Use of modified and petroleum -impregnated bentonite mulch as an eco-friendly stabilizer of wind erodible sands

Abstract

This study aimed to develop a method for the management of petroleum pollutants released into the environment using modified bentonite and to evaluate the use of petroleum-impregnated modified bentonite, as an eco-friendly and resistant mulch to stabilize mobile sands exposed to wind erosion. Bentonite was modified using hexa-decyl-tri-methyl-ammonium bromide to increase its capacity for petroleum adsorption. The resistivity to breakdown of the produced mulch was determined against wind, runoff, and by drainage water caused by simulated rainfall. Results showed that the basal spacing of the modified bentonite increased 162% compared to unmodified bentonite and it was able to adsorb petroleum, 5 times its base weight. The produced mulch was resistant against wind flows up to 16.7 m s⁻¹ with no soil loss during 5 min, while the untreated sandy soil started to move at a threshold speed of 10.3 m s⁻¹ (with a soil loss rate of 53 g m⁻² s⁻¹) and the tray of soil was fully eroded after 135 s. Analysis of the drainage waters which passed through the mulch showed that mulch 2 (ratio 5:1, sandy soil: modified clay + unmodified clay (1:1) mixed by petroleum) retained more polycyclic aromatic hydrocarbons compounds, compared to mulches 1 (ratio of 5:1 sandy soil: unmodified bentonite mixed with petroleum) and 3 (ratio 5:1:0.5, sandy soil: unmodified clay: modified clay mixed by petroleum). Analysis of the runoff water samples also showed that PAHs retention in mulch 2 is significantly higher than the amounts retained by mulches 1 and 3.