Selecting activated carbon for water and wastewater treatability studies

Abstract

A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters <10, 10-15, 15-28, and >28 A˚, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection. A comprehensive table of iodine, phenol, methylene blue, and tannic numbers of common activated carbons is a useful database to environmental professionals for selecting few high-potential activated carbons to be evaluated in an efficient water/wastewater treatability study.

Adsorption of methyl tert-butyl ether (MTBE) from aqueous solution by porous polymeric adsorbents

“…Adsorption isotherms of MTBE over the polymeric adsorbents at 298 K. the postcrosslinked polymer has the highest adsorption capacity towards aqueous MTBE. Note that Huajing GAC used in this study had a BET surface area of 661.3 m 2 g −1 , whereas commercial activated carbons with surface area more than 800 or even 1000 m 2 g −1 demonstrated much higher adsorption capacity for MTBE [11,12]. Taking the manufacturing costs into consideration, the postcrosslinked polymer is not yet cost competitive relative to activated carbon.…”

“…A large amount of adsorption isotherms as well as breakthrough curves [11,12,15,17] were compiled and used to characterize the adsorption properties. Among the potential adsorbents for the abatement of aqueous MTBE, synthetic resin adsorbents with high surface area and tunable pore structure have proved to be the promising candidates [20].…”

“…Adsorption treatment using porous materials such as activated carbon [7][8][9][10][11][12], zeolites [7,13,14] and synthetic resins [8,[14][15][16][17][18][19] has been adopted to remove aqueous MTBE. A large amount of adsorption isotherms as well as breakthrough curves [11,12,15,17] were compiled and used to characterize the adsorption properties.…”

Granular activated carbon adsorption process for removing trichloroethylene from groundwater

“…12,14 Batch activated carbon-solution contact runs were first conducted to obtain the four adsorptive capacity indicators of the GAC samples using the established procedures.…”

Enhanced carbon adsorption treatment for removing cyanide from coking plant effluent

“…The pairs of X/M & C f were correlated by the Freundlich adsorption isotherm model: X/M = kC f 1/n . The experimental data and the model best-fit straight lines were plotted as the isotherms in log-log scale[24,33].…”