Determining the Adsorption of Cadmium to Diatoms as a Function of pH

Heavy metal contamination has been rapidly increasing in recent years due to exponential acceleration in using these toxic elements in various industrial, agricultural, domestic, and technological applications. Once in the environment, heavy metals can’t be volatilized like other common pollutants (pesticides, hydrocarbons etc.), impeding their ability to degrade rapidly. Cadmium is considered one of the most ecotoxic metals, exhibiting adverse effects on all biological processes of humans, animals and plants. This poses a severe threat to organisms in the food web, including humans, as heavy metals are known to bioaccumulate. Various ecological interfaces (minerals, microbes, etc.) adsorb metals and impact their cycling. Thus, many factors (pH, water chemistry, etc.) must be considered to predict distribution and complexation of metals in particular environments. The ability to predict the fate of Cd in aquatic environments is imperative, and diatoms play a significant role in the degradation, speciation, and detoxification of hazardous metals. Diatoms are photosynthetic organisms found in aquatic ecosystems. When they die, they sink and accumulate, forming sediments. When an aquatic ecosystem is contaminated with Cd, it’s crucial to understand its mobility; will it remain in the water, or will it be removed by sorbing to sediments? This research investigated how Cd sorbs to diatoms as a pH (2-10) function and Cd: diatom ratio. The Inductively Coupled Plasma- Optical Emission Spectrometer (ICP-OES) was used to analyze the amount of Cd remaining in the water sample. FTIR was used to identify the adsorption of Cd to the diatoms. Department: Physical Sciences Faculty Mentor: Dr. Janice Kenne