CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Agricultural activity produces large quantities of residues that are often discarded, burnt in the open or left to rot, with consequences for the environment. In Nigeria, crops such as cocoa, plantain and oil palm are processed on a large scale, and the husks, peels and empty fruit bunches that remain are among the most common agro-wastes. These residues are rich in organic matter and in mineral elements, particularly potassium, which remain in the ash when the organic matter is burnt off (Hussein et al., 2026). Converting such wastes into useful products, a process known as waste valorisation, can reduce disposal problems while creating value for farmers, processors and small-scale entrepreneurs.

One long-standing use of plant ash is as a source of alkali. Soap is made by saponification, in which a fat or oil reacts with a strong alkali, usually sodium hydroxide or potassium hydroxide, to give soap and glycerol. Making soap from ash-derived alkali is an old craft in Nigeria and in many other West African countries. Ashes of plantain peels, cassava peels, palm bunch, wood and similar materials are leached with water, and the resulting alkaline extract is used to saponify local oils and fats (Okunola et al., 2019). The product is commonly known as African black soap. Dependence on imported caustic potash has been identified as a cost problem for soap makers in Nigeria, which makes local alkali sources attractive (Okunola et al., 2019).

The alkali in plant ash is mainly in the form of potassium compounds, notably potassium carbonate and potassium hydroxide, together with some sodium compounds. Researchers have studied the production of potassium carbonate from cocoa pod husks (Kone et al., 2020), the use of cocoa husks as a sustainable resource for alkali production (Maliki et al., 2020), the production of potash from green and ripe plantain peels (Kouadio et al., 2025), and the use of potassium hydroxide from plantain peel ash for saponification (Komba et al., 2025). Cocoa pod ash has also been used to make black soap, whose chemical properties, including total fatty matter, free alkali, pH and lather volume, were reported to be comparable with those of other local soaps (Ajongbolo et al., 2020).

The alkali content of an ash is not the same for every material. A recent study that compared alkali extracts from plantain peel, cocoa pod husk and cassava peel found significant differences in ash content, in the pH of the extracts (9.77 to 11.46) and in their molarity (0.01 to 0.80 mol/dm³), and concluded that plantain peel and cocoa pod husk gave the most effective alkali extracts because of their higher potassium and sodium content (Hussein et al., 2026). Differences in material, burning conditions and extraction methods mean that the alkali content of ash from a given agro-waste has to be measured rather than assumed. The usual approach is to prepare an aqueous ash extract and determine its alkalinity by titration with a standard acid, which allows the alkali content to be expressed in terms of an equivalent amount of potassium hydroxide.

This study determines the alkali content of ash obtained from three common agricultural wastes in Nigeria, namely cocoa pod husk, plantain peel and palm fruit bunch, in order to compare them as sources of alkali.

1.2 Statement of the Problem

Agro-wastes such as cocoa pod husk, plantain peel and palm fruit bunch are produced in large quantities and are often disposed of by open burning or dumping, which pollutes the environment and wastes a potentially useful resource. At the same time, soap makers and other small-scale industries need alkali, and commercial alkalis such as sodium hydroxide and imported caustic potash are costly (Okunola et al., 2019). Local producers have long used ash-derived alkali, but they usually do so without knowing how strong it is. Without reliable data on the alkali content of different ashes, it is hard to standardise the amounts used, to compare materials, or to choose the best source.

Existing studies have focused largely on individual materials, such as plantain peel or cocoa pod husk, and on soap properties (Ajongbolo et al., 2020; Hussein et al., 2026; Komba et al., 2025), so comparative data on the alkali content of cocoa pod husk, plantain peel and palm fruit bunch determined under the same conditions remain limited in the literature reviewed. This study addresses that gap by determining the alkali content of the three materials under uniform laboratory conditions.

1.3 Aim and Objectives of the Study

The aim of the study is to determine the alkali content of ash from cocoa pod husk, plantain peel and palm fruit bunch. The specific objectives are to:

1. collect the agricultural waste samples and prepare ash from each by controlled burning;
2. prepare aqueous extracts of the ash and determine their pH;
3. determine the alkali content of each extract by titration with a standard acid;
4. compare the alkali content of the three agricultural wastes; and
5. assess the suitability of the ash extracts as alternative sources of alkali for soap production and other uses.

