Optimal Preservation of Oil-Containing Sands Using Zeolite: A Physical and Chemical Analysis

Abstract

Several approaches have been proposed to improve oil-contaminated soil remediation. However, the role of zeolite, a safe, clean, economical, and environmentally friendly material, in removing crude oil (CO) from contaminated soils remains unclear. This paper addresses this gap with respect to CO-contaminated sands (COCS) and aims to assess zeolite’s capability as a geo-environmentally adaptable material to mitigate the adverse impacts of oil pollution on sandy soils. The cyclic simple shear behavior and chemical analysis of coarse and fine-grain silicate sands are investigated and compared in response to CO contamination. Clean sand specimens were prepared with 60% relative density, whereas COCS specimens were prepared using a 6% crude oil contamination level. This study examines the impact of CO contamination and the use of an environmentally friendly stabilizer through simple shear tests (under static and cyclic conditions), consolidation experiments, and Fourier-transform infrared spectroscopy (FTIR). Optimal pollution adsorption was achieved by adding 6% zeolite to fine-grained sand, resulting in a 31.61% increase in the shear modulus index and an 18.70% increase in the friction angle index. Using 8% zeolite improved the shear modulus and friction angle indexes in coarse-grained sand by 21.69% and 11.83%, respectively. FTIR results showed a 45% and 59% enhancement in coarse and fine sands, respectively, indicating the positive role of zeolite in stabilizing COCS through pollutant adsorption. The superior performance of zeolite in fine-grained compared with coarse-grained sand is justified by its higher specific surface area and porous surface.