Novel silica sol-gel passive sampler for mercury monitoring in aqueous systems

A novel passive sampler for mercury monitoring was prepared using organosilica sol-gel materials. It comprises a binding layer with thiol groups for mercury complexation and a porous diffusive layer through which mercury can diffuse and arrive at the binding layer. Our study demonstrated that this new sampler follows the principle of passive sampling. The mass of mercury accumulated in the binding layer depends linearly on the mercury concentration in solution, the sampling rate and the exposure time. A typical sol-gel sampler is characterized by a diffusive layer of 1.2 μm, in which mercury ions diffuse with a coefficient of D = 0.09 × 10−6 cm2 s−1, resulting in an uptake Rs of 8.8 mL h−1. The capacity for mercury uptake is approximately 0.64 μg cm−2. Mercury diffusion and binding in the passive sampler are independent of the type of mercury-chloride complex, which potentially opens the door to use this device for mercury monitoring in a wide range of natural waters.

► We developed a novel silica sol-gel passive sampler for mercury monitoring in water. ► Sampling devices are easily prepared and have long shelf life. ► Capacity for mercury uptake capacity is approximately 0.64 μg per cm2. ► Mercury ions diffuse with a coefficient of 0.09 × 10−6 cm2 s−1 in sol-gel. ► Sampling rate of 8.8 mL h−1 for mercury ions is independent of chloride concentration.