Fred S. Cannon

A QSAR-like analysis of the adsorption of endocrine disrupting compounds, pharmaceuticals, and personal care products on modified activated carbons

Rapid small-scale column tests (RSSCTs) examined the removal of 29 endocrine disrupting compounds (EDCs) and pharmaceutical/personal care products (PPCPs). The RSSCTs employed three lignite variants: HYDRODARCO 4000 (HD4000), steam-modified HD4000, and methane/steam-modified HD4000. RSSCTs used native Lake Mead, NV water spiked with 100-200 ppt each of 29 EDCs/PPCPs. For the steam and methane/steam variants, breakthrough occurred at 14,000-92,000 bed volumes (BV); and this was 3-4 times more bed volumes than for HD4000. Most EDC/PPCP bed life data were describable by a normalized quantitative structure-activity relationship (i.e. QSAR-like model) of the form: where TPV is the pore volume, rho(mc) is the apparent density, CV is the molecular volume, C(o) is the concentration, (8)chi(p) depicts the molecules compactness, and FOSA is the molecules hydrophobic surface area.

Changes in GAC pore structure during full-scale water treatment at Cincinnati : a comparison between virgin and thermally reactivated GAC

During full-scale water treatment operation at the Richard Miller water treatment plant (Cincinnati, Ohio) we frequently evaluated the changes in pore volume distributions of a reactivated (F-400) granular activated carbon (GAC), as compared with that of its virgin counterpart. The reactivated GAC had experienced six cycles of water treatment and thermal reactivation. The reactivated GAC was slightly more effective at removing TOC (total organic carbon) than was the virgin GAC during the first half-year of service. Yet, the pore size distributions of the two GACs were very different. The virgin GAC was mostly microporous, with less mesopores. Conversely, the reactivated GAC was mostly mesoporous, with less micropores. For the virgin GAC, adsorption changed the volume of pores below 50 A in width most significantly, and there was minor change in pores larger than 50 A. In contrast, the reactivated GAC showed the greatest volumetric change in pores that were 100 to 500 A in width.

Characterization of organic matter from natural waters using tetramethylammonium hydroxide thermochemolysis GC-MS

Abstract The tetramethylammonium hydroxide (TMAH) thermochemolysis method was recently introduced for the qualitative characterization of organic matter from natural waters (NOM). Such characterizations were usually of a qualitative nature, and any semiquantitative assessments of individual compounds were often achieved by measuring relative areas and assuming unity as a response factor. In this paper we evaluate the quantitative measurement of many identified products characteristic of lignin and NOM using an internal standard approach. The relative standard deviation for most quantified compounds was between 1 and 10%. Four NOM samples, isolated by low-temperature, low-pressure evaporation and freeze-drying, were collected from temperate as well as tropical climates. Large variations were found between samples with respect to the distribution of compounds such as fatty acids, lignin-derived compounds, carbohydrate-derived compounds, and protein-derived compounds. We quantified most lignin-derived and aromatic TMAH products as well as fatty acids (as their methyl esters, FAME) that were found in this set of NOM samples. The contribution of lignin-derived compounds to the total quantified TMAH product distribution in these four samples varied between 21 and 35%. The contribution of FAMEs ranged from 32 to 51% whereas the contribution from non-lignin aromatic compounds was 24–32%. TMAH thermochemolysis potentially provides significant information about NOM sources, compared with other degradative techniques, since both lignin-derived compounds and lipids can be quantitatively and simultaneously investigated.

Reaction mechanism of calcium-catalyzed thermal regeneration of spent granular activated carbon

Thermal regenerations were conducted on a spent granular activated carbon (GAC) that had served in a water treatment plant for about four years and contained 1.8% calcium. Oxidation was conducted in steam, CO2, or steam plus CO2, at 650–950°C. As described earlier, when steam and CO2 were employed together, the regenerated products pore structure maintained greater micropore volume at high temperatures ( > 800°C) than at low temperatures (<750°C). The work herein has linked this distinction to differences in reaction rate limitations: at high temperatures, with both oxidants employed together, the water-gas shift reaction (H2O + CO = H2 + CO2) limited overall rate, whereas at low temperatures, the C(O) gasification step limited overall rate. The CO2 created via the water gas shift reaction served as the primary oxidant. Although steam served only as a secondary oxidant, its presence also facilitated more extensive oxidant transfer to the carbon surface.

Overcoming calcium catalysis during the thermal reactivation of granular activated carbon: Part I. Steam-curing plus ramped-temperature N2 treatment

Tailored thermal reactivations overcame calcium catalysis by first steam-curing spent GAG at 648 K for 60 min, and then thermally treating it in nitrogen under temperatures that ramped up to 1123 K, while some H2O remained temporarily sorbed within the GAC pores and the furnace enclosure. Pore volume distribution measurements using the density functional theory (DFT) software package revealed that this strategy increased the pore volume between 5.4 and 32 A when compared to that of its virgin counterpart, or when compared to those of spent GAGs that were conventionally reactivated. The 5.4–32 A pore range is important in terms of removing small organics from drinking water. These particular widths also represented convenient demarcations from our argon adsorption experimental protocol. The steam-curing plus ramped-temperature approach also achieved the same micropore volume (width <20 A) as that found in the virgin GAC, and also more pores between 5.4 and 100 A in width, when compared to its virgin counterpart. Pores between 5.4 and 100 A cover an important range for removing the full molecular size distribution of organics that enter a GAC bed during drinking water treatment.

