Self-Activation Process for Biomass Based Activated Carbon

Transcription

1 BioProducts Manufacturing Laboratory Society of Wood Science & Technology 58 th International Convention Renewable Materials and the Bio-Economy Self-Activation Process for Biomass Based Activated Carbon Presented by: Changlei Xia June 8 th, 2015 Authors: Changlei Xia and Sheldon Q. Shi PhD Candidate and Associate Professor Department of Mechanical and Energy Engineering, University of North Texas, Denton, TX 76203, USA Changlei.Xia@unt.edu (C. Xia), Sheldon.Shi@unt.edu (S.Q. Shi)

2 Activated Carbon A crude form of graphite with a random or amorphous structure, which is highly porous with large surface area and exhibit a broad range of pore sizes. Generally, activated carbon has a surface area in excess of 500 m 2 /g determined by the gas adsorption testing (Wikipedia). Powdered activated carbon Granular activated carbon Bead activated carbon Hamerlinck, Y., D.H. Mertens and E.F. Vansant, Activated Carbon Principle in Separation Technology, Elsevier New York 2

3 Traditional Processes Physical/thermal activation Physical/thermal activation uses a mild oxidizing gas, e.g. CO 2, water steam, etc., to eliminate the bulk of the volatile matters, followed by partial gasification, the porosity and more surface area of the materials are developed. Raw materials Carbonization Thermal treatment Carbon materials Activation Thermal treatment Under CO 2, steam, etc. Activated Carbon Chemical activation Chemical activation method employs chemicals (such as acid, strong base, or salt) to increase the surface area. Raw materials Reagents loading KOH, ZnCl 2, K 2 HPO 4, etc. Treated materials Carbonization & Activation Thermal treatment Activated Carbon Carbonization Thermal treatment Carbon materials Reagents loading KOH, ZnCl 2, K 2 HPO 4, etc. Treated Carbon 3

4 Self-Activation Process An environmental friendly process Shi, Sheldon Q. and Changlei Xia. "Porositization process of carbon or carbonaceous materials." U.S. Patent Application 14/211,357, filed March 14, Biomass C + H 2 + CO + CH 4 +H 2 O + CO 2 + 4

5 Outline Self-Activation Water Purification Conclusions By-Products Syngas Self-Activation vs. Non-Activation Pyrolysis Parameters BET Surface Area Pore Volumes Iodine Number Tannin Value Copper(II) Absorption Rhodamine 6G Data Summery 5

6 By-Products Syngas Main syngas at the equilibrium of 1 lb. biomass Volume (L) Ratio (%) Syngas H CO CH H CO Data calculated from FactSage (online software) Applications Gas fuel Methanol Etc. CO 2 Activation Self- Activation Main exhaust Burn enthalpy (KJ/m 3 )* Applications of by-products CO 2 incombustible - Greenhouse effect H 2 and CO Gas fuel, methanol, etc. Environmental Cost Value Additional - cost for CO 2 Friendly - Useful syngas * The enthalpy Syngas from coal gasification by water is

7 Self-Activation vs. Non-Activation Required BET Value of Activated Carbon for Drink Water Purification Biomass, e.g. kenaf bast and core, sugarcane bagasse and leaf, coconut fiber, peanut shell, sawdust, etc. are successfully processed BET values of self-activated carbon increase by 160% 760% compared with non-activated carbon 7

8 SEM Observation Non-activation Self-activation 8

9 Pyrolysis Parameters Yield vs. Temperature Yield vs. Dwelling Time Pyrolysis time: 10 hours Pyrolysis temperature: 1,000 C 9

10 BET Surface Area Yield vs. ln(sa BET ) Total surface area produced by 1 g kenaf core 10

11 Pore Volume Yield vs. Total pore volume Yield vs. Meso-Macropore volume Yield vs. Micropore volume 11

12 Water Purification The requirements of Powdered Activated Carbon (PAC) for drinking water cleaning purpose (AWWA B600 Powdered Activated Carbon by American Water Works Association) Physical requirements Performance requirements Optional tests Moisture: 8% Apparent density: g/cc Particle size distribution: 99% pass a No. 100 sieve 95% pass a No. 200 sieve 90% pass a No. 325 sieve BET surface area: 500 m 2 /g Iodine number: 500 mg/g Tannin value: capability for absorbing high molecular weight impurities MIB/Geosmin test: capability for removing odor, and estimation of the sale price for the PAC products Selected PACs for the tests BET surface area (m 2 /g) Dubinin-Radushkevich micropore volume (cm 3 /g) PAC-I PAC-II PAC-III Calgon AC* * Calgon AC purchased from Calgon Carbon Corporation. BJH mesomacropore volume ( Å) (cm 3 /g) IUPAC nomenclature Micropore: 2nm Mesopore: 2-50nm Macropore: >50nm 12

