Water Resources Research Act Program

Details for Project ID 2014RI117B

Carbon-Based Renewable Hydrogel Nanocomposites for Water Purification

Institute: Rhode Island
Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $18,737 Total Non-Federal Funds: $37,999

Principal Investigators: Samantha Meenach

Abstract: Water pollution is one of the most pervasive problems affecting people throughout the world. In particular, water contamination due to the indiscriminate disposal of industrial wastewater is a global environmental concern. Wastewater can be produced by many different industries including metallurgical, chemical manufacturing, tannery, production of polymers and mining, and can contain many kinds of toxic dyes and heavy metal ions. These contaminants can cause severe environmental problems, such as mass mortality of aquatic animals and extinction of species. Overall, the removal of contaminants from industrial wastewater is necessary to ensure safe water for all as well as for protection of the environment. The objectives of this project are to develop a renewable temperature-responsive hydrogel nanocomposite system and to demonstrate the capability of these materials to more effectively remove water contaminants. The system will be composed of a temperature-responsive polymer and two nanomaterials, carbon nanotubes and graphene oxide, which will act as the contaminant adsorbents. The initial experiments in this project will serve to optimize the swelling and adsorbent loading, which is necessary to ensure the largest swelling capacity and loading possible for the system. The materials will then be evaluated for their adsorption capacity and subsequent desorption and reuse. The thermoresponsive nature of the material will be exploited to facilitate more thorough desorption and removal of contaminants prior to reuse. I hypothesize that this hydrogel nanocomposite system will result in enhanced contaminant removal in comparison to pure carbon nanotube and/or graphene oxide while allowing for the reuse of the system. To test my hypothesis, I propose to complete the following goals: • Goal 1: To rationally design the swelling and nanoparticulate loading characteristics of carbon nanotube and graphene oxide-based hydrogel nanocomposites for use in water purification applications and evaluate their physicochemical characteristics. The nanocomposite system will be designed to allow for maximum swelling capacity, which will allow for the intake of large quantities of water while using a minimum amount of polymer matrix. The loading of the adsorbent materials will also be evaluated to ensure maximum loading so that the greatest amount of contaminants can be removed from polluted water. • Goal 2: To assess the adsorption capacity of the hydrogel nanocomposite systems towards a variety of contaminants including heavy metal ions, dyes, and organic compounds. The adsorption capacity of the hydrogel systems will be evaluated by exposing the dry materials to a water solution with model pollutants and measuring the amount of these contaminants remaining in the solution with time. This information will allow for the determination of the appropriate adsorption isotherm model that corresponds to the response of the materials. Overall, the effects of hydrogel swelling capacity and nanoparticulate loading on the adsorption capacity will be evaluated. • Goal 3: To evaluate the responsive nature and subsequent renewability of the hydrogel nanocomposites to enhance the cost-effectiveness of the material. Due to the presence of temperature-responsive polymer, after absorption is complete, the gel will be exposed to an acidic solution at moderately high temperature to facilitate the removal of contaminants. This will be possible through desorption of the contaminants in the acidic solution and elimination of water from the material via the temperature of the solution as the hydrogel will deswell and “force” the water out of the system. The adsorption capacity of the same system will then be evaluated to determine its capacity for renewability. The proposed work will result in a hydrogel nanocomposite system that exhibits enhanced adsorption capacity for a wide variety of water contaminants. This system will be more effective than pure hydrogel and pure nanoparticulates and offers many advantages over these including multifaceted adsorption and renewability.