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Preparation of modified carbonic adsorbent for purification of cottonseed oil
Section 8. Food processing industry
Salihanova Dilnoza Saidakbarovna, Ph. D., senior scientist of the laboratory\ "Colloid Chemistry" doctoral institute of General and Inorganic Chemistry Institute of the Academy of Science Republic of Uzbekistan.
E-mail: [email protected] Pardaev Gulomnazar Eshbaevich, deputy chairman of Association of Food Industry enterprises of the Republic of Uzbekistan E-mail: [email protected] Eshmetov Izzat Dosimbatovich, senior staff scientist laboratory "Colloid Chemistry" doctoral institute of General and Inorganic Chemistry Institute of the Academy of Science Republic of Uzbekistan of Academy of Science Republic of Uzbekistan.
E-mail: [email protected] Agzamkhodjaev Anvarxodja Ataxodjaevich, doctor of chemical scientist, professor, international academy of ecology and life protection sciences (IAELPS), manager laboratory "Colloid Chemistry" institute of General and Inorganic Chemistry Institute of the Academy of Science Republic of Uzbekistan.
E-mail: [email protected]
Preparation of modified carbonic adsorbent for purification of cottonseed oil
Abstract: The novel carbonic adsorbents have been obtained by thermic pyrolysis of initial and preliminarily treated the Angren brown coal by Na2C03 solution and their physico and adsorption properties have been studied. It was determined that effective carbonic adsorbents with the greatest porosity and size of pores were obtained at pyrolysis temperature 500°С. It was shown that cottonseed oil bleach (clean) with carbonic adsorbent treated by thermal at 500°С without Na2C03 addition, the oil acid number reduced from 0,55 to 0,23 mg КОН/g, coloration from 15,2 to 10,7red figures at 0,02 dark blue ones. Moreover, use of initial adsorbent thermo treated at 500°С without Na2C03 of addition carbonic adsorbent, the oil acid number reduced from 0,55 to 0,11 mg КОН/g, coloration from 15,2 to 7,5 red figures at 0,00 dark blue ones, and at that, the largest yield of bleached oil reached up to 97,4%.
Keywords: adsorbent, coal, carbonic adsorbent, pyrolysis, modification, cottonseed oil, coloration, acid number.
Introduction. Last decade in Uzbekistan the tendency to production of refined vegetable oil, in particularly cottonseed oil with low coloration and long-term preservation them have been increased. In world practice the adsorption refining (bleach) of vegetable oil have already had wide spread occurrence, i. e. obtained at this product does not only meet consumer demand, but also it allows to remove oxidation product out of the oils, including free radical and other carcinogenic impurities.
Producers compel to collect not only optimal regime of oil bleach as well as to use more effective adsorbents in the processes.
Comparative analysis have shown that some adsorbents possess high activity, the best hydrodynamic behaviors during the filtration, low oil absorption, low moisture content (up to 10%) which provide long-term period work of filter and high sorption ability [1].
Activated carbons, i.e carbonic adsorbents adsorb various organic substances out of oil based on their
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Section 8. Food processing industry
specificity properties. They are used widely in fat-and-oil industry as adsorbents.
Carbonic adsorbents are highly porous carbonic materials obtained by high-temperature processing without air admission (pyrolysis) of different wood species, turf, and coal got from vegetable and animal objects (sawdust, wood chippings and etc.), rich in carburets [2].
However, thermal pyrolysis of coal is not always available to obtain highly porous and selective carbonic adsorbents that in the first place combined with component composition of raw material and regimes of high-temperature processing.
Adsorptive capacity of activated carbonic adsorbents depends from increase of surface contact due to porosity. Specific surface of the active carbonic adsorbents makes usually 400-900 m 2/g, and their adsorption properties to a considerable extent depend from structure of coal, porosity value and division them on sizes. Coal structure renders appreciable influence on adsorption speed and determines form of isotherm and numbers of adsorbed molecules with different sizes. Active carbonic adsorbents depending on dominant size pores symbolically can be divided into three groups: macro porous, finely porous, and mixed porous. Macropores’ amounts are appreciated in a range10-4 mm, and their specific surface is
0.5-2 m-2/g. Radius of transition pores is in a range 1.610-7-2-10-7 mm, and its specific surface is 20-70 m-2/g, mean radius of pores makes less 1.6-10-7mm, but its specific surface is higher 100 m-2/g. Macropores and transition pores play role as transport link and adsorptive capacity generally defined by microporous structure of active adsorbents [3].
The active carbonic adsorbents with various structure (porosity), different adsorption properties and function are obtained depending on type of raw material, regime of pyrolysis, activators and activation method. Vital importance for their preparation is selection of raw material, mode it preparation, pyrolysis temperature, method of carbonized raw activation: gas-vapor, activation by pyrolysis, carbonization with additive of chemical active inorganic substances and mixed activation including those or others ones [2].
In consideration of importance of chemisorptions processes at bleach of cottonseed we selected one from the bottom of the method of modified carbonic adsorbents from local coals.
