. .

W A T E R P O L L U T I O N R E D U C T I O N

T H R O U G H

R E C O V E R Y O F D E S IZI N G W A S T E S

DEPARTMENT OF TEXTILE CHEMISTRY SCHOOL OF TEXTILES

NORTH CAROLINA STATE UNIVERSITY RALEIGH, NORTH CAROLINA 27607

for t he

ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND MONITORING

Project 12090 EOE

January 1972

--- For sale by the Superintendent of Documents, U.S. Oovemment Printing Office, Wasblngton, D.C. 20402 - Prlce 60 cents

T h i s report has been reviewed by the E n v i r o n n e n t a l P ro tec - t i c n Agency and apprcYJe6 f o r p u b l i c a t i o n . not sig: i i fy t n a t t h e cofitents necessarily r-ef1ec-t t h e views and policies of t h e E n v i r c n m n t a l F ro tcc t ion Agency, nor does ment ion of trade names o r commercial p r o d u c t s c o n s t i t u t e endorsement or recomiendation f o r use.

Approval does

3 ii

ABSTRACT

Processes for precipitating f rom desizing wastes the synthetic warp s izes , carboxymethyl cellulose ( CMC) and polyvinyl alcohol ( P V A ) , were inve s tigate d. cer ta in multivalent metal sal ts , such as aluminum sulfate and f e r r i c chloride.

Carb oxyme thy1 cellulose is precipitated quantitatively by

Aluminum sulfate is the more suitable for s ize recovery .

Cycles of sizing, desizing and s ize recovery were performed on cotton- polyester ( 65:35) yarns , s tar t ing with commercial CMC, and continuing with only the recovered mater ia l . After four cycles, the performance of the recovered CMC on a Callaway s lasher was sat isfactory and resu l t s with the s ized yarns on a warp-shed tes te r were equivalent to resu l t s with yarns s ized with new CMC.

Two copolymers of P V A were prepared , one of which was precipitated f rom dilute solution by aluminum sulfate and f e r r i c chloride, the other by acidification, ials indicate that these, or similar, copolymers may be effective, recovera- ble warp s izes .

Evidence was obtained that acclimatization of sewage bac ter ia to CMC and P V A occurs upon prolonged contact in a laboratory activated- sludge unit.

Pre l iminary sizing t r ia l s with smal l samples of m a t e r -

This r epor t was submitted in fulfillment of Pro jec t 12090 EOE under the sponsorship of the Water aua l i ty Office, Environmental Protect ion Agency,

Key words: acclimatization, alum, carboxymethyl cellulose, industr ia l wastes , pollution abatement, polyvinyl alcohol, precipitation, r euse , textiles , warp s ize s ,

3 iii

CONTENTS

Section Page

I . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 11 . Recommendations . . . . . . . . . . . . . . . . . . . . . . 111 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . .

Recovery Methods . . . . . . . . . . . . . . . . . . . . Scope and Purpose of Pro jec t . . . . . . . . . . . . . . Background Information . . . . . . . . . . . . . . . . .

IV . Studies and Discussion . . . . . . . . . . . . . . . . . . . Recovery and Reuse of Carboxymethyl

Cellulose ( CMC) . . . . . . . . . . . . . . . . . . . . Recovery of Polyvinyl Alcohol ( P V A )

f r o m Desizing Wastes . . . . . . . . . . . . . . . . . Removal of Desizing Products of Starch from

Desizing Wastes . . . . . . . . . . . . . . . . . . . Biodegradation of Carboxymethyl Cellulose ( CMC) . . . Biodegradation of Polyvinyl Alcohol ( P V A ) . . . . . . . .

V . Acknowledgement . . . . . . . . . . . . . . . . . . . . . . VI . References . . . . . . . . . . . . . . . . . . . . . . . . . VU . Publications and Patents . . . . . . . . . . . . . . . . . VI11 . Appendices . . . . . . . . . . . . . . . . . . . . . . . .

Appendix A . Laboratory Procedures . . . . . . . . . Appendix B . Related Li terature . . . . . . . . . . . .

1

3

7

7

16

17 20 22

3 3

35

37

39 41 47

V

FIGURES

No. - Page

I

1. Chemical Equations for ( a) Precipit.ation of CMC with F i l t e r Alum and ( b ) Solution of the Prec i - pitate with Sodium H,ydroxide 8 . . . . . . . . . . . . . . .

2. Chemical Transformations in the Preparat ion of P V A Copolymers. . . . . . . . . . . . . . . . . . . . . . 18

3. Treatment of CMG with Activated Sludge Developed in Laboratory . . . . . . . . . . . . . . . . . . . . . . . 24

4. Removal of CMC with Activated Sludge Developed in Laboratory . . . . . . . . . . . . . . . . . . . . . . . 25

5. Treatment of CMC with Activated Sludge f rom Dan River Treatment Plant . . . . . . . . . . . . . . . . . . . . 27

6 . Removal of CMC with Activated Sludge f rom Dan River Treatment Plant . . . . . . . . . . . . . . . . . 28

7. Treatment of P V A with Activated Sludge Developed in Laboratory . . . . . . . . . . . . . . . . . . . . . . . 30

8. Removal of P V A with Activated Sludge Developed in Labora to ry . . . . . . . . . . . . . . . . . . . . . . . . 31

9. Laboratory Activated-Sludge Unit, Consisting of Aeration Chamber ( A ) and Separation Basin ( B ) . . . . . . . . . . . . . . . . . . . . . . . . . 45

vi

TABLES

No. - Page

1.

2.

3.

4.

5.

6.

7.

a.

9.

10.

Recovery Alum

of CMC by . . . . . . Precipitation with F i l t e r . . . . . . . . . . . . . . . .

Sizing with CMC . New and Recovered . . . . . . Resul ts f rom Warp-Shed Tes te r on Yarns Sized

. . . . . . . . . .

9

10

with New and Recovered CMC . . . . . . . . . . . . . . 12

Data on CMC Size Recovered by Precipitation . . . . . . . Data on Supernatant f rom Precipitation of CMC Size. . . . Resul ts f r o m Warp-Shed Tes te r on Yarns Sized

with P V A and P V A Copolymers . . . . . . . . . . . . . Synthetic Sewage Feed . . . . . . . . . . . . . . . . . . . . Removal of CMC with Activated Sludge Developed

in Laboratory . . . . . . . . . . . . . . . . . . . . . . Removal of CMC with Activated Sludge f rom Dan

River Treatment P lan t . . . . . . . . . . . . . . . . . Removal of P V A with Activated Sludge Developed

in Laboratory . . . . . . . . . . . . . . . . . . . . . .

vii

13

14

19

21

23

26

29

. . , .\.-- " ....

SECTION I

C ONCLUSIONS

1. desizing wastes by precipitation with aluminum sulfate ( f i l ter a lum) has been developed on a laboratory scale. that the process may have practical applications. The recovered CMC may be suitable fo r reuse as a warp s ize; i f not, it may be disposed of as a solid without fur ther treatment.

A process for recovering carboxymethyl cellulose ( CMC) f rom

Considerable testing indicates

2. ( P V A ) f r o m desizing wastes has been developed also, although it has not been tes ted a s thxoughly as the CMC process .

A s imi la r process for recovering a modified polyvinyl alcohol

3. tional warp-s ize-grade P V A f r o m desizing wastes. mater ia l by precipitation, without a pr ior concentrating step, does not

An at t ract ive procedure was not found for recovering the conven- Recovery of this

-) seem feasible.

