PowerPoint

Hajime Tamon

Department of Chemical Engineering, Kyoto University, JapanPreparation and Characterization of Waste-Derived Activated Carbons

7th Regional Conference in Chemical EngineeringYogyakarta, Indonesia, December 2-3, 2014

1Solid WastesMore and more solid wastes are produced by society and industry, and landll sites are becoming full and hard to nd.

If activated carbons (ACs) are produced from solid wastes, the production can be a two-fold solution to environmental problems and effective reuses of wastes.2Problems on AC ProductionActivated carbons are produced from raw materials that contain rich carbon.

Industrial and house-hold wastes contain relatively rich carbon, but the composition is variable and inhomogeneous.

Solid wastes have been considered to be unfavorable raw materials for activated carbons. 3Good idea on pre-treatment for steam-activation

Activated carbons from six kinds of solid wastesObjectivePreparation of mesoporous activated carbons from solid wastes4Outline of TalkPreparation of mesoporous activated carbons from solid wastes

Porous characteristics of activated carbons prepared

Application to gas adsorption

Application to liquid adsorption5Outline of TalkPreparation of mesoporous activated carbons from solid wastes

Porous characteristics of activated carbons prepared

Application to gas adsorption

Application to liquid adsorption6Solid wastes as raw materials of activated carbons

(A) RDF, (B) PET pellets, (C) Waste coffee beans, (D) LFG, (E) Waste tires, (F) PET bottles7 From municipal solid wastes discarded in a city of JapanContained mainly papers, wood, garbage, plastics, and a little metal compounds.Briquetted cylindrical RDF (diameter: ca. 2 cm, length: ca. 5 cm) Contained calcium hydroxide (Ca(OH)2)Refuse derived fuel (RDF)

8 B) Pellets (diameter: ca 2 mm, length: ca 2 mm) of PET (polyethylene telephthalate) C) Waste coffee beans (diameter: ca 1 mm, length: ca 1 mm) exhausted from a can coffee industry

Waste PET pellets and waste coffee beans9 Waste tires were cut, crushed, ground, and centrifuged while steel wires and fabric cords contained were removed.

Particle size: smaller than 0.6 mm. Waste tires

10Waste generated during the lactic acid fermentation from garbage (LFG) LFG was dried, crushed and used for a raw material of activated carbons.

LFG11Waste PET bottles were collected from a supermarket, and cut into squares (length: ca. 5 mm). PET bottles

12Preparation of activated carbonPrepared by carbonization and steam-activation of solid wastes.

Not developed pore structure.

Ash prevents uniform development of pores because of rapid catalytic gasification.

Acid treatment of char is effective for steam-activation.Activated carbon

Steam-activationCarbonization in inert atmosphere13Mixing cheap metal salts with raw materials.Removal of metal salts by acid treatment after carbonizationWashing and dryingAdd following procedures to conventional steam-activation.Pre-treatment for steam-activationCarbonization in inert atmosphereSteam-activationActivated carbonMixing metal salts with solid wastesAcid treatmentWashing and drying14Not necessary for RDF, waste tires and LFG because they contain metal salts as ash.Ca(NO3)24H2O, Ca(OH)2, etc. are mixed for waste PET pellets, waste coffee beans and PET bottles.Mixing of metal salts

15Outline of TalkPreparation of mesoporous activated carbons from solid wastes

Porous characteristics of activated carbons prepared

Application to gas adsorption

Application to liquid adsorption16Porous properties of waste-derived activated carbonsA: Mixed raw materials with Ca(NO3)24H2O and treated with 1.0N HCl prior to steam activation.B: Treated with 1.0N HCl prior to steam activation.C: Mixed raw materials with Ca(OH)2 and treated with 2.64N HNO3 prior to steam activation.Raw materialsPre-treatmentSBET [m2/g]Vmic [cm3/g]Vmes [cm3/g]AC-PETPET bottlesA12000.400.95AC-TireWaste tiresB10000.480.79AC-RDFRDFB5200.170.27AC-CoffeeCoffee beansC10200.560.48AC-LFGLFGB7000.280.39AC-Com9100.390.2417Porous properties of waste-derived activated carbonsAC-Coffee, AC-Tire and AC-PET have lots of micropores. All carbons have more mesopores than AC-Com.Pre-treatment effectively develops mesopores. Raw materialsPre-treatmentSBET [m2/g]Vmic [cm3/g]Vmes [cm3/g]AC-PETPET bottlesA12000.400.95AC-TireWaste tiresB10000.480.79AC-RDFRDFB5200.170.27AC-CoffeeCoffee beansC10200.560.48AC-LFGLFGB7000.280.39AC-Com9100.390.2418Pore size distributions of waste-derived activated carbons

