2006 International Conference on

Nanotechnology, April 26-28, 2006

Atlanta, GA

New Production Method for Nano Silica Sol and its Application for Papermaking

Presented by: Yoshiaki Koga

Title : ManagerCompany : TOKUYAMA Corporation

Contents1.Introduction

2.Production method and properties of silica sol

3.Apprication of silica sol

a) retention aid for papermaking

b) waste water treatment agent for papermaking

4.Demonstration unit

5.Conclusion

1.IntroductionColloidal silica has been used widely as a retention and drainage aid

In papermaking industry.

But, Silica sol could be rarely used in papermaking and water

treatment. Because silica sol has the following disadvantages.

1.Poor stability of their quality

2.Low productivity of silica sol

We have developed the new production method of silica sol with

particle size 3-5nm using Y-shaped apparatus and found that this

silica sol may be used as a retention aid and a wastewater treatment

agent for papermaking by controlling polymerization viscosity of sol.

We can easily produce high concentration silica sol of 15% SiO2.

a) ReactionSodium silicate water

Y-shaped Aging Silica sol dilutedSulfuric acid Apparatus (15%) silica sol

Na2O•3SiO2 + H2SO4 3SiO2 + Na2SO4 + H2O

b) Raw materials

Sodium Silicate liquid :28 ~29 (g/100ml)(Na2O•3SiO2) M.R 3.0 ~3.2

Sulfuric acid :20 ~22 (g/100ml)

c) Reaction condition

Temp. : 30 ~40 ºCSiO2 contents : 14 ~16 (g/100ml)Aging Viscosity : 10 ~12 mPa·s

pH : 1.5 ~1.8

Figure 1 Production method of Silica sol by using Y-shaped Apparatus

2. Production Method and properties of Silica Sol

Item Conventional New

Reactor High Power agitator Y-shaped apparatus

Heater Use No use

SiO2 concentration (%) 6 Max 14 ~ 16

Reaction time (min.) 60 at moment

Reaction Temp. (ºC) 65 30 ~ 40

Aging time (min.) 140 90 ~120

Figure 2 Comparisons Between conventional and New Production methods

Silica sol 6% Silica sol 14 ~16%Productivity: 5 ~10 times

agitatorsodium silicate

Sulfuric acid

sulfuric acid10m/sec. over

sodium silicate10m/sec. over

Figure.3 Reaction part of Y-shaped apparatus

Fig.4 Relationship between SiO2contents and effect of coagulation

0

2

4

6

8

10

12

14

0 5 10 15 20 25

SiO2content at reaction (g/100ml)

Turb

idity

(NTU

)

0.8

0.9

1

1.1

1.2

1.3

1.4

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Aging viscosity (mPa·s )

Turb

idity

(NTU

)

Fig.5 Relationship between aging viscosity and effectof coagulation in raw water

Fig.6 Relationship between Aging Viscosity and effectof retention

RDDT: Light transmittance of white water (filtrate by 100 mesh)

Aging Viscosity (mPa·s)

RD

DT

(TM

%)

60

65

70

75

80

2 4 6 8 10 12 14 16

100ppm200ppm

Fig.7 Particle size of silica sol by Dynamic LightScattering

Silica Sol Silica Sol Silica Sol

Fig.8 Particle size distribution by number

Silica Sol 1 Silica Sol 2 Silica Sol 3

Part

icle

siz

e

Aging viscosity

Figure 9 Characteristic of Viscosity as Function of SiO2 Concentration

and Aging Time (at reaction step)

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11 12 13Aging Time (Hr)

Visc

osity

[mPa

·s]

10.07%30ºC

13.24%30ºC

11.76%30ºC

10.75%30ºC

15.25%30ºC

21.02%33ºC

Fig.10 Stability of a diluted Silica sol

Visc

osity

(mPa

·s)

Days

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40 45 50

SiO2: 0.76%SiO2: 1.26%SiO2: 1.69%SiO2: 2.07%SiO2: 2.66%

0.76%1.26%1.69%

2.07%2.66%

Aging Temp:30ºC

Sodium silicate

Reaction Aging dilution diluted silica sol

Sulfuric acid

Ferric chloride

Use for drinking water and waste watertreatment

Use for retention aid in papermaking

Aluminum sulfate

Use for waste water treatment in papermaking

Figure 11 Application of silica sol.

(Y shapedapparatus)

(by water)

3. Application of Silica Sol

Fig.12 Evaluation of Retention Aidin Laboratory

(Retention)

RDDT: Light transmittance of white water(filtrate by 100mesh wire)

Dosage of silica (ppm)

30

35

40

45

50

0 100 200 300

RD

DT

(TM

%)

silica sol

colloidal silica

silica sol

Fig.13 Evaluation Retention Aidin Laboratory (Ash

retention)

5.0

5.5

6.0

6.5

7.0

0 100 200 300Dosage of silica (ppm)

Ash

con

tent

(%)

silica sol

colloidal silicasilica sol

Fig.14 Evaluation Retention Aid in Laboratory (Drainage)

35

40

45

50

55

60

0 100 200 300

Dosage of silica (ppm)

Dra

inag

e tim

e (s

ec)

silica solcolloidal silicasilica sol

Cationic Silica solCalcium carbonate Retention Aid

Stuff box Fan pump Screen Inlet To machine

White water

Fig.15 Simplified Flow Chart for the Mill Trial

Table 1. Condition of the Mill Trial and Results1) Condition of the Mill Trial

Paper type : PPC (neutral paper)Capacity : 240 tons/dayBasis weight : 60 ~64 g/m2

Wire speed : 950 m/min.

