Adsorptive capacities of activated carbon for organic constituents of wastewaters

Abstract

The adsorptive capacities of activated carbon for major organic constituents (target compoun8s) of a wide variety of wastewater were measured in pure water and in actual ioastewater samples. Competitive adsorption due to the presence of other organic compoolentg of total organic carbon of the wastewater (background TOC) reduced carbon capacities for aU target compounds in the wastewaters from the respective pure water isotherms. The capacity reduction for a target compound was found to depend on the relative adsorptivity of the target compound versus competing compounds (poorly adsorbed TOC components produced a small reduction in capacity for a more strongly adsorbed target compound), and the fraction of the background TOC attributable to the target compound.Those findings were validded by carbon column adsorption breakthrough duta.

Granular activated carbon adsorption process for removing trichloroethylene from groundwater

“…15 After the carbon particles and the TCE solution were mixed for a given time (2,4,6,12, and 48 h), the rotation was stopped, and then the bottles were placed vertically to allow the particles to settle. TCE of the clear supernatant was extracted by hexane and then measured by GC/ECD.…”

Improved methods for carbon adsorption studies for water and wastewater treatment

“…It is clear that granular carbon treatment technology is more efficient in an application that requires a very high degree of target compound removal. Indeed, the granular carbon treatment process has been successfully used in meeting effluent discharge limits of Ͻ1 part per billion (ppb) [5,7]. Figure 1 presents relationships of capacity utilization rates of different breakthrough curves and the carbon bed change criteria.…”

“…Standard procedures, with improvements such as smaller-size samples, were used for the iodine and methylene blue runs [1,4,7,8,13,14]. All isotherm experiments used a head-to-bottom rotation method [5], to provide effective mixing for the carbon particles (Ͻ180 mesh) and the test solutions; the time required to establish the equilibrium condition was determined for each adsorbate, such as 2 h for phenol, 8 h for methylene blue, and 12 h for tannic acid. The test results, adsorptive capacity (X/M) and final residual (equilibrium) concentration (C f ), were correlated by the Freundlich adsorption isotherm and plotted with the data for easy comparison of relative capacities.…”

“…These isotherms allow easy compari- Table 4 presents the definition, application, and conversion formulas for the four capacity indicators. Table 5 presents the experimental procedure and data for calculation of phenol number; a similar table can be used for isotherm runs for tannic acid (for calculation of tannic acid number), other organic compounds of interest, or gross organic concentration parameters such as total organic carbon (TOC), chemical oxygen demand (COD), and light absorbance at a specific wavelength [1,4,5,11]. A carbon slurry was used to introduce very small amounts of carbon; otherwise, pulverized carbon may be added directly to the test sample.…”

“…Depending on the nature of the pollutants (volatility, adsorbability, biodegradability, and concentration in the feed), sample availability, type, and scale of the study (on-site or off-site, bench or pilot study), the most effective breakthrough experiments may use small and mini size traditional or pressurized micro carbon columns [1,2,[5][6][7]. Although carbon columns of different sizes have all been used with varying degrees of success, there is yet no report of how to conduct the most cost effective breakthrough experiments for a specific application.…”