4. t o CMC and P V A occurs upon prolonged contact in a laboratory activated sludge unit.

Evidence was obtained that acclimatization of sewage bacter ia

The synthetic s izes then exhibit biodegradable character is t ics .

5. s ta rch f rom desizing wastes was not found.

A precipitation method for recovering the desizing products of

6. Examination of enzymatic desizing wastes , from starch-sized fabrics, obtained f r o m a nearby textile plant, showed that none of the low-molecular-weight sugars was present. The s t a rch was degraded to a m o r e water-soluble mater ia l but the degradation was only partial , leaving products of molecular weights higher than those of the simple sugars .

3 1

.. I . . .. . *. . _.... .. '

SECTION I1

RECOMMENDATIONS

1. be given fur ther evaluation and development on a l a rge r scale . cooperative project , supported by a Demonstration Grant, using pilot-plant facilities located at an industrial plant, with supporting laboratory work at the University, is recommended.

The process for precipitating CMC f rom desizing wastes should A

2 . In recovering CMC f r o m desizing was tes , emphasis should be placed on obtaining ma te r i a l suitable for r euse as a warp s ize , on the recovered ma te r i a l should be made to determine the extent to which r euse is possible.

Tes ts

3. The development of a process f o r the recovery f rom desizing wastes of a warp s ize based on a modified P V A should be continued. plated method of recovery is similar to the coagulation and precipitation scheme that w a s sucessful with CMC. should be followed by tes t s on the recovered ma te r i a l to determine its suitability for r e u s e as a warp size.

The contem-

A sat isfactory recovery procedure

4. Other processes for recovering warp s izes f rom desizing wastes should be investigated, 'It is important that eagerness to promote the processes for recovering CMC and P V A does not lead to overlooking other processes , possibly employing new warp- s ize modifications , which might t u rn out to be bet ter . An example would be to employ a s a warp s ize a polymer, such as methyl cellulose, which is soluble in water at room tempera ture but insoluble in hot water ; the s ize would be applied and removed at room tempera ture and then precipitated and recovered f r o m the desizing waste upon heating.

5. Because of the exceedingly l a rge amount of s t a rch used in sizing texti le yarns , fur ther exploratory work should be ca r r i ed out on chemi- ca l and physical methods for removing the desizing products of s t a rch f rom desizing wastes . Such methods should be compared with the usual biological p rocesses for removing these products.

3

3

SECTION I11

INTRODUCTION

Background Information

Removal of the s ize with which the warp ( length-wise) yarns a r e coated to make the weaving of the fabr ic possible is a common operation in the preparation of cloth for dyeing and finishing. s izes for yarns of cellulose ( cotton, rayon) and cellulose blends i s s t a r ch and modified s tarches. These materials a r e biodegradable and, because they a r e used in relatively la rge quantities - - 5 to 15% of ya rn weight, amounting to over 300,000,000 pounds annually in this country, contribute heavily ( 45-70% of total) to the biochemical oxygen demand ( BOD-5) of textile finishing wastes.

The basis of most warp

In recent yea r s cer ta in water-soluble, synthetic polymers, with a much lower BOD-5 than s ta rch , have been introducd for use a s warp s izes . these materials, carboxymethyl cellulose ( CMC) and polyvinyl alcohol ( P V A ) have gained the widest use. Although cost of these mater ia ls is higher than that of s ta rch , ( approximately 66/ lb for s tarch, 8-18bllb for modified s ta rches , 316/lb for P V A , and 356/lb for CMC, all in the unformulated s ta te ) , particularly with the synthetics and cotton- synthetic blends, which tend to offset this cost differential. The use of these compounds, therefore, can be expected to increase in the coming yea r s as the use of synthetic f ibers increases .

Of

they have cer ta in advantages in performance,

Besides having a low BOD-5, have been promoted a l so as a means of reducing the pollution potential of desizing wastes. ( COD) of CMC is about as high as that of s ta rch , however, and the COD of P V A is higher, Fu r the rmore , resul ts a l ready obtained in this labora- to ry as well as in others, indicate that adaptation of bacter ia to carboxy- methyl cellulose ( 9 ) and probably to polyvinyl alcohol ( 11) as well, does occur over a prolonged period of t ime.

giving increased operating efficiencies, the synthetic warp s izes ,

The chemical oxygen demand

Research to decrease the waste load from the desizing of fabr ics , there- fore, may be concerned with developing m o r e effective and less expensive t reatment methods or with developing processes for recovering and reusing the desizing products. desirable whenever it is possible and, indeed, to represent almost the ult imate in pollution control.

The la t ter alternative appears to be the more

5

Recovery Methods

The contemplated methods of recovering desizing products were precipitation, evaporation, and combinations of the two. Emphasis was placed on precipita- tion methods which do not requi re evaporation or other concentrating proce- du res because, for economic reasons , the process should be as s imple as pos s ible.

Two general methods may be considered for precipitating warp s izes f rom desizing wastes. In one method, the warp s ize is chosen, or modified chemically before application, so that it can be readily precipi ta ted f rom dilute solution by a suitable precipitating agent. In the other method, the desizing wastes a r e t reated in a manner to modify the warp s ize s o that i t m a y be readily precipitated.

The scheme for recovering carboxymethyl cellulose ( CMC) is an example of the f i r s t method, which appears a l so to offer a good way for recovering polyvinyl alcohol ( P V A ) . The second method has provided the approach taken in a t tempts to develop a method for removal of conventional warp-size-grade P V A f r o m desizing was tes because, without chemical modification, this P V A does not possess react ive s i tes which w i l l permi t it t o be precipitated f rom dilute solution by a s imple precipitating react ion, F o r the same reason, this approach w a s taken in attempts to develop a method for removal of the desizing pr oducts f rom s ta rch- des izing wastes ,

Scope and Purpose of P ro jec t

The scope and purpose of the pro jec t a r e defined by the objectives which were

( a) fabr ics s ized with carboxymethyl cellulose ( CMC) , polyvinyl alcohol ( P V A ) , and s t a rch - - - in forms suitable for final disposal;

to develop processes for the recovery of desizing was te s - - - f rom

( b) able form---with the recognition that reuse , as a size, of the desizing products f r o m s ta rch is not possible, since s t a rch is degraded during desizing;

t o develop processes for the recovery of desizing was tes in a reuse-

( c ) t o obtain m o r e complete data on the biodegradation of the synthetic warp s i zes , CMC and P V A , thus gaining information on the fate of these ma te r i a l s in biological t rea tment sys t ems and in s t r eams .

The experiments c a r r i e d out to a t ta in these objectives were l imited to the laborator ies and pilot plant of the Department of Textile Chemistry, North Carolina State University.

6

SECTION I V

STUDIES AND DISCUSSION

Recovery and Reuse of Carboxymethyl Cellulose ( CMC)

The l i terature s ta tes that sodium carboxymethyl cellulose ( CMC) m a y be precipitated as an insoluble sa l t of aluminum, copper, lead, uranium o r zirconium ( 6 ) , titative recovery of warp- size-grade CMC can be obtained by precipitation f rom a 0.1% solution with aluminum sulfate ( f i l ter a lum) . The recovered material, which retained a small amount of aluminum, appeared to be suita- ble for solid disposal after dewatering, On the other hand, the CMC, precipitated with alum, dissolved in dilute sodium hydroxide and was found suitable for fur ther use as a sizing agent f o r cotton yarn. Performance of the recovered CMC on the Callaway s lasher , a laboratory sizing machine, was sat isfactory and the resul ts obtained with the s ized yarns on a warp shed t e s t e r , which simulates loom performance9 were comparable to those obtained with yarns sized with new CMC.

