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Synthesis of Zeolite a from Silicate Raw Materials and its Application in Formulations of Detergents
579 B. Drzaj, S. Hocevar and S. Pejovnik (Editors), Zeolites © 1985 Elsevir Science Publishers B. V. Amsterdam - Printed in Yugoslavia
SYNTHESIS OF ZEOLITE A FROM SILICATE RAW MATERIALS AND ITS APPLICATION IN FORMULATIONS OF DETERGENTS S. DONEVSKA 1, J. TANEVSKI 1 and N. DASKALOVA 2 l"Alkaloid", Research Institute, 91000 Skopje, Yugoslavia 2"OHIS", OOZT "Bi1jana", 91000 Skopje, Yugoslavia
ABSTRACT The conditions for synthesis of zeolite A with natural silicate raw materials of Macedonian origin were examined. The optimal compositions of the starting reaction mixtures as well as synthesis conditions were determined. With this investigation it was concluded that the zeolite A produced from Macedonian silicate raw materials is suitable for use in detergent formulations. INTRODUCTION The method most often used worldwide for the synthesis of zeolite A is the one whereby hydroge1s are obtained by mixing sodium silicate and sodium aluminate (ref. 1). At present a lot of attention has been paid to the natural silicate raw materials as potential sources of cheaper zeolite A production. Many silicates have been tested, among them kaolin clay as the most promising one (ref. 2). The method of synthesis, starting from kaolin, involves its thermal treatment at JOOoC fOr the purpose of transforming it into metakaolin and then its recrystallization into zeolite A under certain conditions (ref. 3). The use of other silicate raw materials (different types of clays and tuffs) invo1v.es many problems because these materials are po1ymineral with different kinds of impurities. The possibil ities of using a natural volcanic glass in different zeolite syntheses were investigated, but the final products did not meet the quality of the comercial ones (ref. 4). Considering the amphoteric characteristic of al1ophane, its use in zeolite A synthesis has been reported in Japan (ref. 5-6). The treatment of diatomite with 10-15% solution of sodium hydroxide has been used in the USSR for zeolite A preparation (ref. 7). Drzaj et al. have developed a method for synthesizing zeolites A and X starting with bentonites from different regions in Yugoslavia (ref. 8-9).
580
CHEMICAL AND MINERALOGICAL PROPERTIES OF THE EXAMINED SILICATE RAW MATERIALS Usually a suitable pretreatment of the raw materials in the synthesis of zeolites has to be undertaken. Therefore the knowledge of the chemical and mineralogical characteristics of the starting raw materials is of great importance. It is well known that in the case of kao1 in clays thermal pretreatment is. tbemost widely used one, while chemical treatment is the most common in the case of bentonite clays (ref. 9). In order to reduce the production expenses as much as possible we examined the possibility of bypassing the chemical treatment and thermal pretreatment of the starting raw materials. Therefore careful preliminary investigations were made of different silicate raw materials from Macedonia, among which the following four from table 1 have proved to be the most promising. TABLE 1 Chemica1 composition of the raw materials Raw material Opalized tuff Kaol inized tuff Pumice tuff Halloysite clay
Symbol 51 52 53 54
5i0 2
A1 203
96,75 1,52 85,00 9,88 69,40 15,84 42,17 29,08
Fe203
CaD
MgO
Na 20
K20
0,78 0,57 1,71 0,44
0,43 0,70 1,40 1,25
0,08 0,10 0,72 0,92
0,10 0,15 1,70 0,38
0,12 4,70 0,65
The raw material Sl contains a high percentage of Si02 mostly in amonphous state and some minerals such as tridimite, cristobalite and smaller quantities of quartz. feldspar and limonite. Koalinized tuff is a polymineral raw material composed mostly of tridimite and kaolinite with small quantities of quartz, limonite and other minerals. The raw materials 51 and 52 are fine grained materials of amorphous nature that are mostly easy to grind. The pumice tuff S3 is si 1icate mtnera1 predomi nantly of amorphous nature. The crystalline phase composed of al-bite, oligoclase, orthoclase and anorthite takes about 20%. The halloysite clay S4 is"a pure clay with v.ery low presence of other minerals. EXPERIMENTAL The influence of the following factors on the quality of zeolite A was studied through systematic inv.estigations: - appropriate actiyation of the starting raw materials, - composition of the initial mixtures, which were analyzed for the content of 5i02• A1 203, Na 20 and H20, - stirring efficiency of the reaction mixtures, - crystallization kinetics.
