Tyndallmetric Examination of Filtered Liquors A. B. CUMMINS AND M. S. BADOLLET, Johns-Manville Research Laboratories, Manville, N. J.
M
OST filtering operations are carried out for the purpose of removing suspended solid matter from the dispersion medium. While in many cases the primary object of the filtration is to dewater the solids as effectively as possible or to secure a liquid only relatively free from the dispersed phase, there are also many filtrations in which the principal objective is to remove as effectively as possible all traces of solids from the liquid medium. In both classes of filtrations the rate of flow is highly important, and numerous investigations which have been carried out from both theoretical and practical standpoints have been of great value to the filtration engineer (1, 6, 18, 26). However, relatively little work has been reported on the effectiveness of filtration as determined by the quality of the filtrate. This latter is of the utmost importance in the numerous types of filtrations carried out primarily to obtain a high degree of purification or the nearly complete removal of solids and colloidal matter from the liquid. The effectiveness of a filtration as determined by the extent to which suspended solids have been removed is judged ordinarily and most readily by the appearance of the filtrate, which may be described as turbid, cloudy, hazy, clear, brilliant, sparkling, etc. More precise evaluation has been impossible in most cases because of the lack of suitable test methods and instruments for examining filtrates. Nephelometric and turbidimetric methods have been fairly satisfactory only for comparatively cloudy filtrates and for unfiltered liquids (8-16). Very clear or brilliant filtrates on the other hand have offered great difficulties and most measurements have been made by comparison methods which are essentially qualitative in nature and which depend to a l a r g e extent upon the opinions and the judgments of the individual o p e r a t o r s . For the examination a n d comparisons of very “clean” filtrates a d v a n t a g e must be taken of the Tyndall beam p r i n c i p l e i n order to show up the minute t u r b i d i t i e s VIEW OF FIGURE1. GENERAL present. Tyndall beam measurements have been made in a quantitative manner for a number of dispersed systems (1-5, 7, 17, 19-24, 26, 27-33). None of the methods Or apparatus described, has been particularly suitable for the clarity examination of highly clarified liquid media. T K ~paper is a preliminary reporton an apparatusand a method developed specifically for the quantitative examination of filtered or highly clarified liquids. Because of the small amount of turbidity in such liquids, the great variation in their character, the presence of color, and especially because of the necessity for the precise determination of small differences, this problem has presented considerable diffi-
oulty. The method and apparatus as developed have been useful in both theoretical and practical investigations on filtration, in the solution of specific filtration problems, and in the evaluation of filter aids and their effect on filtration. An objective of the study has been to provide an apparatus of high accuracy and yet one sufficiently simple and inexpensive to be suitable for use a t filter-press stations as well as in the laboratory. Further investigations are now in progress, intended to make further improvements of the apparatus, and include studies of a wide range of industrial filtrations.
DESCRIPTION OF APPARATUS The principle of the method is to measure photometrically the intensity of the Tyndall beam produced in the filtrate by passing into it, under standard conditions, a controlled and constant light beam. The turbidity or clarity is expressed directly in photometric units. The apparatus consists essentially of a constant primary light source, an appropriate optical system for the incident beam, a suitable mounting for the cell containing the liquid, an optical system for the examination of the Tyndall beam, and an appropriate photometric measuring system, which may provide for the direct comparison of the Tyndall beam with a secondary standard light source, with a split beam from the primary light source, or by the use of the photoelectric cell or the photographic plate. In the apparatus described, the first method has been used. The Macbeth illuminometer (Leeds and Korthrup Company) has been satisfactory for most mmoses and is shown here as one of the simplest and least expensive set-ups tried (Figure 1). The cell containing t h e liquid to be examined is,placed in a holder indicated at C, suspended from an acc u r a t e mechanical stage which permits the movement of the