Gc 8a gas chromatograph

Photocatalytic decomposition of acetic acid was carried out over Pt-loaded WO₃ photocatalysts (Pt/WO₃) in gaseous phase. Pt-loading on WO₃ photocatalysts was carried out by the photodeposition method sequentially from an aqueous methanol (10 vol%) solution of H₂PtCl₆·6H₂O.^{30 (link)} The loading amount of Pt was fixed at 0.5 wt% of WO₃ for all of the photocatalysts.
Photocatalytic decomposition of acetic acid was performed in a 225 cm³ Pyrex cylindrical reaction vessel (64 mm in diameter) with a quartz top window. The photocatalyst, containing 30 mg of WO₃, was spread on the slide glass (38 mm × 26 mm) and set in the vessel. After closing the vessel, 1 μl of acetic acid (17.5 μmol) was introduced into the vessel. After acetic acid had been fully vaporized and had reached an absorption equilibrium in the vessel, the sample was photoirradiated with a 300 W Xe lamp though the quartz top window. CO₂ was analyzed with a Shimadzu GC-8A gas chromatograph equipped with a TCD detector and an activated carbon column, and organic compounds were analyzed with a Shimadzu GC-2014 gas chromatograph equipped with a BID detector and a TC-FFAP column. For the analyses, a portion of the gas phase was sampled with an air-tight syringe at appropriate intervals.

All chemical analyses were carried out at the Geosciences Environnement Toulouse (GET) laboratory. Cation (Na+, K⁺, Ca²⁺, Mg²⁺, Ba²⁺, Sr²⁺, and Si⁴⁺) and total sulfur (reported as SO₄) concentrations were measured using an ICP-OES Horiba Jobin Yvon Ultima2^®. The dissolved inorganic carbon content (DIC) and the non-purgeable dissolved organic carbon content (NPOC) were measured with a Shimadzu^® analyzer. The analytical precisions for the ICP-OES and the carbon analyzer are 5% and 2%, respectively. The anion concentrations (Cl⁻, SO₄²⁻, NO₃⁻, NO₂⁻, F⁻) were measured by ionic chromatography (Dionex ICS 2000^® liquid chromatographer).
Dissolved gas analysis was performed using a headspace equilibration method adapted from Magen et al. [31 (link)]. Briefly, a headspace representing about 10% of the vial volume (10 mL) was created in the collection bottle by water displacement with argon, then the bottle was manually shaken for 1 min and placed on a shaker for 1 h. The composition of the headspace gas was determined using a Shimadzu GC 8A gas chromatograph equipped with a thermal conductivity detector (GC/TCD) and a concentric column CTR1 (Alltech, Deerfield, IL, USA), as described by Mei et al. [17 (link)]. Argon was used as carrier gas at a flow rate of 60 mL/min; the temperature of the injector and the detector was fixed at 150 °C.

Methane and carbon dioxide concentrations in the two biofilter inlet and exit streams were determined using a Shimadzu GC-8A gas chromatograph (GC) equipped with a thermal conductivity detector. Separation was achieved using an Alltech Hayesep DB 100/120 column with helium as the carrier gas. To assess whether methane removal originated from microbial action or system leakage, one hour before analysis argon (1% (v/v)) was introduced to the gas stream entering the biofilter as an inert internal standard. A cold trap was used to remove humidity from the gas stream prior to injection into the GC. Analyses were performed in triplicate every three days with concentrations determined relative to the internal argon standard based on peak areas. Biofilter performance was evaluated on the basis of empty bed volume to facilitate comparison with other studies. Methane inlet load (IL), methane removal efficiency (RE), methane elimination capacity (EC), and carbon dioxide production rate (PCO₂) were calculated using the equations listed in Table II.