SEGH Articles

The nano way to cleaner water

04 April 2012
Nanomaterials provide potential for waste water remediation and metal removal and recycling. We envisage that this composite can cheaply and effectively be incorporated into a variety of configurations to improve water treatment.

Decontaminating polluted waste water costs millions but a new discovery by scientists at the University of Brighton could result in huge savings as well as delivering safer, cleaner water. The research, recently published in the journal Angewandte Chemie International Edition, represents a significant shift in our understanding of (nano)chemistry. Mercury is a serious contaminant so this breakthrough could save millions of pounds.

It is generally accepted that when silver is reduced to nano-sized particles, it can only extract a certain amount of mercury. However, Dr Kseniia Katok, working in the Nanoscience and Nanotechnology Group at Brighton, was able to reduce nanoparticles of silver to below 35 nano-metres in diameter (the equivalent of splitting a single human hair into 3,000 separate strands) and found that this allowed almost twice as much mercury to be removed from water.

The team's breakthrough opens the way for more effective, cheaper ways of cleaning mercury-contaminated water. Existing clean-up methods for mercury-contaminated water have either low mercury removal capabilities, leave a large chemical waste footprint or are not energy efficient.

Mercury is found naturally in the environment, but levels of inorganic mercury have increased significantly in recent decades as a result of industrial processes, and mining activities. If mercury contamination occurs, a hugely expensive decontamination process is required, as occurred in Squamish in Canada where the whole of the waterfront was subject to a huge clean-up starting in the 1990s. The seafront town had been subjected to years of industrial pollution because of its forestry industry which began in the early 20th century. Just the chemicals used to clean the water cost around $50,000,000. The Brighton scientists say their research shows that using silver nanoparticles would cost a few thousand rather than tens of millions of pounds for the materials, although a device containing the silver nanoparticles capable of processing large quantities of water would need to be developed.

Dr Raymond Whitby, head of the Nanoscience and Nanotechnology Group, said: "The amount of mercury taken into silver nanoparticles defies our current understanding and promises a number of exciting developments. For example, it should lead to improved water treatment, removing greater quantities of selected heavy metals more quickly and perhaps more cheaply than before."

One key element in Dr Katok's discovery is her use of chemically-modified quartz sand, which reduces silver particles to a nanoscale with a high degree of purity. Sergey Mikhalovsky, the university's Professor of Materials Chemistry and Dr Katok's co-supervisor, said: "This is the biggest difference between our silver and that prepared by other commonly-used methods such as citrate reduction, which typically leaves residual chemical groups on the surface of the silver nanoparticles. These can cause unwanted side reactions that may have limited its effectiveness." He anticipates that modified quartz could be used in other chemical groupings and might, in the future, aid the extraction and recycling of precious metals such as platinum, palladium and gold.

Andy Cundy, the university's Professor of Applied Geochemistry and Dr Katok's lead supervisor, said: "These findings enable a major shift towards the use of nanomaterials for waste water remediation and metal removal and recycling. We envisage that this composite can cheaply and effectively be incorporated into a variety of configurations to improve water treatment, initially targeting mercury, which remains one of the key environmental contaminants globally."

Professor Andy Cundy, University of Brighton.

Keep up to date

SEGH Events

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Characteristics of PM 2.5 , CO 2 and particle-number concentration in mass transit railway carriages in Hong Kong 2017-08-01


    Fine particulate matter (PM2.5) levels, carbon dioxide (CO2) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m3, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m3). The CO2 concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm3, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R 2 = 0.834) was observed between passenger numbers and CO2 levels, with each passenger contributing approximately 7.7–9.8 ppm of CO2. The real-time measurements of PM2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM2.5 levels and PNC. Assessment of the risk associated with PM2.5 exposure revealed that children are most severely affected by PM2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk.

  • Comparison of chemical compositions in air particulate matter during summer and winter in Beijing, China 2017-08-01


    The development of industry in Beijing, the capital of China, particularly in last decades, has caused severe environmental pollution including particulate matter (PM), dust–haze, and photochemical smog, which has already caused considerable harm to local ecological environment. Thus, in this study, air particle samples were continuously collected in August and December, 2014. And elements (Si, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Mo, Cd, Ba, Pb and Ti) and ions ( \({\text{NO}}_{3}^{-}\) , \({\text{SO}}_{4}^{2-}\) , F, Cl, Na+, K+, Mg2+, Ca2+ and \({\text{NH}}_{4}^{+}\) ) were analyzed by inductively coupled plasma mass spectrometer and ion chromatography. According to seasonal changes, discuss the various pollution situations in order to find possible particulate matter sources and then propose appropriate control strategies to local government. The results indicated serious PM and metallic pollution in some sampling days, especially in December. Chemical Mass Balance model revealed central heating activities, road dust and vehicles contribute as main sources, account for 5.84–32.05 % differently to the summer and winter air pollution in 2014.

  • Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan 2017-08-01


    The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000–2012.