Gc 2014c

The photocatalytic reaction was conducted on an all glass automatic on-line trace gas analysis system (Labsolar-6A) and SHIMAZU gas chromatograph (GC-2014C). The hydrogen generated in the reactor was automatically entered into the gas chromatograph for detection. Fifty milligrams of catalyst was placed in the reactor and a 100 mL aqueous solution containing 10 mL of lactic acid was poured into the reactor. The reactor temperature was kept at 278 K by a low temperature thermostatic bath. The light source is a 300 W Xe lamp (λ ≥ 350 nm).

The reactants identification was carried out by Shimadzu QP 2010 Plus gas chromatography-mass spectrometry (GC-MS) with an Rtx-5MS column (30.0 m × 0.25 mm × 0.25 μm). The oven temperature was held at 60 °C for 5 min, and ramped to 260 °C for another 5 min at 12 °C/min. The injector and detector temperature were set at 280 °C and 285 °C, respectively.
The content of 1,2-propanediol (mol/L) was determined by a gas chromatograph (GC, Shimazu GC-2014C, Shimazu, Kyoto, Japan) equipped with a flame ionization detector (FID) and WondaCap FFAP capillary column (30.0 m × 0.25 mm × 0.25 μm). The initial column temperature was 60 °C holding for 5 min, and ramped to 260 °C at a rate of 12 °C/min. Both the injector and the detector temperature were set at 280 °C. The quantification was analyzed by the standard curves of each standard substance, using dodecane as the internal standard. The yield (%) of 1,2-PDO in the reaction bulk was calculated as Equation (1).
$$\mathrm{Yield} \left(\%\right)=\frac{{\mathrm{m}}_{\mathrm{i}}}{{\mathrm{m}}_0} \times 100\%$$
where mi (g) is the mass quantity of 1,2-PDO and m₀ (g) refers to the mass of the PLA material.
The conversion (%) of PLA feedstock was calculated as Equation (2).
$$\mathrm{Conversion} \left(\%\right)=\frac{\left({\mathrm{m}}_0-{\mathrm{m}}_{\mathrm{r}}\right)}{{\mathrm{m}}_0} \times 100\%$$
where m_r (g) is the mass quantity of residues and m₀ (g) refers to the mass of the PLA material.

Hydrogen and organic acids were determined by gas chromatography (GC-2014C, Shimadzu, Kyoto, Japan), equipped with a thermal conductivity detector, as detailed in a previous study^{67 (link)}. The ratio of α-1,4/1,6 oligosaccharides was determined with the Amylose/Amylopectin Assay Kit (Megazyme, Wicklow, Ireland). Organic acids and glucose were analyzed by high-performance liquid chromatography with refractive index and ultraviolet detectors and a Bio-Rad Aminex HPX-87H column. The analysis was performed using 5 mM sulfuric acid as the mobile phase at 55 °C with a flow rate of 0.5 mL min⁻¹. The total starch concentration was determined by the DNS method.