581
All of the silicate raw materials were activated with granulated sodium hy0C. droxide at 200-400 After this treatment a certain quantity of water and sodium aluminate was added under intensive stirring. This operation was followed by thermal treatment in closed Teflon containers at 1000C. At certain intervals samples were taken out, filtered and washed to neutral reaction. Some experimental results obtained are given in tables 2, 3, 4 and 5. TABLE 2 Initial reaction mixtures for synthesis of zeolite A using raw material Sl Composition in mol/A1 203 Na 20 Si02 H20 5 2 210 4 2 210 3 2 210 2,5 1,5 150 2,5 2 150 2,5 2,5 150 4 2 250 4 2 80 Time of crystallization 5h
Rate of crystal1ization, %
Impurities
95 95 95 95 90 80 95 90
TABLE 3 Initial reaction mixtures using raw material S2 Composition in mol/A1 20 3 Na 20 Si0 2 H20 4 1,5 210 4 1,8 210 4 2 210 2,5 2 210 3 2 210 3 1,8 210 Time of crystallization 6h
Rate of crystal1ization, % 95 95 95 70 90 95
Impurities HS
Pc Pc
TABLE 4 Initial reaction mixtures using raw material S3 Composition in mol/A1 203 Si0 2 Na 20 H 20 5 2 210 4 2 210 3 1,8 210 2,75 2 210 2 2 210 4 1,5 210 4 1,8 210 Time of crystallization 6h
Rate of crystal1i zat ion , %
80 95
Impurities HS
90
70
60
80 95
Pc
HS
582 TABLE 5
Initial reaction mixtures using raw material S4
Composition in mol/A1 203 Na 20 Si02 H20
Rate of crystallization, %
Pretreatment of S4 at 700 0C 2,4 1,6 125 2,8 1,6 140 3,2 1,8 195 Activation of S4 with Na~H only 2 1,7 150 3,5 1,8 150 4 2 200
95 95 95 90 100 95
Time of crystalImpurities lization, h
HS
6 6 6
HS
4 4 4
The figures 1, 2, 3 and 4 represent electron scanning micrographs of some samples with different raw materials. The shape and the size of the crystals can be determined from the figures 1, 2, 3 and 4.
Fig. 1 Electron micrograph of zeolite A obtained using Sl' On the obtained zeolite A samples some other physical and chemical measurements, important for their use in detergents, were made. Thus experiments were made with detergent "AS", a product of "OHIS"-Skopje, by formulations with different percentage of substitution of NaTPP by zeolite A. Physical and chemical characteristics of the detergent "AS" with 50% substitution of NaTPP by zeolite A are identical or very similar to those obtained with the formulations of detergent with NaTPP only.
583
Fig. 2 Electron micrograph of zeolite A obtained using 52'
Fig. 3 Electron micrograph of zeolite A obtained using 53'
Fig, 4 Electron micrograph of zeolite A obtained using 54'
584
DISCUSSION The initial gel composition and its preparation are very important factors which determine the quality of the final products. Thus, the initial gels with higher content of Si02 favoured zeolite Pc formation, while those with higher alkalinity favoured the formation of zeolite HS. The optimal crystallization temperature was 90-100 oC. Depending on the starting silicate material, the optimal time of crystallization was 5-6 hours. In the case of the halloysite the time of crystallization was only 4 hours. The optimal composition of the initial reaction mixtures was in the range 2,5-4 Na 20.A1 203.1,5-2 Si02·150-250 H20, where the degree of crystallization between 95-100% was achieved without presence of zeolites Pc and HS. CONCLUSION The method for synthesizing zeolite A that was used in this work appeared to be successful in the case of all examined raw silicates. The best results were obtained with opaliz.ed tuff and halloysite, with a degree of crystallinity of and without presence of other zeolites; Previoabout 95%, particle size l-5~m us chemical and thermal treatment at higher temperature was not applied to the starting raw materials. In this way in the synthesis of zeolite A a successful use was made of natural silicates without application of water glass as a starting material. From the obtained results it can be concluded that zeolite A produced from Macedonian silicate raw materials is suitable for use in detergent formulations. This research showed that the obtained zeolite A does not deteriorate the quality of the deterQent and does not damage the fabrics. REFERENCES 1 R.M. Milton, Patent USA, 2882243 (1959). 2 P.A. Howell, Patent USA, 3 114 603 (1963). 3 D.W. Breck, Zeolite Molecular Sieves, John Wi.1ey and Sons, New York, 1974, pp. 313-320. 4 R.Aiel10, R.Sersale, C. Colella, Molecular Sieve Zeolites, Adv. Chern. Ser. 101, Amer. Chern. Soc., Washington D.C. 1971, p. 51. 5 T. Ueda, K. Sato, Y. Nakamara, Patent USA, 3 535 075 (1970). 6 T. Ueda, K. Sato, Y. Nakamara, Patent USA, 3 674 426 (1972). 7 o.s. MdivniSvi1i, L. 1. Uridija, Patent SSSR, 500183 (1976). 8 S. Sari~, S. Flis, A. Zajc, B. Drzaj, Symposium of technology of manufacture of petrol and gas, Zadar,1980. 9 A. lajc, Thesis, University of Ljubljana, 1979.
