초록
<P><B>Abstract</B></P> <P>This study was devoted to investigate production of hydrogen gas from acid hydrolyzed molasses by <I>Escherichia coli</I> HD701 and to explore the possible use of the waste bacterial biomass in biosorption technology. In variable substrate concentration experiments (1, 2.5, 5, 10 and 15 g L<SUP>−1</SUP>), the highest cumulative hydrogen gas (570 ml H<SUB>2</SUB> L<SUP>−1</SUP>) and formation rate (19 ml H<SUB>2</SUB> h<SUP>−1</SUP> L<SUP>−1</SUP>) were obtained from 10 g L<SUP>−1</SUP> reducing sugars. However, the highest yield (132 ml H<SUB>2</SUB> g<SUP>−1</SUP> reducing sugars) was obtained at a moderate hydrogen formation rate (11 ml H<SUB>2</SUB> h<SUP>−1</SUP> L<SUP>−1</SUP>) from 2.5 g L<SUP>−1</SUP> reducing sugars. Subsequent to H<SUB>2</SUB> production, the waste <I>E. coli</I> biomass was collected and its biosorption efficiency for Cd<SUP>2+</SUP> and Zn<SUP>2+</SUP> was investigated. The biosorption kinetics of both heavy metals fitted well with the pseudo second-order kinetic model. Based on the Langmuir biosorption isotherm, the maximum biosorption capacities (<I>q</I> <SUB>max</SUB>) of <I>E. coli</I> waste biomass for Cd<SUP>2+</SUP> and Zn<SUP>2+</SUP> were 162.1 and 137.9 (mg/g), respectively. These <I>q</I> <SUB>max</SUB> values are higher than those of many other previously studied biosorbents and were around three times more than that of aerobically grown <I>E. coli</I>. The FTIR spectra showed an appearance of strong peaks for the amine groups and an increase in the intensity of many other functional groups in the waste biomass of <I>E. coli</I> after hydrogen production in comparison to that of aerobically grown <I>E. coli</I> which explain the higher biosorption capacity for Cd<SUP>2+</SUP> or Zn<SUP>2+</SUP> by the waste biomass of <I>E. coli</I> after hydrogen production. These results indicate that <I>E. coli</I> waste biomass after hydrogen production can be efficiently used in biosorption technology. Interlinking such biotechnologies is potentially possible in future applications to reduce the cost of the biosorption technology and duplicate the benefits of biological H<SUB>2</SUB> production technology.</P> <P><B>Highlights</B></P> <P>► The highest H<SUB>2</SUB> yield by <I>Escherichia coli</I> was obtained at a moderate H<SUB>2</SUB> formation rate. ► The waste <I>E. coli</I> biomass can be used as an efficient biosorbent for Cd<SUP>2+</SUP> and Zn<SUP>2+</SUP>. ► The waste <I>E. coli</I> biomass was better than many other biosorbents for Cd<SUP>2+</SUP> and Zn<SUP>2+</SUP>. ► The waste <I>E. coli</I> was better than aerobically grown <I>E. coli</I> for biosorption. ► Interlinking biosorption and H<SUB>2</SUB> biotechnologies is possible in future applications.</P>