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The Effect Of Particle Size On The Extraction Of Oil From Groundnut

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The aim of this research project was to determine the effect of particle size on the extraction of oil from groundnut.

The successful extraction of the project require the following steps

i.            Collection of the seeds

ii.          Preparation of the seeds

iii.        Particle size reduction

iv.         Extraction process etc.

The groundnut seed for this project research was purchased from a local market in Enugu Metropolis. Also, the method used in this project research is solvent extraction method. The solvent used  in  the exraction is n-hexane, this n –hexane was used because of its hight yield of oil recovery after extraction. The extraction was carried was carried out using 280g of size reduced groundnut with 600ml of n-hexane. Different particle sizes were used in this experiment using sizes screens of 10mm, 20mm, 40mm, 60mm, and 80mm respectively. The yield with hexane as solvent used in 10mm, 20mm, 40mm, 60mm and 80 mm are 41.3% 25%, 33.93%, 44% and 55.5% respectively. From this experiment, it now shows that the smaller the particle size, the greater the yield of oil recovered. And from experiment the smallest particle size is 80mm and is gives the highest yield of oil of about 55.5%. in conclusion, the particle size plays important role in leaching operation. Because they either increase the rate of leaching or reduce the rate of leaching. Particle size increase the rate of leaching if the groundnut seeds are property crushed. Furthermore, the smaller the size the greater is the interfacial are between the solvent and solid. And this will help to increase the rate of diffusion of oil from the particle.















Title page                                                                        i

Letter of transmittal                                                       ii

Certification/approval                                                    iii

Dedication                                                                       iv

Acknowledgment                                                            v

Abstract                                                                          vi

Table of content                                                              viii

Definition of terms nomenclature                                  xi



1.0      Introduction                                                  1

1.1      Background of the study                                        1

1.2      Statement of the problem                                       3

1.3      Purpose/aims/objectives of the study                   4

1.4      Scope and limitation of the study                          5

1.5      Method research                                                     8

1.6      Significance of the study                                        8



2.0     Literature review                                           10

2.1      Extraction                                                               10

2.2      Factors influencing the rate of extraction             12

2.3      Mass transfer in leaching operations                     15

2.4      Equipment for leaching                                          18

2.5      Leaching of coarse solids                                        20

2.6      Counter current washing of solids                         22

2.7      Extraction of oil from vegetable nuts and seeds    25

2.8      Classification of oils                                                27



3.0     Materials and methods                                   31

3.1      Extraction procedure                                              32

3.2      Characterization of oil                                            33

3.3      Acid value                                                               33

3.4      Moisture content.                                                   34

3.5      Saponification value                                               35

3.6      Density                                                                    36



4.0     Results/analysis                                            38


5.0      Discussion                                                              50

References                                                              44









Solvent Extraction: is the separation of the constituents of a liquid solution by contact with another insoluble liquid.

Feed: This can be defined as the solution which is to be extracted.

Raffinate: This is the residual liquid from which has been removed.

Solvent: It is the liquid with which the feed is contacted.

Extract: The Solvent rich product of the operation is called the extract

Distillation: Is a method of separating the components of solution which depends upon the distribution of eh substances between a gas and a liquid phase, applied to case where all components are present in both phases.        





Groundnut is an annual herbaceous plant growing from 30 to 50cm tall. A groundnut seed is composed of two cotyledons, testa, hypocotyls and epicotyl. All except the testa are considered to be part of the embryo.

The cotyledon is the major storage tissue for proteins and 20 to 22% oil.

Groundnut seed undergo epigeal germination in which case the cotyledons or seed leaves are carried above the soil surface. A planted groundnut seed mature after few months.

According to history, groundnuts were domesticated in prehistoric times in peru where the wild ancestors were still found.

Archaeologists have thus far dated the oldest specimen to about 7,600 years before the present Dill Lay and Tom, (2007) now updated it.

The plant was later spread worldwide by European traders. Cultivation in the English colonies of North Americans was popularized by African Americans, who bought the Kikongo word “Goober”. In South American, the groundnut is thought to have first grown in Argentina or Bolivia where the wildest strains grow today.

Groundnut is best planed in February to March is some states usually the rain forest and in many or early June in the Northern States, this variation is as a result of the difference in climate condition equipments.

The climate requirement for the groundnut is about the same as that for after the plant is well established. In general combination of high temperature and low precipitation are unfavorable, groundnut seed produced under high temperature condition tend to be low in oil and oil quality.

Botanical name of groundnut is “Arachis hypogaea”. Hypogea means in botanical world, “Under the earth”. Groundnut is also known by other name though local such as peanuts, and pignuts,

The stalk at the base of the ovary called the pedicel, elongates rapidly and turns downward to burry the fruits several inches in the ground where they complete their development. The entire plants including roots, is removed from the soil during harvesting. 



The statement of the problem in the research project of the effects of particle size on extraction of oil from groundnut, in addition to this, different sample size should be used when carrying out the practical aspect of it in order to know the effect in particle size.

In any process which involves reaction of solvent and solutes processing parameters which affects the optimum yield of the products and if these parameters are not known, checked, controlled or regulated the product end point night result into low product quality and quality or damaged product.

In the process of extraction of oil from groundnut, such parameters should be carefully considered because of the nutritious value of groundnut since any processing parameter neglected may destroy the nutrient content of the groundnut oil.   



The purpose of this research project is simply for the acquisition of the knowledge based on the effect of particle size on the extraction of oil from groundnut. The main purpose of study is to find out the effects processing parameters could have, on the yield of oil from groundnut seed and how there parameters could be regulated in order to ascertain high yield of oil from groundnuts seeds. 



1.4.1      The scope of this research project covers all the areas and processes involved during the extraction of oil from groundnut ranging from picking of the groundnut seeds, drying the seed, size reducing the particle, size separation to dissolving the separated particles in a solvent n-hexane and finally separating the mixture through the process of distillation on which the temperature reading was taken.

The study focused on the optimum yield of oil from groundnut seed putting into consideration and care the effect of processing parameters like temperature, particle size, contact time, solvent solute ratio, on the yield of oil. The study also focused on showing the nutritional value of groundnut oil and its various uses and the need to avoid destruction of those nutrients during the oil extractions.


1.4.2               FOR THE LIMITATION: In a study of this nature one would like to accumulate data from many areas. But in view of length of time allowed for this research such as wide range sample study was almost externally difficult. We then concentrated this practical work in Enugu metropolis. The reason for choosing Enugu metropolis was because of time factor allowed and upon particle consideration including the fact that we know almost every where and things about Enugu metropolis.

Besides, there were some problems that stemmed up during the research work in which some were stated below.          

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