The primary goal of this study was to examine the feasibility of using Pore Surface Diffusion Model (PSDM) as a rapid screening tool to predict breakthrough curves of short bed columns packed with nanomaterial enhanced hybrid-ion exchange media. A novel hybrid-ion exchange media was fabricated by synthesizing titanium dioxide nanostructured endoskeleton inside nitrate selective strong base ion-exchange resin. The properties of the hybrid media were characterized and batch reactor tests were conducted with arsenate (As) and nitrogen-nitrate IJNO 3 − N) as model contaminants in 5 mM NaHCO 3 buffer ultrapure water at final pH = 7.2 ± 0.3 to assess the contaminant removal capacity and develop sorption isotherms. Freudlich sorption isotherm (q = KC e 1/n ) model was used to provide inputs for the PSDM predictions of the contaminants' breakthrough curves. To validate the PSDM breakthrough curve predictions for both model contaminants, continuous short bed packed column tests were conducted under the modeled conditions. Hybrid media regeneration was also conducted with solution mix of 2% KOH and 1% KCl followed by rinse with 0.1% HCl, and the column was operated under same conditions to assess the regeneration efficiency of the media. The results demonstrated that 100% regeneration efficiency could be achieved for nitrate, while only 75% efficiency could be achieved for arsenate under these regeneration conditions. The PSDM was able to successfully predict the breakthrough curves for arsenic and nitrate with relatively high precision, characterized by R 2 ≈ 0.977 and R 2 ≈ 0.930 for arsenate and nitrate, respectively. 448 | Environ. Sci.: Water Res. Technol., 2015, 1, 448-456 This journal is
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.
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 g 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.
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