Abstract
The normal maximum H2 yield in mesophilic biohydrogen (bioH 2) fermentation is ∼2 mol of H2/(mol of glucose). Thermodynamics could be the most fundamental control for bioH2 formation, since proton reduction is strongly energy consuming (+79.4 kJ/(mol of H2)). However, most of the electron equivalents in glucose do not accumulate in H2 but in a range of organic acids and alcohols. Thus, evaluating the hypothesis of thermodynamic control requires the full stoichiometry of the fermentation. We carried out batch bioH2 reactions with a range of pH values that yielded H2 yields from 0 to ∼2 mol of H2/(mol of glucose). We constructed complete electron equivalent (e- equiv) balances for high or low H2 yield by measuring all e- sinks. The highest H2 yield occurred with pH ∼4 and was coincident with major butyrate accumulation; ethanol or lactate correlated to reduced H2 yields at pH 7 and 10, respectively. Although the Gibb's free energies for all overall reactions were similar (-10.6 to -11.2 kJ/(e- equiv)), thermodynamics controlled the H 2-producing reaction coupled to ferredoxin; this reaction was favorable at acidic pH but thermodynamically blocked at pH 10. Also, butyrate formation was the most thermodynamically favorable reaction that produced ATP after glycolysis.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2401-2407 |
| Number of pages | 7 |
| Journal | Environmental Science and Technology |
| Volume | 42 |
| Issue number | 7 |
| DOIs | |
| State | Published - Apr 1 2008 |
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ASJC Scopus subject areas
- Environmental Engineering
- Environmental Science(all)
- Environmental Chemistry
Cite this
Thermodynamic evaluation on H2 production in glucose fermentation. / Lee, Hyung Sool; Salerno, Michael B.; Rittmann, Bruce.
In: Environmental Science and Technology, Vol. 42, No. 7, 01.04.2008, p. 2401-2407.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Thermodynamic evaluation on H2 production in glucose fermentation
AU - Lee, Hyung Sool
AU - Salerno, Michael B.
AU - Rittmann, Bruce
PY - 2008/4/1
Y1 - 2008/4/1
N2 - The normal maximum H2 yield in mesophilic biohydrogen (bioH 2) fermentation is ∼2 mol of H2/(mol of glucose). Thermodynamics could be the most fundamental control for bioH2 formation, since proton reduction is strongly energy consuming (+79.4 kJ/(mol of H2)). However, most of the electron equivalents in glucose do not accumulate in H2 but in a range of organic acids and alcohols. Thus, evaluating the hypothesis of thermodynamic control requires the full stoichiometry of the fermentation. We carried out batch bioH2 reactions with a range of pH values that yielded H2 yields from 0 to ∼2 mol of H2/(mol of glucose). We constructed complete electron equivalent (e- equiv) balances for high or low H2 yield by measuring all e- sinks. The highest H2 yield occurred with pH ∼4 and was coincident with major butyrate accumulation; ethanol or lactate correlated to reduced H2 yields at pH 7 and 10, respectively. Although the Gibb's free energies for all overall reactions were similar (-10.6 to -11.2 kJ/(e- equiv)), thermodynamics controlled the H 2-producing reaction coupled to ferredoxin; this reaction was favorable at acidic pH but thermodynamically blocked at pH 10. Also, butyrate formation was the most thermodynamically favorable reaction that produced ATP after glycolysis.
AB - The normal maximum H2 yield in mesophilic biohydrogen (bioH 2) fermentation is ∼2 mol of H2/(mol of glucose). Thermodynamics could be the most fundamental control for bioH2 formation, since proton reduction is strongly energy consuming (+79.4 kJ/(mol of H2)). However, most of the electron equivalents in glucose do not accumulate in H2 but in a range of organic acids and alcohols. Thus, evaluating the hypothesis of thermodynamic control requires the full stoichiometry of the fermentation. We carried out batch bioH2 reactions with a range of pH values that yielded H2 yields from 0 to ∼2 mol of H2/(mol of glucose). We constructed complete electron equivalent (e- equiv) balances for high or low H2 yield by measuring all e- sinks. The highest H2 yield occurred with pH ∼4 and was coincident with major butyrate accumulation; ethanol or lactate correlated to reduced H2 yields at pH 7 and 10, respectively. Although the Gibb's free energies for all overall reactions were similar (-10.6 to -11.2 kJ/(e- equiv)), thermodynamics controlled the H 2-producing reaction coupled to ferredoxin; this reaction was favorable at acidic pH but thermodynamically blocked at pH 10. Also, butyrate formation was the most thermodynamically favorable reaction that produced ATP after glycolysis.
UR - http://www.scopus.com/inward/record.url?scp=41649109093&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=41649109093&partnerID=8YFLogxK
U2 - 10.1021/es702610v
DO - 10.1021/es702610v
M3 - Article
C2 - 18504972
AN - SCOPUS:41649109093
VL - 42
SP - 2401
EP - 2407
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 7
ER -