ABSTRACT
Breakdown and utilization of cellulose are critical for the bioenergy sector; however, current cellulose-to-energy conversion schemes often consume large quantities of unrecoverable chemicals, or are expensive, due to the need for enzymes or high temperatures. In this paper, we demonstrate a new method for converting cellulose into soluble compounds using a mixture of Fe2+ and Fe3+ as catalytic centers for the breakdown, yielding Fe3O4 nanoparticles during the hydrothermal process. Iron precursors transformed more than 61% of microcrystalline cellulose into solutes, with the composition of the solute changing with the initial Fe3+ concentration. The primary products of the breakdown of cellulose were a range of aldaric acids with different molecular weights. The nanoparticles have concentration-dependent tuneable sizes between 6.7 and 15.8 nm in diameter. The production of value-added nanomaterials at low temperatures improves upon the economics of traditional cellulose-to-energy conversion schemes with the precursor value increasing rather than deteriorating over time.
ABSTRACT
A novel light-to-bioenergy system produced 3.5 times the baseline methane output using a co-culture of cyanobacteria (Oscillatoria sp.) and a methanogenic microbial community. Analysis of micronutrients in the system during the growth phase indicated that cobalt, iron, nickel and zinc were not appreciably consumed. The stable consumption and return of macronutrients calcium and magnesium were also observed. Essential macronutrients nitrogen, in the form of nitrate, and phosphorus showed no cycling during the growth phase and were depleted at rates of 0.35mg/L/day and 0.40µg/L/day, respectively. Biofilm formation increased the resilience of biomass to bacterial degradation in an anaerobic digester, as shown by viability assays of cyanobacterial biofilms in the co-culture.