SYNTHESIS OF ZEOLITE A FROM SILICATE RAW MATERIALS AND ITS APPLICATION IN FORMULATIONS OF DETERGENTS S. DONEVSKA 1, J. TANEVSKI 1 and N. DASKALOVA 2 l"Alkaloid", Research Institute, 91000 Skopje, Yugoslavia 2"OHIS", OOZT "Bi1jana", 91000 Skopje, Yugoslavia
ABSTRACT The conditions for synthesis of zeolite A with natural silicate raw materials of Macedonian origin were examined. The optimal compositions of the starting reaction mixtures as well as synthesis conditions were determined. With this investigation it was concluded that the zeolite A produced from Macedonian silicate raw materials is suitable for use in detergent formulations. INTRODUCTION The method most often used worldwide for the synthesis of zeolite A is the one whereby hydroge1s are obtained by mixing sodium silicate and sodium aluminate (ref. 1). At present a lot of attention has been paid to the natural silicate raw materials as potential sources of cheaper zeolite A production. Many silicates have been tested, among them kaolin clay as the most promising one (ref. 2). The method of synthesis, starting from kaolin, involves its thermal treatment at JOOoC fOr the purpose of transforming it into metakaolin and then its recrystallization into zeolite A under certain conditions (ref. 3). The use of other silicate raw materials (different types of clays and tuffs) invo1v.es many problems because these materials are po1ymineral with different kinds of impurities. The possibil ities of using a natural volcanic glass in different zeolite syntheses were investigated, but the final products did not meet the quality of the comercial ones (ref. 4). Considering the amphoteric characteristic of al1ophane, its use in zeolite A synthesis has been reported in Japan (ref. 5-6). The treatment of diatomite with 10-15% solution of sodium hydroxide has been used in the USSR for zeolite A preparation (ref. 7). Drzaj et al. have developed a method for synthesizing zeolites A and X starting with bentonites from different regions in Yugoslavia (ref. 8-9).
580
CHEMICAL AND MINERALOGICAL PROPERTIES OF THE EXAMINED SILICATE RAW MATERIALS Usually a suitable pretreatment of the raw materials in the synthesis of zeolites has to be undertaken. Therefore the knowledge of the chemical and mineralogical characteristics of the starting raw materials is of great importance. It is well known that in the case of kao1 in clays thermal pretreatment is. tbemost widely used one, while chemical treatment is the most common in the case of bentonite clays (ref. 9). In order to reduce the production expenses as much as possible we examined the possibility of bypassing the chemical treatment and thermal pretreatment of the starting raw materials. Therefore careful preliminary investigations were made of different silicate raw materials from Macedonia, among which the following four from table 1 have proved to be the most promising. TABLE 1 Chemica1 composition of the raw materials Raw material Opalized tuff Kaol inized tuff Pumice tuff Halloysite clay
Symbol 51 52 53 54
5i0 2
A1 203
96,75 1,52 85,00 9,88 69,40 15,84 42,17 29,08
Fe203
CaD
MgO
Na 20
K20
0,78 0,57 1,71 0,44
0,43 0,70 1,40 1,25
0,08 0,10 0,72 0,92
0,10 0,15 1,70 0,38
0,12 4,70 0,65
The raw material Sl contains a high percentage of Si02 mostly in amonphous state and some minerals such as tridimite, cristobalite and smaller quantities of quartz. feldspar and limonite. Koalinized tuff is a polymineral raw material composed mostly of tridimite and kaolinite with small quantities of quartz, limonite and other minerals. The raw materials 51 and 52 are fine grained materials of amorphous nature that are mostly easy to grind. The pumice tuff S3 is si 1icate mtnera1 predomi nantly of amorphous nature. The crystalline phase composed of al-bite, oligoclase, orthoclase and anorthite takes about 20%. The halloysite clay S4 is"a pure clay with v.ery low presence of other minerals. EXPERIMENTAL The influence of the following factors on the quality of zeolite A was studied through systematic inv.estigations: - appropriate actiyation of the starting raw materials, - composition of the initial mixtures, which were analyzed for the content of 5i02• A1 203, Na 20 and H20, - stirring efficiency of the reaction mixtures, - crystallization kinetics.
