UDC615.32:338.314

Zaytsev,O.І., Boyko,M.M., Nefedova,L.V.

National Pharmaceutical University

determination of the rational QUANTITY OF EXTRAGENT during production of extracts FROM plant raw materials

The article sets the criteria of techno-economic substantiation of the extraction process, introduces the prediction technique of optimal quantity of extragent during the process of plant raw materials extraction and breakeven conditions of the extraction process found.

Key words:extraction, optimization, quantity of extragent, techno-economic indicator.

problem definition

The selection of extragent quantity is one of the most important questions appearing during the extraction process. Engaging a great extragent quantity allows gettinghigher level of extraction of theextractive substance, but at the same time it requiresmorefunds for alreadyused expensiveextragent.The selection of extragent quantity,whichis suppliedforextraction, may bedetermined onlyon the grounds of techno-economic substantiation.Numerousfactors of economical efficiency forprocess conduction are known. But these factorsappear to be cumbersome in determination and that is whywe think that profitability index of the process is the mostapplicable one:effectiveness of circulating fund element usage in order toincreaseprofitability of manufacture. The extragent quantity (or funds spend on consumable extragent quantity) is a circulating fund element during the conduction of extractionwithpermanent quantity ofplant raw materials (orper 1kg),which may be changedin the course of extraction. Profitability of manufacture is determined by the funds of theacquired extract, and which also may berepresented by the sumof extractive substances valuein theextragent and by extragent value inthe extract.

Consequently, techno-economic indicator of the effectiveness of the extraction process conductionis profitability of the processthatis determined by the followingformula:

,(1)

Which must have the greatest significancefor the requirements of the process conduction(quantity of extragent, whichis being consumed) determined.

In case of conduction of extraction process, the quantity of substances obtained is determined by material balance anddynamic dependencies of the process[6].

analysis of the latest studiesandpublications

Extraction of medical plant raw materials hasbeen in a wide usein manufacturing of drugs withnatural compounds, as a centralphase of biologically active substances extraction with furtherconversion into extractsanddrug products[2,5,7]. Extraction processfromsolid raw materialsdepends on general laws ofmass-transfer, features ofplant tissue andphysicochemical affinity of dissolvent withthe substanceextracted [1,3,6].

formulation OF PARTS OF THE COMMON PRoBLEM, WHICH HAVE NOT BEEN resolved BEFORE

While examiningliterature references on the subject ofoptimisation of extragent quantityduringmanufacture ofplant raw materials extracts,the authorsdid not manage to findthe consideration ofthisproblem regarding profitability of the extraction process.

formulation OF the objectives of the article

The purpose of this work was todetermine thecriteria oftechno-economic substantiation in order todefine the optimal quantity of extragent, whichis suppliedduring extraction ofplant raw materials; to offer theprediction technique ofengaging the optimum quantity of extragentwhileextractingplant raw materials; to findbreakeven conditions of the extraction process.

summary of basic MATERIAL of the study

The material balance on theextractive substance is as follows:

(2)

whereisthe quantity of the initial plant raw materials calculated as solid substance,kg;

is the quantity ofthe initial extragentandextragent in theextract, kg;

is the quantity of extragent in the extractthatis detainedby the solid substance, kg;

is therelative concentration of extractive substances respectively in initial plant raw materials andin raffinate per 1 kgof solid substance;

is the relative concentration of extractive substances per 1 kg of theextract.

Certainly the extraction process is conducted untilthe state of equilibrium is reached. That is why the concentration ofextractive substance in the extractand inthe raffinate (oil meal) is figured outin accordance withconsideration for the theory ofmass transfer under equilibrium conditions,the connection between which is described by the substance distribution ratio (m) betweenphases (solidandliquid) as follows:

(3)

The distribution ratio,as a rule, has afixed value (orclose toa fixed value), that can be foundexperimentally.

In addition, such feature of solid substance as extract retentionin its structure as a process product, influences technical-and-economic index.Eachstructure of solid substance corresponds to its ownfixed value of retention coefficient (), thatcan be foundinadditionalstudies with thefollowing calculation:

(4)

Equations (2)-(4) let usconductcalculations of the extraction process determiningoutgoing flows andconcentrations. It enables us,with consideration of extragent price ()andextractive substance (),to explicate the equation (1) to such a form:

(5)

whereis an extractive substances price-extragent price ratio;

is a coefficient of extragent surplus, that is to say an initial extragent quantity-plant substance quantity ratio.

In accordance with the mathematical analysis law, whensearching for maximum value ,the equation (5) should bedifferentiated and thenequalled tonil, determining .As a result of differentiation a cumbersome quadratic equation regarding was obtained, the solutionof whichwas considered to be.

In addition, a breakeven point [4] is a very interestingtechnical-and-economic index, regarding conduction of the extraction process:it is the profit fromthe realization of received extractthatequalsfunds spent on theexpended extragent. In other words,what should the correlation extragent/raw materials look like, so as the coefficient from the formula (5) equals one? After some mathematicaltransformations the correlation extragent/raw materials in the breakeven pointof conduction of the extraction process can be found as follows:

(6)

Owing to the analytical models obtained,the influence offeatures of the system (the initial quantity ofextractive substance inraw materials, equilibrium separation coefficient of extractive substance betweensolidandfluidphases, coefficient of extract retention that is performed bysolidsubstance, andextractive substance price-extragent price ratio)on theoptimalcorrelationextragent/raw materials was studied. The results of the studiesare represented in Tables1–4.

