Activated charcoal impregnated with gold/platinum nanoparticles: An innovative approach to gaseous mercury sampling and quantification

In this study, gold/platinum‐coated activated charcoal was prepared and functioned as a collector for ultra‐trace gaseous mercury analysis. Commercial activated charcoal was ground to the sizes of 500–1000 µm and was impregnated with 1% (w/w) of different ratios of gold and platinum (10:0, 9:1, 7:3, v/v) using sodium borohydride 1%. mercury. The sorbents can be used to collect gas samples and be able to collaborate with a mercury quantitatively analysis method cold vapor gold‐trap atomic absorption spectroscopy (CV‐amalgam‐AAS) to enhance the sensitivity, accuracy, and reduce sample processing time. Gaseous elemental mercury sorption efficiency was investigated regarding various flow rates, durations and temperatures. The sorbents can quantitatively retain mercury up to 200 °C, and as the platinum concentration increases, the collection efficiency rises. Mercuric chloride and methyl‐mercury chloride were loaded onto the sorbents and then heated (in argon) at 700 °C to evaluate the reduction efficiency between the carbonaceous substrate and oxidized mercury. The sorbents were successfully applied for liquefied petroleum gas and flue gas sampling. The precision of 2–3% of relative standard deviation and recovery of over 97% for field measurement were achieved. This study also used gold‐coated sand for field sampling, and it demonstrated poor repeatability and high breakthrough compared to gold/platinum‐coated activated charcoal in flue gas sampling.