cell in two directions (parallel and at 90’ to the path of the incident light beam). T h e e x a c t position of the cell is read by vernier scales. PHOTOMETRIC TYNDALLMETER The cell is of plane-surfaced optical glass. The tube B houses the optical system for the incident light beam. A , the primary light source, is a 6-volt, 5-ampere concentrated filament lamp, mounted in such a manner as to be centered accurately by means of three set screws. It may also be focused and clamped securely in position when the proper focus is secured. For maintaining a constant light intensity from this bulb a strictly uniform current must be supplied to the filament. This is provided from ordinary 110-volt alternating current by of the control panel K which is provided with a transformer, variable resistances, ballast tube, and suitable voltmeters and ammeters. Satisfactory constant current can be secured also from fully charged storage batteries of large capacity. The incident beam o tical system consists of lens La, lens Lg, slit 8, and lens La. TEe latter twolenses and the slit may be focused by adjustments in their positions, as indicated by knobs
328
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INDUSTRIAL AND ENGINEERING CHEMISTRY
1, 2, and 3. The width of the slit opening is also adjustable in a vertical position by knobs 4 and 5 located on op osite sides of tube B. The incident light beam is aligned with t i e axis of the emergent beam optical system by means of knob 6. The emergent or Tyndall light beam system is housed in tube E and in the Macbeth illuminometer head. Lenses L1 and Ln are located in E as i n d i c a t e d . The LummerBrodhun Dhotometric cube is located a t P and lens La is-located in the telescope supplied with the Macbeth instrument. The Macbeth illuminometer H consists of the head containing the photometric cube, the telesco e for viewing the illuminated fields to be matcffed, and a t u b e that contains a diaphragmed carriage in which is mounted a small bulb which is the comparison light source. The position of the lamp carriage is adjustable by a rack and pinion upon which is engraved a direct reading scale calibrated in foot-candles. The intensity of the comparison light is therefore controlled by the distance of the bulb from the photometric cube the scale following the inverse square law. The comparison lam is s t a n d a r d i z e d by reference to a standarf light source. The control instrument for the Macbeth reference lamp is shown as M .
In operation the e m e r g e n t Tyndall beam from the liquid under examination is projected and uniformly d i s t r i b u t e d over the inner c i r c l e of t h e Lummer-Brodhun cube. The outer circle is illuminated by the reference light of the Macbeth instrument. The intensity of the outer circle is adjusted to match the intensity of the inner circle and the value of the intensity of the emergent beam is read directly from the calibrated scale. Photometric matches are readily obtained and can be checked with accuracy by various operators. Provision is made for measuring wide variations in intensity by the use of calibrated neutral screens and for the m a t c h i n g of colored light by the use of suitably selected color screens.
329
By studying the course of the rays in Figure 2, the method of obtaining this double uniformity of illumination is clearly demonstrated.' The line A B represents the size of the Tyndall beam covered by lens L1. The two rays 1, 1 proceed from point A to points n and b, the opposite sides of lens L1. Likewise, the two rays 2,2 proceed from B to points a and b. Stated in another way, the light which emanates from point A and which lies within the angle formed by rays 1, 1 is uniformly distributed over the lens L,and the light which emanates from the point B and which lies within the angle formed by rays 2, 2 is also uniformly distributed over lens L1. It follows that light which emanate8 from all points between A and B also fills lens L1 uniformly. Therefore, as the intensity of illumination a t each point on lens L1 is a resultant of the light from all points between A and B, the intensit a t all points on lens L1will be equal, no matter how much t l e light varies in intensity from point to point between A and B, and therefore lens L1is uniformly filled with light. Rays 1 , 1 proceed from lens Lt as rays I,, l b and are united a t point A' in the plane IO,to form an image of A . Rays 2, 2 proceed from lens L1as rays 2,, 2b and are united a t point B', in the plane Io. Lens L1 is laced a t twice its focal length from the Tyndall beam afid theregre the image plane Iois a t twice the focal length on the other side of lens L1 and the image A'B' is equal in size to A B .
R
B
C
FIGURE2.