1.4 Justification of the Study

Growing interest in low-cost and environmentally friendly substitutes for commercial alkalis has focused attention on agricultural residues as raw materials (Hussein et al., 2026). Using waste for alkali reduces disposal problems, lowers dependence on imported chemicals, and supports small businesses such as local soap producers (Okunola et al., 2019). Because the alkali content differs between materials (Hussein et al., 2026), systematic determination is needed to guide the choice of raw material and to allow the amount of alkali used in soap making to be controlled. The results will give producers and researchers a quantitative basis for choosing among the three wastes.

1.5 Scope and Limitations of the Study

The study covers the determination of the alkali content of ash from three agricultural wastes: cocoa pod husk, plantain peel and palm fruit bunch. It involves preparing the ash, extracting the alkali with water and determining the alkali content and pH of the extracts. It does not cover full soap production or the detailed characterisation of the soap, and it does not study the elemental composition of the ash beyond alkali content. The results apply to the samples collected and to the burning and extraction conditions used, and may differ for materials from other sources, varieties or conditions of burning.

1.6 Significance of the Study

The findings will provide quantitative data on the alkali content of three widely available agricultural wastes. Local soap makers can use them to select suitable raw materials and to standardise their recipes. Researchers and students may use the results as a basis for further work on alkali from agro-wastes and on ash-based soap and other products. The study also supports sustainable waste management and the creation of income from waste, in line with the findings of recent work on the valorisation of agricultural residues (Hussein et al., 2026).

1.7 Definition of Terms

Agricultural waste: Residues left over from the production and processing of crops, for example husks, peels and empty fruit bunches.

Ash: The inorganic residue left after plant material is burnt, consisting mainly of metal oxides, carbonates and other mineral salts.

Alkali content: The amount of alkaline substances, such as carbonates and hydroxides of potassium and sodium, present in a sample or extract, usually expressed as an equivalent amount of potassium hydroxide or as molarity.

Saponification: The reaction of a fat or oil with a strong alkali to produce soap and glycerol.

Potash: A potassium-rich alkaline material obtained by leaching plant ash, consisting mainly of potassium carbonate.

Titration: A laboratory method of measuring the concentration of a substance in solution by reacting it with a solution of known concentration.

References

Ajongbolo, K., et al. (2020). Chemical properties of local black soap produced from cocoa pod ash and palm oil waste. International Journal of Trend in Scientific Research and Development, 4(6). https://www.ijtsrd.com/papers/ijtsrd33487.pdf

Hussein, B. T., Nwaedozie, J. M., Namadi, M. M., & Ado, K. (2026). Production and characterization of alkali extracts from plantain peel, cocoa pod husk, and cassava peel ash for industrial applications. FUDMA Journal of Sciences, 10(7), 117–123. https://doi.org/10.33003/fjs-2026-1007-4979

Komba, D. P., Lebbie, S. E., Conteh, D., Turay, I., & Yongai, I. (2025). Potassium hydroxide in plantain peels ash and its uses as a source of saponification. World Journal of Advanced Research and Reviews, 28(3). https://doi.org/10.30574/wjarr.2025.28.3.4221

Kone, K., Akueson, K., & Norval, G. (2020). On the production of potassium carbonate from cocoa pod husks. Recycling.

Kouadio, K. K. A., Soro, L. C., Kossonou, Y. K., & Anin, A. L. (2025). Production of potash from green and ripe plantain peels. Science Journal of Analytical Chemistry, 13(4), 96–103. https://doi.org/10.11648/j.sjac.20251304.13

Maliki, M., Ifijen, I. H., & Omorogbe, S. O. (2020). Cocoa husks: A sustainable resource for alkali production. International Journal of Biological and Chemical Sciences, 14(7), 2652–2658.

Okunola, O. J., Siaka, A. A., & Abdulkareem, O. A. (2019). Optimization of soap production using mango peels ash as alkali source. FUDMA Journal of Sciences, 3(4), 343–351.