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 destroyed or desorbed most of the MIBK within the first inch of a GAC bed. AO regeneration also removed a fourth of the MIBK in the next five inches of the packed GAC bed. Several byproducts were created by the MIBK destruction, which generally contained one-to-three fewer carbon atoms than does MIBK, and also contained more oxygen functional groups. 417 Downloaded by [Monash University Library] at 20:06 03 February 2015 418 F.S. Cannon et al.Concurrent with these experiments, thermogravimetric analysis (TGA) tests were performed to evaluate the rate and extent of MIBK adsorption onto virgin GAC, and revealed that the MIBK adsorption capacity was fairly insensitive to the ranges of concentration and temperature that were employed. A modeling analysis of the diffusion characteristics onto virgin GAC revealed that during the time frame of three to five hours, the mass transfer rate appeared to be governed by restricted diffusion.

Effect of Advanced Oxidants Generated Via Ultraviolet Light on a Sequentially Loaded and Regenerated Granular Activated Carbon Biofilter

“…and, for all practical purposes, was completely removed by 3 in. 28 This penetration became greater with prolonged exposure of the dry GAC bed to O 3 and AO.…”

“…The reasons for this enhanced removal stems both from (1) the ability of the AO and O 3 to convert a fraction of the MIBK to smaller and more oxygenated byproducts, and (2) the influence that AO and O 3 have in causing MIBK to desorb from the GAC surface. 25,27,28 These features are limited by the extent to which O 3 and AO can penetrate into the GAC bed.…”

“…25 This also created a total advanced oxidant concentration of 6920 -11,540 ppm as O 3 , 25,27 as determined by the idometric method. [27][28][29] The total advanced oxidants that the iodometric method will monitor include hydrogen peroxide, OH*, HO 2 * O 3 , and a host of radical scavengers (but it will not monitor O 2 ). The O 3 and advanced oxidant levels were at the high end of this range when a new UV bulb was installed, and the levels decayed to the lower levels as the bulb life progressed.…”

Ozone Injection into an Activated Carbon Bed to Remove Hydrogen Sulfide in the Presence of Concurrent Substances

“…Hwang et al 12 examined the use of ozonation in addition to granular activated carbon adsorption and aerated biofilters for removing dissolved odorous compounds in wastewater. Cannon et al 13 and Dusenbury and Cannon 14 reported regeneration of activated carbon for volatile organic compound (VOC) control by an advanced oxidation process utilizing hydroxyl radicals originating from ozone. The reaction of ozone with H 2 S in the air phase is expressed by the following equation: 15,16 …”

Determination of the Adsorption Isotherm of Vapor-Phase Mercury Chloride on Powdered Activated Carbon Using Thermogravimetric Analysis

“…For instance, TGA has been used to determine reaction rate and to establish kinetic models during the pyrolysis of waste tires 17 and both the adsorption rate and the kinetic models of volatile organic compounds by activated carbon. 18 However, the use of TGA to investigate the adsorption by activated carbon of heavy metals is uncommon. Therefore, this study aimed to apply the TGA technique to measure the adsorptive capacity of HgCl 2 (which is the predominant species of mercury emitted from MSW incinerators) on PAC, to evaluate the influence of adsorption temperature on the adsorptive capacity of PAC, and to investigate the adsorption isotherms of HgCl 2 on PAC.…”