OPTICAL
DIAGRAM OF TYND.4LLMETER
Rays 1, and 1 b proceed from A' to lens Lz and from there they are projected parallel. Rays 2, and 2b proceed from B' to lens Lnand from there are projected parallel. The arallel rays 1 , and l b intersect the parallel rays 2, and 2 b in tRe plane I L , ray lointersects ray 2. a t a' and ray l b intersects ray 2b at b'. plane of the exit pu il of lens La all the figit from the filament This establishes the two conditions for uniformity of illumination is collected in a smalfcircle and all the rays from any point on the of the image a'b'. First, as the rays from point A' and from filament are traveling parallel. This forms a uniform circle of point B' and consequently from all other points on A'B' are light of maximum intensity and the slit S is placed therefore to traveling as parallel bundles, and as each parallel bundle covers coincide with this circle. Lens Le projects a reduced image of the image a%',the latter must be uniformly illuminated. Second, this intensely illuminated slit in the cell C containing the liquor. the rays l,, 2, proceeding from point a on lens L1 intersect a t The emergent Tyndall light from the cell is collected by lens a' to form an image of a; the rays l b , 2 b proceeding from point L1and imaged in the plane IO(A'B'). A diaphragm is inserted b on lens L1 intersect at b' to form an image of b; consequent1 at this point to block out all light from the Tyndall beam except a uniformly illuminated image a'b' is formed of the uniform$ for a 2-mm. circle a t the center of focus of the incident beam. illuminated lens surface ab. Rays Id, 1 h ' continue traveling parallel to lens Ls and are The diaphragm indicated by the dotted line is inserted in the plane of the Tyndall beam image A'B'. As this image is equal therefore focused in the rear focal plane of Le at the point A". in size to the Tyndall beam itself, a 2-mm. diaphragm in the Similarly, rays 2,', 2b' are focused a t the point B". Therefore, plane A'B' is equivalent to an imaginary diaphragm of 2-mm. in the plane Io' an image A"B" of the image A'B' is formed. opening laced in the lane of the Tyndall beam. Lens Lzis This image is in the plane of the lens of $he eye. At the same located t i e distance o?one focal length from plane IOand its time from lens Lt to the plane lo*rays 1. and 2,' are traveling parallel and rays 1b' and 2b' are traveling parallel. Therefore, exit pupil lies slightly more than one focal length to the rearthat is, in the plane IL. In this plane the light from the Tyndall as the lens of the eye is focused for parallel light, rays 1,' and 2,' beam is focused as a uniformly illuminated circle. The plane of are united on the retina (plane I L ~ )a,t the point a" and rays the inner circle of the photometer cube P i s therefore in the plane 17,' and 21', are united a t the point b . Therefore, the retina receives a focused image of the uniformly illuminated inner circle of IL. The inner and outer circles of cube P are viewed by lens LS of the photometer cube. The optics of the comparison beam light is much the same as placed a t one focal length from At the exit pupil, each oint on the that of the emergent beam. The principal parts of the illumione focal length behind lens La, aly',",;skm two circles are parallel, and the lens of the eye !ked in this nometer H (Figure 1) consist of the movable light M attached plane adjusts itself for parallel light and focuses t i e two circles to the scale RR and the ground glasses 0 (Figure 2). The intensity of light emanating from the ground glasses is varied by on the retina. In the plane of the photometer cube IL, uniformity of illumina- moving the light M , the degree of intensity being read on scale tion is obtained simultaneously in two ways. First, the image RR. The ground glasses 0 scatter the light rather uniformly in all of the Tyndall beam which is not uniformly intense over its surface is focused by lens Lz a t infinity; therefore, in the plane directions and thus illuminate the reflecting surface in photometer IL, all rays from each point in the Tyndall beam are parallel cube P. For simplicity parallel bundles 4,, 41 and Bo, 31 are and the resultant image in this plane is a uniform circle of light. shown emanating from the ground glasses 0. As lens LIis adSecond, lens L2 focuses in the plane IL an image of lens L1 which justed for infinity focus, these ra s are imaged in the pupil of the eye A"B" as image 3 , 4 . A t txe same time, the c rays and d is a uniformly illuminated surface as &own in Figure 2.
