Carbon Nanotubes Electrochemical Membrane for Detection of Organic and Inorganic Pollutants in Water

Andrea Buffa, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel (andrea.buffa@mail.huji.ac.il)
Daniel Mandler, Institute Of Chemistry, Hebrew University Of Jerusalem, Jerusalem, Israel

In 2015, more than 800 million people did not have access to safe and contaminant free drinking water. Water from wells and springs is contaminated by a variety of organic and inorganic pollutants coming from anthropogenic and natural sources such as arsenic containing rocks. Yet, also apparently safe tap water can hide threats since it can be polluted accidentally or on purpose along the supply chain. Even improper plumbing in old buildings can release poisonous heavy metals into drinking water. The major barrier that prevents careful water control is the lack of an inexpensive and simple in-situ analytical system that warns against major contaminants. The development of an easy to use and accessible (also to undeveloped countries) analytical method is still a challenge in analytical chemistry.

We aim at contributing to accomplish this goal by developing a carbon nanotubes (CNT) electrochemical filter membrane able to detect ppb levels of both organic and inorganic pollutants. The high sensitivity of the method is achieved by pumping the water sample through the CNT membrane electrode, which accumulates the pollutants to be detected in a short time. The cost efficiency derives from using a simple syringe filter holder for building the electrochemical flow system. With this system, we detected 64 ppt of copper and 7.5 ppb arsenic by anodic stripping voltammetry.

Due to the adsorptive properties of CNTs, the CNT membrane electrode is basically a fixed bed adsorption system able to detect organic contaminants by adsorptive stripping voltammetry. Organic contaminants such as tartrazine, parathion and diquat were determined in ppb levels by adsorptive stripping voltammetry by a simple and time efficient procedure. Moreover, the flow system is scalable and can be applied for large scale water treatment since the CNT membrane can be easily electrochemically regenerated.