Combined hydrous ferric oxide and quaternary ammonium surfactant tailoring of granular activated carbon for concurrent arsenate and perchlorate removal

Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid small-scale column tests (RSSCTs) with these dually prepared media employed synthetic waters that were concurrently spiked with arsenate and perchlorate; and these trial results showed that the quaternary ammonium surfactants enhanced arsenate removal bed life by 25-50% when compared to activated carbon media that had been preloaded merely with iron (hydr)oxide; and the surfactant also enhanced the diffusion rate of arsenate per the Donnan effect. The authors also employed natural groundwater from Rutland, MA which contained 60 microg/L As and traces of silica, and sulfate; and the authors spiked this with 40 microg/L perchlorate. When processing this water, activated carbon that had been tailored with iron and cationic surfactant could treat 12,500 bed volumes before 10 microg/L arsenic breakthrough, and 4500 bed volumes before 6 microg/L perchlorate breakthrough. Although the quaternary ammonium surfactants exhibited only a slight capacity for removing arsenate, these surfactants did facilitate a more favorably positively charged avenue for the arsenate to diffuse through the media to the iron sorption site (i.e. via the Donnan effect).

Applicability of adsorption equations to argon, nitrogen and volatile organic compound adsorption onto activated carbon

Abstract This research evaluates adsorption equations for argon, nitrogen, and volatile organic compound adsorption onto several commercially available activated carbons that represented a broad range of pore volume character, from predominantly microporous to predominantly mesoporous. For all these carbons, both the recently introduced (Paulson PD, Cannon FS, submitted to Carbon) Modified Freundlich equation and the Dubinin–Astakhov equation accurately characterized adsorption behavior in the relative pressure range of 1.0×10−5 to 0.1 for argon adsorption onto six different activated carbons and for nitrogen adsorption onto two different activated carbons. In particular, the Modified Freundlich equation offered a slightly better fit to the experimental data for mesoporous carbons in the full relative pressure range, and to all activated carbons in the relative pressure range of 10−2.5 to 0.1. Micromeritics’ density functional analysis software further used this argon and nitrogen adsorption data to characterize these activated carbons by their pore volume distribution. The Modified Freundlich’s v0MF term correlated best to the cumulative pore volume up to 60 A and the Dubinin–Astakhov’s v0DA term correlated best to the cumulative pore volume up to 30 A as determined via density functional theory. In addition, the research herein identified a consistency in the adsorption behavior of methylisobutylketone, m-xylene, and argon at their respective boiling points.

Advanced oxidant regeneration of granular activated carbon for controlling air‐phase VOCs

Abstract The Pennsylvania State University is researching an advanced oxidation (AO) system for controlling volatile organic compounds (VOCs) (Cannon et al. 1994). The system includes an air‐phase photolytic chamber, an air/water stripping tower, and granular activated carbon (GAC) beds, and the work herein describes he evaluation of the GAC beds. Field GACs have been evaluated, which had previously been loaded with VOCs and regenerated with AO for several years at several full scale installations. Full scale response then was simulated in laboratory‐scale experiments. Results revealed that following 500 to 1000 daily loading and regeneration cycles, one field GAC lost 35% of its micropore volume, and 17–35% of its capacity to adsorb several VOCs. Under another condition, for a furniture coating GAC, 80% of the micropore volume was lost after several years of loading and reactivation cycles, and 23 to 63% of the VOC adsorption capacity was lost. Laboratory results revealed that prolonged AO regeneration d...

A continuous pilot-scale system using coal-mine drainage sludge to treat acid mine drainage contaminated with high concentrations of Pb, Zn, and other heavy metals

A series of pilot-scale tests were conducted with a continuous system composed of a stirring tank reactor, settling tank, and sand filter. In order to treat acidic drainage from a Pb-Zn mine containing high levels of heavy metals, the potential use of coal-mine drainage sludge (CMDS) was examined. The pilot-scale tests showed that CMDS could effectively neutralize the acidic drainage due to its high alkalinity production. A previous study revealed that calcite and goethite contained in CMDS contributed to dissolutive coprecipitation and complexation with heavy metals. The continuous system not only has high removal efficiencies (97.2-99.8%), but also large total rate constants (K(total), 0.21-10.18h(-1)) for all heavy metals. More specifically, the pilot system has a much higher Zn(II) loading rate (45.3gm(-3)day(-1)) than other reference systems, such as aerobic wetland coupled with algal mats and anoxic limestone drains. The optimum conditions were found to be a CMDS loading of 280gL(-1) and a flow rate of 8Lday(-1), and the necessary quantity of CMDS was 91.3gL(-1)day(-1), as the replacement cycle of CMDS was determined to be 70 days.

Comparison of Hydroxyl Radical Generation for Various Advanced Oxidation Combinations as Applied to Foundries

The authors monitored hydrogen peroxide (H2O2), ozone (O3), and apparent hydroxyl radical (OH·) concentrations in the liquid phase, along with gas phase ozone when operating an advanced oxidation (AO) system that included H2O2, O3, sonication, and underwater plasma (UWAP). The OH· radical converted non-fluorescent terephthalic acid to fluorescent hydroxyterephthalic acid (HTA). As determined from HTA formation, when a 500 ppm H2O2 dose in tap water was combined with O3 and sonication, nearly twice as much OH· (0.72 ppm) accumulated than with H2O2 alone. When UWAP accompanied H2O2, O3, and sonication, these together generated 15–35% more OH· than when UWAP was excluded. When ozone was introduced into this AO system, the AO system decomposed almost all the O3. This research has been conducted as a part of a study that has appraised this advanced oxidation system (Sonoperoxone) in green sand foundries, where it has diminished volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions by 20–75%; and clay and coal consumption by 20–35%.