Effects of Varied Electrodes on Electrokinetic Remediation (EKR) of Crude Oil-Contaminated Lateritic Soil

Crude oil contamination severely degrades the geotechnical properties of soils, rendering them unsuitable for engineering applications. This study investigates the effects of four electrode materials—carbon, stainless steel, platinum, and titanium—on the efficiency of Electrokinetic Remediation (EKR) of crude oil-contaminated lateritic soil obtained from an oilfield site in Nembe Creek, Bayelsa State, Nigeria. Laboratory EKR experiments were conducted using a direct current supply of 30 V with a voltage gradient of 0.5–2.0 V/cm, employing 0.1 M sodium sulphate as the anolyte and 0.05 M sodium dodecyl sulphate as the catholyte. Geotechnical characterisation, including Atterberg limits, particle size distribution, specific gravity, compaction (BSL, WAS, BSH), unconfined compressive strength (UCS), California Bearing Ratio (CBR), and Total Petroleum Hydrocarbon (TPH) analyses, was conducted on both contaminated and remediated soil samples in accordance with BS 1377 (1990). Results show that platinum electrode achieved the highest TPH removal efficiency of 80.34%, followed by titanium (77.81%), stainless steel (73.03%), and carbon (71.63%). Post-remediation UCS values ranged from 266.6 to 751.5 kN/m², with stainless steel recording the highest strength across all compactive effort levels; however, all values fell short of the 1,720 kN/m² base material threshold stipulated by TRRL (1977) but meeting the requirement for 687–1,373 kN/m² range recommended by Ingles and Metcalf (1972) for sub-base. The highest CBR value of 72% was attained with stainless steel at BSH energy level, meeting sub-base and sub-grade but not base material requirements of the Nigerian General Specifications (2016). Stainless steel electrodes are recommended for practical EKR applications due to their superior geomechanical performance, cost-effectiveness, and availability.