Solid Liquid Extraction

8/9/2019 Solid Liquid Extraction

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Solid-Liquid Extraction


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Introduction

• Defnition: Methods o removing oneconstituent rom a solid by means oa liquid solvent

• !enerally also "no#n as leaching$lixiviation or #ashing

• %idely used #hen thermal ormechanical method is not &ossible


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Introduction

• Solid liquid extraction &rocedures includes – 'ontact a&&ro&riate solvent to transer the

soluble constituent into solvent

–Se&aration and #ashing o solution rom theresidual solid

• Exam&les: – Extraction o sugar rom sugar beets

– Extraction o oil rom oil bearing seeds

– Extraction o coconut mil" rom coconut

– Extraction o oil rom soy bean (a"es


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'om&arison )et#een LLEand SLE

• *igure +: Liquid-Liquid Extraction

• *igure ,: Solid Liquid Extraction

Source: htt&:..###guntde.do#nload.extraction/english&d

http://www.gunt.de/download/extraction_english.pdfhttp://www.gunt.de/download/extraction_english.pdf


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Equi&ments used orextraction

• Se&arator *unnel

• Soxhlet Extractor

*igure 0: *igure 1:


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• )ollman Extractor

• 2otocel Extractor


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'345I4636S '3645E2'622E45LE7'8I4!

• 5he solid is not moved &hysically rom stage to stage

• 5he liquids is being moved rom stage to stage

*igure:9: 'ountercurrent leaching &rocess

; &hase < the liquid &hase =rom stage 4 to stage +>

L &hase < the liquid carried #ith the solid =rom stage + tostage 4>

Exhausted solids leave Stage 4

'oncentrated solution over(o# rom Stage +


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'345I4636S '3645E2'622E45LE7'8I4!

• Solution retained by entering solid$ x a

• Solution retained by leaving solid$ x b

• Fresh solvent entering the system$ y b

• Concentrated solution leaving the system$ y a

Equilibrium 2elationshi&• Equilibrium is attained #hen the solute is com&letely dissolved

and the concentration o the solution so ormed is uniorm

• 5he concentration o the liquid retained by the solid leavingany stage is the same as that o the liquid over(o# rom thesame stage

• 5he equilibrium relationshi& is sim&ly x b= y.


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3&erating line

• 6se Mc'abe 5hiele Method i the o&eratingline is straight

• In leaching$ the o&erating line is al#ays

straight• 5he equilibrium line is on 19oline


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Exam&le:

3il is to be extracted rom meal by means o ben?eneusing a continuous countercurrent extractor 5he unit isto treat +$@@@ "g o meal =based on com&letely

exhausted solid> &er hour 5he untreated meal contains1@@ "g o oil and is contaminated #ith ,9"g oben?ene 5he resh solvent mixture contains +@"g o oiland A99 "g o ben?ene 5he exhausted solids are tocontain A@"g o unextracted oil Ex&eriments carried

out under conditions identical #ith those o the&roBected battery sho# that the solution retainedde&ends on the concentration o the solution$ as sho#nin the ollo#ing table


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Concentration, kgoil/kg

solution

Solutionretained,

kg/kg solid@ @9

@+ @9@9@, @9+9@0 @90@1 @99@9 @9C+@A @99

@C @A,

*ind:=a> the concentration o thestrong solution$ or extract=b> the concentration o the

solution adhering to the

extractedsolids=c> the mass o solution

leaving #ith the extractedmeal=d> the mass o extract

=e> the number o stagesrequired7ll quantities are given onan hourly basis


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Solution:

Let x and y be the mass ractions o oil in the under(o# and

over(o# solutions 7t the solvent inlet$

Determine the amount and com&osition o the solution in thes&ent

solids by trial I x b= 0.1$ the solution retained$ rom 5able$

is @9@9 "g."g 5hen


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Solution:

*rom 5able $the solutionretained is @9@C "g."g:

)en?ene in the under(o# at Lb

is 9@C - A@ < 11C "g.h7t the solid inlet$


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Solution

e> Determine the inlet and exit concentrations or the frststage and locate the o&erating line or the remainingstages

Since x+ < ya< @A@$ solution retained is @99 "g."g solid


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5he &oints xn $ xnF+ $xa $ ya and xb$ yb defne a slightlycurved o&erating line

*our ideal stages are required

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Solid Liquid Extraction