ELEMENTARY OPTICSOF APPARATUS The image of the Elament F is focused by the double lens combination L, in the plane of the entrance u il of lens L5. In the
ANALYTICAL EDITION
330
rays are each traveling parallel. Therefore, the lens of the eye images cd on the retina as a ring of light surrounding the circle of light from the emergent beam.
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TABLE11. CLARIFICATION OF VARNISH DESCRIPTION OF SAMPL.
INTENBITY O F
TYNDALL BEAM Foot-candles
APPLICATION OF APPARATUS Clarity examinations of filtered liquids can be made with the apparatus described with both speed and accuracy. When the apparatus is in adjustment, determinations can be completed within an average of 2 minutes. The apparatus is highly sensitive, however, and care must be taken to have the cells and optical parts scrupulously clean when examinations are made in which small differences are significant. Examples are given below for a number of widely different types of filtration. In some of the examples the differences are considerable and the turbidities high, thus permitting relatively easy readings. I n others the differences and turbidities are small,
166
Original varnish unclarified Same, clarified by centrifuge (2500r. p. m., 30 min.) Same, gravity filtration with paper Same, vacuum filtration with triple thickness of paper Same, pressure filtration with diatomaceous filter aid
151
109 97 60
FILTRATION OF BEEFEXTRACT The clarification of biological extracts and pr-parations is a very difficult problem because‘ of the type of impurities present. Table I11 gives the results of removing suspended material from beef extract by various methods. TABLE111. CLARIFICATION OF BEEFEXTRACT DESCRIPTION OF SAMPLES
INTENSITY OF TYNDALL BEAM Foot-candles
1 2 3 4 6
Unfiltered beef extract Filtered through two layers of flannel cloth Filtered through alundum crucible Filtered through cotton plug Filtered through diatomaceous filter aid
262 2 19 190 122 39
The above methods of removing suspended material show that greatly varying degrees of clarification are obtained by various means and that these differences can be measured tyndallmetrically. The clarification secured by the filter aid filtration is obviously superior. 01 60
50
40
3’0
m m M/MEN$TY
20
/O
60.
LI
0
GNUS]
FIGURE3 calling for refined work. It is for accurately measuring small differences in these low turbidities that the apparatus was specifically developed. CLARIFICATION OF WATER The use of the apparatus is shown by reference to a relatively simple type of clarification-i. e., in water purification. Comparisons are given in Table I for the turbidities of water purified by conventional methods. TABLEI. CLARIFICATION OF WATER
1 2 3 4
MISCELLANEOUS FILTRATIONS A number of other industrial filtrates are listed as a miscellaneous group and show interesting differences. The amounts of turbidity present in these materials vary considerably, as shown by the tyndallmetric data. At the start of a filtration cycle the degree of clarification is usually poor as compared with the final results; yet even at the start there is a very marked decrease in dispersed particles as shown by the Tyndall beam intensity of early fractions of filtrate as compared with the original liquors. The filtrates reported in Table IV were obtained from pressure filter press operations using Celite filter aids. TABLEIV. MISCELLANEOUS INDUSTRIAL FILTRATIONS (Tyndallmetric readings expressed as foot-candles) BEFORE STARTOF ENDOF HOUR FILTRATION CYCLE CYCLE
KINDOF MATERIAL Glue INTENSITY OF DESCRIPTION OF SAMPLE TYNDALL BEAM Wine Beer, Foot-candles Pectin Untreated t a water, Manville, N. J. 2.55 Coffee extract Same after &ration through Berkefeld filter 0.70 Dry cleaner’s solvent Same: after filtration throueh auantitative filter paper 1.15 Same; after treatment with alum and filtration through paper 0.57
.
High Tyndall beam intensities indicate greater turbidity. Within limits and for practical purposes the degree of clarification is inversely proportional to the intensity of the Tyndall beam. In making comparisons of this kind it is, of course, necessary to confine comparisons to liquors of the same general character. The results show that filtration through rigid, porous filters is highly effective, but that alum treatment is superior. Manville tap water is representative of average domestic water. Readings as above are accurate to 0.05 foot-candles. CLARIFICATION OF VARNISH I n the manufacture of high-quality varnish, clarification is necessary to secure the final “polish” or clarity desired. This clarification may be effected by the use of centrifugals or by pressure filtrations. A sample of good quality varnish was clarified by various means and examinations of the clarified varnish were made with the clarity apparatus. The results are shown in Table 11.