Material and method. The Angren coals grade of 2BSC (brown, slab, coarse) and for check experiment grade of BAC (birch activated carbon) (made in Russia) were the object of our studies. The refined cottonseed
oil with acid number 0.55 mg КОН/g and 15.2 red and 2.1 dark blue figures at 35 yellow one were used for bleach process. Coloration of the oil was defined at Lovibonde color measure [4], and acid number by titration [5].
Results and discussion. It is necessary to note that for adsorption refining of cottonseed, used adsorbents must have highly porosity, selectivity and hydrophobic property (wetting angle of adsorbent by water “a” should been more 90°). The Angren coal is hydrophile and water-wet due to the presence of carboxyl and hydroxyl groups in it. Therefore, the coal is not required to use for cottonseed oil bleach. It is necessary to attach coal hydrophobic properties, for example, by thermic pyrolysis. During the pyrolysis process, carboxyl and hydroxyl groups have decomposed that lead to hydro-phobization its organic mass. In this study we presented researches on influence of pyrolysis temperature on the physico-chemical properties of the Angren coal.
Sifted and ground Angren coal with size 2-5 mm was subjected to thermic pyrolysis without air admission at temperature 300, 500 and 700 °C on the laboratory facility. The experiments were conducted in the following way: air-dried sample with weight 50 g was filled in the reactor representing cylindricity capacity made of heat-resistant material which is blind-ended-work piece. Subsequent the reactor with sample was heated until predetermined temperature without air permission. Porosity determination on acetone was conducted conformity according to techniques [6]. Preliminary dried until reaching a constant mass active coal was filled in weighted graduated cylinder with volume 100 ml (diameter 25 mm). The filling process was performanced up to 100 ml mark with portion at 15-20 g, which densified by shaking cylinder after filling each portion. The cylinder with coal weighted at accuracy up to 0,01 g and filled by acetone till constant level one above coal. After 30 min. abundance of acetone was poured off. Then the cylinder with coal was weighted.
The coal porosity on acetone х (in volume.%) calculated by formula [6]:
.. (GL- GCJ-100 (Glc- GCJ
«X — —
Pv p
Where Gcc. - weight of cylinder with coal before soaking by acetone, g;
Gcc. — weight of cylinder with coal after soaking by acetone, g;
p — density of acetone at temperature of experience, g/cm3;
V = 100 cm3 — volume of active coal.
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Preparation of modified carbonic adsorbent for purification of cottonseed oil
In order to compare check as well as active coal grade mic pyrolysis at 300, 500, 700 оС. The results summa-of BAC with its certain porosity was defined after ther- rized in Table 1.
Table 1. - Effect of activation temperature on porosity of active carbonic adsorbents
№ Coal grade Temperature, °C Porosity on acetone,%
1 2 BSC (The Angren coal) initial 33,1
2 Activated coal grade of BAC x) (check) initial 36,1
3 2 BSC (The Angren coal) 300 44,4
4 Activated coal grade of BAC x) (check) 300 46,7
5 2 BSC (The Angren coal) 500 48,4
6 Activated coal grade of BAC x) (check) 500 49,4
7 2 BSC (The Angren coal) 700 52,6
8 Activated coal grade of BAC x) (check) 700 55,7
From given data (Table 1) shown that porosity on acetone of the Angren coal grade of 2 BSC makes 44,4% at 300°C, 48,4% at 500 °C, and 52,6% 700°C. It can be seen that pyrolysis of the Angren coal is enough at 500 °C without air permission. Moreover, the coal adsorbent obtained based on thermic pyrolysis (500 °C) of the Angren coal has porosity at level active coal grade of BAC. However, necessary to note
that when the thermic pyrolysis of the Angren coal at 700 °C, gas removed into atmosphere, i. e. they too pollute environmental.
In order to define the most effective carbonic adsorbent, comparative bleach of cottonseed oil was carried out with use them in quantity 2% with the mass of oil. The results cottonseed oil bleach presented in Table 2.
Table2. - Indexes of bleached (refined) cottosedd oil obtained by carbonic adsorbents
№ Name of coal Pyrolysis temperature, °C Yield bleached oil,% Acid number of oil, mg КОН/g Coloration of oil at 35 yellow in 13,5 cm cuvette layer
red figures dark blue figures
Initial data of refined cottonseed oil 0.55 15.2 2.1
1 2 BSC (The Angren coal) initial 92.5 0.41 13.3 1.9
2 Activated coal grade of BAC x) (check) initial 93.9 0.35 12.5 1.7
3 2 BSC (The Angren coal) 300 94.4 0.31 12.6 1.4
4 Activated coal grade of BAC x) (check) 300 95.1 0.30 11.0 1.0
5 2 BSC (The Angren coal) 500 96.6 0.23 10.7 0.2
6 Activated coal grade of BAC x) (check) 500 96.9 0.22 9.5 0
Table 2 presentes that adsorbents obtained by thermic pyrolysis of the Angren coal for bleaching power do not make well-known coal grade of BAC (check). Then the most optimal results reached on thermal activated (500 °C) Angren coal grade of 2 BSC.