581
All of the silicate raw materials were activated with granulated sodium hy0C. droxide at 200-400 After this treatment a certain quantity of water and sodium aluminate was added under intensive stirring. This operation was followed by thermal treatment in closed Teflon containers at 1000C. At certain intervals samples were taken out, filtered and washed to neutral reaction. Some experimental results obtained are given in tables 2, 3, 4 and 5. TABLE 2 Initial reaction mixtures for synthesis of zeolite A using raw material Sl Composition in mol/A1 203 Na 20 Si02 H20 5 2 210 4 2 210 3 2 210 2,5 1,5 150 2,5 2 150 2,5 2,5 150 4 2 250 4 2 80 Time of crystallization 5h
Rate of crystal1ization, %
Impurities
95 95 95 95 90 80 95 90
TABLE 3 Initial reaction mixtures using raw material S2 Composition in mol/A1 20 3 Na 20 Si0 2 H20 4 1,5 210 4 1,8 210 4 2 210 2,5 2 210 3 2 210 3 1,8 210 Time of crystallization 6h
Rate of crystal1ization, % 95 95 95 70 90 95
Impurities HS
Pc Pc
TABLE 4 Initial reaction mixtures using raw material S3 Composition in mol/A1 203 Si0 2 Na 20 H 20 5 2 210 4 2 210 3 1,8 210 2,75 2 210 2 2 210 4 1,5 210 4 1,8 210 Time of crystallization 6h
Rate of crystal1i zat ion , %
80 95
Impurities HS
90
70
60
80 95
Pc
HS
582 TABLE 5
Initial reaction mixtures using raw material S4
Composition in mol/A1 203 Na 20 Si02 H20
Rate of crystallization, %
Pretreatment of S4 at 700 0C 2,4 1,6 125 2,8 1,6 140 3,2 1,8 195 Activation of S4 with Na~H only 2 1,7 150 3,5 1,8 150 4 2 200
95 95 95 90 100 95
Time of crystalImpurities lization, h
HS
6 6 6
HS
4 4 4
The figures 1, 2, 3 and 4 represent electron scanning micrographs of some samples with different raw materials. The shape and the size of the crystals can be determined from the figures 1, 2, 3 and 4.
Fig. 1 Electron micrograph of zeolite A obtained using Sl' On the obtained zeolite A samples some other physical and chemical measurements, important for their use in detergents, were made. Thus experiments were made with detergent "AS", a product of "OHIS"-Skopje, by formulations with different percentage of substitution of NaTPP by zeolite A. Physical and chemical characteristics of the detergent "AS" with 50% substitution of NaTPP by zeolite A are identical or very similar to those obtained with the formulations of detergent with NaTPP only.
583
Fig. 2 Electron micrograph of zeolite A obtained using 52'
Fig. 3 Electron micrograph of zeolite A obtained using 53'
Fig, 4 Electron micrograph of zeolite A obtained using 54'
584
DISCUSSION The initial gel composition and its preparation are very important factors which determine the quality of the final products. Thus, the initial gels with higher content of Si02 favoured zeolite Pc formation, while those with higher alkalinity favoured the formation of zeolite HS. The optimal crystallization temperature was 90-100 oC. Depending on the starting silicate material, the optimal time of crystallization was 5-6 hours. In the case of the halloysite the time of crystallization was only 4 hours. The optimal composition of the initial reaction mixtures was in the range 2,5-4 Na 20.A1 203.1,5-2 Si02·150-250 H20, where the degree of crystallization between 95-100% was achieved without presence of zeolites Pc and HS. CONCLUSION The method for synthesizing zeolite A that was used in this work appeared to be successful in the case of all examined raw silicates. The best results were obtained with opaliz.ed tuff and halloysite, with a degree of crystallinity of and without presence of other zeolites; Previoabout 95%, particle size l-5~m us chemical and thermal treatment at higher temperature was not applied to the starting raw materials. In this way in the synthesis of zeolite A a successful use was made of natural silicates without application of water glass as a starting material. From the obtained results it can be concluded that zeolite A produced from Macedonian silicate raw materials is suitable for use in detergent formulations. This research showed that the obtained zeolite A does not deteriorate the quality of the deterQent and does not damage the fabrics. REFERENCES 1 R.M. Milton, Patent USA, 2882243 (1959). 2 P.A. Howell, Patent USA, 3 114 603 (1963). 3 D.W. Breck, Zeolite Molecular Sieves, John Wi.1ey and Sons, New York, 1974, pp. 313-320. 4 R.Aiel10, R.Sersale, C. Colella, Molecular Sieve Zeolites, Adv. Chern. Ser. 101, Amer. Chern. Soc., Washington D.C. 1971, p. 51. 5 T. Ueda, K. Sato, Y. Nakamara, Patent USA, 3 535 075 (1970). 6 T. Ueda, K. Sato, Y. Nakamara, Patent USA, 3 674 426 (1972). 7 o.s. MdivniSvi1i, L. 1. Uridija, Patent SSSR, 500183 (1976). 8 S. Sari~, S. Flis, A. Zajc, B. Drzaj, Symposium of technology of manufacture of petrol and gas, Zadar,1980. 9 A. lajc, Thesis, University of Ljubljana, 1979.