Technology to efficiently eliminate toxic metals in water Trace amounts of metals can contaminate drinking water with toxic effects on human health and the environment. Scientists developed highly sensitive and selective detection and filtration technology to combat this growing problem. Industrial Technologies © Thinkstock Mercury (Hg), silver (Ag) and arsenic are naturally occurring elements found in trace amounts in soil, rocks and the atmosphere. They are also present in some types of industrial wastewater. When they make their way into aquatic streams, they can have harmful and toxic effects. Major public health problems in several parts of the world recently have raised the alarm on this issue, yet efficient detection methods are lacking. Scientists initiated the EU-funded project 'Metal-containing hybrid materials for water remediation from trace heavy metals' (HY-REM) to address this issue. Researchers developed cost-effective innovative devices with high selectivity and affinity that are also time-saving. Nanomaterials — novel cubic complexes of silicon, oxygen and hydrogen (polyhedral oligomeric hydrido silsesquioxane (POSS)) and metal nanoparticles (NPs), were used either alone or in combination. A number of hybrid composite materials were synthesised and characterised within the scope of the project. Scientists optimised POSS production to obtain composites with narrow pore size distribution to support selectivity of pores for certain ion sizes. In addition, uniform distribution of functionalised groups that form reactive sites for binding metal ions was also achieved in these POSS composites. Silica with attached silicon hydride groups efficiently and quickly removed Hg from water over a wide range of pH values and Hg concentrations. POSS hybrid materials with various functional groups also demonstrated enhanced loading of Hg. In addition, silica with immobilised Ag NPs rapidly removed inorganic Hg from a water solution at room temperature. This was accompanied by a colour change potentially useful in easy readout of results. Finally, hydride silica groups on silica showed great potential for fast and efficient removal of radioactive Ag, a key contaminant in nuclear waste. HY-REM demonstrated the optimised production of silica-based composites containing novel nanomaterials well suited to manufacture of efficient water filtration devices. Given the rising concern of contamination by heavy metals and radioactive Ag, HY-REM technology could contribute significantly in safeguarding public and environmental health.
