h u e l l 2181 filter paper
44.4 6.2
44.3 6.2
Carbon content, % w/w Hydrogen content, % w/w Ash content, ppm Na Ca Mg Κ
Experiments
not
65 determined II II II
750 175 67 21 5
Particle size
90% w/w