The samples of wine, glue, beer, and coffee extract examined exhibited very prominent Tyndall effects and after the start of the filtration cycle dropped to approximately the same clarification value. This would indicate that the easily removable suspended colloidal impurities are removed almost immediately, leaving the extremely small suspended particles to build up in the interstices of the filter cake and form a more impervious and effective filtering medium. This is shown by compbring the data a t the beginning and at the end of the filtration cycles. In all cases except pectin, the degree of clarification a t the end of the cycle is greatly improved. ACCURACY OF APPARATUS AND METHOD
The accuracy of the apparatus is shown by a series of tests made with a quartz suspension. (Figure 3) The quartz suspension was made by dispersing finely ground quartz in water. Then by settling and decantation, a fraction was secured containing only particles smaller than 0.25 micron in size. This fine dispersion was then diluted with turbidity-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
331
free water to give a series of dispersions containing definite and systematically varying amounts of particles, the size of which was the same for all dispersions. The results show that the Tyndall beam intensity is a direct function of the concentration of particles (number of particles per unit volume).
which are effectively removed only by a very efficient filtration. Small clarity differences are known to occur throughout the course of a filtration cycle, the clarity ordinarily improving regularly as the filter cake builds up. Table VI shows this change of clarity with the length of cycle for the three filter aids with three different raw sugars. APPLICATIONS OF CLARITY MEASUREMENTS TO CANE-SUGAR Particle counts are again given for reference. These results were obtained in a laboratory filtration under REFININGINDUSTRY the following conditions: Temperature, 80" C.; density of 111 the refining of raw sugar the importance of the liquor, 60" Brix; filter aid, 0.385 per cent on weight of sugar station in the refining process is fully recognized. Melted solids; length of cycle, 30 minutes; pressure, 10 to 40 raw sugar is difficult and expensive to filter and most refineries pounds at end of cycle, The above results were obtained in this country now depend entirely upon diatomaceous filter earlier in the development of the apparatus, and while of satisaids for the clarification of their sugar liquors. Special grades factory accuracy are subject to the objection that the intensiof these filter aids have been developed to meet particular ties of the Tyndall beams somewhat low for the ,,lose requirements. The degree of clarity of filtered raw sugar comparisons. liquors is highly important, aS Small differences in clarity Table VI1 gives the results of another series of tests made show UP strikingly in all subsequent refining steps, PartiCu- with an entirely different raw sugar but with the same filter lady in bone-char decolorization, in evaporating, in crystalliz- aids. In this case the apparatus used was exactly as shown in ing, in the final recoveries obtained, and in the quality of the ~i~~~~1, Clarity cuts in this were taken at refined sugar. Up to the present there have been no m&hods frequent intervals of the last 15 minutes of the 30-minute of clarity evaluation available to the sugar industry that have cycle, The tyndallmetric results are expressed here first as met adequately the requirements of sensitivity and accuracy. foot-candles intensity and then as the reciprocals of these As the apparatus described has been developed Principally values, which givesfigures that may be used more readily in for use in the sugar industry, some examples of its use in the expressing the clarities. solution of practical problems will be given. The differences between the degrees of clarity obtained with differentfilter aids and with a given raw sugar are shown TABLE 'I1* OF AQusTIN SuQAR CLARITY (RECIPROCAL in Table V. Similar figures are given for the count of colTIMEOF CLARITYTYNDALL BEAM OF TYNDALL loidal particles as measured bb an ultra-microscopic method FILTERAID CUT INTENSITY INTENSITY) recently developed at the Johns-Manville Research Laboratories. This method will be described in a subsequent paper. TABLEV. EXAMINATION OF 60° BRIXRAWSUQAR FILTRATES (15-30 MIN. FRACTIONS) CLARITY EXPRESSED AMOUNT AS TYNDALL LIQUOR OF FILTER PARTICLE BEAM EXAMINED RATEOF FLOW AID USED COUNT INTENSITY Uals./sq. f t . / Liters/sq. Number/cc. hr. meter/hr. % X 1010 Foot-candles Unfiltered raw sugar 143.0 16.2 Filtered with 236.4 0.38 7.7 0.65 filter aid 1 5.8 Filtered with filter aid 2 14.1 574.5 0.38 16.3 1.08 Filtered 1 , 65 filter awith id3 36.3 1478.9 0.38 57.7
..
