Determination Of Alkali Content In Some Agricultural Waste Product Such As Cocoa Pod Husk, Plantain Peel And Palm Fruit Bunch

Introduction

1.1 Background of the Study

Lubricating grease is produced by dispersing thickening agents in mineral or synthetic oil. Several thickening agents exist but soap-base is the most popular. Several soap bases like sodium, lithium, calcium, aluminum etc. are used in lubricating grease production. Soap comprises of the metallic salts of long chain monocarboxylic acids. Generally, soap making is based on alkaline hydrolysis of fat and oil in a reaction known as saponification, according to the equations (1.1) and (1.2).

C3H5(OOCR)3 + 3NaOH 3NaOOCR + C3H5OH …. (1.1)

(Fat) (Sodium Hydroxide) (Soap) (Glycerol)

OR

C3H5(OOCR)3 + 3KOH 3KOOCR + C3H5OH … (1.2)

(Fat) (Potassium Hydroxide) (Soap) (Glycerol)

These soaps give different properties to the grease and they have different formulations, structure, and characteristics. Other thickening agents include Organoclay, Polymer, Silica etc. All these soaps are formulated from manufactured alkalis. However, there is a prospect of formulating lubricating grease from alkalis derived from the ashes of agricultural waste such as plantain peel, since local soap production has been achieved using these alkalis as reported by Nwoko, (1980) and Onyegbado et. al (2002). According to Adewuji, et al (2008), several agricultural wastes of vegetable origin yield high potash when combusted. These materials include plantain peels, cassava peels, palm bunch, wood, cocoa pod, banana leaves, maize cob, wood, sugar beet waste and many others. When these materials are burnt in air, the resulting ashes contain oxides of potassium and sodium which when dissolved in water yield the corresponding hydroxides (equations 1.3 and 1.4). These agricultural wastes are readily and locally available in abundance.

Na2O + H20 2NaOH …… (1.3)
K2O + H20 2KOH ……. (1.4)

As at present, these local alkalis are not used in grease production since no stoichiometry has been developed for them. The local production of potash from these agricultural wastes has been observed to be a cheaper alternative source of this much needed chemical used in the production of soap and other alkalis based products (Adewuji et al, 2008). The making of soap using vegetable matter has been an age old craft, unfortunately the soaps that were made then, were soft, black, smelly and corrosive to the hands (Umeh-Idika and Maduakor; 2013) However Onyeagbado (2004) has produced solid odourless soap using alkali extracted from plantain peel ash. The ash derived alkali contains varying concentrations of different metals. Since emulsion of Ca, Li and many other metal soaps and their mixtures are used in most lubricating greases and are often called thickener (Thorsten et al., 2002), the soap made from alkali derived from plantain peel ash could be useful as a thickener in lubricating greases and will be more economical than those from inorganic sources. The presence of other metals besides K and Na at higher concentrations limits the foamability of the soaps and Olabanji, et al (2012) suggested that this could be an advantage to use them as grease thickeners since foamability is not a desirable quality in lubricating greases.
Although at present, palm oil and palm kernel oil for local soap production (as source of fat and oil) in Nigeria are readily available, nearly all the alkali for soap making is imported (Onyegbado et al 2002). Edewor (1984) estimated an annual availability of over 30,000 tonnes of KOH derivable from cocoa-pod waste alone, in the country, which more than meet the importation requirements of KOH and NaOH of 26,000 tonnes in 1985 but the knowledge gap in developing the formulation for using this type of alkali has hampered the technical, economic and social benefits derivable from their use. Onifade (1994) asserted that the dumping of cocoa-pod wastes in concentrated heaps on the farms (the usual practice in Nigeria) was adverse to soil fertility and that hogs and other livestock could not completely remove the total wastes available, as fodder. According to (Umeh-Idika and Maduakor, 2013) several agricultural wastes are littered all over the environment and accumulation of these wastes poses a serious health hazard. Apart from being an eyesore, even their proper disposal is a waste of resources which are potential source of raw materials needed in soap making. Therefore, such agricultural wastes could be converted to potash and used for soap making and consequently, lubricating grease production.

1.2 Objective

The general objective of the study is the determination of alkali content in some agricultural waste product such as cocoa pod husk, plantain peel and palm fruit bunch and the alternative transformation of these agricultural wastes into end products such as lubricants and grease derived from pod husk, plantain peel and palm fruit bunch.

1.3 Justification of the study

Studies have been conducted on production of soap using alkalis from ashes of agricultural wastes (Onyeagbado et al, 2004, Onifade, 1994, Olabanji et al, 2012) but there are little or no information on production of lubricant grease from any of these alkalis. It is therefore pertinent to conduct studies on the production of lubricant grease using plantain peel ash as the source of alkali. This will provide the information on the consistency of the grease it can produce and know whether this consistency falls within the acceptable standards. Plantain peel ash was chosen as the source of the bio-alkali because there is sufficient scientific information available from the analysis of its alkali from various sources (Nwoko, 1982, Onyegbado et. al. 2002, and Oluremi et al, 2012). This will enhance straightforward research on its suitability as a good grease thickener, without recourse to auxiliary analysis of the bioalkali extract.