The Mechanics Involved in Removing Copper Ions Using Hydrochars, Activated Carbons, and Resins
According to the World Health Organization around 785 million people do not have a good source for their drinking water.  The lack of clean water comes from a lack of access to proper water treatment methods, and the presence of heavy metals in rivers and coastal areas, due in a large part, to industrial run-off. Sorption techniques that use different materials including hydrochars, activated carbons, and resins can be used to clear heavy metals and organic compounds from water. Biomass is a cost effective supply due to its large abundance and when carbonized, yields chars that can be used as adsorbents. Hydrothermal carbonization (HTC) is the process where biomass is converted to hydrochar. In this work, hydrochars were compared to traditional adsorbents for the removal of copper ions in a copper nitrate solution. Incorporating acids such as acrylic acid and vinyl sulfonic acid into the HTC process was done to see how adding an acid affects the performance of the hydrochars ability to remove copper ions. These hydrochars were then activated with a base solution, which improved the hydrochar’s ability to remove copper ions. Lastly, FTIR and titration of sorption materials was done to understand how adsorption of copper ions is related to the material’s acid concentration. The results showed that hydrochars exhibit a strong intensity of carboxylic acids on their surface. In addition, activation helped to ionize the hydrochars’ acid sites to give the char a more negatively charged surface to adsorb the positively charged copper ions. Overall, activated hydrochars have adsorption capacities that are comparable to traditional adsorption materials and that there is promise in exploring these materials as adsorbents in wastewater treatment.