The application of thermally activated layered double hydroxides for the water purification

Overview

Topic status: We're looking for students to study this topic.

Layered double hydroxides (LDHs) or hydrotalcites are known as anionic clays. The LDHs carry a positive surface charge which is counterbalanced through the intercalation of anions between the LDH layers. These LDH materials can be readily synthesised in the laboratory and may be made to function as anion exchangers. LDHs can be thermally activated to increase their chemical reactivity and can then be used to remove, for example, toxic anions from aqueous media. A source of LDHs is ‘red mud’, a waste by-product of the alumina industry. The seawater neutralisation process used in the alumina industry causes the reaction of aluminate (AlOH4-), sodium hydroxide (NaOH) and sodium carbonate (Na2CO3), in red mud, with magnesium chloride (MgCl2), in seawater, to form hydrotalcite (Mg6Al2(OH)16CO3•xH2O).

The objective of this research project is to apply thermally activated LDHs for the removal of selected anions from drinking water.

Research activities

This research will focus on optimising the thermal activation process of both synthetic hydrotalcite and hydrotalcite formed during the seawater neutralisation process. If overheating occurs during the activation stage, the hydrotalcite structure will be permanently damaged and adsorption capacities severely affected. The thermally activated hydrotalcites will be tested on a range of anionic species commonly found in drinking water. A comparison of adsorption capacities will be required for the synthetic and industrially synthesised hydrotalcite samples. Leaching tests will also be performed on the hydrotalcites to see if the removal process is permanent. Additional leaching tests will be undertaken for red mud as other phases may dissociate over time in aqueous solutions. Students working on this project will coordinate tests with Rio Tinto Alcan.

Expected outcomes

The project objectives are to:

  • prepare synthetic hydrotalcite and seawater/red mud derived hydrotalcite
  • characterise the two types of hydrotalcites
  • determine the performance of the hydrotalcite samples in the removal of anionic species commonly found in drinking water

Duration of project

Up to 8 weeks; specific times can be tailored to the individual needs of the student (generally between the hours of 9am and 5pm) within the general time period mid-November 2011 to mid-February 2012.

Study level
Vacation research experience scholarship
Supervisors
QUT
Organisational unit

Science and Engineering Faculty

Research area

Chemistry

Contact
Please contact the supervisor for enquiries.