Study process refining oil derived from low-grade cotton seeds

It is shown that the quality of refined cottonseed oil, derived from pre-clarified on modified carbamide clay adsorbents (MCCA-4) of crude oil higher than obtained from conventional crude oil extracted from low-grade cotton seeds.

Cottonseed oil derived from the seeds of III-IV and non-seed varieties, as well as deviations as a result of the technological modes in the step of obtaining, extraction and distillation miscella particularly relate to a range of oil, called «hard refined». These types of oil are characterized by a substantial content of free fatty acids, phospholipids, unsaponifiable lipids and colorants: chlorophyll, gossypol and its derivatives and modified forms or predominant content of coloring substances in the moderate acidity oil.

In recent years, the amount of low grade seeds entering the cotton processing enterprise, was 30–40 % of [1,2]. Therefore, the proportion of hard refined oil with regard to quality seeds and violations of technological regimes increased to 10–20 % of the total volume of recycled cotton unrefined oil [2].

Having accompanying substances of cotton oil limits the use for different purposes and especially for food. Therefore, began to take measures for their ennobling and refining the most available methods, including alkaline treatment oil and miscella [3,4].

Intense dark color cottonseed oil oxidation products give native gossypol and melanoidin compounds which are formed by self-heating and heat-treated seeds. Furthermore, in the moisture-heat processing cotton at high temperatures myatki formed complex compound and gossypol derivatives of chlorophyll, which also change the color of the crude oil produced.

Complexity cotton refining of oil having a high chroma is to use alkali solutions with a high concentration (more than 250 g / l) in a large excess (200 %), which entails a significant loss of valuable oil, alkali and others [5].

One way of solving this problem is considered preliminary clarification of the crude oils derived from low-grade and non-cotton seeds, using an effective adsorbent. Analysis of literary sources for refining cotton oil showed that it is necessary to improve the existing technology of refining oil derived from low-grade and non-cotton seeds, as there are a number of disadvantages: large amounts of wasted materials, significant consumption of alkali, etc., a low yield of the final product that negative impact on the technical and economic indicators of oil companies.

Subjects and methods of the research: Modified carbamide clay adsorbent (MCCA) was obtained by impregnating clay adsorbent with 30 % carbamide solution and drying it at 95–100⁰ C to a residual moisture content of 7–8 %. Ready MCCA stored in a closed desiccator.

Experiments on the preliminary clarification of crude dark oil cottonseed oil using MCCA and refining of low-concentration alkaline solution are carried out in a laboratory setting, the circuit shown in Fig.1.

Fig. 1. Laboratory unit for pre-lightening dark cotton crude oil and their alkali refining:

1-tripod; 2-reactor; 3-stove oil bath; 4-body bath; 5-cover; 6-agitator; 7-oil tank; 8-engine; 9-thermometer; 10-LATR; 11-rheostat

Acid number was determined by potentiometric oil and indicating method using as an indicator of a 1 % alcoholic solution of thymolphthalein [6]:

-       The color of cottonseed oil was determined by Lovibond colorimeter [7];

-       Gossypol quantification was performed by HPLC [8].

Experimental: we, on the basis of local clays using the method of impregnation and activation obtained MCCA that effectively clarified oil to their stage of purification FUSO-tank and filter presses. [9]

According to the existing technology of vegetable oil to alkali refining crude oil is filtered in the frame filter presses, the resulting precipitate is sent to FUSO-tank and further, into the fryer. However, microparticles MCCA may remain in the oil, directed by alkali refining. Therefore, it is necessary to study their impact on the efficiency of the alkali refining oils. This end, the comparative oil refining, obtained by a conventional method and the preliminary clarification using thermally activated MCCA-4 [10]. Experiments were conducted at a temperature of 80–85⁰ Cand stirring the oil at 100 rev / min. The results are shown in Table 1.

Indicators of raw, pre-bleached and refined oil derived from low-grade and non-standard mixture of cotton seed (50:50)

From Table 1 it is evident that bleaching prior crude oil obtained from low-grade and non-cotton seeds using MCCA 5 % by weight of the oil positively impact on the quality and yield of the refined oil.

Using high performance liquid chromatography (HPLC), samples were investigated previously clarified crude MCCA and oil derived from low grade and mixtures thereof with non-seeded. The results are shown in Fig.1 and 2.

Fig. 1. Chromatogram analysis of gossypol content in the crude oil obtained from the low-grade cotton seed

Fig. 2. Chromatogram analysis of gossypol content in the pre MCCA clarified oil derived from the seeds of low grade cotton

Discussion and results: From Figures 1 and 2 shows that by pre-clarification of crude oil produced from low-grade cotton seed using MCCA-4 in an amount of 5 % by weight of the oil content of gossypol is reduced by about 20–25 % which is favorable for the subsequent processes of refining and bleaching oil.

Consequently the use of prior clarification crude oil obtained from low-grade cotton seed using MCCA enhances the effectiveness of subsequent processes of refining and bleaching of oil.

This method of pre-lightening crude oil derived from low-grade cotton seed on MCCA was tested in the forepress workshop of OJSC «Koson oil-extraction».

The crude oil in the OJSC «Koson oil-extraction» was obtained from the low-grade (III and IV grades) cotton seeds. Modified carbamide clay adsorbent prepared by impregnating a clay adsorbent, 30 % aqueous carbamide solution, followed by drying it at a temperature of 95–100⁰ C to residual moisture of the adsorbent 7–8 %.

The resulting modified adsorbent was introduced into the crude oil after the press (in the initial portion conveying oil in FUSO-tank) in an amount of 2–6 % of the total weight of the oil (according to the color of the crude oil). In order to select the required number of MCCA to lighten the crude oil derived from low-grade (III and IV grades) and non-cotton seeds, experiments were performed in a production environment, according to the current technological requirements.

Preliminary clarification oils beneficial effect on the subsequent process of refining. Given that increasing the number MCCA reduces yield a clarified oil amount added was 4.3 % of the total weight of the crude oil.

Conclusion: Thus, conducted in OJSC «Koson oil-extraction» pilot production study showed that the proposed technology previous clarification crude oil derived from low-grade and non-cotton seeds using MCCA gives positive results in reducing chroma crude oil, its acid Numbers content of unsaponifiables, moisture and volatile matter, etc. Therefore, this technology can be recommended for use in the processing of low-grade and non-cotton seeds.

References:

1.                 Sergeev A. P. Improving the efficiency of the refining of vegetable oils. Tashkent, 2002.

2.                 Ilyasov A. N. Studies on the development of efficient technologies in oil industry. Tashkent, 2006.

3.                 Sergeev A. G. Cotton oil refining. -Moscow 1959.

4.                 Sergeev A.G, Sterlin B. Y. Refining of cottonseed oil by emulsification / / Oil Industry. — Moscow, 1953.

5.                 Kopeykovsky V. M. Danilguk S. I. Garbuzova G. I. Technology production of vegetable oils: Light and Food Industry, 1982.

6.                 Manual method of research, technical-chemical control and accounting of production in oil industry. V. P. Rzhehin, A. G. Sergeev 1964.

7.                 Cottonseed oil. Method of measurement of color. -Tashkent. State Standard 1994.

8.                 Heftman E. Хроматография. Практическое приложение метода.

9.                 Akhmedov A. N. Improving the technology of complex refining of oils derived from low-grade cotton seeds. Tashkent, 2012.

10.             Akhmedov A. N. Suvanova F. U. Use of adsorbents for purification of modified cottonseed oil. Karshi 2011.