13 Iodine number (mg/g) Iodine Number small molecular impurity absorption Iodine number is a parameter to evaluate the activated carbon mainly for the micropore sizes up to 20 Å capability for absorbing small molecular impurities It measures the adsorption ability of iodine from the liquid solution. The minimum iodine number requirement of PAC for drink water cleaning is 500 mg/g. Performance Increasing PAC-I Calgon AC PAC-II PAC-III PAC-I PAC-II PAC-III Calgon AC Surface area (m 2 /g) Micropore volume (cm 3 /g) PAC-I PAC-II PAC-III Calgon PAC Meso-macropore volume (cm 3 /g) 13

14 Tannin Value big molecular impurity absorption Tannin value (mg/l) Tannin value is defined as the concentration of activated carbon in milligrams per liter required to reduce the standard tannic acid concentration from 20 mg/l to 2 mg/l. The lower of Tannin value, the higher of performance. 700 Performance Increasing Calgon AC PAC-I PAC-II PAC-III PAC-I PAC-II PAC-III Calgon AC Surface area (m 2 /g) Micropore volume (cm 3 /g) PAC-I PAC-II PAC-III Calgon PAC Meso-macropore volume (cm 3 /g) 14

15 Copper(II) Absorption Procedure 50mg AC mixing with 100mL 200mg/L CuBr 2 aqueous solution The concentration was determined by UV/vis spectrophotom eter Performance Increasing Calgon AC PAC-I PAC-II PAC-III Surface area (m 2 /g) Micropore volume (cm 3 /g) PAC-I PAC-II PAC-III Calgon PAC Meso-macropore volume (cm 3 /g) 15

16 Removed Rhodimine 6G Conc. of Rhodimine 6G (μm) Rhodamine 6G Absorption Procedure 50mg AC mixing with 50mL 400μM/L (0.1916g/L) Rhodamine 6G aqueous solution % 99.8% 99.6% 99.4% 99.2% 99.0% 2h mixing 24h mixing Residual ~12 times PAC-I PAC-II PAC-III Calgon AC Removel 2h mixing 24h mixing PAC-I PAC-II PAC-III Calgon AC Calgon AC PAC-I PAC-II PAC-III Performance Increasing 2h mixing Water PAC-I PAC-II PAC-III Calgon AC 24h mixing Surface area (m 2 /g) Micropore volume (cm 3 /g) PAC-I PAC-II PAC-III Calgon PAC Meso-macropore volume (cm 3 /g) 16

17 DATA Summery BET surface area (m 2 /g) Micropore volume (cm 3 /g) Meso-Macropore volume (cm 3 /g) Iodine Number (mg/g) Tannin Value (mg/l) Cu(II) (200mg/L) removed (final conc. mg/l) Rhodamine 6G (4μM) removed (final conc. μm) PAC-III (2296) PAC-III (0.809) PAC-III (2.329) PAC-III (2120) PAC-III (103) PAC-III (5.1) PAC-III (0.27) High performance low performance PAC-II (2266) PAC-II (0.783) PAC-II (0.962) PAC-II (2040) PAC-II (266) PAC-II (5.1) PAC-II (0.28) PAC-I (901) Calgon AC (0.402) PAC-I (0.269) Calgon AC (1053) PAC-I (469) Calgon AC (5.6) PAC-I (0.28) Calgon AC (836) PAC-I (0.395) Calgon AC (0.052) PAC-I (952) Calgon AC (633) PAC-I (7.2) Calgon AC (3.26) 17

18 Conclusions Self-activation compared with CO 2 activation An environmental friendly process High performance activated carbon products Useful syngas Cost saving Water purification performance of biomass based activated carbon from self-activation process Specific pore size for absorbing relative molecular-size impurity High performance activated carbon for absorbing both small- and big-molecular impurities is possible The activated carbon from self-activation can have better water-cleaning qualities than commercial obtained 18

19 Thanks for your attention! Questions? And welcome to my poster for any question.