Min. 0-3 3-6 6-9 9-12 12-21 21-30 0-3 3-6 6-9 9-12 12-21 21-30 0-3 3-6 6-9 9-12 12-21 21-30
1
2
3
..
The results show an interesting and consistent relationship between the number of colloidal particles unremoved by filtration and the Tyndall beam intensities of the filtrates. The differences noted between the filtrates from the three filter aids tested are highly significant in sugar practice. Such differences show the degree of refinement necessary in this measurement. The clarity figures have been found to be better criteria of liquor quality to the refiner than the particle counts. Apparently the over-all optical effect as measured by the Tyndall beam intensity is an index of those colloidal impurities which are most troublesome in refining and
Foot-candles 66.1 25.0 16.7 11.5 8.9 8.0 43.3 25.2 15.7 13.0 10.6 9.7 46.0 35.0 29.6 25.2 10.0 15.5
1.78 4.00 6.37 8.70 11.22 12.50 2.31 3.97 6.37 7.70 9.43 10.30 2.18 2.86 3.38 3.97 5.27 6.45
TABLEVIII. EXAMINATION OF VARIOUS REFINERY LIQUORS 1 2 3 4 5
DBSCRIPTION OF SAMPLE
TYNDALL BEAMINTENSITY Foot-candles
60. Brix so!ution of refined sugar
6.5 9.4 10.2 28.0 38.5 38.5a 44.0"
First char liquor First char liquor Second char liquor Thin char liquor 6 Dark colored char liquor, limed 7 Very dark char liquor a Uncorrected for color
As illustrative of the utility of clarity measurements of refinery liquors other than filter-press filtrates, a series of tyndallmetric readings is given in Table VI11 for various char liquors. These figures clearly show that readily
IN DEQREE OF CLARIFICATION WITH TIMEOF FILTRATION CYCLE TABLEVI. CHANQE
KINDOF SUGAR LIQUOR Average filtering Hawaiian raw sugar Low filterability Cuban raw sugar Very easily refined Cuban raw sugar
FILTER AID USED 1 2 3 1 2 3 1 2 3
CLARITY OF FILTRATES EXPRESSED AS INTENSITY OF TYNDALL BEAM 3;6 6715 15:30 min. min. min. min. Foot-candles 073
11.20 5 80 7.40 11.50 5.06 6.00 3.65 3.40 5.00
4.40 3.15 5.70 4.00 2.76 4.70 2.18 2.02 3.60
2.07 2.08 3.65 1.94 1.76 2.75 1.16 1.45 2.45
1.04 1.78 2.55 1.27 1.28 1.04 0.93 1.15 1.64
PARTICLE COUNT PER C C . x loLQ RATH~ OP FLOW 15-30 MIN, FRACTION GaZ./sq. Liters/sq. ft./hr. meter/hr. 8.0 21.6 27.7 5.8 21.6 34.7 14.3 14.6 30.0
5.7 16.9 62.6 4.2 10.0 27.5 8.6 17.5 44.6
232.2 688.5 2143.0 171.1 407.4 1120.4 350.4 712.9 1817.1
ANALYTICAL EDITION
332
measured differences obtain in various refinery liquors. The liquors referred to here were obtained during regular operation a t a typical Atlantic Coast refinery. Further figures and comparative readings for these important refinery liquors under a variety of conditions cannot be given here. It may be stated, however, that the value of the apparatus for the examination of various refinery liquors, especially char liquors, is equally as great as for raw sugar filtrates. The same may be said for washed sirup.
