Invasive species or sustainable water filters? A student-led laboratory investigation into locally sourced biomass-based adsorbents for sustainable water treatment

Abstract

Abstract Designing sustainable products requires a holistic consideration of issues at the Food-Energy-Water Nexus. One of the world’s greatest challenges is to insure clean water access for all inhabitants. Across the globe, communities often suffer from metal contamination in their water. We must develop low-cost, sustainable materials to treat this contamination, without putting undue stress on other systems. Biomass-based carbon adsorbents are often touted as one potential solution, but to be sustainable the biomass must be locally sourced, not grown on land that could be used to cultivate food, not require extensive water to grow, and not need undue amounts of energy to process. In this laboratory investigation, students were challenged to use a locally available, problematic biomass – phragmites, an invasive species in the Muddy River in Boston, Massachusetts – to develop a green adsorbent to remove metals from water. Specifically, students focused on the removal of manganese, as it is a local problem for several Massachusetts communities. Students activated the phragmites biomass using a room and low (40 °C) temperature KOH treatment, which opened the porous network of the reed to enable adsorption of Mn+2 upwards of 8 mg/g of biomass. In doing this experiment, students were exposed to the concept of adsorption, a separation process not often covered in the traditional chemistry curriculum. Students gained experience in performing adsorption isotherm experiments using atomic adsorption spectroscopy and UV–Vis spectrophotometry and learned to analyze data within adsorption isotherm models. Finally, students made connections between their laboratory data and adsorption theory, and how this data can be used to design greener materials to address environmental issues.