Ea r ly work on this project established that xn a lmost quan-

Chemical equations for the conversion of CMC ( warp-size-grade) to the water- insoluble aluminum carboxymethyl cellulose and for the reaction of the la t ter with sodium hydroxide to give a solution of CMC again a r e shown in Figure 1,

Data on precipitation of CMC f rom 0.15 solution with fi l ter alum a r e shown in Table 1. A ra t io of alum to CMC of 0.71 is enough to form the aluminum sa l t of CMC but a la rger ra t io i s necessary to give rapid coagulation and precipitation and to form a clear supernatant. The leveling of recovery at 96% of the original weight occurs because commercial , warp- size- grade CMC contains about 4 % sodium chloride, a by-product in its manufacture, which i s not precipitated by alum. natant with increasing alum- CMG ratios ref lects the increasing amounts of excess alum which remain in solution.

The increase in total solids in the super-

A se r i e s of cycles of sizing, desizing, and s i z e recovery was car r ied out, start ing with f resh , commercial , warp- s ize-grade CMC and, in subsequent operations, contiriuing with only the ma te r i a l recovered from the previous step. The sizing t r ia l s were car r ied out on a blended yarn of cotton and polyester ( 65:35) with an add-on of s ize of approximately ten percen't of ya rn weight. Wax, ten percent based on s ize , was added to the initial s ize bath only; apparently i t i s recovered along with the CMC upon precipitation with alum, The scale of these operations i s shown ic Table 2. shows a l so the disproportionately high attr i t ion, ar is ing from mechanical losses , which occurs in working with relatively smal l amounts of mater ia ls e

The preceding table shcws that these losses did not occur because the p re - cipitation and recovery of CMC was incomplete.

This table

Such l o s s e ~ , of course,

7

A1 fn + - 0*7n Na2S0, -f- C4,H702 ( OH) 2 . 3 ( 0 CH2COO - 3 ) o. 7 2

A1 ( OH) 3 0.7n

3 Tn + - C'H702 ( OH) 2. ( 0 CH2COOiNa) ,,, -f

Figure 1. F i l t e r Alum and ( b ) Solution of the Precipi ta te with Sodium Hydroxide

Chemical Equations f o r ( a ) Precipitation of CMC with

I

T a b l e 1: Recovery of CMC by P r e c i p i t a t i o n with F i l t e r Alum ( from 0.1% solu t ion of CMC)

_I-- - .--- --- .-...--̂ - --.--+-----.

S u p e r n a t a n t R a t i o by weight P r e c i p i t a t e To ta l Sol ids A o p e a r a n c e

A l u m / C M C R e c o v e r e d ( $ ) ( wt % )

0 . 5 0 81

0 . 7 5 95

0 . n51 cloudy

0 . 0 6 5 s l igh t ly c loudy

clear 1.00 96 0 .085

1. 2 5 95 0 .099 c l e a r

1. 50 96 0.127 c l e a r

c l e a r 2 .00 96 0.166

w ‘ 0

R e u s e No.

S iz ing so ln p r e p a r e d ( gal. )

Concn. of s i z i n g soln ( w t $)

pH of s i z ing s o h

W a r p s i z e d ( yd)

T a b l e 2: Sizing with CMC .. New and R e c o v e r e d ( Y a r n : Cot ton-polyes te r ( 65:35) blend)

1 2 3 4

10 5 2 0.4

8-9 8 -9 8 -9 8 -9 13

7 . 3 8 . 0 7 . 5 7 . 3 9.0

6000 3600 1800 600 60

I R u n N o . 2 3 4 5

Sol ids in des i z ing l iquor ( w t (a)

1.10 1..05 1.05 0 . 9 7

- .if-

. . ..

would not be near ly a s large proportionately in a la rge , plant operation.

After four cycles, the performance of the recovered CMC on the Callaway s lasher was still satisfactory and the results obtained with the sized yarns on a warp-shed tes te r were equivalent to those obtained with yarns sized with new CMC ( S e e Table 3) e On the fifth cycle, however, the resul ts on the warp-shed tes te r were slightly poorer in that the percent of shed was higher, the clinging was grea te r , and there were m o r e stops. The poorer resu l t s might be due to an accumulation of impurit ies in the recovered CMC o r they might be due to the method of application which was less easily controlled because of the small amount of recovered CMC remaining at this point,

The propert ies of the s ize at the severa l stages of recovery a r e shown in Table 4. swollen floc was dried in an oven at 105OC and ground to a powder before dissolving for reuse; in Runs 4 and 5 , the swollen floc was dissolved directly, eliminating the t ime and expense of two unnecessary steps. The continuous diminution in m o u n t of recovered s ize because of mechanical losses was r e m a r k e d on above. The decrease in CMC content of the recovered mater - ial and the increase in residues remaining at 6oo0C a r e undoubtedly due to a build-up of impurit ies. The high value for res idues obtained for the new CMC is probably due largely to the presence of sodium chloride which is formed as a by-product in the manufacture of CMC. The aluminum con- tent of the recovered mater ia l is apparently leveling off at about 4$, a value which does not appear excessive since the theoretical aluminum content of aluminum carboxymethyl cellulose is 3.0%-

In Runs 2 and 3, the CMC recovered f rom the previous run a s a

The steady decrease in the total solids and the CMC content of the super- natant f rom the recovery of s ize ( s e e Table 5 ) occur red undoubtedly because a l a rge r amount of alum was added in the la t te r precipitations. The increase was made when i t was realized that the rapid precipitation and settling, obtained with la rger amounts of alum, would be required for a pract ical plant operation; the slight increase in the amount of mater - ial recovered is of secondary importance. content of the supernatant f rom the la t te r recoveries a l so reflects this change.

The increase in the aluminum

The brown color of the recovered CMC showed that some of the natural impuri t ies of the cotton component of the ya rnp and probably the spinning oil used on the polyester component a s well, a r e retained by the CMC during recovery, while the yellow o r tan color of the liquor remaining indi- cates that some of these mater ia l s remain in solution. tes t s mentioned abovep howeverp indicate that these mater ia l s have no deleterious effects during four cycles of operations--and perhaps, longer- - and the appearance of the yarns after desizing indtcates that none i s retained by the yarns .

The performance

11

Table 3: Results from Warp Shed Tes te r on Yarns Sized with New and Recovered CMC

Run No.

Reuse No.

Size add-on ( wtk)

Shed ( w t $ )

F iber in shed ( wt$ )

stops

Clinging rat io ( f ) '

Warp tested ( yd)

1 2 3 4 5

1 2 3 4

8.7 10.6 9.0 10.7 13. 5

3 . 1 2.7 2 .7 2 .7 3. 3

40 55 50 30 50

0 0 1 1 2

50 25 50 25 50+

20 - 20 20 20 20

Table 4: Date on CMC Size Recovered by Precipitation

Run No.

Reuse No.