QUALITYOF REFINEDSUQARS The quality of refined sugars is reflected very strikingly in the clarity of concentrated sirup$ made u p from the sugars. This test is recognized by refiners and by the trade as giving a valuable index of the purity of the sugars. Table IX shows the results obtained from the examination of a number of refined sugars.
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a number of turbidimetric and tyndallmetric measurements totally unrelated to filtration. The apparatus appears to be well suited for the accurate estimation of minute traces of chlorides, sulfates, etc., it being possible to determine amounts down to less than 0.01 part per million. Other applications, such as in biological work, are suggested.
ACRKOWLEDQMENT Acknowledgment is made of the interest and cooperation of M. C. Miller of the Johns-Manville Research Laboratories and of W. Zeiler of E. Leitz, Inc., in the design and construction of parts of the apparatus. LITERATURE CITED
(1) Baker, F. P., IND.ENQ.CREM.,13, 610, 1163 (1921). (2) Bloor, W. R., J. Bid. Chem., 22, 145 (1915). (3) Brisooe, H. V. A., and Little, H. F., J. Chem. SOC.,105, 1310 (1914). OF REFINED SUQARS AS SHOWN B Y f4) Drver. Q.. and Gardner. A. D.. Biochem. J.. 10.399 (1916). TABLEIX. QUALITY , TYNDALLMETRIC READINQS (5) Gans, R., 2. Physik, 17; 353 G923). INTENEITY OF (6) Hatschek, E., J. SOC.Chem. Ind., 27, 538 (1908). DHIBCRIPTION OF SAMPLES TYNDALL BEAM (7) Ingslake, R., Trans. Optical SOC.(London),26, 53 (1925). 1 Highest quality refinery "specialty" sugar 1.0 (81 . . Kamerlinah-Onnes, and Keeson, W. H., Verslao. Akad. Weten2 High quality confectionery sugar 1.7 schappei Amsterdam, 16, 667 (1908). 3 Highly purified sugar (laboratory pr,ocess) 2.1 Refinery cube sugar 4 2.4 (9) Kangro, W., 2. physik. Chem., 87, 257 (1914). 5 High quality beet sugar 2.7 (10) Kleinmann, H., Biochem. Z . , 99, 115 (1919); Kolloid-Z., 27, 236 6 Cuban refinery sugar No. 1 3.4 (1920). 7 Granulated beet sugar 5.0 8 Granulated cane sugar No. 1 .b.8 (11) Kober, P. A., J. Biol. Chem., 13, 485 (1913). 9 Granulated cane sugar No. 2 6.2 1 0 , 5 5 6 (1918). (12) Ibid., 29, 155 (1917); J. IND.ENQ.CHEM., 10 Granulated cane sugar No.3 6.8 (13) Kober, P. A., and Graves, S. S., Ibid., 7, 843 (1915). 11 Cuban refinery sugar No.2 7.4 12 Porto Rioan vegetable char sugar 9.1 (14) Kober, P. A., and Klett, R. E., J. Biol. Chem., 47, 19 (1921). 13 Granulated cane Bugar No.4 9.4 (15) Lamb, A. B., Carleton, P. W., and Meldrum, W. B., J. Am. Chem. SOC.,42, 241 (1920). An example is given below of an actual refinery test to (16) Le Blanc, M., 2. Elektrochem., 19, 794 (1914). compare the effect of two different types of filtration upon (17) Lednicky, A., Kolloid-Z., 23, 12 (1923). the quality of the filtrates obtained. I n this case the actual (18) Lewis, W. R., and Almy, C., J. IND.ENQ.CHEM.,4, 528 (1912). W., Z. anorg. Chem., 74, 207 (1912); Kolloid-Z., differences in the clarities of the filtrates was small and could (19) Mecklenberg, 5, 149 (1914). not be determined with certainty by any means available a t (20) Mecklenberg, W., and Valentiner, S., 2. Instrumentenk., 34, the refinery; yet the difference in quality of sugars eventually 209 (1914); Kolloid-Z., 14, 172 (1914); Ibid., 15, 149 (1914); Physik. Z., 15, 267 (1914). crystallized from these