Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z(1), 7.8-15.6 g/L), seawater-oil temperature (Z(2), 25-45 degrees C), sorbent dose (Z(3), 1-3 g), and sorbent particle size diameter (Z(4), 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L-9(3(4))) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z(1), Z(3), and Z(4), while the biosorptive capacity is related to Z(1) and Z(3). The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z(1) (7.8 g/L), Z(3) (3 g), and Z(4) (1.18 mm), as well as at Z(1) (15.6 g) and Z(3) (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g(-1). The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Automated summary

This study evaluated the effects of maize cob sorbent on the biosorptive removal efficiency and capacity of crude oil from seawater, and optimized various factors. The results showed that the maize cob sorbent could effectively remove crude oil pollution under suitable conditions, and had the potential to be an inexpensive and effective natural sorbent.