F o r m when dissolved

Dry weight ( l b )

CMC content ( $ )

Aluminum content ( $ )

Residue at 6OO0C ($ )

1 2 3 4 5

1 2 3 4

dry d ry d r y s w 011 en swollen

5.4 3.5 1.5 0.25

92 84 82 7 2

powder powder powder floc floc

0 3.3 4 . 3 4.0 4.3

33 10.8 15.0 16.0 22 .9

Table 5: Data on Supernatant from Precipitation of CMC Size

Solids ( w t $)

CMC ( w t $ )

Aluminum content ( ppma)

0.6 0.6 0.5 0.4

0.04 0.03 0.006 0 . 0 0 3

2 25 375 400 400

4.0 3 .9 3.7 3 .8 PH

P

3

1 i

, .

The accumulation of impurities can be expected to reach harmful proportions eventually, however, and some of the recovered s ize will have to be discarded as a solid waste and replaced with f resh CMC. This exchange most probably should be made gradually, beginning with the f i r s t recovery, to an extent which permits attainment of steady- s ta te conditions.

. Material costs in the recovery of CMC f rom desizing wastes by precipitation with f i l ter alum a r e favorable. The cur ren t pr ices of CMC i s approximately 35 d / l b and that of f i l ter alum 3 d/lb. Since approximately one pound, o r less, of filter alum is used in the recovery of one pound of CMC, the ma te r i a l cost of recovery i s somewhat l e s s than 10% of that of the CMC recovered.

Carboxymethyl cellulose is precipitated also from dilute aqueous solution by f e r r i c chloride but the floc is more voluminous and does not sett le a s well. The cost of f e r r i c chloride i s about 4 k/lb, somewhat higher than that of alum, but the stoichiometry is such that only about 805as much is required fo r com- plete precipitation of CMC. Material costs of the two in the precipitation process , therefore would be about the same. Because of the retention of a smal l amount of i ron in the precipitate and of the known adverse effect of i ron during bleaching, however, this precipitant does not appear to be use- ful in recovering CMC intended fo r reuse. of aluminum in s izes recovered f r o m desizing liquors by precipitation with alum does not appear to present any problem in s ize reuse.

The presence of a small amount

The process for precipitating and recovering CMC from desizing wastes should be given e-raluation and development on a l a rge r sca le , Emphasis should be placed on obtaining ma te r i a l suitable for reuse a s a warp s ize . A cooperative project, supported by a Demonst:.ction Grant, using the facil i t ies at a textile-finishing plant, with supporting laboratory and pilot- plant work at the University, appears to be a prefer red way of performing the fur ther work required. A br ie f outline of this work is as follows.

1. Desizing of fabr ics , s ized with CMC, would be ca r r i ed out at the textile-finishing plant, using equipment normally used in the industry. The fabrics would be supplied by the textile plant. 2. Equipment would be designed and constructed for precipitating and separating the CMC f rom the bulk of the desizing wastes. This equip- ment would be t r ied in the plant and modified i f necessary. 3. The CMC, recovered in the f o r m of a sludge, would be taken to the University and dewatered to the desired extent by centrifuging 4. The dewatered CMC, s t i l l highly swollen with water, would be dis- solved in sodium hydroxide to make a new desizing solution. would be s ized on a Callaway s lasher and tested on a warp-shed tes te r . 5 . and r euse to se rve as a control and to guide in making improvements in subsequent trials. 6. Successful resul ts in the preceding stages would be followed by weaving t r ia l s on full-scale looms a t the University.

Warp yarns

Chemical analysis would be made throughout the process of recovery

15

Recovery of Polyvinyl Alcohol ( P V A ) f rom Desizing Wastes

The work with polyvinyl alcohol ( PVA) has not progressed as far a s that with CMC. An attractive procedure was not found for precipitating and recovering the conventional warp- s ize-grade P V A f rom desizing wastes , although a number of mater ia ls that will insolubilize P V A a r e reported in the l i t e ra ture ( 1, 2, 10) . These mater ia ls are classified below accord- ing to the effect produced on PVA; there is some overlapping in the classi - f i c at ion, how eve r ,

Precipi tants . Polyvinyl alcohol is insoluble in solutions of many sal ts and can be precipitated f rom solution by addition of a sal t such as sodium sul- fa te or sodium carbonate. Desizing wastes are s o dilute, howevers that the amount of sal t required would be impractical and would c rea t e a pollution problem i ts elf.

Insolubilizers. The water res i s tance of films and coatings of P V A can be increased by incorporating any of a number of insolubilizing agents. agents include the amine- o r amide-formaldehyde condensates, such as dimethyl01 urea , trimethyol melamine and the various compositions used to impar t durable-press propert ies to cellulosic fabrics; aldehydes, such as formaldehyde, glyoxal, and hydroxyadipaldehyde; polyvalent metal sal ts and complexes, f rom such meta ls a s aluminum, chromium, copper, iron, nickel, and titanium; and organic titanates. Insolubilization of PVA by these mater ia l s , however, i s l imited to dried films, usually with baking, and cannot be applied to aqueous solutions.

These

Gelling agents. A number of compounds can cause gellation of solutions of PVA in water . These compounds include cer ta in dyes, such as Congo Red; phenolic compounds, such as resorcinol , catechol, phloroglucinol, gallic acid, salicylamide, and 2 , 4 - dihydroxybenzoic acid; and inorganic complex- ing agents, such a s borax- - a particularly effective gelling agent, cer ta in vanadates, and compounds of tr ivalent chromium and of tetravalent t i ta- nium. These compounds cause gellation only in P V A solutions in which the concentration of P V A is higher than that likely to be encountered in desizing wastes and, of course, gellation of the ent i re solution provides no means of separating the P V A .

Consideration of the l i terature cited above, together with qualitative experi- ments with borax, phenolic compounds, and aldehydes, l ed to the conclu- sion that precipitating and recovering conventional warp- s ize- grade P V A f r o m desizing wastes , without a pr ior concentrating step, would be difficult i f not impossible.

16

A modified P V A has been prepared which is precipitated f rom dilute solution by f i l ter alum. This mater ia l was prepared by emulsion copolymerization of vinyl acetate with a relatively small amount of acryl ic acid and hydrolysis of the result ing copolymer. Figure 2. tity for conclusive evaluation a s a warp s ize , some preliminary resul ts have been obtained on the Callaway s lasher and the warp-shed tes te r . was routine but the resu l t s on the warp-shed t e s t e r were poor in comparison with those obtained with commercial warp-size-grade PVA. ial performed at all, however, is an indication that, with proper adjustment of composition and molecular weight, it should be a satisfactory warp size.

The chemical transformations are shown in Although this mater ia l has not been prepared in sufficient quan-

Slashing

That this ma te r -

Similar considerations apply to another modification of P V A which was pre- pared recently and found to be precipitated f rom dilute solution by lowering the pH to about 3. Mater ia l costs in a recovery process based on acidifica- tion should be low ( sulfuric acid: about 1.5bllb) , prepared by the copolymerization in emulsion of vinyl acetate, acryl ic acid and dibutyl maleate , followed by partial hydrolysis of the resulting copolymer. These transformations a r e shown in Figure 2.

This modified P V A was

Results f rom the warp-shed tes te r on cotton-polyester ( 65:35) yarns s ized with these copolymers a r e shown in Table 6.

