Determination of Adsorbable Organic Halogen in Wastewater This is the default title slide for Thermo Fisher Scientific Determination of Adsorbable Organic Halogen in Wastewater Jingli Hu, Jeff Rohrer, and Kirk Chassaniol Thermo Fisher Scientific, Sunnyvale, CA

Outline AOX (Adsorbable Organic Halogen) Combustion IC Ion Chromatography Methods Results and Conclusions

AOX Introduction Organohalogens are toxic and persistent compounds Given high priority in the monitoring and control of environmental pollution AOX represents the equivalent amount of fluorine, chlorine, and bromine contained in organic compounds, expressed as chloride substances that can be adsorbed from water onto activated carbon Organic halogen compounds cannot be directly analyzed by ion chromatography (IC) Automated combustion ion chromatography (CIC) is often used to determine these organic halogen contaminants.

Diagram of a CIC System

CIC System Components In CIC, the samples, including halogen-containing compounds, are first combusted and the resultant gases are released into an absorption solution, which is directly injected into an IC system Ion Chromatography System Gas Absorption Unit Furnace Solid/Liquid Autosampler

Reagent-free Ion Chromatography (RFIC) System

Hydroxide Eluent Generation EluGen KOH Cartridge [KOH]  Current Flow rate [ + ] Pt anode (H2O 2H+ + ½O2 + 2e–) Vent K+ Electrolyte Reservoir K+ Cation-exchange connector KOH Generation Chamber Pump H2 H2O KOH + H2 Degas Unit KOH CR-ATC Anion Trap [–] Pt cathode (2H2O + 2e– 2OH– + H2) 14538-04

The Role of Chemical Suppression (KOH) Eluent (KOH) Sample F-, Cl-, SO42- Analytical Column (Anion Exchanger ) Anion Suppressor (Cation Exchanger) HF, HCl, H2SO4 in H2O KaF, KCl, K2SO4 in KOH Waste H+ Without Suppression Counter Ions µS F- SO42- Cl- Time With Suppression K+ 11309-02

Thermo Scientific Dionex Electrochemically Regenerated Suppressors

Sample Preparation Wastewater samples (50 mL) were absorbed onto granular activated carbon (GAC) columns The column was then washed with 20 mL of sodium nitrate washing solution (0.01 M) at 2–3 mL/min to displace inorganic chloride ions A rod was used to push the carbon from the column into a sample boat Samples were analyzed with CIC strong acids are subject to a strong electrostatic exclusion caused by the negative charge of the stationary phase, which prevents them from penetrating the pores in the packing material weak acids, such as organic acids, the degree they can penetrate the pores is determined by the size of the charge (think of it as pKa), which results in differences in elution time (separation). However, in actuality, a hydrophobic interaction also occurs with some of the packing substrate (styrene-divinylbenzene), which can delay the elution of hydrophobic organic acids in particular electrostatic exclusion due to negatively-charged stationary phase, hydrophobic interaction with the stationary phase matrix penetration into stationary phase pores, determine elution times.

Combustion Conditions

IC Conditions Thermo Scientific™ Dionex™ Integrion™ HPIC™ System

Separation of a Standard Anion Mixture Standard halide solutions were directly injected into the IC to yield well resolved peaks within 10 min

Determination of AOX in (A) Wastewater and (B) Spiked Wastewater Figure shows an overlay of chromatograms of unspiked and spiked wastewater. As the figure shows, the Dionex IonPac AS18-4μm column and suppressed conductivity detection achieve excellent resolution and sensitive detection for AOX.

Calibration Data, Retention Time, and Peak Area Precisions (n = 3) To determine the calibration ranges, the peak responses to concentration were determined using triplicate injections of calibration standards (Table ). The excellent retention time stability and peak area precision are consistent with results typically obtained when using an electrolytically generated high-purity potassium hydroxide eluent.

Recovery of AOX Spiked in DI Water (n=3) Working AOX standard trichlorophenol stock solution (1,000 mg/L Cl–), 4-fluorobenzoic acid solution (100 mg/L F–), and 4-bromoacetanilide stock solution (200 mg/L Br–) were used to spike AOX into DI water. Four spike levels were chosen and three replicate analyses were done on each level to determine the analysis accuracy and precision. Table 2 shows the recovery for AOF, AOCl, and AOBr spiked in DI water at all four levels. All three organic halides demonstrate acceptable recovery (85–115%). Good precision was achieved as evidenced by the relative standard deviation (RSD) values calculated from the three replicates (1.4–5.1).

Recoveries of AOX Spiked in Wastewaters (n = 3) Three wastewater samples were obtained from local wastewater plants. Three replicates were performed for each sample. Table summarizes the recoveries for AOX spiked in wastewater samples. AOF, AOCl, and AOBr all demonstrated excellent recovery (95–105%).

Conclusions AOX can be precisely and accurately determined in wastewater using combustion ion chromatography Analysis was automated using the Mitsubishi AQF–2100H system in combination with the Dionex Integrion HPIC system with a Dionex IonPac AS18-4μm column Suppressed conductivity detection selectivity detects only anionic species in aqueous solution from the absorbed combustion gas Eluent generation frees the analyst from the need to prepare eluent, eliminates the handling of strong base, and removes a possible source of error

Thermo Scientific AppsLab Library of Analytical Applications Thermo Scientific Application Note 72333: Determination of adsorbable organic halogen in wastewater using a combustion ion chromatography system https://appslab.thermofisher.com

CIC Application Notes AN72693: Determination of total fluorine, chlorine, and sulfur in aromatic hydrocarbons by oxidative pyrolytic combustion followed by ion chromatography AU72588: Determination of Chlorine, Bromine, and Sulfur in Polyethylene Materials using Combustion IC with a Carbonate/Bicarbonate Eluent AN72573: Determination of Halogens in Polymers and Electronics using a Combustion Ion Chromatography System AN72349: Determination of Chlorine, Bromine, and Sulfur in Polyethylene Materials using Combustion Ion Chromatography AN72333: Determination of Adsorbable Organic Halogen in Wastewater using a Combustion Ion Chromatography System AN72268: Determination of Fluoride in Tea using a Combustion Ion Chromatography System AN1145: Determination of Halogens in Coal Using Combustion Ion Chromatography TN72211: Combustion Ion Chromatography with a Dionex Integrion HPIC System