Analysis of Hydrothermal Carbon By Raman Spectroscopy

With the Flint, Michigan water crisis, lead contamination has become a visible concern in the public eye. The scale of the problem is gaining recognition, with over 2,000 water systems serving 6 million people in the US recently classified as contaminated with lead. While heavy metal remediation technologies such as coagulation and flocculation are feasible for developed countries, developing countries are limited in their ability to treat on a large scale.

Adsorption is a scalable, easy to implement technology for water treatment, with possible adsorbents such as silicates and activated carbon. Activated carbon is biomass or char subjected to high temperature gas treatment or acidic conditions, forming a denser carbon species with high surface area. Activated carbon, though versatile in its adsorption ability for both organics and metals, may be prohibitively expensive to implement on a large scale, and raises questions in the chemicals consumed and waste produced in its synthesis.

An alternative to this is hydrothermal carbon, or hydrochar, a carbon produced from treatment of biomass in low temperature water. As a result, hydrochar has a greater amount of acidic groups than AC, making it a promising candidate for adsorption of aqueous metals due to its great hydrophilicity and surface interactions. IR and Raman Spectroscopy were used to characterize hydrochar as a function of reaction time. This provides chemical information about the hydrochar that we will correlate to the adsorption behavior, allowing for us to design the hydrothermal process for production of better heavy metal adsorbents. To quantify our material as an adsorbent we have tested the copper adsorption capacity of our hydrothermal chars, and two industry grade activated carbons via UV VIS spectroscopy.