Removal of Desizing Products of Starch f rom Desizing Wastes

Starch and the desizing products from starch-sized fabrics a r e biodegrada- ble and a r e largely removed f rom textile-plant wastes by biological t rea t - ment sys tems. Biodegradation, of course , resul ts in the formation of a sludge which mus t be disposed of by other means. Exploratory attempts were made in the present work to find a procedure for removing s ta rch- desizing products by chemical precipitation.

Examination by thin-layer chromatography ( TLC) of enzymatic desizing wastes , f r o m s ta rch-s ized fabrics , obtained f rom a nearby textile plant, showed that none of the low-molecular-weight sugars--dext rose , mal tose, maltotriose, etc. - - w e r e present. The s t a rch was degraded, of course, but the products were s t i l l polymers of relatively high molecular weight. Fur ther enzymatic t reatment of the desizing wastes in the laboratory produced the sugars . waste f rom another plant which employed a caustic desizing of s ta rch- sized fabrics. If these textile plants a r e typical, an e r r o r has been made by wr i te rs who have assumed that s ta rch desizing wastes consist most ly of dextrose and other sugars of relatively low molecular weight.

Similar resul ts were obtained with a desizing

The above observation suggested that a means might be found for precipi- tating and recovering starch-desizing wastes as polymers ra ther than as

17

( a ) CH2=CHOCOCH, + CH2 = CHCOOH -+

F - - P ---CHZ- CH __-__ CH2- CH ____ -

I 0

-t

COOH ‘ I CO

- CH, i. a - ’-b

6H.L ~ *. - COONa -

( b ) CH2= CHOCOCH, + CH, = CHCOOH + CH = CH

GO CO’

.o 0

co ;

Figure 2 . Chemical Transformations in the Preparation of Polyvinyi Alcohol Copolymers

18

Table 6: Resul ts f rom Warp-Shed T e s t e r on Yarn Sized with P V A and P V A Copolymers

a. Vinol 540 polyvinyl alcohol ( P V A )

b. Vinol 125 polyvinyl alcohol ( P V A )

c. Vinyl a lcohol /acryl ic acid copolymer

d. Vinyl a lcohol /acryl ic acid/dibutyl maleate copolymer

S amp1 e I la 2a gb qb 5c g d ~ _ _ ~ ~~ ~- -

Size add-on ( w t f )

Shed ( w t $)

F i b e r in shed ( w t f )

s tops

Clinging ra t io ( 4 6 )

Warp tes ted ( yd)

Concn. of s ize ( wt $)

12.5 11.7 8 .3 8.1 11. 5 8 .8

0.7 0 . 8 0 . 6 0 . 8 4.1 5 . 6

4.6 50 75 7 5 67 66

0 0 0 0 5 2

2 5 25 2 5 25 75 75

20 20 20 20 12 20

9 .8 9 .8 8.0 8 . 0 10.0 7 . 7

sugar derivatives. The oxidation of s tarch to give a mater ia l containing aldehyde, ketone and carboxylic- acid functions is recorded in numerous publications in the l i terature and, indeed, "oxidrzed starch" i s a commer- c ia l product widely used in the paper industry (12 ) . w e r e ca r r i ed out on s tarch solutions ( 1 % ) to determine i f carboxyl groups might be introduced into the s ta rch molecule and permi t precipitation with polyvalent metal salts in the same manner a s CMC. The oxidizing agents were sodium hypochlorite, a common textile bleach a s well as the oxidant used to prepare commercial "oxidized starch"; sodium chlorite, another common textile bleach; and sodium bromite, a starch-desizing agent. None of the oxidations performed s o farp however, gave a product which was precipitated with fi l ter alum or f e r r i c chloride. "oxidized s tarches" ( Stayco G , Stayco M and Stayco S- -different viscosity grade t reated with alum but none gave a significant amount of precipitate.

Oxidation experiments

Solutions ( 1 % ) of three

of oxidized corn s ta rch f rom A. E. Staley Manufacturing Co. ) were

Biodegradation of Carboxvmethvl Cellulose CMC)

i

In the f i r s t exploratory experiment on the biodegradation of CMC;, a labor- a tory aerat ion chamber ( small- scale activated- sludge unit) w+s arranged for the continuous feed of a dilute (0.035) solution of CMC containing the necessary mineral nutrients. Bacter ia l seed was obtained f rom a munici- pal sewer . The CMC solution ( 5 l i t e r s ) was passedthrough the aeration chamber ( 2-liter capacity) and recirculated for four weeks. of this t ime, a 2 0 % reduction of the CMC content, measured spectrophoto- met r ica l ly ( see Appendix A ) culation was discontinued at this point and the ent i re mass was t r ans fe r r ed to a five-li ter flask for aerat ion in a static condition, a s impler procedure which seemed likely to accomplish the same resu l t a s aeration with r ec i r - culation. off.

A t the end

of the circulating solution was noted. Recir-

Reduction of CMC content advanced to about 35% and then leveled No fur ther reduction occurred even over a prolonged period.

In another experiment, after a suitable sludge ( MLSS = 1500 m g / l ) had been developed f rom sewage bac ter ia and a synthetic sewage feed ( see Table

were replaced gradually in increments of 10% over a period of 12 weeks with a n equivalent amount of CMC ( b a s e d on COD) . aeration chamber was approximately 14 hours . of the CMC concentration, measu red spectrophotometrically ( s e e Appendix A ) , between the influent and effluent s t r eams was noted after seve ra l weeks and this reduction increased with increasing substitution of the organic ma t t e r by CMC. increased to about 6 5 % af ter eight weeks. Reductions at this level continued f o r 10 weeks and then began to decline. ( MLSS) began to decline at the same t ime, indicating that the sys tem was experiencing a nutrrtional deficiency.

7 ) , the organic mater ia ls (dex t rose , s ta rch , yeas t ex t rac t ) in the feed

The detention t ime in the A t rend toward reduction

At 100% substitution it was 15% h the beginning and i t

The mixed-liquor suspended solids

This resu l t was r,ot unexpected since

I 20

Table 7. Synthetic Sewage Feed

Ingredients Amount ( mg. ,

Yeast extract 15 8

Dextrose

Starch

NH, C1

CaC1, 2H20

FeS04 7H2O

MnSO, H 2 0

MgSO, 7H,@

K2HP04

T apw at e r

COD

80

80

6 3

10

10

10

300

40. 3

t o 1 l i ter

300 m g / l

21

the feed for some time had contained no proteins or vitamins--CMC was the on1.y organic mater ia l in the feed. a r e shown in Table 8 and in F igures 3 and 4 .