filtrates was recognized. A. F. C., British Patent 137,637 (1920); Trans. Optical Table X shows the result secured by the Tyndallmetric (21) Pollard, SOC.,26, 63 (1925). examination of these filtrates. (22) Richards, T. W., Proc. Am. Acad. Arts Sci., 30, 369 (1894). (23) Richards, T. W.. and Wells, R. C., Am. Chem. J., 31,235 (1904). CQMPARISON OF PAPER PULP AND DIATOMACEOUS TABLE S. E., and Elliott, F. A., J . Am. Chem. SOC.,43, 531 FILTER AID FILTRATIONS CONDUCTED IN SUQAR REFINERY (24) Sheppard, (192 1). INTENBITY OF TYNDALL BEAM (25) Smith, V., J. SOC.Chem. Ind., 36, 1031 (1917); U. S. Patent Filtrate from After 1,232,989 (1917). DEBCRIPTION OF SAMPLE press concentration (26) Sperry, D. R., Chem. &Met. Eng., 15,198 (1918); 17,161 (1916). Foot-candles Foot-candles (27) Tolman, R. C., and Vleit, E. B., J. Am. Chem. SOC.,41, 297 1 Liquor filtered with paper pulp 8.0 9.1 (1919). 2 Liquor filtered with diatomaceous filter aid 7.1 8.3 (28) Tswett,'M., 2. physik. Chem., 36, 45 (1901). The differences in the clarities of these two filtrates was (29) Weinberg, A. A,, Biochem. Z., 125, 292 (1921). (30) Wells, P. V., J. Am. Chem. SOC.,44, 267 (1922). confirmed in this case by extensive ultra-microscopic and (31) Wells, P. V., Phys. Rev., 4 , 3 9 6 (1914) ; Bur. Standards, Bull. 15, colloid studies, the results of which agreed entirely with the 693 (1920). tyndallmetric readings. (32) Wells, R. C., Am. Chem. J.,35, 99 (1906). (33) Wilke, E., and Handoosky, H., Ann. Physik, 42, 1145 (1913).
. , ~ * .
-
, .
I
.
x.
OTHERAPPLICATIONS OF APPARATUS
While beyond the scope of this paper, the authors wish to point out that the apparatus described has been tried for
Corrosion tests have been made CORROSION IN SULFONATORS. at the plant of Endicott Johnson Corporationin cooperation with the International Nickel Company to establish the behavior of metals in sulfonators under actual operating conditions. The specimens insulated from one another were fastened on a spooltype s ecimen holder that was submerged within the sulfonator. In tRe first series of tests the specimens were exposed during the sulfonation of 10 batches of neat's-foot oil by a process in which 66' BB. sulfuric acid was added to the oil over a period of about 1 hour, after which the reaction proceeded for about 6 hours at a maximum temperature of 34' C. At the end of 6 hours a saturated sodium chloride brine was added t o the mixture, which was then thoroughly agitated and allowed t o settle overnight, after which the sulfonated oil was drawn off.
R ~ ~ C E I VApril E D 4, 1933. Presented before the Division of Industrial and Engineering ChemiBtry at the 82nd Meeting of the American Chemical Society, Buffalo, N. Y., August 31 to September 4, 1931.
In the second series 66" BB. sulfuric acid was allowed t o react with cod liver oil over a period of about 6 hours, after which a 15 er cent sodium chloride brine was added and agitated as in the grst case, allowed t o settle overnight, and then drawn off. The oil was finally neutralized with alkali. Corrosion rates were as follows: ME~TAL Lead Chromium-nickel iron (18-8) bl -N -i-r____ ,
iMonel metal Ni-Resist Plain cast iron
CORROBION RAT&?.MQ. PER 89. DM. PER BATCH Sulfonated Sulfonated neat's-foot oil caator 011 .(Ob I Y
I
426
,111 -vu
22
30 ..
34
25 11
90
29 120
10,000
