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

Abstract

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.

Three-dimensional, printed water-filtration system for economical, on-site arsenic removal

“…Even when iron (III) oxide was used in such studies, various maximum adsorption capacities were reported depending on which supporting material was used. As shown in Table 2, various maximum adsorption capacities [16,17,19,52,53] that depended on the supporting material have been reported for an iron-oxide absorbent, and the 3D, printed PLA filter used in this study was found to be very good for removing As (III) from contaminated water.…”

The effect of metal (hydr)oxide nano-enabling on intraparticle mass transport of organic contaminants in hybrid granular activated carbon

“…Samples were continuously agitated for a period of 3 days at T = 20 ± 2 °C, prior to filtering through a GF/F membrane. This contact time was found sufficient for pseudo-equilibration of occur (Hristovski et al, 2008b;Medpelli et al, 2015). The equilibrium concentrations of the model dyes were determined via UV/VIS spectroscopy (Genesis 20 UV/VIS spectrophotometer) at λ METHYL ORANGE = 464 nm and λ METHYLENE BLUE = 665 nm.…”

“…Nanotechnology has demonstrated a great potential for resolving major challenges associated with existing small-scale water treatment systems by exploiting the unique size-dependent characteristics of nanomaterials to develop novel high-performance nanoenabled sorbents or catalysts (Qu et al, 2013a). Frequently, nanomaterials are embedded inside commercially available macroporous adsorbents or ion-exchange resin to 1enable simultaneous removal of multiple contaminants with different chemistries; 2reduce the size and complexity of the sorbent systems by eliminating the need for multimodular solutions; and (3) minimize the operations and management (O&M) requirements of a small-scale water treatment system (Savagel and Diallo, 2005;Sylvester et al, 2006;Hristovski et al, 2008a;Lin and SenGupta, 2009;Ali, 2012;Xu et al, 2012;Medpelli et al, 2015;Dale et al, 2016). Because of these attributes, the nanoenabled hybrid sorbents appear to be particularly advantageous for uses in small, rural, and poor communities of developing countries, which do not have the finances or technological know-how to employ a complex centralized solution for treating water sources contaminated with multiple contaminants (Sarkar et al, 2007;Shannon et al, 2008;Brame et al, 2011).…”

3D structure of oil droplets in hardened geopolymer emulsions

“…Composite materials made of geopolymer (GP) cement and organic liquids (oils) have been proposed recently for the synthesis of porosity‐controlled media, for example, as thermal insulating foams or filtration supports, for the management of radioactive organic liquid waste, and as phase change materials (PCM)…”

“… after GP hardening and oil washing, the method provides hierarchical meso and macroporous materials, with spherical macropores on the order of 20‐50 μm associated to 2 μm pores on the macropore walls, and GP mesopores (smaller than 50 nm). They have proven efficient for arsenic filtration from underground waters or for filtering organic dyes from aqueous solutions …”