The resul ts of this experiment

F o r another experiment, a sample of sludge was obtained f rom a smal l , experimental aerated lagoon used by Dan River, Inc. , Danville, Virginia, in treating a portion of i ts plant effluents. This plant uses CMC almost exclusively a s a warp s ize and i ts wastes had been discharged to the lagoon f o r over two years . a laboratory activated-sludge unit which was fed continuously with a CMC solution ( 0. 0 3 % ) containing essent ia l mineral nutrients ( see Table 7 ) . A r e duc ti on in CM C concentration, measured s pe ct r ophotome t r i cally ( s e e Appendix A ) between influent and effluent s t r eams was noted

level af ter five weeks and remained in this range for about 10 weeks. At the end of this time i t declined precipitously, along with the M U S , indicating that the system was reacting to a nutritional deficiency. resul ts a r e shown in Table 9and in Figures 5 and 6 ,

The sludge sample ( M I S S = 2000 m g / l ) was used in

*almost immediately. This reduction increased and reached the 70- 80%

These

Biodegradation of Po1,yvinyl Alcohol ( P V A )

After a suitable sludge ( MLSS = 1800 m g / l ) had been developed in a laboratory activated- sludge unit f r o m sewage bacter ia and a synthetic sewage feed ( see Table 7 ) I the organic mater ia ls (dex t rose , s ta rch , yeast ex t rac t ) in the feed were replaced gradually in increments of 10% over a period of 18 weeks with a n equivalent amount of P V A . The deten- tion t ime in the aeration chamber was approximately two days. A trend toward a reduction of the P V A content, ( see Appendix A ) , between the influent and effluent s t r e a m s was noted af ter four weeks ( 40% substitution of P V 4 ) and this reduction continued to increase with increasing t ime and substitution of PVA. approximately 60 after 16 weeks ( 90 $ substitution of P V A ), remained in the 60-65% range for an additional 17 weeks, and then began to decline-- apparently as a resu l t of nutritional deficiency. The resu l t s of this experi- ment a r e shown in Table 10 and in F igures 7 and 8 .

measured spectrophotometrically

It reached

i

2 2

.

T a b l e 8: R e m o v a l of CMC with Act iva ted Sludge Developed in L a b o r a t o r y

Date

8 /14/70

9 /11/ 70

9 /18/ 70

9 / 2 3 / 7 0

9 130 170

10 / 7 / 7 0

10 / 14 / 7 0

11 / 11/ 7 0

11 / 18 / 7 0

11 / 25 / 7 0

121 2 /70

12 /9 /70

12 /16 / 70

121 30 /7C

1 / 7 / 7 1

1/15 / 71

1 /20 /71

2 / 5 / 7 1

3/11/71

5 /14/71

5/17/71

Time ( w e e k s )

8

12

13

13

15

16

17

21

2 2

23

24

25

26

2 8

29

30

31

33

38

47

47 I.I

Subs titu- t ion of CMC ( % )

70

80

90

100

100

100

100

10 0

10 0

100

100

10 0

10 0

10 0

100

100

10 0

100

10 0

100

100 .I--

CMC Concent ra t ion

Influent ( % I

0.0180

0.0210

0.0230

0 .0250

0 .0295

0 .0255

0 .0290

0 .0280

0 .0300

0 .0340

0 .0330

0 .0320

0 .0305

0.0280

0.0315

0 .0330

0.0310

0.0315

0 .0330

0 .0295

0 .0290

Eff luent ( % )

0.0160

0.0190

0.0210

0 . 0215

0 .0220

0.0210

0.0240

0 .0205

0.0110

0 0130

0,0170

0 * 0120

0.0150

0 .0050

0 .0085

0.0130

0.0110

0 .0200

0.0240

0 .0255

0.0240

Reduct ion ( % )

11

10

9

14

25

18

17

29

6 3

6 2

48

6 3

52

8 2

7 3

61

6 5

34

27

14

17

2 s

Y M a 5 cn 4

a al rd > c,

.rl U

m

Q, k

2 3 .rl

b(

I I I 1 I

lo Tl= m c\J 0 0 0 0

-. 0 0 0

0 8 0 0 V v

j

24

3

al M

0 0 0 0 0 O 0 00 a d- N -

2 5

T a b l e 9 : R e m o v a l of C M C wi th Act iva ted Sludge f r o m Dan R i v e r T r e a t m e n t Plant

9/15/70 1 9/17/70 1 9/18/70

9 / 2 3 / 7 0 I 3 9 / 3 0 / 7 0 I

10 /7 /70 I

10/12/70 t 10/21/70 t 10/28/70 i

11/4/70

11/11/70 1 11/18/70 1 11/25/70 1 12 /2 /70 ! 12 /9 /70 f 12/16/70

12 /30 /70 , e 1 /6 /71

!

1/15/71 I

*

5

I

0

2 d a y s

3 d a y s

1

2

3

4

5

6

7

8

9

10

11

12

13

15

16

17

18 i

L Z Y

0.027

0.027

0 .034

0 .029

0 .028

0 . 0 2 8

0.029

0 .029

0 .029

0.027

0 . 0 3 4

0 .030

0.030

0 .031

0 .031

0 .028

0.030

0 .030

0 .0275

0 .027

0 .024

0.015

0.015

0.016

0.012

0 .009

0 .009

0.010

0 . 0 0 5

0 .006

0 .007

0 .006

0.007

0.011

0 .024

0 . 0 2 8

0 .029

0 .026

0

11

56

48

4 3

57

69

69

66

81

8 2

77

80

77

65

14

7

3

5

26

.. In

Q, k 5 M

c.1 .A

I-

* 0 0 0 0 0 0

(Ye) 3iN3 A 0 NOILVtJLN33N03

n

cn 4L W

; U

27

i

0, M a

.. 9

TablelO: Removal of PVA with Activated Sludge Developed in Laboratory

Date

9/25/70

10 /23/ 70

12/10/70

12 /17 / 70

116 171

1/21/71

2 / 19 / 7 1

5/14/71

5 /17/71

Time ( w e e k s )

0

4

11

12

15

17

21

33

33

I ____-,____ _-_- ----.--.----- _-I__.-

P V A Concentration > Substitu- t ion of PVA f Influent

10

40

70

80

80

90

10 0

10 0

100

i

. . 2,

0.0125

0.020

0.026

0.026

0.026

0.024

0.026

0.026

I ( 8 ) ; ( % ) I Effluent Reduction

8 t 0.0115 .;

1

1 50 0.010

0.006 1 77

0.014 ! 46

0.009 'r ' 65

I

0.010 !! 58 i 0.010 i 6 2 I

2 9

CJ 0

0.05

0.04

0.03

0 . 0 2

0.0 I

0.00

Figure 7 : Treatment of P V A with Activated Sludge Developed in L,aboratory

L - INFLUENT a0

IO 20

TIME ( W E E K S )

30

o i l d Q .. co

o k I M .4

h

3 9

0 N

0 -

0 0 0 0 0 O 0 00 u) e N

31

SECTION V

ACKNOWLEDGEMENT

This repor t was prepared by Carl E. Bryan, Pro jec t Director , with the ass i s tance of the other people engaged in the work on the project.

The major p a r t of the bench-scale labora tory studies, ir-cluding the analytical work, was c a r r i e d out by Peggy S. Harr ison. The warp-sizing experiments , together with the t r ia l s on the warp-shed t e s t e r , were per - formed by Charles D. Livengood and Gene G. Floyd. The copolymers of vinyl acetate and vinyl alcohol were prepared by Samia G. Saad.

Plant was te samples were obtained through the courtesy of Burlington Industr ies , Inc. , Cone Mills Corporation, and Dan River , Inc.

The in te res t and advice of Charles Smallwood, Jr., Department of Civil Engineerings throughout the Lourse of this invest igat im is acknow- ledged with p leasure . experiments were held with h im and with W i l l i a m S. Galler and F rank J. Humenik, a l so of the Department of Civil Engineering.

Helpful d:scussions regarding the biodegradatioc

’ Ear ly phases of the work, including the preparat ion of the r e sea rch proposal, were suppcrted by :he Water ReJources Research Institute of the University of North Carclina, David H. Howells, Director. This support was essent ia l and i s hereby acknowledged.

