During the last 10 years, nanotechnology has emerged as a suitable platform technology for addressing global sustainability challenges, especially in terms of energy, water, food, habitat, transportation, mineral resources, green manufacturing, clean environment, climate change, and biodiversity. Key advances include the development of (1) more efficient renewable energy generation and storage technologies, (2) improved water treatment and desalination membranes, (3) improved food safety (detection and tracking) systems, (4) more efficient separation systems for recovering valuable metals, (5) miniaturized sensors that can detect and monitor pollutants more efficiently, and more effective environmental remediation technologies, (6) more efficient CO2 capture media, and (7) microchip fabrication processes that use less materials, energy, and water.
In the next 10 years, the power of nanotechnology should be used to develop and commercialize the next generation of sustainable products, processes, and technologies. Priority areas will include (1) water desalination and reuse, (2) CO2 capture and transformation to useful products and (3) green manufacturing. Current reverse osmosis (RO) desalination membranes have limited water recovery (e.g., 40–70%) and require high pressure (e.g., 10–70 bar) to operate and generate significant amounts of liquid wastes that need to be disposed. Thus, a key priority in water desalination and reuse is to develop the next generation of low-pressure membranes (e.g., 0.5-5 bar) with high water recovery (> 95%) and capability to:
- Reject dissolved anions and cations from saline water (e.g., brackish water and seawater)
- Reversibly and selectively bind and release dissolved anions and cations in saline water
- Extract clean water, nutrients, and other valuable compounds from domestic and industrial wastewater
Current CO2 capture media only perform a single function, i.e., separate CO2 from flue gases. Thus, a key priority in climate change mitigation and reduction of greenhouse gas emissions is to develop:
- Size- and shape-selective media with nanocages that can capture CO2 and convert it to useable products
- Membrane reactors with embedded nanocages that can capture CO2 and convert it to useable products
– Nano Bubbles:
Based on such characteristics of tiny (nano and micro) bubbles as charge, lower buoyancy and longer existence in water, nano and micro-bubbles have potential applications in a number of fields, and a great deal of research on nano-bubbles has been conducted in recent years Micro and nano-bubble technologies have attracted great attention due to their wide application range in science and industry, such as mining industries, water treatment processes, biomedical engineering, food processing and nanomaterial industries In mining industries, nano-bubbles can be used in the flotation process to effectively increase the process performance. Nano-bubbles generated by hydrodynamic cavitation have been found to increase the contact angle of solids and as a result the attachment force, bridge fine particles to form aggregates, minimize slime coating, remove oxidation layers on particle surfaces and consequently reduce reagents consumption.
– Nanoparticle Flotation Collectors:
Flotation is a critical operation in the isolation of valuable minerals from natural ore.
Before flotation, chemical collectors are routinely added to ground ore slurries.
Collectors selectively bind to mineral-rich particles, increasing their hydrophobicity thus promoting selective flotation. Conventional collectors are small surfactants with a short hydrocarbon tail (2-6 carbons) and a head group, such as xanthate. In this work, much larger hydrophobic polystyrene nanoparticles are evaluated as potential flotation collectors. Experiments involving both clean model mineral suspensions and complex ultramafic nickel ores confirm that conventional water-soluble molecular collectors could be partially or completely replaced by colloidal hydrophobic nanoparticle flotation collectors.
The ability of nanoparticles to induce flotation has been demonstrated by floating hydrophilic, negatively charged glass beads with cationic polystyrene nanoparticle collectors. Mechanisms and key parameters such as nanoparticle hydrophobicity and nanoparticle adsorption density have been identified. Electrostatic attraction promotes the spontaneous deposition of the nanoparticles on the glass surfaces raising the effective contact angle to facilitate the adhesion of beads to air bubbles. The pull-off force required to detach a glass sphere from the air/water interface of a bubble into the water was measured by micromechanics. Coating with nanoparticles allows the beads to attach remarkably firmly on the air bubble. As little as 10% coverage of the bead surfaces with the most effective nanoparticles could promote high flotation efficiencies, whereas conventional molecular collector requires 25% or higher coverage for a good recovery.
Contact angle measurements of modified glass surfaces with a series of nanoparticles that covered a range of surface energies were used to correlate the nanoparticle surface properties with their ability to promote flotation of glass beads. Factors influencing nanoparticle deposition on glass, such as nanoparticle dosage, nanoparticle size, conditioning time have been investigated with a quartz crystal microbalance (QCM).
Deposition kinetics has been analyzed according to Langmuir kinetics model.
Surface functionalized nanoparticles enhance the ability of nanoparticle collectors to selectively deposit onto surfaces of the desired mineral particles in the presence of gangue materials. Poly (styrene-co-vinylimidazole) based nanoparticle collectors have been developed to selectively deposit onto nickel mineral (pentlandite) in the presence of Mg/Si slime. Flotation tests of ultramafic nickel ores with these nanoparticle collectors have shown improvements in both pentlandite recovery and selectivity. However, costeffective applications of nanoparticle flotation collectors have yet to be identified.
-Nanotechnology and environment:
Nanotechnological products, processes and applications are expected to contribute significantly to environmental and climate protection by saving raw materials, energy and water as well as by reducing greenhouse gases and hazardous wastes. Using nanomaterials therefore promises certain environmental benefits and sustainability effects, which are outlined in this dossier. Note, however, that nanotechnology currently plays a rather subordinate role in environmental protection, whether it be in research or in practical applications. Environmental engineering companies themselves attach only limited importance to nanotechnology in their respective fields.
There are also some nanostructures with photocatalytic activity, like Zinc Oxide, applied for the treatment of environmental pollution (Sung et al. 2010). The nanomembranes, nanoadsorbents and nanostructures with photocatalytic activity can be used to purify indoor air volumes or to separate out contaminates in automobile tailpipes and factory smokestacks and prevent these contaminants entering the atmosphere.
One of the outstanding roles of nanotechnology is improving energy and resource efficiency in the chemical industry. The explosion and developments in nanotechnology have exhibited significant impacts on the understanding, practice and applications of catalysis. Nanocatalysts can be used to increase the yield of chemical reactions and reduce the amount of environmentally damaging side products. Catalysis provides controls over the rates at which chemical bonds are Typical structures of nanomaterials with potential applications for adsorption: a dendrimer, b fullerene, c zeolite, d carbon nanotube 88 2 From Nanotechnology to Nanoengineering broken and formed. Therefore, it is the key to energy conversion and environmental protection in chemical manufacturing and transportation. In the chemical industry, nanocatalysts with improved properties boost energy and resource efficiency. High hopes are placed in nanotechnologically optimized products and processes for energy production and storage. Novel lighting materials with nanoscale layers of plastic and organic pigments enhance conversion rate from energy to light.