Selective adsorption of 3-monochloropropane-1,2-diol esters and glycidyl esters from palm oil using zeolite and coconut shell activated carbon

Abstract

Palm oil is a major edible oil, yet its refining process leads to the formation of hazardous contaminants, particularly 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE), which occur at higher concentrations than in other vegetable oils. This study explores an adsorption-based purification approach using a binary mixture of coconut shell–derived activated carbon and natural mordenite zeolite. The adsorbents exhibited distinct bulk densities (0.45 and 0.658 g/cm³, respectively) and were applied at 3 wt% in batch experiments conducted at 45 °C with varied mixing ratios (1:1, 2:1, and 1:2). Kinetic analysis indicated that adsorption followed a pseudo-second-order model, suggesting chemisorption as the dominant mechanism. The maximum adsorption capacities reached 0.552 mg/g for 3-MCPDE and 0.578 mg/g for GE. The highest efficiency was obtained with a 1:1 ratio under simultaneous mixing, reducing 3-MCPDE and GE concentrations by 94.8 % (0.75 ppm) and 94.4 % (0.69 ppm), respectively. Statistical analysis confirmed that adsorption time and mixing mechanism significantly affected removal efficiency (p < 0.05). Overall, the combined use of activated carbon and mordenite demonstrated synergistic performance in targeting both polar and non-polar contaminants, providing a cost-effective and scalable strategy for safer palm oil refining and improved compliance with food safety standards.