The support of the major par t of the program by the Federa l Water Pollution Control Administration, l a t e r the Enirir onmental Protection Agency. and the help provided b.y Harold J . Snyder, Jr., the Grant P ro jec t Officer, is gratefully acknowledged.

3 3

-I SECTION VI

REFERENCES

1. A i r Reduction Co. , Inc. Technical Bulletin, "Airco Vinol Polyvinyl Alcohol", 1965.

2. E. I. DuPont de Nemours and Coo , Inc. , Technical Bulletins, "Elvanol Polyvinyl Alcoholtf, 1968, and "Increasing Water Resistance of Elvanol Polyvinyl Alcohol", 1969.

3. Eyler , R. W. , and R. T. Hall, "Determination of CMC in Paper", P a p e r Trade Journal, - 125 ( 1 5 ) , 59-62 (1947) .

4. FWPCA Methods for Chemical Analysis of Water and Wastes, U. S. Department of the Interior, November, 1969.

5 . Finley, Joseph H. , '?Spectrophotometric Determination of Polyvinyl Alcohol in Paper Coatings", Analytical Chemistry, - 33 ( 13) , 1925-7 (1961) .

6. Hercules , Inc. e Technical Bulletin, "Analytical Procedures for the Assay of CMC and Its Determination in Formulations", 1966.

7 . Humenik, F r a n k J. , North Carolina State University, private communi- cat ion.

8. McKinney, Ross E. Microbiology for Sazitary Engineers, McGraw- Hill Book Co. Inc. , New York, 1962.

9. Moore, Glenn E. , Virginia State Water Control Board, private communi- ca t ion.

10. Pr i tchard , J. G. , Polyvinyl Alcohol - - Basic Proper t ies and Uses, Gordon and Breach Science Publ ishers , New York, 1970.

11. Pullekines, John J . , A i r Reduction Co, Inc. private communication.

12. Rober t s , Hugh J , "Nondegradative Reactions of Starch',' in Chemistry and Technology of Starch, edited by Roy L. Whistler and Eugene F. Paschal , Academic P r e s s , Inc. , New York, 1965, Vol . 1, pp. 439-93.

13. Sorenson, Wayne R. , and Tod W . Campbell, Preparat ive Methods of Poly- m e r Chemistry, Interscience Publishers, Inc. New York, Second Edition, 1968.

35

14. Stahl, Egon, arrd U, Kaltenbach. "Sugars and Derivatives", in Thin- Layer Chromatography = - A Laboratory Handbook, edited by Egon Stahl, Academic P r e s s p Inc.@ New York, 1965, pp. 461-9.

15. Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Inc. New York, Twelfth Edition, 1965

36

SECTION VI1

PUBLICATIONS AND PATENTS

A paper based on a portion of this work was presented before the 20th Southern Water Resources and Pollution Control Conference in Chapel Hill, North Carolina on April 2 , 1971 and before a meeting of the Northern Piedmcnt Section of the American Association of Textile Chemists and Colorists in Durhams North Carolina on April 17, 1971. It is expected that this paper and others resulting f rom this work will be submitted for publication.

37

SECTION VIII

APPENDICES

39

APPENDIX A - LABORATORY PROCEDURES

Materials

Yarn: desizing experiments.

Sodium carboxymethyl cellulose ( CMC) : cellulose G u m 7L, w a s obtained f rom Hercules, Inc.

Polyvinyl alcohol ( P V A ) : duPont de Numours and Co., Inc. ( Elvanol 51-05) and A i r Reduction Co. Inc. ( Vinol 125 and Vinol 540) . Starch: Douglas pear l cornstarch from Penick and Ford , Ltd.

A 40/1 cotton-polyester ( 65:35) yarn was used in the sizing and

A warp-size-grade CMC, labelled

Warp-size-grade PVA was dbtained f rom E. I.

Aluminum sulfate ( f i l ter a lum) :

F e r r i c chloride: Baker and Adamson, Reagent A. C .S . , No. 1736.

Other chemicals: highest quality available commercially.

F i she r Scientific Co., Technical, No. A-611..

The reagents used in the analytical work were of the

Methods

Sizing, Desizing, and Size Recovery

Sizing: tory sizing machine, and 252 ends were s ized in a single pass .

Desizing: The s ized yarns were desized in batches in an autoclave using hot ( 200-210'F) water. Each batch ( about 1700 g ) of y a r n was treated for 30 minutes with three consecutive portions ( each, about 15 l i t e r s ) of water and, to keep the volume of desizing liquor small , the third portion of water used with each batch of ya rn was the f i r s t portion used with the next batch, The total solids of the desizing liquors obtained in this way were approximately 1% ( 10, 000 m g / l ) . Precipitation of size: A 10% ( by weight) solution of f i l ter alum was used in precipitating CMC from desizing wastes although the concentration of precipitant is not a cr i t ical factor. plete precipitation of the CMC and the amount added was f rom 75% to 100% of the weight of CMC recovered ( S e e Table 1) . to CMC resul ted in more rapid coagulation and precipitation with c learer supernatants . Recovery of precipitated size: swollen, fluffy sludge. Dewatering was accomplished by decanting the supernatant, collecting the swollen sludge on a cloth f i l ter , and then further removing excess water by centrifuging. The amount of water in the sludge was reduced to 90% or l ess to permi t the preparation of a new sizing solu- tion of the proper concentration.

The sizing t r ia l s were ca r r i ed out on a Callaway s lasher , a labora-

Enough alum was added to effect com-

The l a rge r ratios of alum

The CMC-alum complex settled a s a highly

41

Solution of recovered size: in sodium hydroxide for reuse a s a warp size. be essential fo r this operation and a laboratory homogenizer ( Eppenbach) was used in the present work. The sodium hydroxide ( 10 '9) was added dropwise to the s t i r r ed sludge and, within a few minutes, a smooth, somewhat cloudy solution with a pH of about 8 , was obtained. Adjustment of the concentration was made by the addition of the proper amount of water.

The recovered CMC-alum complex was dissolved Good agitation was found to

Preparat ion of polyvinyl alcohol copolymers

Polymerization: prepared by emulsion polymerization. multinecked, Pyrex reaction kettle, which was fitted with a mechanical s t i r r e r , a thermometer , a dropping funnel, a reflux condenser and a tube f o r introducing nitrogen above the reaction mixture. The procedure used in the present work i s described in Preparat ive Methods of Polymer Chemistry ( 1 3 ) .

Hydrolysis: were hydrolyzed to the corresponding vinyl alcohol copolymers in methanol solution using sodium methoxide as the catalyst. The reaction was conducted in a multinecked reaction flask which was equipped with a mechanical s t i r r e r p a reflux condenser and a dropping funnel, Prepara t ive Methods of Polymer Chemistry (13) .

Copolymers of vinyl acetate with other monomers were The reaction was ca r r i ed out in a

The vinyl acetate copolymers, prepared as described above,

The procedure i s described in

Oxidation of s t a r ch

Oxidation experiments on Douglas pear l corn s t a rch were ca r r i ed out in Pyrex reaction vesse ls equipped with a s t i r r e r , thermometer , and a drop- ping funnel for addition of reagents a s needed. hypochlorite were performed at room temperature using up to 20$( by wt, solids bas i s ) sodium hypochlorite, based on starch; oxidations with sodium bromite w e r e performed also at room temperature, with up to 5 % ( b y wt) "Preptone" sodium bromite desizing solution, based on s tarch; oxidations with sodium chlorite were at 8OoC, with up to lo$ ( by wt) 'Textone" sodium chlorite bleach, based on s tarch. Reactions were allowed to proceed over a period of 4-5 hours o r longer, and thinning of the s t a rch occurred in every case, but a significant amount of precipi- tate w a s not formed in any case upon addition of alum.

