(578b) Bioinspired Nanomaterials for Environmental Remediation

Porous materials such as silica, carbons, metal organic framework materials, porous polymers and others, are used in a variety of environmental remediation applications such as removal of toxic pollutants from air (e.g. volatile organic compounds VOCs) and water (e.g. toxic metal ions). However, these materials are generally prepared under environmentally damaging conditions, leading to secondary pollution – this only shifts the pollution problem. Taking inspiration from organisms and understanding the molecular principles in biomineralisation, we have developed green nanomaterials (GN) synthesis (Chem. Commun., 2011, 47, 7567). This green method (mild, one-pot and rapid synthesis in water, at room temperature and neutral pH) offers substantial reductions in resources, time and energy usage when compared to traditional routes, yet offers excellent control over the properties and function of the materials. With the examples of VOC removal from air and arsenic removal from water, we demonstrate the applications of GN.

GN exhibited very high extraction efficiencies for a range of VOCs including formaldehyde (Environ. Sci. Technol., 2012, 46, 13354) and monoaromatic hydrocarbons (e.g. benzene, toluene and cumene). Moreover, GN demonstrated significantly higher capacity per unit surface area. Upon probing their porosity, morphology and pore structure, it was observed that the combination of broad pore size distribution, disordered arrangement of pores and the presence of meso- and micro-porosity in GN contributed to their VOC extraction efficiencies and selectivity. These features were compared with other adsorbents including mesoporous silicas.

For water treatment, bioinspired green synthesis was used to prepare, for the first time, a family of iron supported on GN (Chem. Sci., 2017, 8, 567). For arsenate ion removal, they exhibited high extraction efficiencies, high adsorption capacities and superior kinetics (threefold higher than the highest removal rates reported to date). Moreover, a method was developed to regenerate GN allowing for full recovery and reuse of the adsorbent in subsequent extractions; strongly highlighting the potential technological benefits of these new green materials.

It is clear from the results presented herein that GN, which can be prepared with a substantial reduction in secondary pollution, form a viable alternative to traditional porous materials in separations. We have also demonstrated that these materials are scalable and can be manufactured cheaply (Chem. Eng. J., 2014, 244, 483).