Vegetable oils contain impurities such as free fatty acids, phospholipids, and pigments that require removal through refining to improve its quality and usability. In Nigeria, traditional methods are mostly applied as a result of non-availability of required technology. Also, industrial refining methods often rely on imported chemical reagents, which increase production costs and limit local processing capacity. This review explores procedures, benefits and limitations of both traditional and industrial methods of vegetable oils refining. Also, the potential of locally sourced reagents, such as agricultural waste, as viable alternatives in the chemical and physical refining of vegetable oils are discussed. This will encourage circular economy and promote many of United Nations Sustainable Development Goals (UN SDGs), by using renewable materials in separation processes and adding values to the agricultural wastes. Emphasis is placed on the probable effectiveness, economic advantages, and environmental impact of using indigenous materials such as plant-based precipitants, agricultural waste-based alkali solutions and natural adsorbents for vegetable oils refining. Process optimization would help in providing the best condition at each stage of the refining operation and as well alternative routes based on different refining agents.

This study investigated the optimization of crude palm kernel oil (CPKO) deacidification using cocoa pod husk as a sustainable alternative to conventional chemical reagents. Response Surface Methodology (RSM) was employed to evaluate the effects of reaction time, temperature, and adsorbent dosage on free fatty acid (FFA) reduction and physicochemical properties. A central composite design with 20 runs assessed reaction time (16.59–33.41 min), temperature (56.59–73.41°C), and dosage (0.159–1.841% w/w). Results showed FFA reduction from initial values to as low as 0.66% (approximately 88% removal efficiency). Multiple response optimization revealed significant effects across all studied parameters. The quadratic model for FFA was highly significant (F = 35.96, p < 0.0001), with reaction time and adsorbent dosage showing the most prominent effects. Similarly, phospholipid content was significantly reduced (F = 60.07, p < 0.0001), demonstrating the dual functionality of cocoa pod husk. Optimal conditions identified were 25 minutes – reaction time, 65°C – temperature, and 1.0% w/w – dosage of deacidifying agent, with excellent deacidification (1.25% FFA) and oil quality preservation. Cocoa pod husk proved effective and eco-friendly for CPKO deacidification, supporting sustainable oil refining and agricultural waste valorisation.

Paraffin wax deposition is the major flow assurance issue in the oil industry. When the fluid temperature drops below the wax appearance temperature (WAT) due to the temperature differential between the cold areas and the crude oil, paraffin wax forms on the pipeline walls. Wax deposition can have very detrimental effects because it can narrow the internal diameters of pipelines and flowlines, which, if left unchecked, eventually clog these areas and force an activity to stop. However, overcoming the problems at this stage may become very expensive. This study examines the factors influencing paraffin wax deposition and discusses various methods for mitigating wax deposition on inner pipelines walls. It focuses on mechanical, thermal, chemical, bioremediation, and hybrid techniques. The benefits and limitations of each wax mitigation technique are assessed, along with the latest developments in modelling-based paraffin wax deposition mitigation. Although chemical techniques are preferable for treating deep-water wells due to their relatively inexpensiveness, simplicity, and no disruption to production, synthetic chemical inhibitors pose environmental hazardous. However, the advantages of organic chemical additives and bioremediation technique over commercially available synthetic chemical inhibitors are rigorously assessed in this work with regard to environmental benefits, sustainability advantages and improved process safety. This review also identifies the gaps in mitigation of paraffin wax deposition.