Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Calcite, a filter for water-borne arsenic?


An experiment at the Institut Laue-Langevin raises great hopes.

The health of millions of people is threatened by the presence of arsenic in their drinking water. In countries such as India, Bangladesh, Vietnam, Taiwan and Argentina, tens of millions of people drink untreated water containing levels of arsenic between ten and one hundred times higher than that recommended by the World Health Organisation ! Even in France, many sources of water, including mineral waters, will no longer satisfy new standards introduced on 1st January 2004 (which limit the concentration of arsenic in drinking water to 10 ìg L-1).

In order to decontaminate these water supplies, we urgently need to find an inexpensive and efficient method of trapping the arsenic. Studies have recently been conducted at the ILL into the capacity of calcite to capture arsenic. Unlike other substances such as manganese sand, iron oxides or ettringite, which though more efficient are much rarer and more expensive, calcite is in fact the main constituent of limestone and therefore an extremely common mineral.

The experiments using neutrons have been carried out to study the incorporation of arsenic beyond the surface and into the bulk of the sample. Due to the very high resolution of the diffractometer D20, it has been shown that up to 80 mg of arsenic per gram of calcite can be captured by this material ! AsO33– replaces the carbonate (CO32–) in the calcite lattice, which expands to accommodate it. The higher the degree of substitution, the larger the lattice cell becomes.

This discovery raises great hopes, since calcite can be synthetically produced in water purification systems simply by allowing a milk of lime (used in water purification plants and power stations to neutralise effluents and separate pollutants) to react with the carbon dioxide in the air.

Pure (synthetic) calcite could therefore offer a cheap and simple solution for filtering water contaminated with arsenic.

Françoise Vauquois | alfa
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>