Mesopore development for AC-PET and AC-Tire19Surface characteristics of waste-derived activated carbons

Surface of AC-RDF and AC-LFG is not hydrophobic compared with others.20Outline of TalkGeneral information on mesoporous activated carbons

Preparation of mesoporous activated carbons from solid wastes

Porous characteristics of activated carbons prepared

Application to gas adsorption

Application to liquid adsorption21Activated carbonsAcid treatment: 1.0N HClMixing of metal saltspreparation of 6 kinds of charsP1no mixing, P2 mixing of Ca(NO3)24H2O, P3 mixing of Ca(OH)2, P4 mixing of CaCO3, P5mixing of ZnO, P6 mixing of AlNH4(SO4)212H2OCarbonizationAcid treatmentSteam-activationPreparation of activated carbons from PET pelletsMetal saltsPET

22Pore volume of activated carbons prepared from PET

Micropore volumes : 0.2~1.1 cm3/g, mesopore volumes : 0.04~0.90 cm3/g.All groups of carbons have similar micropore volumes.Mesopore development of carbons prepared via pre-treatment is much larger than those without pre-treatment.23SEM images of char surface

A:Char from PETB: Char prepared by mixing of Ca(NO3)24H2O, carbonization and acid treatmentC: Char prepared by mixing of Ca(OH)2, carbonization and acid treatment

Heterogeneity of surface is different from each other.24Change of char structure by pre-treatment

Raw materialmetal saltCarbonizationAcid treatmentRaw materialCarbonization

Many disorganized carbons Disordered orientation of organized carbons Metal saltDisorganized carbonsOrganized carbons Less disorganized carbons Uniform orientation of organized carbons25CO2 adsorption on activated carbons prepared from PET

Burnoff does not influence amount adsorbed so much.Amount adsorbed on 2A series carbons are smaller than other carbons.P1P22525refAC-Com26

P1P22525refAC-ComAmounts of C2H6 adsorbed on all carbons of P2 group increase with burnoff. Amount adsorbed on 2A series carbons of P1 group is clearly small.Pre-treatment increases C2H6 adsorption.C2H6 adsorption on activated carbons prepared from PET27

Amount of nC4H10 adsorbed on all groups of carbons increase with burnoff.Amounts adsorbed on 1A and 2A series carbons of P2 are much larger than commercial activated carbon.P1P22525refAC-ComnC4H10 adsorption on activated carbons prepared from PET28Amounts of iC4H10 adsorbed on all groups of carbons increase with burnoff.Similar results to nC4H10 adsorption are obtained.

P1P22525iC4H10 adsorption on activated carbons prepared from PET29Outline of TalkGeneral information on mesoporous activated carbons

Preparation of mesoporous activated carbons from solid wastes

Porous characteristics of activated carbons prepared

Application to gas adsorption

Application to liquid adsorption30Molecular size of adsorbates

PhenolBlack 531Adsorption equilibria on waste-derived activated carbonsPhenolBlack-5

252532ConclusionsThe proposed pre-treatment for steam-activation is effective to improve mesoporosity of activated carbons.Activated carbons prepared from RDF and LFG are more hydrophilic than carbons from PET and waste tires.Activated carbons prepared by the pre-treatment have large adsorption capacity of nC4H10 and iC4H10. Activated carbons with many mesopores and hydrophobic surface are useful to adsorption of large molecules. Activated carbons were produced from six kinds of solid wastes by steam-activation. 33Thank you for your attention.

Solid wastes34Raw material of RDF

Composition of municipal wastes (raw material of RDF)WasteWt% (dry basis)Plastics12.3Combustibles(papers, clothes, woods, etc.)54.6Garbages32.0Noncombustibles1.135Composition of RDF

Combustibles (wt%)83.7Ultimate analysis of ash (wt%)Ash (wt%)16.3Calcium15.1Aluminium 8.91Ultimate analysis of combustibles (wt%)Iron 7.23Carbon51.6Magnesium 2.45Hydrogen 7.65Potassium 2.19Nitrogen 1.00Sodium 2.13Oxygen39.6Manganese 0.21Sulfur 0.03Zinc 0.06Chloride 0.12Copper 0.05Nickel 0.03Others61.636Pore size distributions of activated carbons prepared from PET

P1P2P3P4P5P637