2011 Buyers' Guide 2011 Buyers' Guide - International Fiber Journal

ar graphs for article 1,1,1-Trichloroethane).Comparison of BET Surface Area, Total Pore Volume and High Adsorption Energy Pore VolumesSample BET Surface Total Adsorption High Adsorption Energy 20-29 (cal/cc)Number Area Sq meters/gram Pore Volume cc/100g Pore Volume cc/100gZ-261 278 16.14 0.83Z-262 274 15.87 0.79Z-263 293 17.18 0.80Z-264 238 13.55 0.78Z-265 307 17.01 0.03 Table 2.DISCUSSION OF RESULTSThe isotherms andtrichloroethane bar graphsclearly show sample Z-265 asthe poorest performer of thefive samples. Samples Z 261thru Z-264 were provided bythe project sponsor Aquamira Technologies.However, the total adsorptionpore volume, BET surface area and iodinenumbers are best for Z-265 asshown in Table 2. The BET surface areaand total pore volume correlate with theiodine number, so sample Z-265 wouldhave the highest iodine number. The adsorptionpotential energy and pore volumedistributions presented in Table 1provide the total pore volumes at adsorptionpotential and high energy porevolumes at cumulative adsorption potentials20 thru 29 cal/cc.The reason for this apparent performancediscrepancy between ASTMand GAED test results is the relative volumeof high adsorption energy pore volumesin the five samples. If only classicaltesting: BET surface area and iodinenumber were used the wrong carbonwould be chosen for trace organic removalbecause they only show the totalloading capacities. By also using GAEDit revealed the best vendors carbon fortrace aqueous organic removal applicationsbecause the high energy pore volumesare determined in addition to thetotal pore volumes. In trace contaminantapplications only the high energy bindingsites are used, which is a small partof the total pore volume.Aquamira Technologies provided thefirst four samples in the GAED tests. Thebest carbons have the higher adsorptionenergy binding sites. Aquamira sampleswere the best performing samples by afactor of 27. This relative performance isbased on equal weight of both sorbents.From a user viewpoint the best carbonwould last 27 times longer than the relativelypoor performer.It is important to use GAED advancedtesting methods as a second opinion. Werecommend using ASTM, AWWA tests,and GAED to solve problems. GAED canhelp solve real-world problems not solvableonly with standard methods asdemonstrated here. GAED provides alow cost way to obtain isotherms withbetter analytical precision.Prior testing of carbon blocks withGAED has demonstrated that granularactivated carbon particles combined withwww.filtnews.com • August 2010 • 23