2) ResultsRetention aid Silica sol Colloidal SilicaDosing (ppm) 200 180 200T-Retention rate (%) 78.9 78.0 76.5Ash Retention rate (%) 43.3 42.5 38.1Reduce 3K steam (%)(Silica sol/colloidal silica) 17 15 1

Fig.16 Retention Effect at the Mill TrialTime (Hr:min.)

60.0

62.0

64.0

66.0

68.0

70.0

72.0

8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30

RD

DT(

%)

Colloidal Silica 200ppmSilica Sol 200ppmSilica Sol 180ppm

Fig.17 One pass total and ash retention at the Mill TrialTime (Hr:min.)

Colloidal silica 200ppm

Silica sol 200ppm

20

40

60

80

9:30 10:30 11:00 12:00 13:00 14:00 14:55 16:00 17:00

Ret

entio

n (%

) 180ppm

one pass total retentionon pass ash retention

Fig.18 Ink Receptivity of paper at the Mill Trial

Time (Hr:min.)

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30

Ink

Rec

eptiv

ity

Silica Sol 200ppmSilica Sol 200 180ppmColloidal Silica

Table 2. Application to paper waste water

1. SamplesSample Turbidity COD pH

Raw White water 1300 ~1500 6.7diluted White water (1) 93 ~ 100 97 6.2 ~7.2diluted White water (2) 420 ~ 434 407 6.6 ~7.2

2. Treatment method

diluted White water pH control dosing PSAL pH control9 ~12 6 ~7

dosing organic flocculant settling settling water1~2(mg/L) 10min. turbidity

COD

Diluted silica sol PSAL Aluminum Sulfate

Fig.19 coagulation property of Polysilicate Aluminum (PSAL)

0.0

2.0

4.0

6.0

8.0

2 4 6 8 10 12pH

Al c

onte

nts

in s

ettle

wat

er (m

g/L)

CoagulationpH6~ 8

PSAL 0.25 (Si/Al: mol.ratio)

Fig.20 stability of storage of Polysilicate Aluminum

Days

Al:2.44g/100ml,pH:2.26

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8

Visc

osity

(mP

a·s)

PSAL M.R: 0.25

Temp:30ºC

Fig.21 Comparison between ALUM and PSAL coagulant

(at the diluted White Water (2) sample)

0

2

4

6

8

10

0 100 200 300 400 500 600Dosing Al (mg-Al/L)

turb

idity

(NTU

) ALUM PSAL

Table 3. Results for white Water Treatment

1.Turbidity Sample PSAL-0.25 organic flocculant Turbidity

(mg-Al/L) (mg/L) (NTU)Before After

Dilute White Water(1) 5 1 98 1.2Dilute White Water(2) 100 2 404 1.3

2.CODSample PSAL-0.25 organic flocculant COD cut. rate

(mg-Al/L) (mg/L) (mg/L) (%)Before After

Dilute White Water(1) 5 1 97 22 77Dilute White Water(2) 100 2 407 85 79

Fig.22 Application model for papermaking

Silica sol production process

silica sol

aluminum sulfate

Paper manufacturing Wastewater treatmentprocess Process

precipitate

Treated water Fuel and Raw material forRecycling Process Cement

Fig.23 Demonstration unit

Size:3600 x 1650 x H2250Aging Tank :300L (42kg-SiO2/batch)

4. Production Unit

5.ConclusionSilica sol by the new method can be used as a retention aid and a waste water treatment agent for papermaking by controlling polymerization viscosity of sol. It has the following advantages.

1. High productivity (15% SiO2)

2. Good stability of quality and better retention and drainage effect for a neutral PPC grade.

3. Better Ink receptivity for paper than colloidal silica.

4. Very simple production unit and cost effective process.

5. Decrease in energy cost and solution of some environmental issues.

We hope that our technology can contribute to a paper company.END

Thank you for audience.

Others

Calibration curve varies with the production method of Silica

Calibration Curve of BET Surface Area and Sears Titer

0

200

400

600

800

1000

1200

0 10 20 30 40 50

Sears method 0.1N-NaOH Titer (ml)

BET

Met

hod

Spec

ific

surf

ace

area

(m2 /g

)

SEARS Line

Precipitated Silica

Gel Silica

Fumed Silica

A.Meffert Line *A.Meffert Line

*:Z.Anal.Chem.249,231-233(1970)

y = 32x - 25y = 23 x - 118y = 26 x - 5y = 26 x - 36y = 25x - 35

Particle size start to change from about 10 of aging viscosity .

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 2 4 6 8 10 12 14 16 18 20

Aging viscosity [mPa·s]

Part

icle

siz

e [n

m] [

D(v

)(0.5

) ]

neutralization ratio: 1.15, aging Temp : 40 ºC neutralization ratio: 1.15, aging Temp.: 30 ºCneutralization ratio: 1.10, aging Temp.: 30 ºC neutralization ratio: 1.30, aging Temp.: 30 ºC

Relationship between aging viscosity and particle size of silica sol