SIPS 2018

DETAILLED PROGRAM OVERVIEW

Nanotechnologies for Removing Contaminants From Water
Raphael Semiat¹;
¹TECHNION IIT, Haifa, Israel;
PAPER: 11/AdvancedMaterials/Invited (Oral)
SCHEDULED: 16:20/Tue./Guaratiba (60/2nd)

ABSTRACT:
The challenges in water management are among the most important problems facing the world today. The shortage of clean water is at the heart of critical health issues in developing countries, and is the focus of ecological and safety concerns in even the most highly developed nations. To adequately provide water for drinking and agriculture, we must reclaim polluted water, purify water with different degrees of salinity, and improve the effectiveness of water handling (storage and delivery) systems, ranging from desalination plants to waste water treatment facilities to home water purification systems. We must remove contaminants that include inorganics (metals and ions), organics (e.g. toxic waste, pharmaceuticals) and microorganisms (e.g. bacteria). At the heart of these diverse problems stands the need for new ways to clean water, to safely dispose of the extracted waste, and to properly reuse the cleaning systems. Nanotechnologies stem from new developments in micro-electronics; however, new tools developed recently allow us to better understand problems related to water. Many of the problems that exist are related to nano-size and smaller particles, like viruses and molecular size contaminants. Nanotechnology may be used for modern, improved water treatment techniques. Nanoparticles can be used for water purification, provided their proper removal from the product. This is essential, since some of those materials may be dangerous for drinking, off spec for purified water, or cause problems to membranes, as in higher cleaning steps. In nano-particles categories, those based on oxides of iron, titanium, and other metals may be included, as they act as catalysts for oxidation of dissolved organic matter to water and CO2. They may also act as nano-adsorbents for removal of heavy metals and other molecules from water. Other uses of nanoparticles are in new membranes design, controlling the known properties of current membranes and/or production of new types of membranes that may possess better properties. Uses of properties of nano-particles, as monitors in modern devices, may give proper information on water quality and contaminant content. The thickness of the active layer of a reverse osmosis membrane is currently in the range of 40-150 nanometers, and is reduced for newer membranes. Controlling pore sizes and pore size distributions in different membranes is comparable to problems associated with the control of lines in modern semi-conductor devices. This presentation will summarize the current situation related to water and nanotechnology, followed by some examples under development.