Immense potential of geopolymeric nanomaterials for sustainability applications

Geopolymer has been extensively studied and utilized as “green cement” in addressing global warming issues, one of the most challenging problems in human sustainability. It is one of the few inorganic material systems that can be produced in a large scale and thus has a potential to truly address such large-scale problems. In connection to the innate “nano” properties of geopolymer materials, we present some of our new progresses in the pursuit of new geopolymeric aluminosilicate nanomaterials and their sustainability applications. We will first briefly describe syntheses and properties of three different types of the new nanomaterials (Figure 1) and will illustrate their uses. For example, nanoporous geopolymer materials could be produced and used as an excellent arsenic absorbent for ground water purification and as a highly effective biodiesel catalyst. High-structure geopolymer nanoaggregates can be synthesized with controlled zeolicity for polymer nanocomposite applications with excellent energy-saving performances. Highly-crystalline hierarchical zeolites have been discovered to show an exceptional CO2 capacity, sorption kinetics, selectivity and regeneration capability essential for cost-effective CO2 separation. Superior ion exchange kinetics of the material has been observed for silver-ion zeolite with a superb antibacterial efficacy against antibiotics-resistant MRSA bacteria. Their out-of-the-lab usages are currently being realized in industry with future goal of megatonic production. Please click Additional Files below to see the full abstract

Iron oxide-modified nanoporous geopolymers for arsenic removal from ground water

Composite materials of hierarchically porous geopolymer and amorphous hydrous ferric oxide were produced and characterized as a new potentially cost-effective arsenic adsorbent. The arsenic removal capabilities of the iron (hydr)oxide (HFO) media were carried out using batch reactor experiments and laboratory scale continuous flow experiments. The Rapid Small-Scale Column Tests (RSSCT) were employed to mimic a scaled up packed bed reactor and the toxicity characteristic leaching procedure (TCLP) test of arsenic adsorbed solid material was carried out to investigate the mechanical robustness of the adsorbent. The best performing media which contained ~20 wt% Fe could remove over 95?µg of arsenic per gram of dry media from arsenic only water matric. The role of the high porosity in arsenic adsorption characteristics was further quantified in conjunction with accessibility of the adsorption sites. The new hierarchically porous geopolymer-based composites were shown to be a good candidate for cost-effective removal of arsenic from contaminated water under realistic conditions owing to their favorable adsorption capacity and very low leachability

Removal of turbidity from washing machine discharge using Strychnos potatorum seeds: Parameter optimization and mechanism prediction

AbstractIn this research an attempt has been made to utilize the Strychnos potatorum seed powder as an environmentally friendly coagulant for the removal of turbidity from washing machine discharge. The performance of this system was also compared with synthetic water. Experimental studies were conducted for the maximum removal of turbidity from washing machine discharge and synthetic turbid water which were varied from 50 to 145 NTU. The effect of operating parameters such as initial turbidity, S. potatorum dosage and pH of the solution was optimized for the maximum removal of turbidity. It was seen that the percentage removal of turbidity lay was between 68–89% and 65–84% for synthetic turbid water and washing machine discharge sample respectively, at an ideal pH of 6–7. The experimental values were compared with the Langmuir and Freundlich isotherm models to understand the extent of influence of the sorption of the particles onto the S. potatorum seed powder. Better results with respect to concordance of experimental data were observed with Langmuir isotherm model, indicating a monolayer sorption of particles onto the S. potatorum seed powder. It was observed from the isotherm study that the sorption may also be influenced in the removal of turbidity to some extent from the washing machine discharge and synthetic water. The prepared material can be effectively utilized for the removal of turbidity from the water

Iron oxide-modified nanoporous geopolymers for arsenic removal from ground water

AbstractComposite materials of hierarchically porous geopolymer and amorphous hydrous ferric oxide were produced and characterized as a new potentially cost-effective arsenic adsorbent. The arsenic removal capabilities of the iron (hydr)oxide (HFO) media were carried out using batch reactor experiments and laboratory scale continuous flow experiments. The Rapid Small-Scale Column Tests (RSSCT) were employed to mimic a scaled up packed bed reactor and the toxicity characteristic leaching procedure (TCLP) test of arsenic adsorbed solid material was carried out to investigate the mechanical robustness of the adsorbent. The best performing media which contained ~20 wt% Fe could remove over 95 µg of arsenic per gram of dry media from arsenic only water matric. The role of the high porosity in arsenic adsorption characteristics was further quantified in conjunction with accessibility of the adsorption sites. The new hierarchically porous geopolymer-based composites were shown to be a good candidate for cost-effective removal of arsenic from contaminated water under realistic conditions owing to their favorable adsorption capacity and very low leachability

Aminated glycidyl methacrylates as a support media for goethite nanoparticle enabled hybrid sorbents for arsenic removal: From copolymer synthesis to full-scale system modeling

AbstractTo achieve short mass transfer zones that enable arsenic removal under high hydraulic loading rates and short empty bed contact times needed for small point-of-use packed bed applications, hybrid media was developed and tested. Cross-linked macroporous glycidyl methacrylate copolymer support media was synthetized, amino modified and in-situ impregnated by goethite nanoparticles via an oxidative deposition in a hydrophilic/hydrophobic (water/xylene) system. The media properties were characterized via scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), X-ray diffraction (XRD), and surface area analysis. Arsenic removal capabilities of the hybrid goethite impregnated media were evaluated by conducting batch sorption tests, developing isotherms and simulating the breakthrough curve with a pore surface diffusion model (PSDM), after being verified by a short bed column (SBC) test. The high porous media (ep ≈ 0.7) contained ∼16% of iron and exhibited Freundlich adsorption capacity parameter of K ≈ 369 (µg g−1)(L µg−1)1/n and Freundlich intensity parameter of 1/n ≈ 0.54. Without engaging in taxing pilot scale testing, the PSDM was able to provide a good prediction of the media's capacity and intraparticle mass transport properties under high hydraulic loading rates