Oxidations with sodium

42

I

Analy s e s

Carboxymethyl cellulose ( CMC) , in desizing liquors and in the effluents f rom laboratory activated-sludge units, was determined by the 2 , 7-dihy- droxynaphthalene colorimetric method ( 3,6) . the carboxymethyl groups in CMC a r e converted to glycolic acid by boiling the sample in 50% sulfuric acid. 2 , 7- dihydroxynaphthalene reagent, which reac ts with the glycolic acid to give a purple color. absorption maximum of 540 q. formaldehyde and substances which yield formaldehyde under the condj- tions of the analysis.

Polyvinyl alcohol ( P V A ) analysis, in the effluents f rom laboratory activated-sludge units, was based on the green color produced by the reaction of PVA with iodine in the presence of boric acid ( 5 ) , intensity of the color is measured at the absorption maximum of 6 9 0 ~ . The principal interfering sustance likely to be encountered in work of the present nature is s ta rch and i ts effect can be eliminated by a pre- t reatment involving acid hydr ol y s i s .

Aluminum, in CMC- alum complexes and in supernatants, was determined by atomic absorption spectroscopy in accordance with the procedure recom- mended in the FWPCA manual for chemical analysis ( 4 ) .

According to this method,

The mixture is then t reated with the

The intensity of this color is measured at its The principal compounds that in te r fe re a r e

The

Total solids were determined gravimetrically b.y the procedure outlined in the FWPCA manual for chemical analysis ( 4 ) . Residues at 6OO0C were determined gravimetrically b,y the procedure given in Standard Methods (15) . Desizing products f rom starch- s ized fabrics were examined by thin-layer chromatography ( TLC) . The adsorbent was Kieselguhr G ( M e r c k ) impregnated with 0.1 M monosodium phosphate and spread onto glass plates; the solvent was a mixture of n-butanol, n-propanol, acetone, ethyl acetate, ammonium hydroxide ( 2 8 % NH, by w t ) and water ( 7:6:7:4:2:4) . plates with a solution of potassium dichromate in sulfuric acid and then drying them in an oven. a number of monographs; one, edited by Stahl (14) , contains a chapter on Sugars and Derivatives which descr ibes analyses of the type ca r r i ed out in this project.

The chromatograms were developed by spraying the

The technique of TLC has been described in

43

Biodegradation Experiments

The biodegradation t r ia ls on CMC and P V A were car r ied out in labora- tory activated-sladge units, of which two types were used. A picture of one such unit, used in the present work in building up and acclimatizing sludges to CMC and P V A , is shown in Microbiology for Sanitary Engineers .. - by McKinney ( 8 ) . It is a rectanguloid chamber, 7" ( width) x 11" ( height) x 13" ( length) , constructed of polymeth.yl methacrylate, and divided verti- cally into four equal compartments, each 7" x 11" x 3", so that four experi- ments can be conducted simultaneously under the same conditions. capacity of each compartment is two liters. Provision is made for contin- uous addition of influent and overflow of effluent, sludge withdrawal, aera- tion and stirring. constructed of Pyrex glass is shown in Figure 9. It was used in the t r ia l of CMC biodegradation with a sludge obtained f rom the waste- t reatment plant of a textile mill which had been using CMC as the predominant warp s ize for severa1,years. four l i t e r s .

The

A diagramatic sketch of the other unit which was

The capacity of the aeration chamber is This unit is designed also for continuous operation.

44

"*)

AIR LIFT S L U D G E R E T U R N

f M E C H A N I C A L S T I R R E R " /

INF

\ = SLUDGE

R E M O V A L

I I I I

Figure 9 : Laboratory Activated-Sludge Unit, Consisting of Aeration Chamber ( A ) and Separation B a s i n ( B ) one foot)

( approximate scale: two i n c h e s =

45

APPENDIX B - RELATED LITERATURE

In the Department of Textile Chemistry of the School of Textiles of North Carolina State University, an exploratory study was made of the possibility of recovering and reusing synthetic, or partially synthetic, warp s izes ( 2) . tu re dealing with textile wastes. expanded and updated ( 5 ) the recovery and r euse of textile processing chemicals, soda used in mercer iza t ion appears to be the outstanding exception ( 1, 4, 6 ) . In the other par t of the study a t North Carolina State University, it w a s found that a CMC sizing solution could be reconsti- tuted, by addition of the required amount of CMC to the dilute desizing wastes, to give a formulation which performed satisfactorily as a warp s ize during weaving.

A l a rge par t of this study was a survey of the l i tera- This surveyo which was recently

showed that l i t t le work had been done on The caustic

More closely related to the work described in this repor t a r e processes described in three recent patents. an alkali s t a r ch phosphate may be used as a warp s i ze for textile yarns; the s ize is easi ly removed without degradation af ter weaving and the desizing liquor, although quite dilute in the examples giveno may be used to make up a new s ta rch phosphate, sizing solution. On the other hand, the s ize may be precipitated f rom the desizing liquor with a divalent caticn,su?h a3 calcium, to leave a waste liquor with low BOD. According to the other two patents ( 7 , 8 ) , alkali metal sal ts of ethylene-acrylic acid copolymers a r e suitable for sizing textile yarns and the size is recoverable f r o m the desizing liquors by precipitation with acid, patents, however, do not appear to have received industrial appli- cation.

According to one patent ( 3 )

The processes descr ibed in these

47

... '1 References Cited

1. Becknell, D. F. "Vses of Caustic Soda Recovered f rom the Mercer iza- , tion P r o c e s s , I f M. S. Thesis, Georgia Xnstitute of Technology, 1965.

2. B e r r i e r , R. N, and H. Y . Jennings, "Recoverable Warp Sizes", P ro - ceedings of the 15th Southern Water Resources and Pollution Control Conference, 81-83 ( 1966) .

3. Bode, H. E. "P rccess for Sizing Textiles and the Disposition of Sizing Wastes Therefrom", U. S. Pat. 3,093, 504 ( June 11, 1963).

4. Jones, L. D., "Recovery of Caustic Soda f rom the Mercerization P rocess , I t M. S. Thesis , Georgia Institute of Technology, 1965.

5. Livengood, C. D. , "Textlie Wastes - A Biblicgraphy," Water Resources Research Institute of the Untversity of North Carolina, Report No. 18, 196 9.

) 6. Nemerow, N. L., and W. R. Steel, "Dia lys . .~ of Caustic Textile Wastes", / 2 Proceedings of the 10th Industrial W a s t e Conference, Purdue University

Engineering Extension Serviceo No. 89, 74-81 ( 1955) . 7. Walter, A . T . , G. M. Bryant and C. L. Purcel l , "Process for Sizing

U. S. 3, 321,819 ( May 30, 1967) , assign- and Desizing Textile F ibers , ed to Union Carbide Corporation.

8. Walter, A. T . , G. M. Bryant and C. L. Purcel l , "Alkali Metal Salts of Ethylene - Acrylic Acid Interpolymers, I * U . S. 3,472,825 ( October 14, 1969) , assigned to Union Carbide Corporation.

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