4.3.1 L-Cysteine (Biomass Model Sample)

The measurements were conducted for 2 min at each temperature. L-Cysteine decomposes and releases several species as shown below:

decomposition

L-cysteine ^ H2S, CO, CO2, SO2, SO3, etc.

Fig. 4.2 SIM (Selected Ion Monitoring) traces of (a) m/z 35 [CO + Li] +, (b) m/z 51 [CO2 + Li] + and (c) m/z 41[H2S + Li]+ at different temperatures (Alif et al. 2011)

Figure 4.2 shows SIM traces of m/z 35 [CO+Li]+, m/z 51 [CO2+Li]+, and m/z 41[H2S + Li]+ at different temperatures.

Starting from 250°C, these gases tend to increase in evolving amount and reach the highest concentrations at 380°C. When Ca(OH)2 was added, the formation of CO (Fig. 4.2a) was suppressed as well as CO2 (Fig. 4.2b) and H2S gas (Fig. 4.2c). These results indicate that these environmentally burdening gases can be suppressed by adding Ca(OH)2. The similar results were reported in another paper, using Na2CO3 as an alkaline additive (Ishida et al. 2009). It should also be note that under supercritical condition, water will act as an oxidizing agent for carbon and heteroat­oms in biowastes to produce their oxides and oxoacid.

The alkaline reagent neutralizes the acids and traps them as their anions in the liquid phase. Consequently, pure hydrogen can be produce with freedom environ­mental load gases CO2 and toxic acids.