Known processes [2] of carbonization with addition of chemical active inorganic substances allow to get modified carbonic adsorbents, directed action. In the bleached oil content residues ofgossypol, chlorophyll, and their derivatives as well as products of oxidation, decomposition and others. In order to remove the residues out ofoil, must use rational adsorbents with high chemisorptions ability.
That’s why, modification of carbonic adsorbents to refine vegetable oils is necessary stages at them production.
To increase specific surface with adsorption activity and chemisorptions ability of active coals in raw material subjected to pyrolysis, activating additives such as ZnCl2, CaCl2, K2CO3, Na2CO3, K2SO4 and others usually introduce duration bleach process. In case secondary treatment conducted them by rare gas or steam to remove volatile and resin substances.
Based on the above cited additives we selected K2SO4 Na2CO3 CaCl2 for modification carbonic adsorbents obtained from the Angren coal grade of 2 BSC.
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Section 8. Food processing industry
The coal treated with 10% solution selected additives rolysis. The pyrolysis conducted at 500 °C. The results of for 2 hours. After 2 hours the coal dried in oven at 105°С pyrolysis are given in Table 3.
until full dry. Then the dried coal fed in reactor for py-
Table 3. - Change porosity and radiuses of carbonic adsorbents’ micropores depending on type of modified additives
№ Coal grade Type of additives for coal Porosity on acetone,% micropores radius, mm
1. 2 BSC (The Angren coal) K2SO4 52.8 1,4110-7
2. 2 BSC (The Angren coal) Na2C°3 55.9 1,5510-7
3. 2 BSC (The Angren coal) M2 48.8 1,23-10-7
4. 2 BSC (The Angren coal) Without additives (check) 48,4 1,18-10-7
As seen from Table 3, the pyrolysis of coal, treated by additives allows to increase porosity and size of carbonic adsorbents micropores. The optimal results were reached when the use Na2CO3, which could be explained partial release of CO2 in the processes of coal treatment and pyrolysis.
When use of the modified carbonic adsorbents, bleach of refined cottonseed oil was carried out, results summarized in Table 4.
Table 4 presents the results of cottonseed oil bleach with use coal adsorbent modified by Na2CO3 where results are better than when use carbonic adsorbent obtained conventional pyrolysis method.
Table 4. - Comparative results of cottonseed oil bleach obtained by conventional and offered methods
№ Type of cottonseed oil Yeild of bleached oil,% Acid number, mg КОН/g Coloration of oil at 35 yellow in 13,5 cm cuvette layer
red figures dark blue figures
1. Initial oil - 0.55 15.2 2.1
2. Bleached oil with use 2 BSC (check) 96.6 0.23 10.7 0.02
3. Bleached oil with use of carbonic adsorbent modified Na2CO3 97.4 0.11 7,5 0.0
It was determined that when bleach of cottonseed oil with use offered adsorbent observed decreasing acid number until 0,11mg КОН/g, and coloration — 8.3 red figure is absent. Moreover, when use carbonic adsorbent obtained conventional pyrolysis method, acid number decreased until 0,23 mg КОН/g, and coloration up to 10.7 red figure is 0.02 dark blue.
Conclusion. Thus, the novel carbonic adsorbents obtained by thermic pyrolysis of initial and preliminarily treated the Angren brown coal by Na2CО3 solution and their physico and adsorption properties have been studied. It was determined that the effective carbonic
adsorbents with largest values of porosity and micropore were obtained at pyrolysis temperature 500°С. It was shown that cottonseed oil bleach with use of initial thermo treated at 500 оС without Na2C03 addition of carbonic adsorbent, the oil acid number reduced from 0,55 to 0,23 mg КОН/g, coloration from 15,2 to 10,7red figures at 0,02 dark blue ones. Moreover, use of initial adsorbent thermo treated at 500°С without Na2C03, of addition carbonic adsorbent, the oil acid number reduced from 0,55 to 0,11 mg КОН/g, coloration from 15,2 to 7,5 red figures at 0,00 dark blue ones, and at that, the largest yield of bleached oil reached up to 97,4%.
References:
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2. Taran N. G. Adsorbents and ionites in food industry, Moscow, Published House “Food industry", 1983, 3. P. 417.
3. Salihanova D. S. Effect of pyrolysis temperature on porosity of carbonic adsorbents obtained from the Angren coals, Uzbek Chemical Journal, 2015, 3. P. 20-25.
4. RST Uz 624-94. Cottonseed oil. Method measurement of coloration, Tashkent: Gosstandart. 1994. P. 7.
5. GOST 05-446. Method determination of acid number, Tashkent, 2013. P. 3.
6. Kolishkin D. A., Mihaylova K. K. Active coal, Reference book, Leningrad, Published House “Chemistry”, 1969, P. 284.
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