Table 1

influence ofequilibrium SEPARATION COEFFICIENT OF EXTRACTIVE SUBSTANCE on theOPTIMAL CORRELATION EXTRAGENT/RAW MATERIALS

Persistent features of the system / Size m / / /


/ 0.3 / 8.1 / 3.3 / 2.4
0.7 / 6.4 / 2.9 / 2.2
1.0 / 6.0 / 2.8 / 2.2
1.4 / 5.7 / 2.7 / 2.1
1.8 / 5.5 / 2.6 / 2.1
2.0 / 5.5 / 2.6 / 2.1
3.0 / 5.3 / 2.6 / 2.1

As it may be seen from Table 1, when the value of the separation coefficient(m) varies in the range from 0.3 to 3.0,the ratio of the optimal extragent surplus andthe coefficientof correlation extragent/raw materials in the breakeven point varies from 2.1 to 2.4.

Table 2

influene of theCOEFFICIENT OF EXTRACT RETENTIONBY SOLID SUBSTANCEonOPTIMAL CORRELATION EXTRAGENT/RAW MATERIALS

Persistent features of the system / Size Ku / / /

.0
/ 1.2 / 3.4 / 1.5 / 2.3
1.5 / 4.3 / 1.9 / 2.2
1.8 / 5.3 / 2.4 / 2.2
2.0 / 6.0 / 2.8 / 2.2
2.3 / 7.0 / 3.3 / 2.1
2.7 / 8.6 / 4.1 / 2.1
3.0 / 9.9 / 4.7 / 2.1
4.0 / 15.2 / 7.3 / 2.1

As it may be seen from Table 2, when the value of the coefficient of retention of the extract (Ku) variesin the range from 1.2 to 4.0,the ratio of the optimal extragent surplusandthe coefficient of correlation extragent/raw materials in the breakeven point varies from 2.1 to 2.3.

Table 3

influence of the quantityofEXTRACTIVE SUBSTANCEin initialplant raw materials onOPTIMAL CORRELATION EXTRAGENT/RAW MATERIALS

Persistent features of the system / Size / / /

.0
/ 0.04 / 10.5 / 5.0 / 2.1
0.07 / 6.9 / 3.2 / 2.1
0.10 / 6.0 / 2.7 / 2.2
0.12 / 5.7 / 2.6 / 2.2
0.14 / 5.4 / 2.5 / 2.2
0.18 / 5.2 / 2.4 / 2.2
0.20 / 5.1 / 2.3 / 2.1
0.25 / 5.0 / 2.3 / 2.2

As it may be seen from Table 3, when the value ofrelative concentration of extractive substancesin initialplant raw materials (Xf) variesin the range from 0.04 to0.25,the ratio of the optimal extragent surplus andthe coefficient of correlation extragent/raw materials in the breakeven point variesfrom 2.1 to 2.2.

Table 4

influence of extractive substance price/extragent priceratioon OPTIMAL CORRELATION EXTRAGENT/RAW MATERIALS

Persistent features of the system / SizeN / / /

.0
/ 50 / 8.5 / 4.0 / 2.1
80 / 6.5 / 3.0 / 2.1
100 / 6.0 / 2.7 / 2.2
130 / 5.5 / 2.5 / 2.2
170 / 5.3 / 2.4 / 2.2
200 / 5.1 / 2.3 / 2.2
300 / 4.9 / 2.2 / 2.2
400 / 4.8 / 2.2 / 2.2
50,000 / 4.4 / 2.1 / 2.2

As it may be seen from Table 4, when the valueofextractive substance price-extragent price ratio (N) variesin the rangefrom 50 to50,000,the ratio of the optimal extragent surplus and the coefficient of correlation extragent/raw materials in the breakeven point varies from 2.1 to 2.2.

From theresults obtained, an interesting dependence may be seen, and it is confined in the fact thatthe correlationchangesin quite anarrow rangeandcan be anacceptable fixed value of 2.2±0.2.

Thispeculiarity enables us tofind anoptimalcorrelationextragent/raw materials with the help of an easiermethod,such as to find a correlation extragent/raw materials without breakeven, using easierequation (6) and multiply it by 2.2 at first.

Analysing the equation (6) and applyingphysical content of the extraction process, the formulashould bemore thannilor:

(7)

In other words, breakeven of the extraction process will be attained,whenextractive substance price/extragent price ratiowill be higher thanthat of thecoefficient of extract retention by the solid substancetothe initialconcentration ofextractive substanceinplant raw materials.

CONCLUSIONS andperspectives of further searches

  1. The criteria of techno-economic substantiation, whereby the optimal quantity of extragent that is supplied during the extraction of plant raw materials can be specified, has been determined;
  2. The prediction technique of engaging optimal extragent quantity during the process of plant raw material extraction has been found;
  3. Optimal breakeven conditions of the extraction process have been obtained.

REFERENCE LIST

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3.Ponomarev,V.D. Extraction of drug raw materials / Ponomarev, V.D. –Moscow: Meditsina, 1976. – 202 p.

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