1、m 9009276 0025422 704(b ANSVASTM D 2355-70(Reapproved 1976)Standard Recommended Practice for LIQUID PHASE EVALUATION OF ACTIVATED CARBON This Standard is issued under the fixed designation D 2355;the number immediately following the designation indicates the year of ori&nal adoption or,in the case o
2、f revision,the year of last revision.A number in parentheses indicates the year of last reapproval.1.scope 1.1 This recommended practice is a general procedure for the evaluation of a test acti-vated carbon versus a reference activated car-bon by the adsorption isotherm technique.It is intended to p
3、rovide a common basis for developing evaluation procedures for acti-vated carbon in liquid phase applications.The basic procedure,called the Adsorbate Rela-tive Efficiency Test,has as its objective the determination of how much test carbon is required to remove a stated percentage(Note)of the impuri
4、ty from an appropriate quantity of a standard test solution as compared to the amount of a reference carbon required to achieve the same degree of purification.NOTE-The example cited in Sections 7 and 8 is based on 90 percent removal of impurity.1.2 If the weight of a reference carbon is M,and the w
5、eight of test carbon is M,then the relative efficiency RE,of the test carbon is as follows:RE=(M,/M,)X 100 1.3 The procedure to be described applies to either powdered or granular activated car-bon.This test applies in practice only when the same degree of equilibrium is obtained in the test as in p
6、ractice.When granular carbon is to be tested by this procedure,a sufficiently long contact time should be allowed to reach equilibrium.Alternatively,the granular car-bon may be pulverized so that all of it passes through a No.325(44-gm)sieve in order to shorten the required contact time to reach equ
7、ilibrium.2.Test Solution 2.1 The test solution shall be a standard solution appropriate to the industry in which the carbon is to be used,if and when a specific industry has established a standard test solu-tion;otherwise,the test solution shall be rep-resentative of the process stream.Both the conc
8、entrations of the impurity and solute and the pH value of the test solution should be standardized.2.2 An appropriate aliquot quantity of said test solution shall be used to obtain two four-point adsorption isotherms and for two blanks.3.Apparatus 3.1 The apparatus required for carrying out this pro
9、cedure shall be compatible with the operating conditions existing in each specific industry.4.Activated Carbon Dosage 4.1 Weigh the carbons on an“as is”basis to the nearest I mg.Determine the moisture;the final results can then be expressed both on an“as is”basis and on a dry basis.4.2 The weights o
10、f a reference carbon must be fixed for each given test solution by prede-termining what dosages are required to obtain an adsorption isotherm over the desired puri-fication range.4.3 The weights of the test carbon must be estimated,since its relative efficiency(RE)is not known.For the present exampl
11、e,it will be assumed that the test carbon is 150 RE and therefore lower dosages will be required to This recommended practice is under the jurisdiction of Current edition effective March 19,1970.Originally is-ASTM Committee D-28 on Activated Carbon.sucd 1965.Replaces D 2355 65 T.339 NOTICE:This stan
12、dard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.9009276 0025423 640 m 4CTb cover the desired purification range.4.4 The dosage schedule shall be as given in Table i.4.5 Weigh the dosages into an appropri
13、ate vessel containing the respective aliquots of the test solution.5.Contact Between Carbon and Solution 5.1 Place the carbon slurries and the blanks into a suitable agitator designed to keep the carbon in suspension at a designated tempera-ture for.a prescribed time necessary to achieve practical e
14、quilibrium.Both the time of contact and temperature shall be made the subjects of separate studies to optimize these conditions for a given application.6.Filtration 6.1 Proper filtration procedure is manda-tory to ensure that a clear brilliant filtrate,free from carbon fines or turbidity,is availa-b
15、le for subsequent analysis of the filtrate.6.2 The conditions of filtration must be determined for each application.6.3 The filtering medium should not im-part,interact with,or remove impurities from the test solution.D 2355 K and i/n are constants for a given adsorp-8.2 If the Freundlich equation i
16、s expressed tion system.logarithmically,log(X/M)=log K+i/n log Ci then it has the form of a straight-line equa-tion,y=o+b x 8.3 Hence,if log(X/M)is plotted against log Ci on rectangular paper,a straight line will normally result.Or,more conveniently,if X/M is plotted against C,on log-log paper,a straight line will also result.8.4 An example is illustrated in Fig.1,on using data taken from Table 2.On Fig.I,the dry basis X J M values for each carbon are plotted against C,.Two adsorption isotherms